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<h3>Table of Contents</h3>
<ul class="link-list" role="directory">
<li><a href="#class-Hash-label-Common+Uses">Common Uses</a>
<li><a href="#class-Hash-label-Hash+Keys">Hash Keys</a>
</ul>
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<h3>Parent</h3>
<p class="link"><a href="Object.html">Object</a>
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<h3>Included Modules</h3>
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<li><a class="include" href="Enumerable.html">Enumerable</a>
</ul>
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<!-- Method Quickref -->
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<h3>Methods</h3>
<ul class="link-list" role="directory">
<li ><a href="#method-c-5B-5D">::[]</a>
<li ><a href="#method-c-new">::new</a>
<li ><a href="#method-c-ruby2_keywords_hash">::ruby2_keywords_hash</a>
<li ><a href="#method-c-ruby2_keywords_hash-3F">::ruby2_keywords_hash?</a>
<li ><a href="#method-c-try_convert">::try_convert</a>
<li ><a href="#method-i-3C">#<</a>
<li ><a href="#method-i-3C-3D">#<=</a>
<li ><a href="#method-i-3D-3D">#==</a>
<li ><a href="#method-i-3E">#></a>
<li ><a href="#method-i-3E-3D">#>=</a>
<li ><a href="#method-i-5B-5D">#[]</a>
<li ><a href="#method-i-5B-5D-3D">#[]=</a>
<li ><a href="#method-i-any-3F">#any?</a>
<li ><a href="#method-i-assoc">#assoc</a>
<li ><a href="#method-i-clear">#clear</a>
<li ><a href="#method-i-compact">#compact</a>
<li ><a href="#method-i-compact-21">#compact!</a>
<li ><a href="#method-i-compare_by_identity">#compare_by_identity</a>
<li ><a href="#method-i-compare_by_identity-3F">#compare_by_identity?</a>
<li ><a href="#method-i-deconstruct_keys">#deconstruct_keys</a>
<li ><a href="#method-i-default">#default</a>
<li ><a href="#method-i-default-3D">#default=</a>
<li ><a href="#method-i-default_proc">#default_proc</a>
<li ><a href="#method-i-default_proc-3D">#default_proc=</a>
<li ><a href="#method-i-delete">#delete</a>
<li ><a href="#method-i-delete_if">#delete_if</a>
<li ><a href="#method-i-dig">#dig</a>
<li ><a href="#method-i-each">#each</a>
<li ><a href="#method-i-each_key">#each_key</a>
<li ><a href="#method-i-each_pair">#each_pair</a>
<li ><a href="#method-i-each_value">#each_value</a>
<li ><a href="#method-i-empty-3F">#empty?</a>
<li ><a href="#method-i-eql-3F">#eql?</a>
<li ><a href="#method-i-fetch">#fetch</a>
<li ><a href="#method-i-fetch_values">#fetch_values</a>
<li ><a href="#method-i-filter">#filter</a>
<li ><a href="#method-i-filter-21">#filter!</a>
<li ><a href="#method-i-flatten">#flatten</a>
<li ><a href="#method-i-has_key-3F">#has_key?</a>
<li ><a href="#method-i-has_value-3F">#has_value?</a>
<li ><a href="#method-i-hash">#hash</a>
<li ><a href="#method-i-include-3F">#include?</a>
<li ><a href="#method-i-initialize_copy">#initialize_copy</a>
<li ><a href="#method-i-inspect">#inspect</a>
<li ><a href="#method-i-invert">#invert</a>
<li ><a href="#method-i-keep_if">#keep_if</a>
<li ><a href="#method-i-key">#key</a>
<li ><a href="#method-i-key-3F">#key?</a>
<li ><a href="#method-i-keys">#keys</a>
<li ><a href="#method-i-length">#length</a>
<li ><a href="#method-i-member-3F">#member?</a>
<li ><a href="#method-i-merge">#merge</a>
<li ><a href="#method-i-merge-21">#merge!</a>
<li ><a href="#method-i-rassoc">#rassoc</a>
<li ><a href="#method-i-rehash">#rehash</a>
<li ><a href="#method-i-reject">#reject</a>
<li ><a href="#method-i-reject-21">#reject!</a>
<li ><a href="#method-i-replace">#replace</a>
<li ><a href="#method-i-select">#select</a>
<li ><a href="#method-i-select-21">#select!</a>
<li ><a href="#method-i-shift">#shift</a>
<li ><a href="#method-i-size">#size</a>
<li ><a href="#method-i-slice">#slice</a>
<li ><a href="#method-i-store">#store</a>
<li ><a href="#method-i-to_a">#to_a</a>
<li ><a href="#method-i-to_h">#to_h</a>
<li ><a href="#method-i-to_hash">#to_hash</a>
<li ><a href="#method-i-to_proc">#to_proc</a>
<li ><a href="#method-i-to_s">#to_s</a>
<li ><a href="#method-i-transform_keys">#transform_keys</a>
<li ><a href="#method-i-transform_keys-21">#transform_keys!</a>
<li ><a href="#method-i-transform_values">#transform_values</a>
<li ><a href="#method-i-transform_values-21">#transform_values!</a>
<li ><a href="#method-i-update">#update</a>
<li ><a href="#method-i-value-3F">#value?</a>
<li ><a href="#method-i-values">#values</a>
<li ><a href="#method-i-values_at">#values_at</a>
</ul>
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<main role="main" aria-labelledby="class-Hash">
<h1 id="class-Hash" class="class">
class Hash
</h1>
<section class="description">
<p>A <a href="Hash.html"><code>Hash</code></a> is a dictionary-like collection of unique keys and their values. Also called associative arrays, they are similar to Arrays, but where an <a href="Array.html"><code>Array</code></a> uses integers as its index, a <a href="Hash.html"><code>Hash</code></a> allows you to use any object type.</p>
<p>Hashes enumerate their values in the order that the corresponding keys were inserted.</p>
<p>A <a href="Hash.html"><code>Hash</code></a> can be easily created by using its implicit form:</p>
<pre class="ruby"><span class="ruby-identifier">grades</span> = { <span class="ruby-string">"Jane Doe"</span> <span class="ruby-operator">=></span> <span class="ruby-value">10</span>, <span class="ruby-string">"Jim Doe"</span> <span class="ruby-operator">=></span> <span class="ruby-value">6</span> }
</pre>
<p>Hashes allow an alternate syntax for keys that are symbols. Instead of</p>
<pre class="ruby"><span class="ruby-identifier">options</span> = { <span class="ruby-value">:font_size</span> <span class="ruby-operator">=></span> <span class="ruby-value">10</span>, <span class="ruby-value">:font_family</span> <span class="ruby-operator">=></span> <span class="ruby-string">"Arial"</span> }
</pre>
<p>You could write it as:</p>
<pre class="ruby"><span class="ruby-identifier">options</span> = { <span class="ruby-value">font_size:</span> <span class="ruby-value">10</span>, <span class="ruby-value">font_family:</span> <span class="ruby-string">"Arial"</span> }
</pre>
<p>Each named key is a symbol you can access in hash:</p>
<pre class="ruby"><span class="ruby-identifier">options</span>[<span class="ruby-value">:font_size</span>] <span class="ruby-comment"># => 10</span>
</pre>
<p>A <a href="Hash.html"><code>Hash</code></a> can also be created through its <a href="Hash.html#method-c-new"><code>::new</code></a> method:</p>
<pre class="ruby"><span class="ruby-identifier">grades</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">grades</span>[<span class="ruby-string">"Dorothy Doe"</span>] = <span class="ruby-value">9</span>
</pre>
<p>Hashes have a <em>default value</em> that is returned when accessing keys that do not exist in the hash. If no default is set <code>nil</code> is used. You can set the default value by sending it as an argument to <a href="Hash.html#method-c-new"><code>Hash.new</code></a>:</p>
<pre class="ruby"><span class="ruby-identifier">grades</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span>(<span class="ruby-value">0</span>)
</pre>
<p>Or by using the <a href="Hash.html#method-i-default-3D"><code>default=</code></a> method:</p>
<pre class="ruby"><span class="ruby-identifier">grades</span> = {<span class="ruby-string">"Timmy Doe"</span> <span class="ruby-operator">=></span> <span class="ruby-value">8</span>}
<span class="ruby-identifier">grades</span>.<span class="ruby-identifier">default</span> = <span class="ruby-value">0</span>
</pre>
<p>Accessing a value in a <a href="Hash.html"><code>Hash</code></a> requires using its key:</p>
<pre class="ruby"><span class="ruby-identifier">puts</span> <span class="ruby-identifier">grades</span>[<span class="ruby-string">"Jane Doe"</span>] <span class="ruby-comment"># => 0</span>
</pre>
<h3 id="class-Hash-label-Common+Uses">Common Uses<span><a href="#class-Hash-label-Common+Uses">¶</a> <a href="#top">↑</a></span></h3>
<p>Hashes are an easy way to represent data structures, such as</p>
<pre class="ruby"><span class="ruby-identifier">books</span> = {}
<span class="ruby-identifier">books</span>[<span class="ruby-value">:matz</span>] = <span class="ruby-string">"The Ruby Programming Language"</span>
<span class="ruby-identifier">books</span>[<span class="ruby-value">:black</span>] = <span class="ruby-string">"The Well-Grounded Rubyist"</span>
</pre>
<p>Hashes are also commonly used as a way to have named parameters in functions. Note that no brackets are used below. If a hash is the last argument on a method call, no braces are needed, thus creating a really clean interface:</p>
<pre class="ruby"><span class="ruby-constant">Person</span>.<span class="ruby-identifier">create</span>(<span class="ruby-value">name:</span> <span class="ruby-string">"John Doe"</span>, <span class="ruby-value">age:</span> <span class="ruby-value">27</span>)
<span class="ruby-keyword">def</span> <span class="ruby-keyword">self</span>.<span class="ruby-identifier ruby-title">create</span>(<span class="ruby-identifier">params</span>)
<span class="ruby-ivar">@name</span> = <span class="ruby-identifier">params</span>[<span class="ruby-value">:name</span>]
<span class="ruby-ivar">@age</span> = <span class="ruby-identifier">params</span>[<span class="ruby-value">:age</span>]
<span class="ruby-keyword">end</span>
</pre>
<h3 id="class-Hash-label-Hash+Keys"><a href="Hash.html"><code>Hash</code></a> Keys<span><a href="#class-Hash-label-Hash+Keys">¶</a> <a href="#top">↑</a></span></h3>
<p>Two objects refer to the same hash key when their <code>hash</code> value is identical and the two objects are <code>eql?</code> to each other.</p>
<p>A user-defined class may be used as a hash key if the <code>hash</code> and <code>eql?</code> methods are overridden to provide meaningful behavior. By default, separate instances refer to separate hash keys.</p>
<p>A typical implementation of <code>hash</code> is based on the object's data while <code>eql?</code> is usually aliased to the overridden <code>==</code> method:</p>
<pre class="ruby"><span class="ruby-keyword">class</span> <span class="ruby-constant">Book</span>
<span class="ruby-identifier">attr_reader</span> <span class="ruby-value">:author</span>, <span class="ruby-value">:title</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">initialize</span>(<span class="ruby-identifier">author</span>, <span class="ruby-identifier">title</span>)
<span class="ruby-ivar">@author</span> = <span class="ruby-identifier">author</span>
<span class="ruby-ivar">@title</span> = <span class="ruby-identifier">title</span>
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">==</span>(<span class="ruby-identifier">other</span>)
<span class="ruby-keyword">self</span>.<span class="ruby-identifier">class</span> <span class="ruby-operator">===</span> <span class="ruby-identifier">other</span> <span class="ruby-keyword">and</span>
<span class="ruby-identifier">other</span>.<span class="ruby-identifier">author</span> <span class="ruby-operator">==</span> <span class="ruby-ivar">@author</span> <span class="ruby-keyword">and</span>
<span class="ruby-identifier">other</span>.<span class="ruby-identifier">title</span> <span class="ruby-operator">==</span> <span class="ruby-ivar">@title</span>
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">alias</span> <span class="ruby-identifier">eql?</span> <span class="ruby-identifier">==</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">hash</span>
<span class="ruby-ivar">@author</span>.<span class="ruby-identifier">hash</span> <span class="ruby-operator">^</span> <span class="ruby-ivar">@title</span>.<span class="ruby-identifier">hash</span> <span class="ruby-comment"># XOR</span>
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">book1</span> = <span class="ruby-constant">Book</span>.<span class="ruby-identifier">new</span> <span class="ruby-string">'matz'</span>, <span class="ruby-string">'Ruby in a Nutshell'</span>
<span class="ruby-identifier">book2</span> = <span class="ruby-constant">Book</span>.<span class="ruby-identifier">new</span> <span class="ruby-string">'matz'</span>, <span class="ruby-string">'Ruby in a Nutshell'</span>
<span class="ruby-identifier">reviews</span> = {}
<span class="ruby-identifier">reviews</span>[<span class="ruby-identifier">book1</span>] = <span class="ruby-string">'Great reference!'</span>
<span class="ruby-identifier">reviews</span>[<span class="ruby-identifier">book2</span>] = <span class="ruby-string">'Nice and compact!'</span>
<span class="ruby-identifier">reviews</span>.<span class="ruby-identifier">length</span> <span class="ruby-comment">#=> 1</span>
</pre>
<p>See also <a href="Object.html#method-i-hash"><code>Object#hash</code></a> and <a href="Object.html#method-i-eql-3F"><code>Object#eql?</code></a></p>
</section>
<section id="5Buntitled-5D" class="documentation-section">
<section id="public-class-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Class Methods</h3>
</header>
<div id="method-c-5B-5D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
Hash[ key, value, ... ] → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
Hash[ [ [key, value], ... ] ] → new_hash
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
Hash[ object ] → new_hash
</span>
</div>
<div class="method-description">
<p>Creates a new hash populated with the given objects.</p>
<p>Similar to the literal <code>{ <em>key</em> => <em>value</em>, ... }</code>. In the first form, keys and values occur in pairs, so there must be an even number of arguments.</p>
<p>The second and third form take a single argument which is either an array of key-value pairs or an object convertible to a hash.</p>
<pre class="ruby"><span class="ruby-constant">Hash</span>[<span class="ruby-string">"a"</span>, <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span>, <span class="ruby-value">200</span>] <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-constant">Hash</span>[ [ [<span class="ruby-string">"a"</span>, <span class="ruby-value">100</span>], [<span class="ruby-string">"b"</span>, <span class="ruby-value">200</span>] ] ] <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-constant">Hash</span>[<span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>] <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
</pre>
<div class="method-source-code" id="5B-5D-source">
<pre>static VALUE
rb_hash_s_create(int argc, VALUE *argv, VALUE klass)
{
VALUE hash, tmp;
if (argc == 1) {
tmp = rb_hash_s_try_convert(Qnil, argv[0]);
if (!NIL_P(tmp)) {
hash = hash_alloc(klass);
