Class: Hash

Inherits:
Object show all
Includes:
Enumerable
Defined in:
hash.c

Overview

A Hash is a collection of key-value pairs. It is similar to an Array, except that indexing is done via arbitrary keys of any object type, not an integer index. Hashes enumerate their values in the order that the corresponding keys were inserted.

Hashes have a default value that is returned when accessing keys that do not exist in the hash. By default, that value is nil.

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods included from Enumerable

#all?, #any?, #chunk, #collect, #collect_concat, #count, #cycle, #detect, #drop, #drop_while, #each_cons, #each_entry, #each_slice, #each_with_index, #each_with_object, #entries, #find, #find_all, #find_index, #first, #flat_map, #grep, #group_by, #inject, #map, #max, #max_by, #min, #min_by, #minmax, #minmax_by, #none?, #one?, #partition, #reduce, #reverse_each, #slice_before, #sort, #sort_by, #take, #take_while, #zip

Constructor Details

- (Object) new - (Object) new(obj) - (Object) new {|hash, key| ... }

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 new used to create the hash. In the first form, the access returns nil. If obj is specified, this single object will be used for all default values. 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.

h = Hash.new("Go Fish")
h["a"] = 100
h["b"] = 200
h["a"]           #=> 100
h["c"]           #=> "Go Fish"
# The following alters the single default object
h["c"].upcase!   #=> "GO FISH"
h["d"]           #=> "GO FISH"
h.keys           #=> ["a", "b"]

# While this creates a new default object each time
h = Hash.new { |hash, key| hash[key] = "Go Fish: #{key}" }
h["c"]           #=> "Go Fish: c"
h["c"].upcase!   #=> "GO FISH: C"
h["d"]           #=> "Go Fish: d"
h.keys           #=> ["c", "d"]

Overloads:

  • - (Object) new {|hash, key| ... }

    Yields:

    • (hash, key)


# File 'hash.c'

/*
 *  call-seq:
 *     Hash.new                          -> new_hash
 *     Hash.new(obj)                     -> new_hash
 *     Hash.new {|hash, key| block }     -> new_hash
 *
 *  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
 *  <i>obj</i> 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.
 *
 *     h = Hash.new("Go Fish")
 *     h["a"] = 100
 *     h["b"] = 200
 *     h["a"]           #=> 100
 *     h["c"]           #=> "Go Fish"
 *     # The following alters the single default object
 *     h["c"].upcase!   #=> "GO FISH"
 *     h["d"]           #=> "GO FISH"
 *     h.keys           #=> ["a", "b"]
 *
 *     # While this creates a new default object each time
 *     h = Hash.new { |hash, key| hash[key] = "Go Fish: #{key}" }
 *     h["c"]           #=> "Go Fish: c"
 *     h["c"].upcase!   #=> "GO FISH: C"
 *     h["d"]           #=> "Go Fish: d"
 *     h.keys           #=> ["c", "d"]
 *
 */

static VALUE
rb_hash_initialize(int argc, VALUE *argv, VALUE hash)
{
    VALUE ifnone;

    rb_hash_modify(hash);
    if (rb_block_given_p()) {
    if (argc > 0) {
        rb_raise(rb_eArgError, "wrong number of arguments");
    }
    ifnone = rb_block_proc();
    default_proc_arity_check(ifnone);
    RHASH_IFNONE(hash) = ifnone;
    FL_SET(hash, HASH_PROC_DEFAULT);
    }
    else {
    rb_scan_args(argc, argv, "01", &ifnone);
    RHASH_IFNONE(hash) = ifnone;
    }

    return hash;
}

Class Method Details

+ (Object) [](key, value, ...) + (Object) []([ [key, value)) + (Object) [](object)

Creates a new hash populated with the given objects. Equivalent to the literal { key => value, ... }. In the first form, keys and values occur in pairs, so there must be an even number of arguments. 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.

Hash["a", 100, "b", 200]             #=> {"a"=>100, "b"=>200}
Hash[ [ ["a", 100], ["b", 200] ] ]   #=> {"a"=>100, "b"=>200}
Hash["a" => 100, "b" => 200]         #=> {"a"=>100, "b"=>200}


# File 'hash.c'

/*
 *  call-seq:
 *     Hash[ key, value, ... ]         -> new_hash
 *     Hash[ [ [key, value], ... ] ]   -> new_hash
 *     Hash[ object ]                  -> new_hash
 *
 *  Creates a new hash populated with the given objects. Equivalent to
 *  the literal <code>{ <i>key</i> => <i>value</i>, ... }</code>. In the first
 *  form, keys and values occur in pairs, so there must be an even number of arguments.
 *  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.
 *
 *     Hash["a", 100, "b", 200]             #=> {"a"=>100, "b"=>200}
 *     Hash[ [ ["a", 100], ["b", 200] ] ]   #=> {"a"=>100, "b"=>200}
 *     Hash["a" => 100, "b" => 200]         #=> {"a"=>100, "b"=>200}
 */

static VALUE
rb_hash_s_create(int argc, VALUE *argv, VALUE klass)
{
    VALUE hash, tmp;
    int i;

    if (argc == 1) {
    tmp = rb_hash_s_try_convert(Qnil, argv[0]);
    if (!NIL_P(tmp)) {
        hash = hash_alloc(klass);
        if (RHASH(tmp)->ntbl) {
        RHASH(hash)->ntbl = st_copy(RHASH(tmp)->ntbl);
        }
        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 v = rb_check_array_type(RARRAY_PTR(tmp)[i]);
        VALUE key, val = Qnil;

        if (NIL_P(v)) continue;
        switch (RARRAY_LEN(v)) {
          case 2:
            val = RARRAY_PTR(v)[1];
          case 1:
            key = RARRAY_PTR(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);
    for (i=0; i<argc; i+=2) {
        rb_hash_aset(hash, argv[i], argv[i + 1]);
    }

    return hash;
}

+ (Hash?) try_convert(obj)

Try to convert obj into a hash, using to_hash method. Returns converted hash or nil if obj cannot be converted for any reason.

Hash.try_convert({1=>2})   # => {1=>2}
Hash.try_convert("1=>2")   # => nil


# File 'hash.c'

/*
 *  call-seq:
 *     Hash.try_convert(obj) -> hash or nil
 *
 *  Try to convert <i>obj</i> into a hash, using to_hash method.
 *  Returns converted hash or nil if <i>obj</i> cannot be converted
 *  for any reason.
 *
 *     Hash.try_convert({1=>2})   # => {1=>2}
 *     Hash.try_convert("1=>2")   # => nil
 */
static VALUE
rb_hash_s_try_convert(VALUE dummy, VALUE hash)
{
    return rb_check_convert_type(hash, T_HASH, "Hash", "to_hash");
}

Instance Method Details

- (Boolean) ==(other_hash)

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.

h1 = { "a" => 1, "c" => 2 }
h2 = { 7 => 35, "c" => 2, "a" => 1 }
h3 = { "a" => 1, "c" => 2, 7 => 35 }
h4 = { "a" => 1, "d" => 2, "f" => 35 }
h1 == h2   #=> false
h2 == h3   #=> true
h3 == h4   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh == other_hash    -> true or false
 *
 *  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
 *  <code>Object#==</code>) the corresponding elements in the other
 *  hash.
 *
 *     h1 = { "a" => 1, "c" => 2 }
 *     h2 = { 7 => 35, "c" => 2, "a" => 1 }
 *     h3 = { "a" => 1, "c" => 2, 7 => 35 }
 *     h4 = { "a" => 1, "d" => 2, "f" => 35 }
 *     h1 == h2   #=> false
 *     h2 == h3   #=> true
 *     h3 == h4   #=> false
 *
 */

static VALUE
rb_hash_equal(VALUE hash1, VALUE hash2)
{
    return hash_equal(hash1, hash2, FALSE);
}