if (RHASH_AR_TABLE_P(tmp)) {
ar_copy(hash, tmp);
}
else {
RHASH_ST_TABLE_SET(hash, st_copy(RHASH_ST_TABLE(tmp)));
}
return hash;
}
tmp = rb_check_array_type(argv[0]);
if (!NIL_P(tmp)) {
long i;
hash = hash_alloc(klass);
for (i = 0; i < RARRAY_LEN(tmp); ++i) {
VALUE e = RARRAY_AREF(tmp, i);
VALUE v = rb_check_array_type(e);
VALUE key, val = Qnil;
if (NIL_P(v)) {
rb_raise(rb_eArgError, "wrong element type %s at %ld (expected array)",
rb_builtin_class_name(e), i);
}
switch (RARRAY_LEN(v)) {
default:
rb_raise(rb_eArgError, "invalid number of elements (%ld for 1..2)",
RARRAY_LEN(v));
case 2:
val = RARRAY_AREF(v, 1);
case 1:
key = RARRAY_AREF(v, 0);
rb_hash_aset(hash, key, val);
}
}
return hash;
}
}
if (argc % 2 != 0) {
rb_raise(rb_eArgError, "odd number of arguments for Hash");
}
hash = hash_alloc(klass);
rb_hash_bulk_insert(argc, argv, hash);
hash_verify(hash);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-c-new" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
new → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
new(obj) → new_hash
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
new {|hash, key| block } → new_hash
</span>
</div>
<div class="method-description">
<p>Returns a new, empty hash. If this hash is subsequently accessed by a key that doesn't correspond to a hash entry, the value returned depends on the style of <code>new</code> used to create the hash. In the first form, the access returns <code>nil</code>. If <em>obj</em> is specified, this single object will be used for all <em>default values</em>. If a block is specified, it will be called with the hash object and the key, and should return the default value. It is the block's responsibility to store the value in the hash if required.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span>(<span class="ruby-string">"Go Fish"</span>)
<span class="ruby-identifier">h</span>[<span class="ruby-string">"a"</span>] = <span class="ruby-value">100</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"b"</span>] = <span class="ruby-value">200</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"a"</span>] <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>] <span class="ruby-comment">#=> "Go Fish"</span>
<span class="ruby-comment"># The following alters the single default object</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>].<span class="ruby-identifier">upcase!</span> <span class="ruby-comment">#=> "GO FISH"</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"d"</span>] <span class="ruby-comment">#=> "GO FISH"</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">keys</span> <span class="ruby-comment">#=> ["a", "b"]</span>
<span class="ruby-comment"># While this creates a new default object each time</span>
<span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">hash</span>, <span class="ruby-identifier">key</span><span class="ruby-operator">|</span> <span class="ruby-identifier">hash</span>[<span class="ruby-identifier">key</span>] = <span class="ruby-node">"Go Fish: #{key}"</span> }
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>] <span class="ruby-comment">#=> "Go Fish: c"</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>].<span class="ruby-identifier">upcase!</span> <span class="ruby-comment">#=> "GO FISH: C"</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"d"</span>] <span class="ruby-comment">#=> "Go Fish: d"</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">keys</span> <span class="ruby-comment">#=> ["c", "d"]</span>
</pre>
<div class="method-source-code" id="new-source">
<pre>static VALUE
rb_hash_initialize(int argc, VALUE *argv, VALUE hash)
{
VALUE ifnone;
rb_hash_modify(hash);
if (rb_block_given_p()) {
rb_check_arity(argc, 0, 0);
ifnone = rb_block_proc();
SET_PROC_DEFAULT(hash, ifnone);
}
else {
rb_check_arity(argc, 0, 1);
ifnone = argc == 0 ? Qnil : argv[0];
RHASH_SET_IFNONE(hash, ifnone);
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-c-ruby2_keywords_hash" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
ruby2_keywords_hash(hash) → hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Duplicates a given hash and adds a ruby2_keywords flag. This method is not for casual use; debugging, researching, and some truly necessary cases like deserialization of arguments.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = {<span class="ruby-value">k:</span> <span class="ruby-value">1</span>}
<span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">ruby2_keywords_hash</span>(<span class="ruby-identifier">h</span>)
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">foo</span>(<span class="ruby-value">k:</span> <span class="ruby-value">42</span>)
<span class="ruby-identifier">k</span>
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">foo</span>(<span class="ruby-operator">*</span>[<span class="ruby-identifier">h</span>]) <span class="ruby-comment">#=> 1 with neither a warning or an error</span>
</pre>
<div class="method-source-code" id="ruby2_keywords_hash-source">
<pre>static VALUE
rb_hash_s_ruby2_keywords_hash(VALUE dummy, VALUE hash)
{
Check_Type(hash, T_HASH);
hash = rb_hash_dup(hash);
RHASH(hash)->basic.flags |= RHASH_PASS_AS_KEYWORDS;
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-c-ruby2_keywords_hash-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
ruby2_keywords_hash?(hash) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Checks if a given hash is flagged by <a href="Module.html#method-i-ruby2_keywords"><code>Module#ruby2_keywords</code></a> (or <a href="Proc.html#method-i-ruby2_keywords"><code>Proc#ruby2_keywords</code></a>). This method is not for casual use; debugging, researching, and some truly necessary cases like serialization of arguments.</p>
<pre class="ruby"><span class="ruby-identifier">ruby2_keywords</span> <span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">foo</span>(<span class="ruby-operator">*</span><span class="ruby-identifier">args</span>)
<span class="ruby-constant">Hash</span>.<span class="ruby-identifier">ruby2_keywords_hash?</span>(<span class="ruby-identifier">args</span>.<span class="ruby-identifier">last</span>)
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">foo</span>(<span class="ruby-value">k:</span> <span class="ruby-value">1</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">foo</span>({<span class="ruby-value">k:</span> <span class="ruby-value">1</span>}) <span class="ruby-comment">#=> false</span>
</pre>
<div class="method-source-code" id="ruby2_keywords_hash-3F-source">
<pre>static VALUE
rb_hash_s_ruby2_keywords_hash_p(VALUE dummy, VALUE hash)
{
Check_Type(hash, T_HASH);
return (RHASH(hash)->basic.flags & RHASH_PASS_AS_KEYWORDS) ? Qtrue : Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-c-try_convert" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
try_convert(obj) → hash or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Try to convert <em>obj</em> into a hash, using <a href="Hash.html#method-i-to_hash"><code>to_hash</code></a> method. Returns converted hash or nil if <em>obj</em> cannot be converted for any reason.</p>
<pre class="ruby"><span class="ruby-constant">Hash</span>.<span class="ruby-identifier">try_convert</span>({<span class="ruby-value">1</span><span class="ruby-operator">=></span><span class="ruby-value">2</span>}) <span class="ruby-comment"># => {1=>2}</span>
<span class="ruby-constant">Hash</span>.<span class="ruby-identifier">try_convert</span>(<span class="ruby-string">"1=>2"</span>) <span class="ruby-comment"># => nil</span>
</pre>
<div class="method-source-code" id="try_convert-source">
<pre>static VALUE
rb_hash_s_try_convert(VALUE dummy, VALUE hash)
{
return rb_check_hash_type(hash);
}</pre>
</div>
</div>
</div>
</section>
<section id="public-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Instance Methods</h3>
</header>
<div id="method-i-3C" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hash < other → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>hash</em> is subset of <em>other</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>}
<span class="ruby-identifier">h2</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>, <span class="ruby-value">c:</span><span class="ruby-value">3</span>}
<span class="ruby-identifier">h1</span> <span class="ruby-operator"><</span> <span class="ruby-identifier">h2</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h2</span> <span class="ruby-operator"><</span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h1</span> <span class="ruby-operator"><</span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> false</span>
</pre>
<div class="method-source-code" id="3C-source">
<pre>static VALUE
rb_hash_lt(VALUE hash, VALUE other)
{
other = to_hash(other);
if (RHASH_SIZE(hash) >= RHASH_SIZE(other)) return Qfalse;
return hash_le(hash, other);
}</pre>
</div>
</div>
</div>
<div id="method-i-3C-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hash <= other → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>hash</em> is subset of <em>other</em> or equals to <em>other</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>}
<span class="ruby-identifier">h2</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>, <span class="ruby-value">c:</span><span class="ruby-value">3</span>}
<span class="ruby-identifier">h1</span> <span class="ruby-operator"><=</span> <span class="ruby-identifier">h2</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h2</span> <span class="ruby-operator"><=</span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h1</span> <span class="ruby-operator"><=</span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> true</span>
</pre>
<div class="method-source-code" id="3C-3D-source">
<pre>static VALUE
rb_hash_le(VALUE hash, VALUE other)
{
other = to_hash(other);
if (RHASH_SIZE(hash) > RHASH_SIZE(other)) return Qfalse;
return hash_le(hash, other);
}</pre>
</div>
</div>
</div>
<div id="method-i-3D-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hsh == other_hash → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Equality—Two hashes are equal if they each contain the same number of keys and if each key-value pair is equal to (according to Object#==) the corresponding elements in the other hash.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">1</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">2</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-value">7</span> <span class="ruby-operator">=></span> <span class="ruby-value">35</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">2</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">1</span> }
<span class="ruby-identifier">h3</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">1</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">2</span>, <span class="ruby-value">7</span> <span class="ruby-operator">=></span> <span class="ruby-value">35</span> }
<span class="ruby-identifier">h4</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">1</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">2</span>, <span class="ruby-string">"f"</span> <span class="ruby-operator">=></span> <span class="ruby-value">35</span> }
<span class="ruby-identifier">h1</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h2</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h2</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h3</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h3</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h4</span> <span class="ruby-comment">#=> false</span>
</pre>
<p>The orders of each hashes are not compared.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">1</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">2</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">2</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">1</span> }
<span class="ruby-identifier">h1</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h2</span> <span class="ruby-comment">#=> true</span>
</pre>
<div class="method-source-code" id="3D-3D-source">
<pre>static VALUE
rb_hash_equal(VALUE hash1, VALUE hash2)
{
return hash_equal(hash1, hash2, FALSE);
}</pre>
</div>
</div>
</div>
<div id="method-i-3E" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hash > other → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>other</em> is subset of <em>hash</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>}
<span class="ruby-identifier">h2</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>, <span class="ruby-value">c:</span><span class="ruby-value">3</span>}
<span class="ruby-identifier">h1</span> <span class="ruby-operator">></span> <span class="ruby-identifier">h2</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h2</span> <span class="ruby-operator">></span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h1</span> <span class="ruby-operator">></span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> false</span>
</pre>
<div class="method-source-code" id="3E-source">
<pre>static VALUE
rb_hash_gt(VALUE hash, VALUE other)
{
other = to_hash(other);
if (RHASH_SIZE(hash) <= RHASH_SIZE(other)) return Qfalse;
return hash_le(other, hash);
}</pre>
</div>
</div>
</div>
<div id="method-i-3E-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hash >= other → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>other</em> is subset of <em>hash</em> or equals to <em>hash</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>}
<span class="ruby-identifier">h2</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>, <span class="ruby-value">c:</span><span class="ruby-value">3</span>}
<span class="ruby-identifier">h1</span> <span class="ruby-operator">>=</span> <span class="ruby-identifier">h2</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h2</span> <span class="ruby-operator">>=</span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h1</span> <span class="ruby-operator">>=</span> <span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> true</span>
</pre>
<div class="method-source-code" id="3E-3D-source">
<pre>static VALUE
rb_hash_ge(VALUE hash, VALUE other)
{
other = to_hash(other);
if (RHASH_SIZE(hash) < RHASH_SIZE(other)) return Qfalse;
return hash_le(other, hash);
}</pre>
</div>
</div>
</div>
<div id="method-i-5B-5D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hsh[key] → value
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Element Reference—Retrieves the <em>value</em> object corresponding to the <em>key</em> object. If not found, returns the default value (see <a href="Hash.html#method-c-new"><code>Hash::new</code></a> for details).</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>[<span class="ruby-string">"a"</span>] <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>] <span class="ruby-comment">#=> nil</span>
</pre>
<div class="method-source-code" id="5B-5D-source">
<pre>VALUE
rb_hash_aref(VALUE hash, VALUE key)
{
st_data_t val;
if (hash_stlike_lookup(hash, key, &val)) {
return (VALUE)val;
}
else {
return rb_hash_default_value(hash, key);
}
}</pre>
</div>
</div>
</div>
<div id="method-i-5B-5D-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hsh[key] = value → value
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<h2 id="method-i-5B-5D-3D-label-Element+Assignment">Element Assignment<span><a href="#method-i-5B-5D-3D-label-Element+Assignment">¶</a> <a href="#top">↑</a></span></h2>
<p>Associates the value given by <code>value</code> with the key given by <code>key</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>[<span class="ruby-string">"a"</span>] = <span class="ruby-value">9</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>] = <span class="ruby-value">4</span>
<span class="ruby-identifier">h</span> <span class="ruby-comment">#=> {"a"=>9, "b"=>200, "c"=>4}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">store</span>(<span class="ruby-string">"d"</span>, <span class="ruby-value">42</span>) <span class="ruby-comment">#=> 42</span>
<span class="ruby-identifier">h</span> <span class="ruby-comment">#=> {"a"=>9, "b"=>200, "c"=>4, "d"=>42}</span>
</pre>
<p><code>key</code> should not have its value changed while it is in use as a key (an <code>unfrozen String</code> passed as a key will be duplicated and frozen).</p>
<pre class="ruby"><span class="ruby-identifier">a</span> = <span class="ruby-string">"a"</span>
<span class="ruby-identifier">b</span> = <span class="ruby-string">"b"</span>.<span class="ruby-identifier">freeze</span>
<span class="ruby-identifier">h</span> = { <span class="ruby-identifier">a</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-identifier">b</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">100</span>).<span class="ruby-identifier">equal?</span> <span class="ruby-identifier">a</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">200</span>).<span class="ruby-identifier">equal?</span> <span class="ruby-identifier">b</span> <span class="ruby-comment">#=> true</span>
</pre>
<div class="method-source-code" id="5B-5D-3D-source">
<pre>VALUE
rb_hash_aset(VALUE hash, VALUE key, VALUE val)
{
int iter_lev = RHASH_ITER_LEV(hash);
rb_hash_modify(hash);
if (RHASH_TABLE_NULL_P(hash)) {
if (iter_lev > 0) no_new_key();
ar_alloc_table(hash);
}
if (RHASH_TYPE(hash) == &identhash || rb_obj_class(key) != rb_cString) {
RHASH_UPDATE_ITER(hash, iter_lev, key, hash_aset, val);
}
else {
RHASH_UPDATE_ITER(hash, iter_lev, key, hash_aset_str, val);
}
return val;
}</pre>
</div>
</div>
</div>
<div id="method-i-any-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
any? [{ |(key, value)| block }] → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
any?(pattern) → true or false
</span>
</div>
<div class="method-description">
<p>See also <a href="Enumerable.html#method-i-any-3F"><code>Enumerable#any?</code></a></p>
<div class="method-source-code" id="any-3F-source">
<pre>static VALUE
rb_hash_any_p(int argc, VALUE *argv, VALUE hash)
{
VALUE args[2];
args[0] = Qfalse;
rb_check_arity(argc, 0, 1);
if (RHASH_EMPTY_P(hash)) return Qfalse;
if (argc) {
if (rb_block_given_p()) {
rb_warn("given block not used");
}
args[1] = argv[0];
rb_hash_foreach(hash, any_p_i_pattern, (VALUE)args);
}
else {
if (!rb_block_given_p()) {
/* yields pairs, never false */
return Qtrue;
}
if (rb_block_arity() > 1)
rb_hash_foreach(hash, any_p_i_fast, (VALUE)args);
else
rb_hash_foreach(hash, any_p_i, (VALUE)args);
}
return args[0];
}</pre>
</div>
</div>
</div>
<div id="method-i-assoc" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
assoc(obj) → an_array or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Searches through the hash comparing <em>obj</em> with the key using <code>==</code>. Returns the key-value pair (two elements array) or <code>nil</code> if no match is found. See <a href="Array.html#method-i-assoc"><code>Array#assoc</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = {<span class="ruby-string">"colors"</span> <span class="ruby-operator">=></span> [<span class="ruby-string">"red"</span>, <span class="ruby-string">"blue"</span>, <span class="ruby-string">"green"</span>],
<span class="ruby-string">"letters"</span> <span class="ruby-operator">=></span> [<span class="ruby-string">"a"</span>, <span class="ruby-string">"b"</span>, <span class="ruby-string">"c"</span> ]}
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">assoc</span>(<span class="ruby-string">"letters"</span>) <span class="ruby-comment">#=> ["letters", ["a", "b", "c"]]</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">assoc</span>(<span class="ruby-string">"foo"</span>) <span class="ruby-comment">#=> nil</span>
</pre>
<div class="method-source-code" id="assoc-source">
<pre>VALUE
rb_hash_assoc(VALUE hash, VALUE key)
{
st_table *table;
const struct st_hash_type *orighash;
VALUE args[2];
if (RHASH_EMPTY_P(hash)) return Qnil;
ar_force_convert_table(hash, __FILE__, __LINE__);
HASH_ASSERT(RHASH_ST_TABLE_P(hash));
table = RHASH_ST_TABLE(hash);
orighash = table->type;
if (orighash != &identhash) {
VALUE value;
struct reset_hash_type_arg ensure_arg;
struct st_hash_type assochash;
assochash.compare = assoc_cmp;
assochash.hash = orighash->hash;
table->type = &assochash;
args[0] = hash;
args[1] = key;
ensure_arg.hash = hash;
ensure_arg.orighash = orighash;
value = rb_ensure(lookup2_call, (VALUE)&args, reset_hash_type, (VALUE)&ensure_arg);
if (value != Qundef) return rb_assoc_new(key, value);
}
args[0] = key;
args[1] = Qnil;
rb_hash_foreach(hash, assoc_i, (VALUE)args);
return args[1];
}</pre>
</div>
</div>
</div>
<div id="method-i-clear" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
clear → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Removes all key-value pairs from <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> } <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">clear</span> <span class="ruby-comment">#=> {}</span>
</pre>
<div class="method-source-code" id="clear-source">
<pre>VALUE
rb_hash_clear(VALUE hash)
{
rb_hash_modify_check(hash);
if (RHASH_ITER_LEV(hash) > 0) {
rb_hash_foreach(hash, clear_i, 0);
}
else if (RHASH_AR_TABLE_P(hash)) {
ar_clear(hash);
}
else {
st_clear(RHASH_ST_TABLE(hash));
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-compact" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
compact → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a new hash with the nil values/key pairs removed</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-keyword">false</span>, <span class="ruby-value">c:</span> <span class="ruby-keyword">nil</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">compact</span> <span class="ruby-comment">#=> { a: 1, b: false }</span>
<span class="ruby-identifier">h</span> <span class="ruby-comment">#=> { a: 1, b: false, c: nil }</span>
</pre>
<div class="method-source-code" id="compact-source">
<pre>static VALUE
rb_hash_compact(VALUE hash)
{
VALUE result = rb_hash_new();
if (!RHASH_EMPTY_P(hash)) {
rb_hash_foreach(hash, set_if_not_nil, result);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-compact-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
compact! → hsh or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Removes all nil values from the hash. Returns nil if no changes were made, otherwise returns the hash.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-keyword">false</span>, <span class="ruby-value">c:</span> <span class="ruby-keyword">nil</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">compact!</span> <span class="ruby-comment">#=> { a: 1, b: false }</span>
</pre>
<div class="method-source-code" id="compact-21-source">
<pre>static VALUE
rb_hash_compact_bang(VALUE hash)
{
st_index_t n;
rb_hash_modify_check(hash);
n = RHASH_SIZE(hash);
if (n) {
rb_hash_foreach(hash, delete_if_nil, hash);
if (n != RHASH_SIZE(hash))
return hash;
}
return Qnil;
}</pre>
</div>
</div>
</div>
<div id="method-i-compare_by_identity" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
compare_by_identity → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Makes <em>hsh</em> compare its keys by their identity, i.e. it will consider exact same objects as same keys.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-value">:c</span> <span class="ruby-operator">=></span> <span class="ruby-string">"c"</span> }
<span class="ruby-identifier">h1</span>[<span class="ruby-string">"a"</span>] <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">compare_by_identity</span>
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">compare_by_identity?</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h1</span>[<span class="ruby-string">"a"</span>.<span class="ruby-identifier">dup</span>] <span class="ruby-comment">#=> nil # different objects.</span>
<span class="ruby-identifier">h1</span>[<span class="ruby-value">:c</span>] <span class="ruby-comment">#=> "c" # same symbols are all same.</span>
</pre>
<div class="method-source-code" id="compare_by_identity-source">
<pre>static VALUE
rb_hash_compare_by_id(VALUE hash)
{
VALUE tmp;
st_table *identtable;
if (rb_hash_compare_by_id_p(hash)) return hash;
rb_hash_modify_check(hash);
ar_force_convert_table(hash, __FILE__, __LINE__);
HASH_ASSERT(RHASH_ST_TABLE_P(hash));
tmp = hash_alloc(0);
identtable = rb_init_identtable_with_size(RHASH_SIZE(hash));
RHASH_ST_TABLE_SET(tmp, identtable);
rb_hash_foreach(hash, rb_hash_rehash_i, (VALUE)tmp);
st_free_table(RHASH_ST_TABLE(hash));
RHASH_ST_TABLE_SET(hash, identtable);
RHASH_ST_CLEAR(tmp);
rb_gc_force_recycle(tmp);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-compare_by_identity-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
compare_by_identity? → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>hsh</em> will compare its keys by their identity. Also see <a href="Hash.html#method-i-compare_by_identity"><code>Hash#compare_by_identity</code></a>.</p>
<div class="method-source-code" id="compare_by_identity-3F-source">
<pre>MJIT_FUNC_EXPORTED VALUE
rb_hash_compare_by_id_p(VALUE hash)
{
if (RHASH_ST_TABLE_P(hash) && RHASH_ST_TABLE(hash)->type == &identhash) {
return Qtrue;
}
else {
return Qfalse;
}
}</pre>
</div>
</div>
</div>
<div id="method-i-deconstruct_keys" class="method-detail ">
<div class="method-heading">
<span class="method-name">deconstruct_keys</span><span
class="method-args">(p1)</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<div class="method-source-code" id="deconstruct_keys-source">
<pre>static VALUE
rb_hash_deconstruct_keys(VALUE hash, VALUE keys)
{
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-default" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
default(key=nil) → obj
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the default value, the value that would be returned by <em><a href="key">hsh</a></em> if <em>key</em> did not exist in <em>hsh</em>. See also <a href="Hash.html#method-c-new"><code>Hash::new</code></a> and <a href="Hash.html#method-i-default-3D"><code>Hash#default=</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span> <span class="ruby-comment">#=> {}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span> <span class="ruby-comment">#=> nil</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span>(<span class="ruby-value">2</span>) <span class="ruby-comment">#=> nil</span>
<span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span>(<span class="ruby-string">"cat"</span>) <span class="ruby-comment">#=> {}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span> <span class="ruby-comment">#=> "cat"</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span>(<span class="ruby-value">2</span>) <span class="ruby-comment">#=> "cat"</span>
<span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">h</span>,<span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">h</span>[<span class="ruby-identifier">k</span>] = <span class="ruby-identifier">k</span>.<span class="ruby-identifier">to_i</span><span class="ruby-operator">*</span><span class="ruby-value">10</span>} <span class="ruby-comment">#=> {}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span> <span class="ruby-comment">#=> nil</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span>(<span class="ruby-value">2</span>) <span class="ruby-comment">#=> 20</span>
</pre>
<div class="method-source-code" id="default-source">
<pre>static VALUE
rb_hash_default(int argc, VALUE *argv, VALUE hash)
{
VALUE args[2], ifnone;
rb_check_arity(argc, 0, 1);
ifnone = RHASH_IFNONE(hash);
if (FL_TEST(hash, RHASH_PROC_DEFAULT)) {
if (argc == 0) return Qnil;
args[0] = hash;
args[1] = argv[0];
return rb_funcallv(ifnone, id_yield, 2, args);
}
return ifnone;
}</pre>
</div>
</div>
</div>
<div id="method-i-default-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
default = obj → obj
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Sets the default value, the value returned for a key that does not exist in the hash. It is not possible to set the default to a <a href="Proc.html"><code>Proc</code></a> that will be executed on each key lookup.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span> = <span class="ruby-string">"Go fish"</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"a"</span>] <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"z"</span>] <span class="ruby-comment">#=> "Go fish"</span>
<span class="ruby-comment"># This doesn't do what you might hope...</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">default</span> = <span class="ruby-identifier">proc</span> <span class="ruby-keyword">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">hash</span>, <span class="ruby-identifier">key</span><span class="ruby-operator">|</span>
<span class="ruby-identifier">hash</span>[<span class="ruby-identifier">key</span>] = <span class="ruby-identifier">key</span> <span class="ruby-operator">+</span> <span class="ruby-identifier">key</span>
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">h</span>[<span class="ruby-value">2</span>] <span class="ruby-comment">#=> #<Proc:0x401b3948@-:6></span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"cat"</span>] <span class="ruby-comment">#=> #<Proc:0x401b3948@-:6></span>
</pre>
<div class="method-source-code" id="default-3D-source">
<pre>static VALUE