- (Object) [](key)

Element Reference---Retrieves the value object corresponding to the key object. If not found, returns the default value (see Hash::new for details).

h = { "a" => 100, "b" => 200 }
h["a"]   #=> 100
h["c"]   #=> nil


# File 'hash.c'

/*
 *  call-seq:
 *     hsh[key]    ->  value
 *
 *  Element Reference---Retrieves the <i>value</i> object corresponding
 *  to the <i>key</i> object. If not found, returns the default value (see
 *  <code>Hash::new</code> for details).
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h["a"]   #=> 100
 *     h["c"]   #=> nil
 *
 */

VALUE
rb_hash_aref(VALUE hash, VALUE key)
{
    VALUE val;

    if (!RHASH(hash)->ntbl || !st_lookup(RHASH(hash)->ntbl, key, &val)) {
    return rb_funcall(hash, id_default, 1, key);
    }
    return val;
}

- (Object) []=(key) - (Object) store(key, value)

Element Assignment---Associates the value given by value with the key given by key. key should not have its value changed while it is in use as a key (a String passed as a key will be duplicated and frozen).

h = { "a" => 100, "b" => 200 }
h["a"] = 9
h["c"] = 4
h   #=> {"a"=>9, "b"=>200, "c"=>4}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh[key] = value        -> value
 *     hsh.store(key, value)   -> value
 *
 *  Element Assignment---Associates the value given by
 *  <i>value</i> with the key given by <i>key</i>.
 *  <i>key</i> should not have its value changed while it is in
 *  use as a key (a <code>String</code> passed as a key will be
 *  duplicated and frozen).
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h["a"] = 9
 *     h["c"] = 4
 *     h   #=> {"a"=>9, "b"=>200, "c"=>4}
 *
 */

VALUE
rb_hash_aset(VALUE hash, VALUE key, VALUE val)
{
    rb_hash_modify(hash);
    hash_update(hash, key);
    if (RHASH(hash)->ntbl->type == &identhash || rb_obj_class(key) != rb_cString) {
    st_insert(RHASH(hash)->ntbl, key, val);
    }
    else {
    st_insert2(RHASH(hash)->ntbl, key, val, rb_str_new4);
    }
    return val;
}

- (Array?) assoc(obj)

Searches through the hash comparing obj with the key using ==. Returns the key-value pair (two elements array) or nil if no match is found. See Array#assoc.

h = {"colors"  => ["red", "blue", "green"],
     "letters" => ["a", "b", "c" ]}
h.assoc("letters")  #=> ["letters", ["a", "b", "c"]]
h.assoc("foo")      #=> nil


# File 'hash.c'

/*
 *  call-seq:
 *     hash.assoc(obj)   ->  an_array  or  nil
 *
 *  Searches through the hash comparing _obj_ with the key using <code>==</code>.
 *  Returns the key-value pair (two elements array) or +nil+
 *  if no match is found.  See <code>Array#assoc</code>.
 *
 *     h = {"colors"  => ["red", "blue", "green"],
 *          "letters" => ["a", "b", "c" ]}
 *     h.assoc("letters")  #=> ["letters", ["a", "b", "c"]]
 *     h.assoc("foo")      #=> nil
 */

VALUE
rb_hash_assoc(VALUE hash, VALUE obj)
{
    VALUE args[2];

    args[0] = obj;
    args[1] = Qnil;
    rb_hash_foreach(hash, assoc_i, (VALUE)args);
    return args[1];
}

- (Hash) clear

Removes all key-value pairs from hsh.

h = { "a" => 100, "b" => 200 }   #=> {"a"=>100, "b"=>200}
h.clear                          #=> {}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.clear -> hsh
 *
 *  Removes all key-value pairs from <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }   #=> {"a"=>100, "b"=>200}
 *     h.clear                          #=> {}
 *
 */

static VALUE
rb_hash_clear(VALUE hash)
{
    rb_hash_modify_check(hash);
    if (!RHASH(hash)->ntbl)
        return hash;
    if (RHASH(hash)->ntbl->num_entries > 0) {
    if (RHASH(hash)->iter_lev > 0)
        rb_hash_foreach(hash, clear_i, 0);
    else
        st_clear(RHASH(hash)->ntbl);
    }

    return hash;
}

- (Hash) compare_by_identity

Makes hsh compare its keys by their identity, i.e. it will consider exact same objects as same keys.

h1 = { "a" => 100, "b" => 200, :c => "c" }
h1["a"]        #=> 100
h1.compare_by_identity
h1.compare_by_identity? #=> true
h1["a"]        #=> nil  # different objects.
h1[:c]         #=> "c"  # same symbols are all same.


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.compare_by_identity -> hsh
 *
 *  Makes <i>hsh</i> compare its keys by their identity, i.e. it
 *  will consider exact same objects as same keys.
 *
 *     h1 = { "a" => 100, "b" => 200, :c => "c" }
 *     h1["a"]        #=> 100
 *     h1.compare_by_identity
 *     h1.compare_by_identity? #=> true
 *     h1["a"]        #=> nil  # different objects.
 *     h1[:c]         #=> "c"  # same symbols are all same.
 *
 */

static VALUE
rb_hash_compare_by_id(VALUE hash)
{
    rb_hash_modify(hash);
    RHASH(hash)->ntbl->type = &identhash;
    rb_hash_rehash(hash);
    return hash;
}

- (Boolean) compare_by_identity?

Returns true if hsh will compare its keys by their identity. Also see Hash#compare_by_identity.



# File 'hash.c'

/*
 *  call-seq:
 *     hsh.compare_by_identity? -> true or false
 *
 *  Returns <code>true</code> if <i>hsh</i> will compare its keys by
 *  their identity.  Also see <code>Hash#compare_by_identity</code>.
 *
 */

static VALUE
rb_hash_compare_by_id_p(VALUE hash)
{
    if (!RHASH(hash)->ntbl)
        return Qfalse;
    if (RHASH(hash)->ntbl->type == &identhash) {
    return Qtrue;
    }
    return Qfalse;
}

- (Object) default(key = nil)

Returns the default value, the value that would be returned by hsh if key did not exist in hsh. See also Hash::new and Hash#default=.

h = Hash.new                            #=> {}
h.default                               #=> nil
h.default(2)                            #=> nil

h = Hash.new("cat")                     #=> {}
h.default                               #=> "cat"
h.default(2)                            #=> "cat"

h = Hash.new {|h,k| h[k] = k.to_i*10}   #=> {}
h.default                               #=> nil
h.default(2)                            #=> 20


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.default(key=nil)   -> obj
 *
 *  Returns the default value, the value that would be returned by
 *  <i>hsh</i>[<i>key</i>] if <i>key</i> did not exist in <i>hsh</i>.
 *  See also <code>Hash::new</code> and <code>Hash#default=</code>.
 *
 *     h = Hash.new                            #=> {}
 *     h.default                               #=> nil
 *     h.default(2)                            #=> nil
 *
 *     h = Hash.new("cat")                     #=> {}
 *     h.default                               #=> "cat"
 *     h.default(2)                            #=> "cat"
 *
 *     h = Hash.new {|h,k| h[k] = k.to_i*10}   #=> {}
 *     h.default                               #=> nil
 *     h.default(2)                            #=> 20
 */

static VALUE
rb_hash_default(int argc, VALUE *argv, VALUE hash)
{
    VALUE key, ifnone;

    rb_scan_args(argc, argv, "01", &key);
    ifnone = RHASH_IFNONE(hash);
    if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
    if (argc == 0) return Qnil;
    return rb_funcall(ifnone, id_yield, 2, hash, key);
    }
    return ifnone;
}

- (Object) default=(obj)

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 Proc that will be executed on each key lookup.

h = { "a" => 100, "b" => 200 }
h.default = "Go fish"
h["a"]     #=> 100
h["z"]     #=> "Go fish"
# This doesn't do what you might hope...
h.default = proc do |hash, key|
  hash[key] = key + key
end
h[2]       #=> #<Proc:0x401b3948@-:6>
h["cat"]   #=> #<Proc:0x401b3948@-:6>


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.default = obj     -> obj
 *
 *  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
 *  <code>Proc</code> that will be executed on each key lookup.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.default = "Go fish"
 *     h["a"]     #=> 100
 *     h["z"]     #=> "Go fish"
 *     # This doesn't do what you might hope...
 *     h.default = proc do |hash, key|
 *       hash[key] = key + key
 *     end
 *     h[2]       #=> #<Proc:0x401b3948@-:6>
 *     h["cat"]   #=> #<Proc:0x401b3948@-:6>
 */

static VALUE
rb_hash_set_default(VALUE hash, VALUE ifnone)
{
    rb_hash_modify(hash);
    RHASH_IFNONE(hash) = ifnone;
    FL_UNSET(hash, HASH_PROC_DEFAULT);
    return ifnone;
}

- (Object) default_proc

If Hash::new was invoked with a block, return that block, otherwise return nil.

h = Hash.new {|h,k| h[k] = k*k }   #=> {}
p = h.default_proc                 #=> #<Proc:0x401b3d08@-:1>
a = []                             #=> []
p.call(a, 2)
a                                  #=> [nil, nil, 4]


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.default_proc -> anObject
 *
 *  If <code>Hash::new</code> was invoked with a block, return that
 *  block, otherwise return <code>nil</code>.
 *
 *     h = Hash.new {|h,k| h[k] = k*k }   #=> {}
 *     p = h.default_proc                 #=> #<Proc:0x401b3d08@-:1>
 *     a = []                             #=> []
 *     p.call(a, 2)
 *     a                                  #=> [nil, nil, 4]
 */


static VALUE
rb_hash_default_proc(VALUE hash)
{
    if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
    return RHASH_IFNONE(hash);
    }
    return Qnil;
}

- (Proc) default_proc=(proc_obj)

Sets the default proc to be executed on each key lookup.

h.default_proc = proc do |hash, key|
  hash[key] = key + key
end
h[2]       #=> 4
h["cat"]   #=> "catcat"


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.default_proc = proc_obj     -> proc_obj
 *
 *  Sets the default proc to be executed on each key lookup.
 *
 *     h.default_proc = proc do |hash, key|
 *       hash[key] = key + key
 *     end
 *     h[2]       #=> 4
 *     h["cat"]   #=> "catcat"
 */

static VALUE
rb_hash_set_default_proc(VALUE hash, VALUE proc)
{
    VALUE b;

    rb_hash_modify(hash);
    b = rb_check_convert_type(proc, T_DATA, "Proc", "to_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;
    default_proc_arity_check(proc);
    RHASH_IFNONE(hash) = proc;
    FL_SET(hash, HASH_PROC_DEFAULT);
    return proc;
}

- (Object) delete(key) - (Object) delete(key) {|key| ... }

Deletes and returns a key-value pair from hsh whose key is equal to key. If the key is not found, returns the default value. If the optional code block is given and the key is not found, pass in the key and return the result of block.

h = { "a" => 100, "b" => 200 }
h.delete("a")                              #=> 100
h.delete("z")                              #=> nil
h.delete("z") { |el| "#{el} not found" }   #=> "z not found"

Overloads:

  • - (Object) delete(key) {|key| ... }

    Yields:

    • (key)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.delete(key)                   -> value
 *     hsh.delete(key) {| key | block }  -> value
 *
 *  Deletes and returns a key-value pair from <i>hsh</i> whose key is
 *  equal to <i>key</i>. If the key is not found, returns the
 *  <em>default value</em>. If the optional code block is given and the
 *  key is not found, pass in the key and return the result of
 *  <i>block</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.delete("a")                              #=> 100
 *     h.delete("z")                              #=> nil
 *     h.delete("z") { |el| "#{el} not found" }   #=> "z not found"
 *
 */

VALUE
rb_hash_delete(VALUE hash, VALUE key)
{
    VALUE val;

    rb_hash_modify(hash);
    val = rb_hash_delete_key(hash, key);
    if (val != Qundef) return val;
    if (rb_block_given_p()) {
    return rb_yield(key);
    }
    return Qnil;
}

- (Hash) delete_if {|key, value| ... } - (Object) delete_if

Deletes every key-value pair from hsh for which block evaluates to true.

If no block is given, an enumerator is returned instead.

h = { "a" => 100, "b" => 200, "c" => 300 }
h.delete_if {|key, value| key >= "b" }   #=> {"a"=>100}

Overloads:

  • - (Hash) delete_if {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.delete_if {| key, value | block }  -> hsh
 *     hsh.delete_if                          -> an_enumerator
 *
 *  Deletes every key-value pair from <i>hsh</i> for which <i>block</i>
 *  evaluates to <code>true</code>.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 *     h = { "a" => 100, "b" => 200, "c" => 300 }
 *     h.delete_if {|key, value| key >= "b" }   #=> {"a"=>100}
 *
 */

VALUE
rb_hash_delete_if(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_modify(hash);
    rb_hash_foreach(hash, delete_if_i, hash);
    return hash;
}

- (Hash) each {|key, value| ... } - (Hash) each_pair {|key, value| ... } - (Object) each - (Object) each_pair

Calls block once for each key in hsh, passing the key-value pair as parameters.

If no block is given, an enumerator is returned instead.

h = { "a" => 100, "b" => 200 }
h.each {|key, value| puts "#{key} is #{value}" }

produces:

a is 100
b is 200

Overloads:

  • - (Hash) each {|key, value| ... }

    Yields:

    • (key, value)
  • - (Hash) each_pair {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.each      {| key, value | block } -> hsh
 *     hsh.each_pair {| key, value | block } -> hsh
 *     hsh.each                              -> an_enumerator
 *     hsh.each_pair                         -> an_enumerator
 *
 *  Calls <i>block</i> once for each key in <i>hsh</i>, passing the key-value
 *  pair as parameters.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.each {|key, value| puts "#{key} is #{value}" }
 *
 *  <em>produces:</em>
 *
 *     a is 100
 *     b is 200
 *
 */

static VALUE
rb_hash_each_pair(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_foreach(hash, each_pair_i, 0);
    return hash;
}

- (Hash) each_key {|key| ... } - (Object) each_key

Calls block once for each key in hsh, passing the key as a parameter.