rb_hash_set_default(VALUE hash, VALUE ifnone)
{
rb_hash_modify_check(hash);
SET_DEFAULT(hash, ifnone);
return ifnone;
}</pre>
</div>
</div>
</div>
<div id="method-i-default_proc" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
default_proc → anObject
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>If <a href="Hash.html#method-c-new"><code>Hash::new</code></a> was invoked with a block, return that block, otherwise return <code>nil</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">h</span>,<span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">h</span>[<span class="ruby-identifier">k</span>] = <span class="ruby-identifier">k</span><span class="ruby-operator">*</span><span class="ruby-identifier">k</span> } <span class="ruby-comment">#=> {}</span>
<span class="ruby-identifier">p</span> = <span class="ruby-identifier">h</span>.<span class="ruby-identifier">default_proc</span> <span class="ruby-comment">#=> #<Proc:0x401b3d08@-:1></span>
<span class="ruby-identifier">a</span> = [] <span class="ruby-comment">#=> []</span>
<span class="ruby-identifier">p</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">a</span>, <span class="ruby-value">2</span>)
<span class="ruby-identifier">a</span> <span class="ruby-comment">#=> [nil, nil, 4]</span>
</pre>
<div class="method-source-code" id="default_proc-source">
<pre>static VALUE
rb_hash_default_proc(VALUE hash)
{
if (FL_TEST(hash, RHASH_PROC_DEFAULT)) {
return RHASH_IFNONE(hash);
}
return Qnil;
}</pre>
</div>
</div>
</div>
<div id="method-i-default_proc-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
default_proc = proc_obj or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Sets the default proc to be executed on each failed key lookup.</p>
<pre class="ruby"><span class="ruby-identifier">h</span>.<span class="ruby-identifier">default_proc</span> = <span class="ruby-identifier">proc</span> <span class="ruby-keyword">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">hash</span>, <span class="ruby-identifier">key</span><span class="ruby-operator">|</span>
<span class="ruby-identifier">hash</span>[<span class="ruby-identifier">key</span>] = <span class="ruby-identifier">key</span> <span class="ruby-operator">+</span> <span class="ruby-identifier">key</span>
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">h</span>[<span class="ruby-value">2</span>] <span class="ruby-comment">#=> 4</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"cat"</span>] <span class="ruby-comment">#=> "catcat"</span>
</pre>
<div class="method-source-code" id="default_proc-3D-source">
<pre>VALUE
rb_hash_set_default_proc(VALUE hash, VALUE proc)
{
VALUE b;
rb_hash_modify_check(hash);
if (NIL_P(proc)) {
SET_DEFAULT(hash, proc);
return proc;
}
b = rb_check_convert_type_with_id(proc, T_DATA, "Proc", idTo_proc);
if (NIL_P(b) || !rb_obj_is_proc(b)) {
rb_raise(rb_eTypeError,
"wrong default_proc type %s (expected Proc)",
rb_obj_classname(proc));
}
proc = b;
SET_PROC_DEFAULT(hash, proc);
return proc;
}</pre>
</div>
</div>
</div>
<div id="method-i-delete" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
delete(key) → value
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
delete(key) {| key | block } → value
</span>
</div>
<div class="method-description">
<p>Deletes the key-value pair and returns the value from <em>hsh</em> whose key is equal to <em>key</em>. If the key is not found, it returns <em>nil</em>. If the optional code block is given and the key is not found, pass in the key and return the result of <em>block</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">delete</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">delete</span>(<span class="ruby-string">"z"</span>) <span class="ruby-comment">#=> nil</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">delete</span>(<span class="ruby-string">"z"</span>) { <span class="ruby-operator">|</span><span class="ruby-identifier">el</span><span class="ruby-operator">|</span> <span class="ruby-node">"#{el} not found"</span> } <span class="ruby-comment">#=> "z not found"</span>
</pre>
<div class="method-source-code" id="delete-source">
<pre>static VALUE
rb_hash_delete_m(VALUE hash, VALUE key)
{
VALUE val;
rb_hash_modify_check(hash);
val = rb_hash_delete_entry(hash, key);
if (val != Qundef) {
return val;
}
else {
if (rb_block_given_p()) {
return rb_yield(key);
}
else {
return Qnil;
}
}
}</pre>
</div>
</div>
</div>
<div id="method-i-delete_if" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
delete_if {| key, value | block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
delete_if → an_enumerator
</span>
</div>
<div class="method-description">
<p>Deletes every key-value pair from <em>hsh</em> for which <em>block</em> evaluates to <code>true</code>.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">delete_if</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">value</span><span class="ruby-operator">|</span> <span class="ruby-identifier">key</span> <span class="ruby-operator">>=</span> <span class="ruby-string">"b"</span> } <span class="ruby-comment">#=> {"a"=>100}</span>
</pre>
<div class="method-source-code" id="delete_if-source">
<pre>VALUE
rb_hash_delete_if(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify_check(hash);
if (!RHASH_TABLE_EMPTY_P(hash)) {
rb_hash_foreach(hash, delete_if_i, hash);
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-dig" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
dig(key, ...) → object
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Extracts the nested value specified by the sequence of <em>key</em> objects by calling <code>dig</code> at each step, returning <code>nil</code> if any intermediate step is <code>nil</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">foo:</span> {<span class="ruby-value">bar:</span> {<span class="ruby-value">baz:</span> <span class="ruby-value">1</span>}}}
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">dig</span>(<span class="ruby-value">:foo</span>, <span class="ruby-value">:bar</span>, <span class="ruby-value">:baz</span>) <span class="ruby-comment">#=> 1</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">dig</span>(<span class="ruby-value">:foo</span>, <span class="ruby-value">:zot</span>, <span class="ruby-value">:xyz</span>) <span class="ruby-comment">#=> nil</span>
<span class="ruby-identifier">g</span> = { <span class="ruby-value">foo:</span> [<span class="ruby-value">10</span>, <span class="ruby-value">11</span>, <span class="ruby-value">12</span>] }
<span class="ruby-identifier">g</span>.<span class="ruby-identifier">dig</span>(<span class="ruby-value">:foo</span>, <span class="ruby-value">1</span>) <span class="ruby-comment">#=> 11</span>
<span class="ruby-identifier">g</span>.<span class="ruby-identifier">dig</span>(<span class="ruby-value">:foo</span>, <span class="ruby-value">1</span>, <span class="ruby-value">0</span>) <span class="ruby-comment">#=> TypeError: Integer does not have #dig method</span>
<span class="ruby-identifier">g</span>.<span class="ruby-identifier">dig</span>(<span class="ruby-value">:foo</span>, <span class="ruby-value">:bar</span>) <span class="ruby-comment">#=> TypeError: no implicit conversion of Symbol into Integer</span>
</pre>
<div class="method-source-code" id="dig-source">
<pre>static VALUE
rb_hash_dig(int argc, VALUE *argv, VALUE self)
{
rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
self = rb_hash_aref(self, *argv);
if (!--argc) return self;
++argv;
return rb_obj_dig(argc, argv, self, Qnil);
}</pre>
</div>
</div>
</div>
<div id="method-i-each" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
each {| key, value | block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
each_pair {| key, value | block } → hsh
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
each → an_enumerator
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
each_pair → an_enumerator
</span>
</div>
<div class="method-description">
<p>Calls <em>block</em> once for each key in <em>hsh</em>, passing the key-value pair as parameters.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">each</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">value</span><span class="ruby-operator">|</span> <span class="ruby-identifier">puts</span> <span class="ruby-node">"#{key} is #{value}"</span> }
</pre>
<p><em>produces:</em></p>
<pre class="ruby"><span class="ruby-identifier">a</span> <span class="ruby-identifier">is</span> <span class="ruby-value">100</span>
<span class="ruby-identifier">b</span> <span class="ruby-identifier">is</span> <span class="ruby-value">200</span>
</pre>
<div class="method-source-code" id="each-source">
<pre>static VALUE
rb_hash_each_pair(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
if (rb_block_arity() > 1)
rb_hash_foreach(hash, each_pair_i_fast, 0);
else
rb_hash_foreach(hash, each_pair_i, 0);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-each_key" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
each_key {| key | block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
each_key → an_enumerator
</span>
</div>
<div class="method-description">
<p>Calls <em>block</em> once for each key in <em>hsh</em>, passing the key as a parameter.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">each_key</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span><span class="ruby-operator">|</span> <span class="ruby-identifier">puts</span> <span class="ruby-identifier">key</span> }
</pre>
<p><em>produces:</em></p>
<pre class="ruby"><span class="ruby-identifier">a</span>
<span class="ruby-identifier">b</span>
</pre>
<div class="method-source-code" id="each_key-source">
<pre>static VALUE
rb_hash_each_key(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_foreach(hash, each_key_i, 0);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-each_pair" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
each_pair {| key, value | block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
each_pair → an_enumerator
</span>
</div>
<div class="method-description">
<p>Calls <em>block</em> once for each key in <em>hsh</em>, passing the key-value pair as parameters.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">each</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">value</span><span class="ruby-operator">|</span> <span class="ruby-identifier">puts</span> <span class="ruby-node">"#{key} is #{value}"</span> }
</pre>
<p><em>produces:</em></p>
<pre class="ruby"><span class="ruby-identifier">a</span> <span class="ruby-identifier">is</span> <span class="ruby-value">100</span>
<span class="ruby-identifier">b</span> <span class="ruby-identifier">is</span> <span class="ruby-value">200</span>
</pre>
<div class="method-source-code" id="each_pair-source">
<pre>static VALUE
rb_hash_each_pair(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
if (rb_block_arity() > 1)
rb_hash_foreach(hash, each_pair_i_fast, 0);
else
rb_hash_foreach(hash, each_pair_i, 0);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-each_value" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
each_value {| value | block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
each_value → an_enumerator
</span>
</div>
<div class="method-description">
<p>Calls <em>block</em> once for each key in <em>hsh</em>, passing the value as a parameter.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">each_value</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">value</span><span class="ruby-operator">|</span> <span class="ruby-identifier">puts</span> <span class="ruby-identifier">value</span> }
</pre>
<p><em>produces:</em></p>
<pre class="ruby"><span class="ruby-value">100</span>
<span class="ruby-value">200</span>
</pre>
<div class="method-source-code" id="each_value-source">
<pre>static VALUE
rb_hash_each_value(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_foreach(hash, each_value_i, 0);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-empty-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
empty? → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>hsh</em> contains no key-value pairs.</p>
<pre class="ruby">{}.<span class="ruby-identifier">empty?</span> <span class="ruby-comment">#=> true</span>
</pre>
<div class="method-source-code" id="empty-3F-source">
<pre>static VALUE
rb_hash_empty_p(VALUE hash)
{
return RHASH_EMPTY_P(hash) ? Qtrue : Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-i-eql-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
eql?(other) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if <em>hash</em> and <em>other</em> are both hashes with the same content. The orders of each hashes are not compared.</p>
<div class="method-source-code" id="eql-3F-source">
<pre>static VALUE
rb_hash_eql(VALUE hash1, VALUE hash2)
{
return hash_equal(hash1, hash2, TRUE);
}</pre>
</div>
</div>
</div>
<div id="method-i-fetch" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
fetch(key [, default] ) → obj
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
fetch(key) {| key | block } → obj
</span>
</div>
<div class="method-description">
<p>Returns a value from the hash for the given key. If the key can't be found, there are several options: With no other arguments, it will raise a <a href="KeyError.html"><code>KeyError</code></a> exception; if <em>default</em> is given, then that will be returned; if the optional code block is specified, then that will be run and its result returned.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch</span>(<span class="ruby-string">"z"</span>, <span class="ruby-string">"go fish"</span>) <span class="ruby-comment">#=> "go fish"</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch</span>(<span class="ruby-string">"z"</span>) { <span class="ruby-operator">|</span><span class="ruby-identifier">el</span><span class="ruby-operator">|</span> <span class="ruby-node">"go fish, #{el}"</span>} <span class="ruby-comment">#=> "go fish, z"</span>
</pre>
<p>The following example shows that an exception is raised if the key is not found and a default value is not supplied.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch</span>(<span class="ruby-string">"z"</span>)
</pre>
<p><em>produces:</em></p>
<pre>prog.rb:2:in `fetch': key not found (KeyError)
from prog.rb:2</pre>
<div class="method-source-code" id="fetch-source">
<pre>static VALUE
rb_hash_fetch_m(int argc, VALUE *argv, VALUE hash)
{
VALUE key;
st_data_t val;
long block_given;
rb_check_arity(argc, 1, 2);
key = argv[0];
block_given = rb_block_given_p();
if (block_given && argc == 2) {
rb_warn("block supersedes default value argument");
}