If no block is given, an enumerator is returned instead.

h = { "a" => 100, "b" => 200 }
h.each_key {|key| puts key }

produces:

a
b

Overloads:

  • - (Hash) each_key {|key| ... }

    Yields:

    • (key)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.each_key {| key | block } -> hsh
 *     hsh.each_key                  -> an_enumerator
 *
 *  Calls <i>block</i> once for each key in <i>hsh</i>, passing the key
 *  as a parameter.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.each_key {|key| puts key }
 *
 *  <em>produces:</em>
 *
 *     a
 *     b
 */
static VALUE
rb_hash_each_key(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_foreach(hash, each_key_i, 0);
    return hash;
}

- (Hash) each {|key, value| ... } - (Hash) each_pair {|key, value| ... } - (Object) each - (Object) each_pair

Calls block once for each key in hsh, passing the key-value pair as parameters.

If no block is given, an enumerator is returned instead.

h = { "a" => 100, "b" => 200 }
h.each {|key, value| puts "#{key} is #{value}" }

produces:

a is 100
b is 200

Overloads:

  • - (Hash) each {|key, value| ... }

    Yields:

    • (key, value)
  • - (Hash) each_pair {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.each      {| key, value | block } -> hsh
 *     hsh.each_pair {| key, value | block } -> hsh
 *     hsh.each                              -> an_enumerator
 *     hsh.each_pair                         -> an_enumerator
 *
 *  Calls <i>block</i> once for each key in <i>hsh</i>, passing the key-value
 *  pair as parameters.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.each {|key, value| puts "#{key} is #{value}" }
 *
 *  <em>produces:</em>
 *
 *     a is 100
 *     b is 200
 *
 */

static VALUE
rb_hash_each_pair(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_foreach(hash, each_pair_i, 0);
    return hash;
}

- (Hash) each_value {|value| ... } - (Object) each_value

Calls block once for each key in hsh, passing the value as a parameter.

If no block is given, an enumerator is returned instead.

h = { "a" => 100, "b" => 200 }
h.each_value {|value| puts value }

produces:

100
200

Overloads:

  • - (Hash) each_value {|value| ... }

    Yields:

    • (value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.each_value {| value | block } -> hsh
 *     hsh.each_value                    -> an_enumerator
 *
 *  Calls <i>block</i> once for each key in <i>hsh</i>, passing the
 *  value as a parameter.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.each_value {|value| puts value }
 *
 *  <em>produces:</em>
 *
 *     100
 *     200
 */

static VALUE
rb_hash_each_value(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_foreach(hash, each_value_i, 0);
    return hash;
}

- (Boolean) empty?

Returns true if hsh contains no key-value pairs.

{}.empty?   #=> true


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.empty?    -> true or false
 *
 *  Returns <code>true</code> if <i>hsh</i> contains no key-value pairs.
 *
 *     {}.empty?   #=> true
 *
 */

static VALUE
rb_hash_empty_p(VALUE hash)
{
    return RHASH_EMPTY_P(hash) ? Qtrue : Qfalse;
}

- (Boolean) eql?(other)

Returns true if hash and other are both hashes with the same content.



# File 'hash.c'

/*
 *  call-seq:
 *     hash.eql?(other)  -> true or false
 *
 *  Returns <code>true</code> if <i>hash</i> and <i>other</i> are
 *  both hashes with the same content.
 */

static VALUE
rb_hash_eql(VALUE hash1, VALUE hash2)
{
    return hash_equal(hash1, hash2, TRUE);
}

- (Object) fetch(key[, default]) - (Object) fetch(key) {|key| ... }

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 an KeyError exception; if default is given, then that will be returned; if the optional code block is specified, then that will be run and its result returned.

h = { "a" => 100, "b" => 200 }
h.fetch("a")                            #=> 100
h.fetch("z", "go fish")                 #=> "go fish"
h.fetch("z") { |el| "go fish, #{el}"}   #=> "go fish, z"

The following example shows that an exception is raised if the key is not found and a default value is not supplied.

h = { "a" => 100, "b" => 200 }
h.fetch("z")

produces:

prog.rb:2:in `fetch': key not found (KeyError)
 from prog.rb:2

Overloads:

  • - (Object) fetch(key) {|key| ... }

    Yields:

    • (key)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.fetch(key [, default] )       -> obj
 *     hsh.fetch(key) {| key | block }   -> obj
 *
 *  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 an <code>KeyError</code> exception; if <i>default</i> is
 *  given, then that will be returned; if the optional code block is
 *  specified, then that will be run and its result returned.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.fetch("a")                            #=> 100
 *     h.fetch("z", "go fish")                 #=> "go fish"
 *     h.fetch("z") { |el| "go fish, #{el}"}   #=> "go fish, z"
 *
 *  The following example shows that an exception is raised if the key
 *  is not found and a default value is not supplied.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.fetch("z")
 *
 *  <em>produces:</em>
 *
 *     prog.rb:2:in `fetch': key not found (KeyError)
 *      from prog.rb:2
 *
 */

static VALUE
rb_hash_fetch_m(int argc, VALUE *argv, VALUE hash)
{
    VALUE key, if_none;
    VALUE val;
    long block_given;

    rb_scan_args(argc, argv, "11", &key, &if_none);

    block_given = rb_block_given_p();
    if (block_given && argc == 2) {
    rb_warn("block supersedes default value argument");
    }
    if (!RHASH(hash)->ntbl || !st_lookup(RHASH(hash)->ntbl, key, &val)) {
    if (block_given) return rb_yield(key);
    if (argc == 1) {
        VALUE desc = rb_protect(rb_inspect, key, 0);
        if (NIL_P(desc) || RSTRING_LEN(desc) > 65) {
        desc = rb_any_to_s(key);
        }
        rb_raise(rb_eKeyError, "key not found: %s", RSTRING_PTR(desc));
    }
    return if_none;
    }
    return val;
}

- (Array) flatten - (Array) flatten(level)

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 Array#flatten, this method does not flatten recursively by default. The optional level argument determines the level of recursion to flatten.

a =  {1=> "one", 2 => [2,"two"], 3 => "three"}
a.flatten    # => [1, "one", 2, [2, "two"], 3, "three"]
a.flatten(2) # => [1, "one", 2, 2, "two", 3, "three"]


# File 'hash.c'

/*
 *  call-seq:
 *     hash.flatten -> an_array
 *     hash.flatten(level) -> an_array
 *
 *  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 Array#flatten, this
 *  method does not flatten recursively by default.  The optional
 *  <i>level</i> argument determines the level of recursion to flatten.
 *
 *     a =  {1=> "one", 2 => [2,"two"], 3 => "three"}
 *     a.flatten    # => [1, "one", 2, [2, "two"], 3, "three"]
 *     a.flatten(2) # => [1, "one", 2, 2, "two", 3, "three"]
 */

static VALUE
rb_hash_flatten(int argc, VALUE *argv, VALUE hash)
{
    VALUE ary, tmp;

    ary = rb_hash_to_a(hash);
    if (argc == 0) {
    argc = 1;
    tmp = INT2FIX(1);
    argv = &tmp;
    }
    rb_funcall2(ary, rb_intern("flatten!"), argc, argv);
    return ary;
}

- (Boolean) has_key?(key) - (Boolean) include?(key) - (Boolean) key?(key) - (Boolean) member?(key)

Returns true if the given key is present in hsh.

h = { "a" => 100, "b" => 200 }
h.has_key?("a")   #=> true
h.has_key?("z")   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.has_key?(key)    -> true or false
 *     hsh.include?(key)    -> true or false
 *     hsh.key?(key)        -> true or false
 *     hsh.member?(key)     -> true or false
 *
 *  Returns <code>true</code> if the given key is present in <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.has_key?("a")   #=> true
 *     h.has_key?("z")   #=> false
 *
 */

static VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
    if (!RHASH(hash)->ntbl)
        return Qfalse;
    if (st_lookup(RHASH(hash)->ntbl, key, 0)) {
    return Qtrue;
    }
    return Qfalse;
}

- (Boolean) has_value?(value) - (Boolean) value?(value)

Returns true if the given value is present for some key in hsh.

h = { "a" => 100, "b" => 200 }
h.has_value?(100)   #=> true
h.has_value?(999)   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.has_value?(value)    -> true or false
 *     hsh.value?(value)        -> true or false
 *
 *  Returns <code>true</code> if the given value is present for some key
 *  in <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.has_value?(100)   #=> true
 *     h.has_value?(999)   #=> false
 */

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];
}

- (Fixnum) hash

Compute a hash-code for this hash. Two hashes with the same content will have the same hash code (and will compare using eql?).



# File 'hash.c'

/*
 *  call-seq:
 *     hsh.hash   -> fixnum
 *
 *  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>).
 */

static VALUE
rb_hash_hash(VALUE hash)
{
    return rb_exec_recursive_outer(recursive_hash, hash, 0);
}

- (Boolean) has_key?(key) - (Boolean) include?(key) - (Boolean) key?(key) - (Boolean) member?(key)

Returns true if the given key is present in hsh.

h = { "a" => 100, "b" => 200 }
h.has_key?("a")   #=> true
h.has_key?("z")   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.has_key?(key)    -> true or false
 *     hsh.include?(key)    -> true or false
 *     hsh.key?(key)        -> true or false
 *     hsh.member?(key)     -> true or false
 *
 *  Returns <code>true</code> if the given key is present in <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.has_key?("a")   #=> true
 *     h.has_key?("z")   #=> false
 *
 */

static VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
    if (!RHASH(hash)->ntbl)
        return Qfalse;
    if (st_lookup(RHASH(hash)->ntbl, key, 0)) {
    return Qtrue;
    }
    return Qfalse;
}

- (Object) index

:nodoc:



# File 'hash.c'

/* :nodoc: */
static VALUE
rb_hash_index(VALUE hash, VALUE value)
{
    rb_warn("Hash#index is deprecated; use Hash#key");
    return rb_hash_key(hash, value);
}

- (Hash) replace(other_hash)

Replaces the contents of hsh with the contents of other_hash.

h = { "a" => 100, "b" => 200 }
h.replace({ "c" => 300, "d" => 400 })   #=> {"c"=>300, "d"=>400}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.replace(other_hash) -> hsh
 *
 *  Replaces the contents of <i>hsh</i> with the contents of
 *  <i>other_hash</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.replace({ "c" => 300, "d" => 400 })   #=> {"c"=>300, "d"=>400}
 *
 */

static VALUE
rb_hash_replace(VALUE hash, VALUE hash2)
{
    rb_hash_modify_check(hash);
    hash2 = to_hash(hash2);
    if (hash == hash2) return hash;
    rb_hash_clear(hash);
    if (RHASH(hash2)->ntbl) {
    rb_hash_tbl(hash);
    RHASH(hash)->ntbl->type = RHASH(hash2)->ntbl->type;
    }
    rb_hash_foreach(hash2, replace_i, hash);
    RHASH_IFNONE(hash) = RHASH_IFNONE(hash2);
    if (FL_TEST(hash2, HASH_PROC_DEFAULT)) {
    FL_SET(hash, HASH_PROC_DEFAULT);
    }
    else {
    FL_UNSET(hash, HASH_PROC_DEFAULT);
    }

    return hash;
}

- (String) to_s - (String) inspect

Return the contents of this hash as a string.

h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300  }
h.to_s   #=> "{\"c\"=>300, \"a\"=>100, \"d\"=>400}"


# File 'hash.c'

/*
 * call-seq:
 *   hsh.to_s     -> string
 *   hsh.inspect  -> string
 *
 * Return the contents of this hash as a string.
 *
 *     h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300  }
 *     h.to_s   #=> "{\"c\"=>300, \"a\"=>100, \"d\"=>400}"
 */

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);
}

- (Object) invert

Returns a new hash created by using hsh's values as keys, and the keys as values.

h = { "n" => 100, "m" => 100, "y" => 300, "d" => 200, "a" => 0 }
h.invert   #=> {0=>"a", 100=>"m", 200=>"d", 300=>"y"}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.invert -> new_hash
 *
 *  Returns a new hash created by using <i>hsh</i>'s values as keys, and
 *  the keys as values.
 *
 *     h = { "n" => 100, "m" => 100, "y" => 300, "d" => 200, "a" => 0 }
 *     h.invert   #=> {0=>"a", 100=>"m", 200=>"d", 300=>"y"}
 *
 */

static VALUE
rb_hash_invert(VALUE hash)
{
    VALUE h = rb_hash_new();

    rb_hash_foreach(hash, rb_hash_invert_i, h);
    return h;

- (Hash) keep_if {|key, value| ... } - (Object) keep_if

Deletes every key-value pair from hsh for which block evaluates to false.

If no block is given, an enumerator is returned instead.

Overloads:

  • - (Hash) keep_if {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.keep_if {| key, value | block }  -> hsh
 *     hsh.keep_if                          -> an_enumerator
 *
 *  Deletes every key-value pair from <i>hsh</i> for which <i>block</i>
 *  evaluates to false.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 */

VALUE
rb_hash_keep_if(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_modify(hash);
    rb_hash_foreach(hash, keep_if_i, hash);
    return hash;
}

- (Object) key(value)

Returns the key for a given value. If not found, returns nil.

h = { "a" => 100, "b" => 200 }
h.key(200)   #=> "b"
h.key(999)   #=> nil


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.key(value)    -> key
 *
 *  Returns the key for a given value. If not found, returns <code>nil</code>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.key(200)   #=> "b"
 *     h.key(999)   #=> nil
 *
 */

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];
}

- (Boolean) has_key?(key) - (Boolean) include?(key) - (Boolean) key?(key) - (Boolean) member?(key)

Returns true if the given key is present in hsh.

h = { "a" => 100, "b" => 200 }
h.has_key?("a")   #=> true
h.has_key?("z")   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.has_key?(key)    -> true or false
 *     hsh.include?(key)    -> true or false
 *     hsh.key?(key)        -> true or false
 *     hsh.member?(key)     -> true or false
 *
 *  Returns <code>true</code> if the given key is present in <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.has_key?("a")   #=> true
 *     h.has_key?("z")   #=> false
 *
 */

static VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
    if (!RHASH(hash)->ntbl)
        return Qfalse;
    if (st_lookup(RHASH(hash)->ntbl, key, 0)) {
    return Qtrue;
    }
    return Qfalse;
}

- (Array) keys

Returns a new array populated with the keys from this hash. See also Hash#values.

h = { "a" => 100, "b" => 200, "c" => 300, "d" => 400 }
h.keys   #=> ["a", "b", "c", "d"]


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.keys    -> array
 *
 *  Returns a new array populated with the keys from this hash. See also
 *  <code>Hash#values</code>.
 *
 *     h = { "a" => 100, "b" => 200, "c" => 300, "d" => 400 }
 *     h.keys   #=> ["a", "b", "c", "d"]
 *
 */

static VALUE
rb_hash_keys(VALUE hash)
{
    VALUE ary;

    ary = rb_ary_new();
    rb_hash_foreach(hash, keys_i, ary);

    return ary;
}

- (Fixnum) length - (Fixnum) size

Returns the number of key-value pairs in the hash.

h = { "d" => 100, "a" => 200, "v" => 300, "e" => 400 }
h.length        #=> 4
h.delete("a")   #=> 200
h.length        #=> 3