if (hash_stlike_lookup(hash, key, &val)) {
return (VALUE)val;
}
else {
if (block_given) {
return rb_yield(key);
}
else if (argc == 1) {
VALUE desc = rb_protect(rb_inspect, key, 0);
if (NIL_P(desc)) {
desc = rb_any_to_s(key);
}
desc = rb_str_ellipsize(desc, 65);
rb_key_err_raise(rb_sprintf("key not found: %"PRIsVALUE, desc), hash, key);
}
else {
return argv[1];
}
}
}</pre>
</div>
</div>
</div>
<div id="method-i-fetch_values" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
fetch_values(key, ...) → array
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
fetch_values(key, ...) { |key| block } → array
</span>
</div>
<div class="method-description">
<p>Returns an array containing the values associated with the given keys but also raises <a href="KeyError.html"><code>KeyError</code></a> when one of keys can't be found. Also see <a href="Hash.html#method-i-values_at"><code>Hash#values_at</code></a> and <a href="Hash.html#method-i-fetch"><code>Hash#fetch</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"cat"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"feline"</span>, <span class="ruby-string">"dog"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"canine"</span>, <span class="ruby-string">"cow"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"bovine"</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch_values</span>(<span class="ruby-string">"cow"</span>, <span class="ruby-string">"cat"</span>) <span class="ruby-comment">#=> ["bovine", "feline"]</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch_values</span>(<span class="ruby-string">"cow"</span>, <span class="ruby-string">"bird"</span>) <span class="ruby-comment"># raises KeyError</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">fetch_values</span>(<span class="ruby-string">"cow"</span>, <span class="ruby-string">"bird"</span>) { <span class="ruby-operator">|</span><span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">k</span>.<span class="ruby-identifier">upcase</span> } <span class="ruby-comment">#=> ["bovine", "BIRD"]</span>
</pre>
<div class="method-source-code" id="fetch_values-source">
<pre>VALUE
rb_hash_fetch_values(int argc, VALUE *argv, VALUE hash)
{
VALUE result = rb_ary_new2(argc);
long i;
for (i=0; i<argc; i++) {
rb_ary_push(result, rb_hash_fetch(hash, argv[i]));
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-filter" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
filter {|key, value| block} → a_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
filter → an_enumerator
</span>
</div>
<div class="method-description">
<p>Returns a new hash consisting of entries for which the block returns true.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">select</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>,<span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">k</span> <span class="ruby-operator">></span> <span class="ruby-string">"a"</span>} <span class="ruby-comment">#=> {"b" => 200, "c" => 300}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">select</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>,<span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v</span> <span class="ruby-operator"><</span> <span class="ruby-value">200</span>} <span class="ruby-comment">#=> {"a" => 100}</span>
</pre>
<p><a href="Hash.html#method-i-filter"><code>Hash#filter</code></a> is an alias for <a href="Hash.html#method-i-select"><code>Hash#select</code></a>.</p>
<div class="method-source-code" id="filter-source">
<pre>VALUE
rb_hash_select(VALUE hash)
{
VALUE result;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
result = rb_hash_new();
if (!RHASH_EMPTY_P(hash)) {
rb_hash_foreach(hash, select_i, result);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-filter-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
filter! {| key, value | block } → hsh or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
filter! → an_enumerator
</span>
</div>
<div class="method-description">
<p>Equivalent to <a href="Hash.html#method-i-keep_if"><code>Hash#keep_if</code></a>, but returns <code>nil</code> if no changes were made.</p>
<p><a href="Hash.html#method-i-filter-21"><code>Hash#filter!</code></a> is an alias for <a href="Hash.html#method-i-select-21"><code>Hash#select!</code></a>.</p>
<div class="method-source-code" id="filter-21-source">
<pre>VALUE
rb_hash_select_bang(VALUE hash)
{
st_index_t n;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify_check(hash);
n = RHASH_SIZE(hash);
if (!n) return Qnil;
rb_hash_foreach(hash, keep_if_i, hash);
if (n == RHASH_SIZE(hash)) return Qnil;
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-flatten" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
flatten → an_array
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
flatten(level) → an_array
</span>
</div>
<div class="method-description">
<p>Returns a new array that is a one-dimensional flattening of this hash. That is, for every key or value that is an array, extract its elements into the new array. Unlike <a href="Array.html#method-i-flatten"><code>Array#flatten</code></a>, this method does not flatten recursively by default. The optional <em>level</em> argument determines the level of recursion to flatten.</p>
<pre class="ruby"><span class="ruby-identifier">a</span> = {<span class="ruby-value">1</span><span class="ruby-operator">=></span> <span class="ruby-string">"one"</span>, <span class="ruby-value">2</span> <span class="ruby-operator">=></span> [<span class="ruby-value">2</span>,<span class="ruby-string">"two"</span>], <span class="ruby-value">3</span> <span class="ruby-operator">=></span> <span class="ruby-string">"three"</span>}
<span class="ruby-identifier">a</span>.<span class="ruby-identifier">flatten</span> <span class="ruby-comment"># => [1, "one", 2, [2, "two"], 3, "three"]</span>
<span class="ruby-identifier">a</span>.<span class="ruby-identifier">flatten</span>(<span class="ruby-value">2</span>) <span class="ruby-comment"># => [1, "one", 2, 2, "two", 3, "three"]</span>
</pre>
<div class="method-source-code" id="flatten-source">
<pre>static VALUE
rb_hash_flatten(int argc, VALUE *argv, VALUE hash)
{
VALUE ary;
rb_check_arity(argc, 0, 1);
if (argc) {
int level = NUM2INT(argv[0]);
if (level == 0) return rb_hash_to_a(hash);
ary = rb_ary_new_capa(RHASH_SIZE(hash) * 2);
rb_hash_foreach(hash, flatten_i, ary);
level--;
if (level > 0) {
VALUE ary_flatten_level = INT2FIX(level);
rb_funcallv(ary, id_flatten_bang, 1, &ary_flatten_level);
}
else if (level < 0) {
/* flatten recursively */
rb_funcallv(ary, id_flatten_bang, 0, 0);
}
}
else {
ary = rb_ary_new_capa(RHASH_SIZE(hash) * 2);
rb_hash_foreach(hash, flatten_i, ary);
}
return ary;
}</pre>
</div>
</div>
</div>
<div id="method-i-has_key-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
has_key?(key) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the given key is present in <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"z"</span>) <span class="ruby-comment">#=> false</span>
</pre>
<p>Note that <a href="Hash.html#method-i-include-3F"><code>include?</code></a> and <a href="Hash.html#method-i-member-3F"><code>member?</code></a> do not test member equality using <code>==</code> as do other Enumerables.</p>
<p>See also <a href="Enumerable.html#method-i-include-3F"><code>Enumerable#include?</code></a></p>
<div class="method-source-code" id="has_key-3F-source">
<pre>MJIT_FUNC_EXPORTED VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
if (hash_stlike_lookup(hash, key, NULL)) {
return Qtrue;
}
else {
return Qfalse;
}
}</pre>
</div>
</div>
</div>
<div id="method-i-has_value-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
has_value?(value) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the given value is present for some key in <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">value?</span>(<span class="ruby-value">100</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">value?</span>(<span class="ruby-value">999</span>) <span class="ruby-comment">#=> false</span>
</pre>
<div class="method-source-code" id="has_value-3F-source">
<pre>static VALUE
rb_hash_has_value(VALUE hash, VALUE val)
{
VALUE data[2];
data[0] = Qfalse;
data[1] = val;
rb_hash_foreach(hash, rb_hash_search_value, (VALUE)data);
return data[0];
}</pre>
</div>
</div>
</div>
<div id="method-i-hash" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hash → integer
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Compute a hash-code for this hash. Two hashes with the same content will have the same hash code (and will compare using <code>eql?</code>).</p>
<p>See also <a href="Object.html#method-i-hash"><code>Object#hash</code></a>.</p>
<div class="method-source-code" id="hash-source">
<pre>static VALUE
rb_hash_hash(VALUE hash)
{
st_index_t size = RHASH_SIZE(hash);
st_index_t hval = rb_hash_start(size);
hval = rb_hash_uint(hval, (st_index_t)rb_hash_hash);
if (size) {
rb_hash_foreach(hash, hash_i, (VALUE)&hval);
}
hval = rb_hash_end(hval);
return ST2FIX(hval);
}</pre>
</div>
</div>
</div>
<div id="method-i-include-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
include?(key) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the given key is present in <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"z"</span>) <span class="ruby-comment">#=> false</span>
</pre>
<p>Note that <a href="Hash.html#method-i-include-3F"><code>include?</code></a> and <a href="Hash.html#method-i-member-3F"><code>member?</code></a> do not test member equality using <code>==</code> as do other Enumerables.</p>
<p>See also <a href="Enumerable.html#method-i-include-3F"><code>Enumerable#include?</code></a></p>
<div class="method-source-code" id="include-3F-source">
<pre>MJIT_FUNC_EXPORTED VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
if (hash_stlike_lookup(hash, key, NULL)) {
return Qtrue;
}
else {
return Qfalse;
}
}</pre>
</div>
</div>
</div>
<div id="method-i-initialize_copy" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
replace(other_hash) → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Replaces the contents of <em>hsh</em> with the contents of <em>other_hash</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">replace</span>({ <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }) <span class="ruby-comment">#=> {"c"=>300, "d"=>400}</span>
</pre>
<div class="method-source-code" id="initialize_copy-source">
<pre>static VALUE
rb_hash_replace(VALUE hash, VALUE hash2)
{
rb_hash_modify_check(hash);
if (hash == hash2) return hash;
if (RHASH_ITER_LEV(hash) > 0) {
rb_raise(rb_eRuntimeError, "can't replace hash during iteration");
}
hash2 = to_hash(hash2);
COPY_DEFAULT(hash, hash2);
if (RHASH_AR_TABLE_P(hash)) {
if (RHASH_AR_TABLE_P(hash2)) {
ar_clear(hash);
}
else {
ar_free_and_clear_table(hash);
RHASH_ST_TABLE_SET(hash, st_init_table_with_size(RHASH_TYPE(hash2), RHASH_SIZE(hash2)));
}
}
else {
if (RHASH_AR_TABLE_P(hash2)) {
st_free_table(RHASH_ST_TABLE(hash));
RHASH_ST_CLEAR(hash);
}
else {
st_clear(RHASH_ST_TABLE(hash));
RHASH_TBL_RAW(hash)->type = RHASH_ST_TABLE(hash2)->type;
}
}
rb_hash_foreach(hash2, rb_hash_rehash_i, (VALUE)hash);
rb_gc_writebarrier_remember(hash);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-inspect" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_s → string
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
inspect → string
</span>
</div>
<div class="method-description">
<p>Return the contents of this hash as a string.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">to_s</span> <span class="ruby-comment">#=> "{\"c\"=>300, \"a\"=>100, \"d\"=>400}"</span>
</pre>
<div class="method-source-code" id="inspect-source">
<pre>static VALUE
rb_hash_inspect(VALUE hash)
{
if (RHASH_EMPTY_P(hash))
return rb_usascii_str_new2("{}");
return rb_exec_recursive(inspect_hash, hash, 0);
}</pre>
</div>
</div>
<div class="aliases">
Also aliased as: <a href="Hash.html#method-i-to_s">to_s</a>
</div>
</div>
<div id="method-i-invert" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
invert → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a new hash created by using <em>hsh</em>'s values as keys, and the keys as values. If a key with the same value already exists in the <em>hsh</em>, then the last one defined will be used, the earlier value(s) will be discarded.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"n"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"m"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"y"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">0</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">invert</span> <span class="ruby-comment">#=> {0=>"a", 100=>"m", 200=>"d", 300=>"y"}</span>
</pre>
<p>If there is no key with the same value, <a href="Hash.html#method-i-invert"><code>Hash#invert</code></a> is involutive.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">3</span>, <span class="ruby-value">c:</span> <span class="ruby-value">4</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">invert</span>.<span class="ruby-identifier">invert</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h</span> <span class="ruby-comment">#=> true</span>
</pre>
<p>The condition, no key with the same value, can be tested by comparing the size of inverted hash.</p>
<pre class="ruby"><span class="ruby-comment"># no key with the same value</span>
<span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">3</span>, <span class="ruby-value">c:</span> <span class="ruby-value">4</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">size</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h</span>.<span class="ruby-identifier">invert</span>.<span class="ruby-identifier">size</span> <span class="ruby-comment">#=> true</span>
<span class="ruby-comment"># two (or more) keys has the same value</span>
<span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">3</span>, <span class="ruby-value">c:</span> <span class="ruby-value">1</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">size</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">h</span>.<span class="ruby-identifier">invert</span>.<span class="ruby-identifier">size</span> <span class="ruby-comment">#=> false</span>
</pre>
<div class="method-source-code" id="invert-source">
<pre>static VALUE
rb_hash_invert(VALUE hash)
{
VALUE h = rb_hash_new_with_size(RHASH_SIZE(hash));
rb_hash_foreach(hash, rb_hash_invert_i, h);
return h;
}</pre>
</div>
</div>
</div>
<div id="method-i-keep_if" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
keep_if {| key, value | block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
keep_if → an_enumerator
</span>
</div>
<div class="method-description">
<p>Deletes every key-value pair from <em>hsh</em> for which <em>block</em> evaluates to <code>false</code>.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<p>See also <a href="Hash.html#method-i-select-21"><code>Hash#select!</code></a>.</p>
<div class="method-source-code" id="keep_if-source">
<pre>VALUE
rb_hash_keep_if(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify_check(hash);
if (!RHASH_TABLE_EMPTY_P(hash)) {
rb_hash_foreach(hash, keep_if_i, hash);
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-key" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
key(value) → key
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the key of an occurrence of a given value. If the value is not found, returns <code>nil</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">200</span>) <span class="ruby-comment">#=> "b"</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">300</span>) <span class="ruby-comment">#=> "c"</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">999</span>) <span class="ruby-comment">#=> nil</span>
</pre>
<div class="method-source-code" id="key-source">
<pre>static VALUE
rb_hash_key(VALUE hash, VALUE value)
{
VALUE args[2];
args[0] = value;
args[1] = Qnil;
rb_hash_foreach(hash, key_i, (VALUE)args);
return args[1];
}</pre>
</div>
</div>
</div>
<div id="method-i-key-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
key?(key) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the given key is present in <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"z"</span>) <span class="ruby-comment">#=> false</span>
</pre>
<p>Note that <a href="Hash.html#method-i-include-3F"><code>include?</code></a> and <a href="Hash.html#method-i-member-3F"><code>member?</code></a> do not test member equality using <code>==</code> as do other Enumerables.</p>
<p>See also <a href="Enumerable.html#method-i-include-3F"><code>Enumerable#include?</code></a></p>
<div class="method-source-code" id="key-3F-source">
<pre>MJIT_FUNC_EXPORTED VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
if (hash_stlike_lookup(hash, key, NULL)) {
return Qtrue;
}
else {
return Qfalse;
}
}</pre>
</div>
</div>
</div>
<div id="method-i-keys" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
keys → array
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a new array populated with the keys from this hash. See also <a href="Hash.html#method-i-values"><code>Hash#values</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">keys</span> <span class="ruby-comment">#=> ["a", "b", "c", "d"]</span>
</pre>
<div class="method-source-code" id="keys-source">
<pre>MJIT_FUNC_EXPORTED VALUE
rb_hash_keys(VALUE hash)
{
st_index_t size = RHASH_SIZE(hash);
VALUE keys = rb_ary_new_capa(size);
if (size == 0) return keys;
if (ST_DATA_COMPATIBLE_P(VALUE)) {
RARRAY_PTR_USE_TRANSIENT(keys, ptr, {
if (RHASH_AR_TABLE_P(hash)) {
size = ar_keys(hash, ptr, size);
}
else {
st_table *table = RHASH_ST_TABLE(hash);
size = st_keys(table, ptr, size);
}
});
rb_gc_writebarrier_remember(keys);
rb_ary_set_len(keys, size);
}
else {
rb_hash_foreach(hash, keys_i, keys);
}
return keys;
}</pre>
</div>
</div>
</div>
<div id="method-i-length" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
length → integer
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the number of key-value pairs in the hash.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"v"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"e"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">size</span> <span class="ruby-comment">#=> 4</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">delete</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> 200</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">size</span> <span class="ruby-comment">#=> 3</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">length</span> <span class="ruby-comment">#=> 3</span>
</pre>
<p><a href="Hash.html#method-i-length"><code>Hash#length</code></a> is an alias for <a href="Hash.html#method-i-size"><code>Hash#size</code></a>.</p>
<div class="method-source-code" id="length-source">
<pre>VALUE
rb_hash_size(VALUE hash)
{
return INT2FIX(RHASH_SIZE(hash));
}</pre>
</div>
</div>
</div>
<div id="method-i-member-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
member?(key) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the given key is present in <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">"z"</span>) <span class="ruby-comment">#=> false</span>
</pre>
<p>Note that <a href="Hash.html#method-i-include-3F"><code>include?</code></a> and <a href="Hash.html#method-i-member-3F"><code>member?</code></a> do not test member equality using <code>==</code> as do other Enumerables.</p>
<p>See also <a href="Enumerable.html#method-i-include-3F"><code>Enumerable#include?</code></a></p>
<div class="method-source-code" id="member-3F-source">
<pre>MJIT_FUNC_EXPORTED VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
if (hash_stlike_lookup(hash, key, NULL)) {
return Qtrue;
}
else {
return Qfalse;
}
}</pre>
</div>
</div>
</div>
<div id="method-i-merge" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
merge(other_hash1, other_hash2, ...) → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
merge(other_hash1, other_hash2, ...) {|key, oldval, newval| block}
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
→ new_hash
</span>
</div>
<div class="method-description">
<p>Returns a new hash that combines the contents of the receiver and the contents of the given hashes.</p>
<p>If no block is given, entries with duplicate keys are overwritten with the values from each <code>other_hash</code> successively, otherwise the value for each duplicate key is determined by calling the block with the key, its value in the receiver and its value in each <code>other_hash</code>.</p>
<p>When called without any argument, returns a copy of the receiver.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h3</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">357</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge</span>(<span class="ruby-identifier">h2</span>) <span class="ruby-comment">#=> {"a"=>100, "b"=>246, "c"=>300}</span>
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge</span>(<span class="ruby-identifier">h2</span>, <span class="ruby-identifier">h3</span>) <span class="ruby-comment">#=> {"a"=>100, "b"=>357, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge</span>(<span class="ruby-identifier">h2</span>) {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">oldval</span>, <span class="ruby-identifier">newval</span><span class="ruby-operator">|</span> <span class="ruby-identifier">newval</span> <span class="ruby-operator">-</span> <span class="ruby-identifier">oldval</span>}
<span class="ruby-comment">#=> {"a"=>100, "b"=>46, "c"=>300}</span>
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge</span>(<span class="ruby-identifier">h2</span>, <span class="ruby-identifier">h3</span>) {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">oldval</span>, <span class="ruby-identifier">newval</span><span class="ruby-operator">|</span> <span class="ruby-identifier">newval</span> <span class="ruby-operator">-</span> <span class="ruby-identifier">oldval</span>}
<span class="ruby-comment">#=> {"a"=>100, "b"=>311, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
</pre>
<div class="method-source-code" id="merge-source">
<pre>static VALUE
rb_hash_merge(int argc, VALUE *argv, VALUE self)
{
return rb_hash_update(argc, argv, rb_hash_dup(self));
}</pre>
</div>
</div>
</div>
<div id="method-i-merge-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
merge!(other_hash1, other_hash2, ...) → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
merge!(other_hash1, other_hash2, ...) {|key, oldval, newval| block}
</span>
</div>
<div class="method-description">
<p>Adds the contents of the given hashes to the receiver.</p>
<p>If no block is given, entries with duplicate keys are overwritten with the values from each <code>other_hash</code> successively, otherwise the value for each duplicate key is determined by calling the block with the key, its value in the receiver and its value in each <code>other_hash</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span>(<span class="ruby-identifier">h2</span>) <span class="ruby-comment">#=> {"a"=>100, "b"=>246, "c"=>300}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>246, "c"=>300}</span>
<span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h3</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">357</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span>(<span class="ruby-identifier">h2</span>, <span class="ruby-identifier">h3</span>)
<span class="ruby-comment">#=> {"a"=>100, "b"=>357, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>357, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h3</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">357</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span>(<span class="ruby-identifier">h2</span>, <span class="ruby-identifier">h3</span>) {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">v1</span>, <span class="ruby-identifier">v2</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v1</span> }
<span class="ruby-comment">#=> {"a"=>100, "b"=>200, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200, "c"=>300, "d"=>400}</span>
</pre>
<p><a href="Hash.html#method-i-update"><code>Hash#update</code></a> is an alias for <a href="Hash.html#method-i-merge-21"><code>Hash#merge!</code></a>.</p>
<div class="method-source-code" id="merge-21-source">
<pre>static VALUE
rb_hash_update(int argc, VALUE *argv, VALUE self)
{
int i;
bool block_given = rb_block_given_p();
rb_hash_modify(self);
for (i = 0; i < argc; i++){
VALUE hash = to_hash(argv[i]);
if (block_given) {
rb_hash_foreach(hash, rb_hash_update_block_i, self);
}
else {
rb_hash_foreach(hash, rb_hash_update_i, self);
}
}
return self;
}</pre>
</div>
</div>
</div>
<div id="method-i-rassoc" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
rassoc(obj) → an_array or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Searches through the hash comparing <em>obj</em> with the value using <code>==</code>. Returns the first key-value pair (two-element array) that matches. See also <a href="Array.html#method-i-rassoc"><code>Array#rassoc</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">a</span> = {<span class="ruby-value">1</span><span class="ruby-operator">=></span> <span class="ruby-string">"one"</span>, <span class="ruby-value">2</span> <span class="ruby-operator">=></span> <span class="ruby-string">"two"</span>, <span class="ruby-value">3</span> <span class="ruby-operator">=></span> <span class="ruby-string">"three"</span>, <span class="ruby-string">"ii"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"two"</span>}
<span class="ruby-identifier">a</span>.<span class="ruby-identifier">rassoc</span>(<span class="ruby-string">"two"</span>) <span class="ruby-comment">#=> [2, "two"]</span>
<span class="ruby-identifier">a</span>.<span class="ruby-identifier">rassoc</span>(<span class="ruby-string">"four"</span>) <span class="ruby-comment">#=> nil</span>
</pre>
<div class="method-source-code" id="rassoc-source">
<pre>VALUE
rb_hash_rassoc(VALUE hash, VALUE obj)
{
VALUE args[2];
args[0] = obj;
args[1] = Qnil;
rb_hash_foreach(hash, rassoc_i, (VALUE)args);
return args[1];
}</pre>
</div>
</div>
</div>
<div id="method-i-rehash" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
rehash → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Rebuilds the hash based on the current hash values for each key. If values of key objects have changed since they were inserted, this method will reindex <em>hsh</em>. If <a href="Hash.html#method-i-rehash"><code>Hash#rehash</code></a> is called while an iterator is traversing the hash, a <a href="RuntimeError.html"><code>RuntimeError</code></a> will be raised in the iterator.</p>
<pre class="ruby"><span class="ruby-identifier">a</span> = [ <span class="ruby-string">"a"</span>, <span class="ruby-string">"b"</span> ]
<span class="ruby-identifier">c</span> = [ <span class="ruby-string">"c"</span>, <span class="ruby-string">"d"</span> ]
<span class="ruby-identifier">h</span> = { <span class="ruby-identifier">a</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-identifier">c</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>[<span class="ruby-identifier">a</span>] <span class="ruby-comment">#=> 100</span>
<span class="ruby-identifier">a</span>[<span class="ruby-value">0</span>] = <span class="ruby-string">"z"</span>
<span class="ruby-identifier">h</span>[<span class="ruby-identifier">a</span>] <span class="ruby-comment">#=> nil</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">rehash</span> <span class="ruby-comment">#=> {["z", "b"]=>100, ["c", "d"]=>300}</span>
<span class="ruby-identifier">h</span>[<span class="ruby-identifier">a</span>] <span class="ruby-comment">#=> 100</span>
</pre>
<div class="method-source-code" id="rehash-source">
<pre>VALUE
rb_hash_rehash(VALUE hash)
{
VALUE tmp;
st_table *tbl;
if (RHASH_ITER_LEV(hash) > 0) {
rb_raise(rb_eRuntimeError, "rehash during iteration");
}
rb_hash_modify_check(hash);
if (RHASH_AR_TABLE_P(hash)) {
tmp = hash_alloc(0);
ar_alloc_table(tmp);
rb_hash_foreach(hash, rb_hash_rehash_i, (VALUE)tmp);
ar_free_and_clear_table(hash);
ar_copy(hash, tmp);
ar_free_and_clear_table(tmp);
}
else if (RHASH_ST_TABLE_P(hash)) {
st_table *old_tab = RHASH_ST_TABLE(hash);
tmp = hash_alloc(0);
tbl = st_init_table_with_size(old_tab->type, old_tab->num_entries);
RHASH_ST_TABLE_SET(tmp, tbl);
rb_hash_foreach(hash, rb_hash_rehash_i, (VALUE)tmp);
st_free_table(old_tab);
RHASH_ST_TABLE_SET(hash, tbl);
RHASH_ST_CLEAR(tmp);
}
hash_verify(hash);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-reject" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
reject {|key, value| block} → a_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
reject → an_enumerator
</span>
</div>
<div class="method-description">
<p>Returns a new hash consisting of entries for which the block returns false.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">reject</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>,<span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">k</span> <span class="ruby-operator"><</span> <span class="ruby-string">"b"</span>} <span class="ruby-comment">#=> {"b" => 200, "c" => 300}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">reject</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>,<span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v</span> <span class="ruby-operator">></span> <span class="ruby-value">100</span>} <span class="ruby-comment">#=> {"a" => 100}</span>