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.length    ->  fixnum
 *     hsh.size      ->  fixnum
 *
 *  Returns the number of key-value pairs in the hash.
 *
 *     h = { "d" => 100, "a" => 200, "v" => 300, "e" => 400 }
 *     h.length        #=> 4
 *     h.delete("a")   #=> 200
 *     h.length        #=> 3
 */

static VALUE
rb_hash_size(VALUE hash)
{
    if (!RHASH(hash)->ntbl)
        return INT2FIX(0);
    return INT2FIX(RHASH(hash)->ntbl->num_entries);
}

- (Boolean) has_key?(key) - (Boolean) include?(key) - (Boolean) key?(key) - (Boolean) member?(key)

Returns true if the given key is present in hsh.

h = { "a" => 100, "b" => 200 }
h.has_key?("a")   #=> true
h.has_key?("z")   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.has_key?(key)    -> true or false
 *     hsh.include?(key)    -> true or false
 *     hsh.key?(key)        -> true or false
 *     hsh.member?(key)     -> true or false
 *
 *  Returns <code>true</code> if the given key is present in <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.has_key?("a")   #=> true
 *     h.has_key?("z")   #=> false
 *
 */

static VALUE
rb_hash_has_key(VALUE hash, VALUE key)
{
    if (!RHASH(hash)->ntbl)
        return Qfalse;
    if (st_lookup(RHASH(hash)->ntbl, key, 0)) {
    return Qtrue;
    }
    return Qfalse;
}

- (Object) merge(other_hash) - (Object) merge(other_hash) {|key, oldval, newval| ... }

Returns a new hash containing the contents of other_hash and the contents of hsh. If no block is specified, the value for entries with duplicate keys will be that of other_hash. Otherwise the value for each duplicate key is determined by calling the block with the key, its value in hsh and its value in other_hash.

h1 = { "a" => 100, "b" => 200 }
h2 = { "b" => 254, "c" => 300 }
h1.merge(h2)   #=> {"a"=>100, "b"=>254, "c"=>300}
h1.merge(h2){|key, oldval, newval| newval - oldval}
               #=> {"a"=>100, "b"=>54,  "c"=>300}
h1             #=> {"a"=>100, "b"=>200}

Overloads:

  • - (Object) merge(other_hash) {|key, oldval, newval| ... }

    Yields:

    • (key, oldval, newval)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.merge(other_hash)                              -> new_hash
 *     hsh.merge(other_hash){|key, oldval, newval| block} -> new_hash
 *
 *  Returns a new hash containing the contents of <i>other_hash</i> and
 *  the contents of <i>hsh</i>. If no block is specified, the value for
 *  entries with duplicate keys will be that of <i>other_hash</i>. Otherwise
 *  the value for each duplicate key is determined by calling the block
 *  with the key, its value in <i>hsh</i> and its value in <i>other_hash</i>.
 *
 *     h1 = { "a" => 100, "b" => 200 }
 *     h2 = { "b" => 254, "c" => 300 }
 *     h1.merge(h2)   #=> {"a"=>100, "b"=>254, "c"=>300}
 *     h1.merge(h2){|key, oldval, newval| newval - oldval}
 *                    #=> {"a"=>100, "b"=>54,  "c"=>300}
 *     h1             #=> {"a"=>100, "b"=>200}
 *
 */

static VALUE
rb_hash_merge(VALUE hash1, VALUE hash2)
{
    return rb_hash_update(rb_obj_dup(hash1), hash2);
}

- (Hash) merge!(other_hash) - (Hash) update(other_hash) - (Hash) merge!(other_hash) {|key, oldval, newval| ... } - (Hash) update(other_hash) {|key, oldval, newval| ... }

Adds the contents of other_hash to hsh. If no block is specified, entries with duplicate keys are overwritten with the values from other_hash, otherwise the value of each duplicate key is determined by calling the block with the key, its value in hsh and its value in other_hash.

h1 = { "a" => 100, "b" => 200 }
h2 = { "b" => 254, "c" => 300 }
h1.merge!(h2)   #=> {"a"=>100, "b"=>254, "c"=>300}

h1 = { "a" => 100, "b" => 200 }
h2 = { "b" => 254, "c" => 300 }
h1.merge!(h2) { |key, v1, v2| v1 }
                #=> {"a"=>100, "b"=>200, "c"=>300}

Overloads:

  • - (Hash) merge!(other_hash) {|key, oldval, newval| ... }

    Yields:

    • (key, oldval, newval)
  • - (Hash) update(other_hash) {|key, oldval, newval| ... }

    Yields:

    • (key, oldval, newval)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.merge!(other_hash)                                 -> hsh
 *     hsh.update(other_hash)                                 -> hsh
 *     hsh.merge!(other_hash){|key, oldval, newval| block}    -> hsh
 *     hsh.update(other_hash){|key, oldval, newval| block}    -> hsh
 *
 *  Adds the contents of <i>other_hash</i> to <i>hsh</i>.  If no
 *  block is specified, entries with duplicate keys are overwritten
 *  with the values from <i>other_hash</i>, otherwise the value
 *  of each duplicate key is determined by calling the block with
 *  the key, its value in <i>hsh</i> and its value in <i>other_hash</i>.
 *
 *     h1 = { "a" => 100, "b" => 200 }
 *     h2 = { "b" => 254, "c" => 300 }
 *     h1.merge!(h2)   #=> {"a"=>100, "b"=>254, "c"=>300}
 *
 *     h1 = { "a" => 100, "b" => 200 }
 *     h2 = { "b" => 254, "c" => 300 }
 *     h1.merge!(h2) { |key, v1, v2| v1 }
 *                     #=> {"a"=>100, "b"=>200, "c"=>300}
 */

static VALUE
rb_hash_update(VALUE hash1, VALUE hash2)
{
    rb_hash_modify(hash1);
    hash2 = to_hash(hash2);
    if (rb_block_given_p()) {
    rb_hash_foreach(hash2, rb_hash_update_block_i, hash1);
    }
    else {
    rb_hash_foreach(hash2, rb_hash_update_i, hash1);
    }
    return hash1;
}

- (Array?) rassoc(key)

Searches through the hash comparing obj with the value using ==. Returns the first key-value pair (two-element array) that matches. See also Array#rassoc.

a = {1=> "one", 2 => "two", 3 => "three", "ii" => "two"}
a.rassoc("two")    #=> [2, "two"]
a.rassoc("four")   #=> nil


# File 'hash.c'

/*
 *  call-seq:
 *     hash.rassoc(key) -> an_array or nil
 *
 *  Searches through the hash comparing _obj_ with the value using <code>==</code>.
 *  Returns the first key-value pair (two-element array) that matches. See
 *  also <code>Array#rassoc</code>.
 *
 *     a = {1=> "one", 2 => "two", 3 => "three", "ii" => "two"}
 *     a.rassoc("two")    #=> [2, "two"]
 *     a.rassoc("four")   #=> nil
 */

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];
}

- (Hash) rehash

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 hsh. If Hash#rehash is called while an iterator is traversing the hash, an RuntimeError will be raised in the iterator.

a = [ "a", "b" ]
c = [ "c", "d" ]
h = { a => 100, c => 300 }
h[a]       #=> 100
a[0] = "z"
h[a]       #=> nil
h.rehash   #=> {["z", "b"]=>100, ["c", "d"]=>300}
h[a]       #=> 100