</pre>
<div class="method-source-code" id="reject-source">
<pre>VALUE
rb_hash_reject(VALUE hash)
{
VALUE result;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
if (RTEST(ruby_verbose)) {
VALUE klass;
if (HAS_EXTRA_STATES(hash, klass)) {
rb_warn("extra states are no longer copied: %+"PRIsVALUE, hash);
}
}
result = rb_hash_new();
if (!RHASH_EMPTY_P(hash)) {
rb_hash_foreach(hash, reject_i, result);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-reject-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
reject! {| key, value | block } → hsh or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
reject! → an_enumerator
</span>
</div>
<div class="method-description">
<p>Equivalent to <a href="Hash.html#method-i-delete_if"><code>Hash#delete_if</code></a>, but returns <code>nil</code> if no changes were made.</p>
<div class="method-source-code" id="reject-21-source">
<pre>VALUE
rb_hash_reject_bang(VALUE hash)
{
st_index_t n;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify(hash);
n = RHASH_SIZE(hash);
if (!n) return Qnil;
rb_hash_foreach(hash, delete_if_i, hash);
if (n == RHASH_SIZE(hash)) return Qnil;
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-replace" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
replace(other_hash) → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Replaces the contents of <em>hsh</em> with the contents of <em>other_hash</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">replace</span>({ <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }) <span class="ruby-comment">#=> {"c"=>300, "d"=>400}</span>
</pre>
<div class="method-source-code" id="replace-source">
<pre>static VALUE
rb_hash_replace(VALUE hash, VALUE hash2)
{
rb_hash_modify_check(hash);
if (hash == hash2) return hash;
if (RHASH_ITER_LEV(hash) > 0) {
rb_raise(rb_eRuntimeError, "can't replace hash during iteration");
}
hash2 = to_hash(hash2);
COPY_DEFAULT(hash, hash2);
if (RHASH_AR_TABLE_P(hash)) {
if (RHASH_AR_TABLE_P(hash2)) {
ar_clear(hash);
}
else {
ar_free_and_clear_table(hash);
RHASH_ST_TABLE_SET(hash, st_init_table_with_size(RHASH_TYPE(hash2), RHASH_SIZE(hash2)));
}
}
else {
if (RHASH_AR_TABLE_P(hash2)) {
st_free_table(RHASH_ST_TABLE(hash));
RHASH_ST_CLEAR(hash);
}
else {
st_clear(RHASH_ST_TABLE(hash));
RHASH_TBL_RAW(hash)->type = RHASH_ST_TABLE(hash2)->type;
}
}
rb_hash_foreach(hash2, rb_hash_rehash_i, (VALUE)hash);
rb_gc_writebarrier_remember(hash);
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-select" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
select {|key, value| block} → a_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
select → an_enumerator
</span>
</div>
<div class="method-description">
<p>Returns a new hash consisting of entries for which the block returns true.</p>
<p>If no block is given, an enumerator is returned instead.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">select</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>,<span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">k</span> <span class="ruby-operator">></span> <span class="ruby-string">"a"</span>} <span class="ruby-comment">#=> {"b" => 200, "c" => 300}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">select</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>,<span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v</span> <span class="ruby-operator"><</span> <span class="ruby-value">200</span>} <span class="ruby-comment">#=> {"a" => 100}</span>
</pre>
<p><a href="Hash.html#method-i-filter"><code>Hash#filter</code></a> is an alias for <a href="Hash.html#method-i-select"><code>Hash#select</code></a>.</p>
<div class="method-source-code" id="select-source">
<pre>VALUE
rb_hash_select(VALUE hash)
{
VALUE result;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
result = rb_hash_new();
if (!RHASH_EMPTY_P(hash)) {
rb_hash_foreach(hash, select_i, result);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-select-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
select! {| key, value | block } → hsh or nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
select! → an_enumerator
</span>
</div>
<div class="method-description">
<p>Equivalent to <a href="Hash.html#method-i-keep_if"><code>Hash#keep_if</code></a>, but returns <code>nil</code> if no changes were made.</p>
<p><a href="Hash.html#method-i-filter-21"><code>Hash#filter!</code></a> is an alias for <a href="Hash.html#method-i-select-21"><code>Hash#select!</code></a>.</p>
<div class="method-source-code" id="select-21-source">
<pre>VALUE
rb_hash_select_bang(VALUE hash)
{
st_index_t n;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify_check(hash);
n = RHASH_SIZE(hash);
if (!n) return Qnil;
rb_hash_foreach(hash, keep_if_i, hash);
if (n == RHASH_SIZE(hash)) return Qnil;
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-shift" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
shift → anArray or obj
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Removes a key-value pair from <em>hsh</em> and returns it as the two-item array <code>[</code> <em>key, value</em> <code>]</code>, or the hash's default value if the hash is empty.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">1</span> <span class="ruby-operator">=></span> <span class="ruby-string">"a"</span>, <span class="ruby-value">2</span> <span class="ruby-operator">=></span> <span class="ruby-string">"b"</span>, <span class="ruby-value">3</span> <span class="ruby-operator">=></span> <span class="ruby-string">"c"</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">shift</span> <span class="ruby-comment">#=> [1, "a"]</span>
<span class="ruby-identifier">h</span> <span class="ruby-comment">#=> {2=>"b", 3=>"c"}</span>
</pre>
<div class="method-source-code" id="shift-source">
<pre>static VALUE
rb_hash_shift(VALUE hash)
{
struct shift_var var;
rb_hash_modify_check(hash);
if (RHASH_AR_TABLE_P(hash)) {
var.key = Qundef;
if (RHASH_ITER_LEV(hash) == 0) {
if (ar_shift(hash, &var.key, &var.val)) {
return rb_assoc_new(var.key, var.val);
}
}
else {
rb_hash_foreach(hash, shift_i_safe, (VALUE)&var);
if (var.key != Qundef) {
rb_hash_delete_entry(hash, var.key);
return rb_assoc_new(var.key, var.val);
}
}
}
if (RHASH_ST_TABLE_P(hash)) {
var.key = Qundef;
if (RHASH_ITER_LEV(hash) == 0) {
if (st_shift(RHASH_ST_TABLE(hash), &var.key, &var.val)) {
return rb_assoc_new(var.key, var.val);
}
}
else {
rb_hash_foreach(hash, shift_i_safe, (VALUE)&var);
if (var.key != Qundef) {
rb_hash_delete_entry(hash, var.key);
return rb_assoc_new(var.key, var.val);
}
}
}
return rb_hash_default_value(hash, Qnil);
}</pre>
</div>
</div>
</div>
<div id="method-i-size" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
size → integer
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the number of key-value pairs in the hash.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"v"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"e"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">size</span> <span class="ruby-comment">#=> 4</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">delete</span>(<span class="ruby-string">"a"</span>) <span class="ruby-comment">#=> 200</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">size</span> <span class="ruby-comment">#=> 3</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">length</span> <span class="ruby-comment">#=> 3</span>
</pre>
<p><a href="Hash.html#method-i-length"><code>Hash#length</code></a> is an alias for <a href="Hash.html#method-i-size"><code>Hash#size</code></a>.</p>
<div class="method-source-code" id="size-source">
<pre>VALUE
rb_hash_size(VALUE hash)
{
return INT2FIX(RHASH_SIZE(hash));
}</pre>
</div>
</div>
</div>
<div id="method-i-slice" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
slice(*keys) → a_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a hash containing only the given keys and their values.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">100</span>, <span class="ruby-value">b:</span> <span class="ruby-value">200</span>, <span class="ruby-value">c:</span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">slice</span>(<span class="ruby-value">:a</span>) <span class="ruby-comment">#=> {:a=>100}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">slice</span>(<span class="ruby-value">:b</span>, <span class="ruby-value">:c</span>, <span class="ruby-value">:d</span>) <span class="ruby-comment">#=> {:b=>200, :c=>300}</span>
</pre>
<div class="method-source-code" id="slice-source">
<pre>static VALUE
rb_hash_slice(int argc, VALUE *argv, VALUE hash)
{
int i;
VALUE key, value, result;
if (argc == 0 || RHASH_EMPTY_P(hash)) {
return rb_hash_new();
}
result = rb_hash_new_with_size(argc);
for (i = 0; i < argc; i++) {
key = argv[i];
value = rb_hash_lookup2(hash, key, Qundef);
if (value != Qundef)
rb_hash_aset(result, key, value);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-store" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
store(key, value) → value
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<h2 id="method-i-store-label-Element+Assignment">Element Assignment<span><a href="#method-i-store-label-Element+Assignment">¶</a> <a href="#top">↑</a></span></h2>
<p>Associates the value given by <code>value</code> with the key given by <code>key</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>[<span class="ruby-string">"a"</span>] = <span class="ruby-value">9</span>
<span class="ruby-identifier">h</span>[<span class="ruby-string">"c"</span>] = <span class="ruby-value">4</span>
<span class="ruby-identifier">h</span> <span class="ruby-comment">#=> {"a"=>9, "b"=>200, "c"=>4}</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">store</span>(<span class="ruby-string">"d"</span>, <span class="ruby-value">42</span>) <span class="ruby-comment">#=> 42</span>
<span class="ruby-identifier">h</span> <span class="ruby-comment">#=> {"a"=>9, "b"=>200, "c"=>4, "d"=>42}</span>
</pre>
<p><code>key</code> should not have its value changed while it is in use as a key (an <code>unfrozen String</code> passed as a key will be duplicated and frozen).</p>
<pre class="ruby"><span class="ruby-identifier">a</span> = <span class="ruby-string">"a"</span>
<span class="ruby-identifier">b</span> = <span class="ruby-string">"b"</span>.<span class="ruby-identifier">freeze</span>
<span class="ruby-identifier">h</span> = { <span class="ruby-identifier">a</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-identifier">b</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">100</span>).<span class="ruby-identifier">equal?</span> <span class="ruby-identifier">a</span> <span class="ruby-comment">#=> false</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">key</span>(<span class="ruby-value">200</span>).<span class="ruby-identifier">equal?</span> <span class="ruby-identifier">b</span> <span class="ruby-comment">#=> true</span>
</pre>
<div class="method-source-code" id="store-source">
<pre>VALUE
rb_hash_aset(VALUE hash, VALUE key, VALUE val)
{
int iter_lev = RHASH_ITER_LEV(hash);
rb_hash_modify(hash);
if (RHASH_TABLE_NULL_P(hash)) {
if (iter_lev > 0) no_new_key();
ar_alloc_table(hash);
}
if (RHASH_TYPE(hash) == &identhash || rb_obj_class(key) != rb_cString) {
RHASH_UPDATE_ITER(hash, iter_lev, key, hash_aset, val);
}
else {
RHASH_UPDATE_ITER(hash, iter_lev, key, hash_aset_str, val);
}
return val;
}</pre>
</div>
</div>
</div>
<div id="method-i-to_a" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_a → array
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Converts <em>hsh</em> to a nested array of <code>[</code> <em>key, value</em> <code>]</code> arrays.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span>, <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">to_a</span> <span class="ruby-comment">#=> [["c", 300], ["a", 100], ["d", 400]]</span>
</pre>
<div class="method-source-code" id="to_a-source">
<pre>static VALUE
rb_hash_to_a(VALUE hash)
{
VALUE ary;
ary = rb_ary_new_capa(RHASH_SIZE(hash));
rb_hash_foreach(hash, to_a_i, ary);
return ary;
}</pre>
</div>
</div>
</div>
<div id="method-i-to_h" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_h → hsh or new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
to_h {|key, value| block } → new_hash
</span>
</div>
<div class="method-description">
<p>Returns <code>self</code>. If called on a subclass of <a href="Hash.html"><code>Hash</code></a>, converts the receiver to a <a href="Hash.html"><code>Hash</code></a> object.</p>
<p>If a block is given, the results of the block on each pair of the receiver will be used as pairs.</p>
<div class="method-source-code" id="to_h-source">
<pre>static VALUE
rb_hash_to_h(VALUE hash)
{
if (rb_block_given_p()) {
return rb_hash_to_h_block(hash);
}
if (rb_obj_class(hash) != rb_cHash) {
const VALUE flags = RBASIC(hash)->flags;
hash = hash_dup(hash, rb_cHash, flags & RHASH_PROC_DEFAULT);
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-to_hash" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_hash → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>self</code>.</p>
<div class="method-source-code" id="to_hash-source">
<pre>static VALUE
rb_hash_to_hash(VALUE hash)
{
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-to_proc" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_proc → proc
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a <a href="Proc.html"><code>Proc</code></a> which maps keys to values.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = {<span class="ruby-value">a:</span><span class="ruby-value">1</span>, <span class="ruby-value">b:</span><span class="ruby-value">2</span>}
<span class="ruby-identifier">hp</span> = <span class="ruby-identifier">h</span>.<span class="ruby-identifier">to_proc</span>
<span class="ruby-identifier">hp</span>.<span class="ruby-identifier">call</span>(<span class="ruby-value">:a</span>) <span class="ruby-comment">#=> 1</span>
<span class="ruby-identifier">hp</span>.<span class="ruby-identifier">call</span>(<span class="ruby-value">:b</span>) <span class="ruby-comment">#=> 2</span>
<span class="ruby-identifier">hp</span>.<span class="ruby-identifier">call</span>(<span class="ruby-value">:c</span>) <span class="ruby-comment">#=> nil</span>
[<span class="ruby-value">:a</span>, <span class="ruby-value">:b</span>, <span class="ruby-value">:c</span>].<span class="ruby-identifier">map</span>(<span class="ruby-operator">&</span><span class="ruby-identifier">h</span>) <span class="ruby-comment">#=> [1, 2, nil]</span>