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.rehash -> hsh
 *
 *  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 <i>hsh</i>. If <code>Hash#rehash</code> is
 *  called while an iterator is traversing the hash, an
 *  <code>RuntimeError</code> will be raised in the iterator.
 *
 *     a = [ "a", "b" ]
 *     c = [ "c", "d" ]
 *     h = { a => 100, c => 300 }
 *     h[a]       #=> 100
 *     a[0] = "z"
 *     h[a]       #=> nil
 *     h.rehash   #=> {["z", "b"]=>100, ["c", "d"]=>300}
 *     h[a]       #=> 100
 */

static VALUE
rb_hash_rehash(VALUE hash)
{
    st_table *tbl;

    if (RHASH(hash)->iter_lev > 0) {
    rb_raise(rb_eRuntimeError, "rehash during iteration");
    }
    rb_hash_modify_check(hash);
    if (!RHASH(hash)->ntbl)
        return hash;
    tbl = st_init_table_with_size(RHASH(hash)->ntbl->type, RHASH(hash)->ntbl->num_entries);
    rb_hash_foreach(hash, rb_hash_rehash_i, (VALUE)tbl);
    st_free_table(RHASH(hash)->ntbl);
    RHASH(hash)->ntbl = tbl;

    return hash;
}

- (Hash) reject {|key, value| ... }

Same as Hash#delete_if, but works on (and returns) a copy of the hsh. Equivalent to hsh.dup.delete_if.

Yields:

  • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.reject {| key, value | block }  -> a_hash
 *
 *  Same as <code>Hash#delete_if</code>, but works on (and returns) a
 *  copy of the <i>hsh</i>. Equivalent to
 *  <code><i>hsh</i>.dup.delete_if</code>.
 *
 */

static VALUE
rb_hash_reject(VALUE hash)
{
    return rb_hash_delete_if(rb_obj_dup(hash));
}

- (Hash?) reject! {|key, value| ... } - (Object) reject!

Equivalent to Hash#delete_if, but returns nil if no changes were made.

Overloads:

  • - (Hash?) reject! {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.reject! {| key, value | block }  -> hsh or nil
 *     hsh.reject!                          -> an_enumerator
 *
 *  Equivalent to <code>Hash#delete_if</code>, but returns
 *  <code>nil</code> if no changes were made.
 */

VALUE
rb_hash_reject_bang(VALUE hash)
{
    st_index_t n;

    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_modify(hash);
    if (!RHASH(hash)->ntbl)
        return Qnil;
    n = RHASH(hash)->ntbl->num_entries;
    rb_hash_foreach(hash, delete_if_i, hash);
    if (n == RHASH(hash)->ntbl->num_entries) return Qnil;
    return hash;
}

- (Hash) replace(other_hash)

Replaces the contents of hsh with the contents of other_hash.

h = { "a" => 100, "b" => 200 }
h.replace({ "c" => 300, "d" => 400 })   #=> {"c"=>300, "d"=>400}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.replace(other_hash) -> hsh
 *
 *  Replaces the contents of <i>hsh</i> with the contents of
 *  <i>other_hash</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.replace({ "c" => 300, "d" => 400 })   #=> {"c"=>300, "d"=>400}
 *
 */

static VALUE
rb_hash_replace(VALUE hash, VALUE hash2)
{
    rb_hash_modify_check(hash);
    hash2 = to_hash(hash2);
    if (hash == hash2) return hash;
    rb_hash_clear(hash);
    if (RHASH(hash2)->ntbl) {
    rb_hash_tbl(hash);
    RHASH(hash)->ntbl->type = RHASH(hash2)->ntbl->type;
    }
    rb_hash_foreach(hash2, replace_i, hash);
    RHASH_IFNONE(hash) = RHASH_IFNONE(hash2);
    if (FL_TEST(hash2, HASH_PROC_DEFAULT)) {
    FL_SET(hash, HASH_PROC_DEFAULT);
    }
    else {
    FL_UNSET(hash, HASH_PROC_DEFAULT);
    }

    return hash;
}

- (Hash) select {|key, value| ... } - (Object) select

Returns a new hash consisting of entries for which the block returns true.

If no block is given, an enumerator is returned instead.

h = { "a" => 100, "b" => 200, "c" => 300 }
h.select {|k,v| k > "a"}  #=> {"b" => 200, "c" => 300}
h.select {|k,v| v < 200}  #=> {"a" => 100}

Overloads:

  • - (Hash) select {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.select {|key, value| block}   -> a_hash
 *     hsh.select                        -> an_enumerator
 *
 *  Returns a new hash consisting of entries for which the block returns true.
 *
 *  If no block is given, an enumerator is returned instead.
 *
 *     h = { "a" => 100, "b" => 200, "c" => 300 }
 *     h.select {|k,v| k > "a"}  #=> {"b" => 200, "c" => 300}
 *     h.select {|k,v| v < 200}  #=> {"a" => 100}
 */

VALUE
rb_hash_select(VALUE hash)
{
    VALUE result;

    RETURN_ENUMERATOR(hash, 0, 0);
    result = rb_hash_new();
    rb_hash_foreach(hash, select_i, result);
    return result;
}

- (Hash?) select! {|key, value| ... } - (Object) select!

Equivalent to Hash#keep_if, but returns nil if no changes were made.

Overloads:

  • - (Hash?) select! {|key, value| ... }

    Yields:

    • (key, value)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.select! {| key, value | block }  -> hsh or nil
 *     hsh.select!                          -> an_enumerator
 *
 *  Equivalent to <code>Hash#keep_if</code>, but returns
 *  <code>nil</code> if no changes were made.
 */

VALUE
rb_hash_select_bang(VALUE hash)
{
    st_index_t n;

    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_modify(hash);
    if (!RHASH(hash)->ntbl)
        return Qnil;
    n = RHASH(hash)->ntbl->num_entries;
    rb_hash_foreach(hash, keep_if_i, hash);
    if (n == RHASH(hash)->ntbl->num_entries) return Qnil;
    return hash;
}

- (Array, Object) shift

Removes a key-value pair from hsh and returns it as the two-item array [ key, value ], or the hash's default value if the hash is empty.

h = { 1 => "a", 2 => "b", 3 => "c" }
h.shift   #=> [1, "a"]
h         #=> {2=>"b", 3=>"c"}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.shift -> anArray or obj
 *
 *  Removes a key-value pair from <i>hsh</i> and returns it as the
 *  two-item array <code>[</code> <i>key, value</i> <code>]</code>, or
 *  the hash's default value if the hash is empty.
 *
 *     h = { 1 => "a", 2 => "b", 3 => "c" }
 *     h.shift   #=> [1, "a"]
 *     h         #=> {2=>"b", 3=>"c"}
 */

static VALUE
rb_hash_shift(VALUE hash)
{
    struct shift_var var;

    rb_hash_modify(hash);
    var.key = Qundef;
    rb_hash_foreach(hash, RHASH(hash)->iter_lev > 0 ? shift_i_safe : shift_i,
            (VALUE)&var);

    if (var.key != Qundef) {
    if (RHASH(hash)->iter_lev > 0) {
        rb_hash_delete_key(hash, var.key);
    }
    return rb_assoc_new(var.key, var.val);
    }
    else if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
    return rb_funcall(RHASH_IFNONE(hash), id_yield, 2, hash, Qnil);
    }
    else {
    return RHASH_IFNONE(hash);
    }
}

- (Fixnum) length - (Fixnum) size

Returns the number of key-value pairs in the hash.

h = { "d" => 100, "a" => 200, "v" => 300, "e" => 400 }
h.length        #=> 4
h.delete("a")   #=> 200
h.length        #=> 3