</pre>
<div class="method-source-code" id="to_proc-source">
<pre>static VALUE
rb_hash_to_proc(VALUE hash)
{
return rb_func_proc_new(hash_proc_call, hash);
}</pre>
</div>
</div>
</div>
<div id="method-i-to_s" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name">to_s</span><span
class="method-args">()</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Hash.html#method-i-inspect">inspect</a>
</div>
</div>
<div id="method-i-transform_keys" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
transform_keys {|key| block } → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
transform_keys → an_enumerator
</span>
</div>
<div class="method-description">
<p>Returns a new hash with the results of running the block once for every key. This method does not change the values.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">2</span>, <span class="ruby-value">c:</span> <span class="ruby-value">3</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_keys</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">k</span>.<span class="ruby-identifier">to_s</span> } <span class="ruby-comment">#=> { "a" => 1, "b" => 2, "c" => 3 }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_keys</span>(<span class="ruby-operator">&</span><span class="ruby-value">:to_s</span>) <span class="ruby-comment">#=> { "a" => 1, "b" => 2, "c" => 3 }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_keys</span>.<span class="ruby-identifier">with_index</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>, <span class="ruby-identifier">i</span><span class="ruby-operator">|</span> <span class="ruby-node">"#{k}.#{i}"</span> }
<span class="ruby-comment">#=> { "a.0" => 1, "b.1" => 2, "c.2" => 3 }</span>
</pre>
<p>If no block is given, an enumerator is returned instead.</p>
<div class="method-source-code" id="transform_keys-source">
<pre>static VALUE
rb_hash_transform_keys(VALUE hash)
{
VALUE result;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
result = rb_hash_new();
if (!RHASH_EMPTY_P(hash)) {
rb_hash_foreach(hash, transform_keys_i, result);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-transform_keys-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
transform_keys! {|key| block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
transform_keys! → an_enumerator
</span>
</div>
<div class="method-description">
<p>Invokes the given block once for each key in <em>hsh</em>, replacing it with the new key returned by the block, and then returns <em>hsh</em>. This method does not change the values.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">2</span>, <span class="ruby-value">c:</span> <span class="ruby-value">3</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_keys!</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">k</span>.<span class="ruby-identifier">to_s</span> } <span class="ruby-comment">#=> { "a" => 1, "b" => 2, "c" => 3 }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_keys!</span>(<span class="ruby-operator">&</span><span class="ruby-value">:to_sym</span>) <span class="ruby-comment">#=> { a: 1, b: 2, c: 3 }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_keys!</span>.<span class="ruby-identifier">with_index</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">k</span>, <span class="ruby-identifier">i</span><span class="ruby-operator">|</span> <span class="ruby-node">"#{k}.#{i}"</span> }
<span class="ruby-comment">#=> { "a.0" => 1, "b.1" => 2, "c.2" => 3 }</span>
</pre>
<p>If no block is given, an enumerator is returned instead.</p>
<div class="method-source-code" id="transform_keys-21-source">
<pre>static VALUE
rb_hash_transform_keys_bang(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify_check(hash);
if (!RHASH_TABLE_EMPTY_P(hash)) {
long i;
VALUE pairs = rb_hash_flatten(0, NULL, hash);
rb_hash_clear(hash);
for (i = 0; i < RARRAY_LEN(pairs); i += 2) {
VALUE key = RARRAY_AREF(pairs, i), new_key = rb_yield(key),
val = RARRAY_AREF(pairs, i+1);
rb_hash_aset(hash, new_key, val);
}
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-transform_values" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
transform_values {|value| block } → new_hash
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
transform_values → an_enumerator
</span>
</div>
<div class="method-description">
<p>Returns a new hash with the results of running the block once for every value. This method does not change the keys.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">2</span>, <span class="ruby-value">c:</span> <span class="ruby-value">3</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_values</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v</span> <span class="ruby-operator">*</span> <span class="ruby-identifier">v</span> <span class="ruby-operator">+</span> <span class="ruby-value">1</span> } <span class="ruby-comment">#=> { a: 2, b: 5, c: 10 }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_values</span>(<span class="ruby-operator">&</span><span class="ruby-value">:to_s</span>) <span class="ruby-comment">#=> { a: "1", b: "2", c: "3" }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_values</span>.<span class="ruby-identifier">with_index</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">v</span>, <span class="ruby-identifier">i</span><span class="ruby-operator">|</span> <span class="ruby-node">"#{v}.#{i}"</span> }
<span class="ruby-comment">#=> { a: "1.0", b: "2.1", c: "3.2" }</span>
</pre>
<p>If no block is given, an enumerator is returned instead.</p>
<div class="method-source-code" id="transform_values-source">
<pre>static VALUE
rb_hash_transform_values(VALUE hash)
{
VALUE result;
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
result = hash_copy(hash_alloc(rb_cHash), hash);
SET_DEFAULT(result, Qnil);
if (!RHASH_EMPTY_P(hash)) {
rb_hash_stlike_foreach_with_replace(result, transform_values_foreach_func, transform_values_foreach_replace, result);
}
return result;
}</pre>
</div>
</div>
</div>
<div id="method-i-transform_values-21" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
transform_values! {|value| block } → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
transform_values! → an_enumerator
</span>
</div>
<div class="method-description">
<p>Invokes the given block once for each value in <em>hsh</em>, replacing it with the new value returned by the block, and then returns <em>hsh</em>. This method does not change the keys.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-value">a:</span> <span class="ruby-value">1</span>, <span class="ruby-value">b:</span> <span class="ruby-value">2</span>, <span class="ruby-value">c:</span> <span class="ruby-value">3</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_values!</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">v</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v</span> <span class="ruby-operator">*</span> <span class="ruby-identifier">v</span> <span class="ruby-operator">+</span> <span class="ruby-value">1</span> } <span class="ruby-comment">#=> { a: 2, b: 5, c: 10 }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_values!</span>(<span class="ruby-operator">&</span><span class="ruby-value">:to_s</span>) <span class="ruby-comment">#=> { a: "2", b: "5", c: "10" }</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">transform_values!</span>.<span class="ruby-identifier">with_index</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">v</span>, <span class="ruby-identifier">i</span><span class="ruby-operator">|</span> <span class="ruby-node">"#{v}.#{i}"</span> }
<span class="ruby-comment">#=> { a: "2.0", b: "5.1", c: "10.2" }</span>
</pre>
<p>If no block is given, an enumerator is returned instead.</p>
<div class="method-source-code" id="transform_values-21-source">
<pre>static VALUE
rb_hash_transform_values_bang(VALUE hash)
{
RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
rb_hash_modify_check(hash);
if (!RHASH_TABLE_EMPTY_P(hash)) {
rb_hash_stlike_foreach_with_replace(hash, transform_values_foreach_func, transform_values_foreach_replace, hash);
}
return hash;
}</pre>
</div>
</div>
</div>
<div id="method-i-update" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
update(other_hash1, other_hash2, ...) → hsh
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
update(other_hash1, other_hash2, ...) {|key, oldval, newval| block}
</span>
</div>
<div class="method-description">
<p>Adds the contents of the given hashes to the receiver.</p>
<p>If no block is given, entries with duplicate keys are overwritten with the values from each <code>other_hash</code> successively, otherwise the value for each duplicate key is determined by calling the block with the key, its value in the receiver and its value in each <code>other_hash</code>.</p>
<pre class="ruby"><span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200}</span>
<span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span>(<span class="ruby-identifier">h2</span>) <span class="ruby-comment">#=> {"a"=>100, "b"=>246, "c"=>300}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>246, "c"=>300}</span>
<span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h3</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">357</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span>(<span class="ruby-identifier">h2</span>, <span class="ruby-identifier">h3</span>)
<span class="ruby-comment">#=> {"a"=>100, "b"=>357, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>357, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h2</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">246</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h3</span> = { <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">357</span>, <span class="ruby-string">"d"</span> <span class="ruby-operator">=></span> <span class="ruby-value">400</span> }
<span class="ruby-identifier">h1</span>.<span class="ruby-identifier">merge!</span>(<span class="ruby-identifier">h2</span>, <span class="ruby-identifier">h3</span>) {<span class="ruby-operator">|</span><span class="ruby-identifier">key</span>, <span class="ruby-identifier">v1</span>, <span class="ruby-identifier">v2</span><span class="ruby-operator">|</span> <span class="ruby-identifier">v1</span> }
<span class="ruby-comment">#=> {"a"=>100, "b"=>200, "c"=>300, "d"=>400}</span>
<span class="ruby-identifier">h1</span> <span class="ruby-comment">#=> {"a"=>100, "b"=>200, "c"=>300, "d"=>400}</span>
</pre>
<p><a href="Hash.html#method-i-update"><code>Hash#update</code></a> is an alias for <a href="Hash.html#method-i-merge-21"><code>Hash#merge!</code></a>.</p>
<div class="method-source-code" id="update-source">
<pre>static VALUE
rb_hash_update(int argc, VALUE *argv, VALUE self)
{
int i;
bool block_given = rb_block_given_p();
rb_hash_modify(self);
for (i = 0; i < argc; i++){
VALUE hash = to_hash(argv[i]);
if (block_given) {
rb_hash_foreach(hash, rb_hash_update_block_i, self);
}
else {
rb_hash_foreach(hash, rb_hash_update_i, self);
}
}
return self;
}</pre>
</div>
</div>
</div>
<div id="method-i-value-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
value?(value) → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the given value is present for some key in <em>hsh</em>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">value?</span>(<span class="ruby-value">100</span>) <span class="ruby-comment">#=> true</span>
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">value?</span>(<span class="ruby-value">999</span>) <span class="ruby-comment">#=> false</span>
</pre>
<div class="method-source-code" id="value-3F-source">
<pre>static VALUE
rb_hash_has_value(VALUE hash, VALUE val)
{
VALUE data[2];
data[0] = Qfalse;
data[1] = val;
rb_hash_foreach(hash, rb_hash_search_value, (VALUE)data);
return data[0];
}</pre>
</div>
</div>
</div>
<div id="method-i-values" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
values → array
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a new array populated with the values from <em>hsh</em>. See also <a href="Hash.html#method-i-keys"><code>Hash#keys</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"a"</span> <span class="ruby-operator">=></span> <span class="ruby-value">100</span>, <span class="ruby-string">"b"</span> <span class="ruby-operator">=></span> <span class="ruby-value">200</span>, <span class="ruby-string">"c"</span> <span class="ruby-operator">=></span> <span class="ruby-value">300</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">values</span> <span class="ruby-comment">#=> [100, 200, 300]</span>
</pre>
<div class="method-source-code" id="values-source">
<pre>VALUE
rb_hash_values(VALUE hash)
{
VALUE values;
st_index_t size = RHASH_SIZE(hash);
values = rb_ary_new_capa(size);
if (size == 0) return values;
if (ST_DATA_COMPATIBLE_P(VALUE)) {
if (RHASH_AR_TABLE_P(hash)) {
rb_gc_writebarrier_remember(values);
RARRAY_PTR_USE_TRANSIENT(values, ptr, {
size = ar_values(hash, ptr, size);
});
}
else if (RHASH_ST_TABLE_P(hash)) {
st_table *table = RHASH_ST_TABLE(hash);
rb_gc_writebarrier_remember(values);
RARRAY_PTR_USE_TRANSIENT(values, ptr, {
size = st_values(table, ptr, size);
});
}
rb_ary_set_len(values, size);
}
else {
rb_hash_foreach(hash, values_i, values);
}
return values;
}</pre>
</div>
</div>
</div>
<div id="method-i-values_at" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
values_at(key, ...) → array
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Return an array containing the values associated with the given keys. Also see <a href="Hash.html#method-i-select"><code>Hash.select</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">h</span> = { <span class="ruby-string">"cat"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"feline"</span>, <span class="ruby-string">"dog"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"canine"</span>, <span class="ruby-string">"cow"</span> <span class="ruby-operator">=></span> <span class="ruby-string">"bovine"</span> }
<span class="ruby-identifier">h</span>.<span class="ruby-identifier">values_at</span>(<span class="ruby-string">"cow"</span>, <span class="ruby-string">"cat"</span>) <span class="ruby-comment">#=> ["bovine", "feline"]</span>
</pre>
<div class="method-source-code" id="values_at-source">
<pre>VALUE
rb_hash_values_at(int argc, VALUE *argv, VALUE hash)
{
VALUE result = rb_ary_new2(argc);
long i;
for (i=0; i<argc; i++) {
rb_ary_push(result, rb_hash_aref(hash, argv[i]));
}
return result;
}</pre>
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