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.length    ->  fixnum
 *     hsh.size      ->  fixnum
 *
 *  Returns the number of key-value pairs in the hash.
 *
 *     h = { "d" => 100, "a" => 200, "v" => 300, "e" => 400 }
 *     h.length        #=> 4
 *     h.delete("a")   #=> 200
 *     h.length        #=> 3
 */

static VALUE
rb_hash_size(VALUE hash)
{
    if (!RHASH(hash)->ntbl)
        return INT2FIX(0);
    return INT2FIX(RHASH(hash)->ntbl->num_entries);
}

- (Object) []=(key) - (Object) store(key, value)

Element Assignment---Associates the value given by value with the key given by key. key should not have its value changed while it is in use as a key (a String passed as a key will be duplicated and frozen).

h = { "a" => 100, "b" => 200 }
h["a"] = 9
h["c"] = 4
h   #=> {"a"=>9, "b"=>200, "c"=>4}


# File 'hash.c'

/*
 *  call-seq:
 *     hsh[key] = value        -> value
 *     hsh.store(key, value)   -> value
 *
 *  Element Assignment---Associates the value given by
 *  <i>value</i> with the key given by <i>key</i>.
 *  <i>key</i> should not have its value changed while it is in
 *  use as a key (a <code>String</code> passed as a key will be
 *  duplicated and frozen).
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h["a"] = 9
 *     h["c"] = 4
 *     h   #=> {"a"=>9, "b"=>200, "c"=>4}
 *
 */

VALUE
rb_hash_aset(VALUE hash, VALUE key, VALUE val)
{
    rb_hash_modify(hash);
    hash_update(hash, key);
    if (RHASH(hash)->ntbl->type == &identhash || rb_obj_class(key) != rb_cString) {
    st_insert(RHASH(hash)->ntbl, key, val);
    }
    else {
    st_insert2(RHASH(hash)->ntbl, key, val, rb_str_new4);
    }
    return val;
}

- (Array) to_a

Converts hsh to a nested array of [ key, value ] arrays.

h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300  }
h.to_a   #=> [["c", 300], ["a", 100], ["d", 400]]


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.to_a -> array
 *
 *  Converts <i>hsh</i> to a nested array of <code>[</code> <i>key,
 *  value</i> <code>]</code> arrays.
 *
 *     h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300  }
 *     h.to_a   #=> [["c", 300], ["a", 100], ["d", 400]]
 */

static VALUE
rb_hash_to_a(VALUE hash)
{
    VALUE ary;

    ary = rb_ary_new();
    rb_hash_foreach(hash, to_a_i, ary);
    OBJ_INFECT(ary, hash);

    return ary;
}

- (Hash) to_hash

Returns self.



# File 'hash.c'

/*
 * call-seq:
 *    hsh.to_hash   => hsh
 *
 * Returns +self+.
 */

static VALUE
rb_hash_to_hash(VALUE hash)
{
    return hash;
}

- (Hash) merge!(other_hash) - (Hash) update(other_hash) - (Hash) merge!(other_hash) {|key, oldval, newval| ... } - (Hash) update(other_hash) {|key, oldval, newval| ... }

Adds the contents of other_hash to hsh. If no block is specified, entries with duplicate keys are overwritten with the values from other_hash, otherwise the value of each duplicate key is determined by calling the block with the key, its value in hsh and its value in other_hash.

h1 = { "a" => 100, "b" => 200 }
h2 = { "b" => 254, "c" => 300 }
h1.merge!(h2)   #=> {"a"=>100, "b"=>254, "c"=>300}

h1 = { "a" => 100, "b" => 200 }
h2 = { "b" => 254, "c" => 300 }
h1.merge!(h2) { |key, v1, v2| v1 }
                #=> {"a"=>100, "b"=>200, "c"=>300}

Overloads:

  • - (Hash) merge!(other_hash) {|key, oldval, newval| ... }

    Yields:

    • (key, oldval, newval)
  • - (Hash) update(other_hash) {|key, oldval, newval| ... }

    Yields:

    • (key, oldval, newval)


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.merge!(other_hash)                                 -> hsh
 *     hsh.update(other_hash)                                 -> hsh
 *     hsh.merge!(other_hash){|key, oldval, newval| block}    -> hsh
 *     hsh.update(other_hash){|key, oldval, newval| block}    -> hsh
 *
 *  Adds the contents of <i>other_hash</i> to <i>hsh</i>.  If no
 *  block is specified, entries with duplicate keys are overwritten
 *  with the values from <i>other_hash</i>, otherwise the value
 *  of each duplicate key is determined by calling the block with
 *  the key, its value in <i>hsh</i> and its value in <i>other_hash</i>.
 *
 *     h1 = { "a" => 100, "b" => 200 }
 *     h2 = { "b" => 254, "c" => 300 }
 *     h1.merge!(h2)   #=> {"a"=>100, "b"=>254, "c"=>300}
 *
 *     h1 = { "a" => 100, "b" => 200 }
 *     h2 = { "b" => 254, "c" => 300 }
 *     h1.merge!(h2) { |key, v1, v2| v1 }
 *                     #=> {"a"=>100, "b"=>200, "c"=>300}
 */

static VALUE
rb_hash_update(VALUE hash1, VALUE hash2)
{
    rb_hash_modify(hash1);
    hash2 = to_hash(hash2);
    if (rb_block_given_p()) {
    rb_hash_foreach(hash2, rb_hash_update_block_i, hash1);
    }
    else {
    rb_hash_foreach(hash2, rb_hash_update_i, hash1);
    }
    return hash1;
}

- (Boolean) has_value?(value) - (Boolean) value?(value)

Returns true if the given value is present for some key in hsh.

h = { "a" => 100, "b" => 200 }
h.has_value?(100)   #=> true
h.has_value?(999)   #=> false


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.has_value?(value)    -> true or false
 *     hsh.value?(value)        -> true or false
 *
 *  Returns <code>true</code> if the given value is present for some key
 *  in <i>hsh</i>.
 *
 *     h = { "a" => 100, "b" => 200 }
 *     h.has_value?(100)   #=> true
 *     h.has_value?(999)   #=> false
 */

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];
}

- (Array) values

Returns a new array populated with the values from hsh. See also Hash#keys.

h = { "a" => 100, "b" => 200, "c" => 300 }
h.values   #=> [100, 200, 300]


# File 'hash.c'

/*
 *  call-seq:
 *     hsh.values    -> array
 *
 *  Returns a new array populated with the values from <i>hsh</i>. See
 *  also <code>Hash#keys</code>.
 *
 *     h = { "a" => 100, "b" => 200, "c" => 300 }
 *     h.values   #=> [100, 200, 300]
 *
 */

static VALUE
rb_hash_values(VALUE hash)
{
    VALUE ary;

    ary = rb_ary_new();
    rb_hash_foreach(hash, values_i, ary);

    return ary;
}

- (Array) values_at(key, ...)

Return an array containing the values associated with the given keys. Also see Hash.select.

h = { "cat" => "feline", "dog" => "canine", "cow" => "bovine" }
h.values_at("cow", "cat")  #=> ["bovine", "feline"]


# File 'hash.c'

/*
 * call-seq:
 *   hsh.values_at(key, ...)   -> array
 *
 * Return an array containing the values associated with the given keys.
 * Also see <code>Hash.select</code>.
 *
 *   h = { "cat" => "feline", "dog" => "canine", "cow" => "bovine" }
 *   h.values_at("cow", "cat")  #=> ["bovine", "feline"]
 */

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;
}