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

#newObject #new(obj) ⇒ Object #new {|hash, key| ... } ⇒ Object

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:

  • #new {|hash, key| ... } ⇒ Object

    Yields:

    • (hash, key)


# File 'hash.c'

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");
}

Class Method Details

.[](key, value, ...) ⇒ Object .[]([ [key, value)) ⇒ Object .[](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'

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);
}

.try_convert(obj) ⇒ Hash?

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

Returns:



# File 'hash.c'

static VALUE
rb_hash_s_try_convert(VALUE dummy, VALUE hash)
{
    return rb_check_hash_type(hash);
}

Instance Method Details

#==(other_hash) ⇒ Boolean

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

Returns:

  • (Boolean)


# File 'hash.c'

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

#[](key) ⇒ Object

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'

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

if (!RHASH(hash)->ntbl || !st_lookup(RHASH(hash)->ntbl, key, &val)) {
if (!FL_TEST(hash, HASH_PROC_DEFAULT) &&
    rb_method_basic_definition_p(CLASS_OF(hash), id_default)) {
    return RHASH_IFNONE(hash);
}

#[]=(key) ⇒ Object #store(key, value) ⇒ Object

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'

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);
}

#assoc(obj) ⇒ Array?

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

Returns:



# File 'hash.c'

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];
}

#clearHash

Removes all key-value pairs from hsh.

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

Returns:



# File 'hash.c'

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);
}

#compare_by_identityHash

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.

Returns:



# File 'hash.c'

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

#compare_by_identity?Boolean

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

Returns:

  • (Boolean)


# File 'hash.c'

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

#default(key = nil) ⇒ Object

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

Returns:



# File 'hash.c'

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);
}

#default=(obj) ⇒ Object

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>

Returns:



# File 'hash.c'

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;
}

#default_procObject

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]

Returns:



# File 'hash.c'

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

#default_proc=(proc_obj) ⇒ Proc

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"

Returns:



# File 'hash.c'

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));
}

#delete(key) ⇒ Object #delete(key) {|key| ... } ⇒ Object

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:

  • #delete(key) {|key| ... } ⇒ Object

    Yields:

    • (key)


# File 'hash.c'

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);
}

#delete_if {|key, value| ... } ⇒ Hash #delete_ifObject

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:

  • #delete_if {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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;
}

#each {|key, value| ... } ⇒ Hash #each_pair {|key, value| ... } ⇒ Hash #eachObject #each_pairObject

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:

  • #each {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:

  • #each_pair {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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

#each_key {|key| ... } ⇒ Hash #each_keyObject

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:

  • #each_key {|key| ... } ⇒ Hash

    Yields:

    • (key)

    Returns:



# File 'hash.c'

static VALUE
rb_hash_each_key(VALUE hash)
{
    RETURN_ENUMERATOR(hash, 0, 0);
    rb_hash_foreach(hash, each_key_i, 0);
    return hash;
}

#each {|key, value| ... } ⇒ Hash #each_pair {|key, value| ... } ⇒ Hash #eachObject #each_pairObject

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:

  • #each {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:

  • #each_pair {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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

#each_value {|value| ... } ⇒ Hash #each_valueObject

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:

  • #each_value {|value| ... } ⇒ Hash

    Yields:

    • (value)

    Returns:



# File 'hash.c'

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

#empty?Boolean

Returns true if hsh contains no key-value pairs.

{}.empty?   #=> true

Returns:

  • (Boolean)


# File 'hash.c'

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

#eql?(other) ⇒ Boolean

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

Returns:

  • (Boolean)


# File 'hash.c'

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

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

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:

  • #fetch(key[, default]) ⇒ Object

    Returns:

  • #fetch(key) {|key| ... } ⇒ Object

    Yields:

    • (key)

    Returns:



# File 'hash.c'

static VALUE
rb_hash_fetch_m(int argc, VALUE *argv, VALUE hash)
{
VALUE key, if_none;
st_data_t 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");
}

#flattenArray #flatten(level) ⇒ 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 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"]

Overloads:



# File 'hash.c'

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;
}

#has_key?(key) ⇒ Boolean #include?(key) ⇒ Boolean #key?(key) ⇒ Boolean #member?(key) ⇒ Boolean

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

Overloads:

  • #has_key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #include?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #member?(key) ⇒ Boolean

    Returns:

    • (Boolean)


# File 'hash.c'

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;
}

#has_value?(value) ⇒ Boolean #value?(value) ⇒ Boolean

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

Overloads:

  • #has_value?(value) ⇒ Boolean

    Returns:

    • (Boolean)
  • #value?(value) ⇒ Boolean

    Returns:

    • (Boolean)


# File 'hash.c'

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];
}

#hashFixnum

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

Returns:



# File 'hash.c'

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

#has_key?(key) ⇒ Boolean #include?(key) ⇒ Boolean #key?(key) ⇒ Boolean #member?(key) ⇒ Boolean

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

Overloads:

  • #has_key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #include?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #member?(key) ⇒ Boolean

    Returns:

    • (Boolean)


# File 'hash.c'

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;
}

#indexObject

:nodoc:



# File 'hash.c'

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

#replace(other_hash) ⇒ 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}

Returns:



# File 'hash.c'

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;
}

#to_sString #inspectString Also known as: to_s

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}"

Overloads:



# File 'hash.c'

static VALUE
rb_hash_inspect(VALUE hash)
{
if (RHASH_EMPTY_P(hash))
return rb_usascii_str_new2("{}

#invertObject

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'

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

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

#keep_if {|key, value| ... } ⇒ Hash #keep_ifObject

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

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

Overloads:

  • #keep_if {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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;
}

#key(value) ⇒ Object

Returns the key of an occurrence of a given value. If the value is not found, returns nil.

h = { "a" => 100, "b" => 200, "c" => 300, "d" => 300 }
h.key(200)   #=> "b"
h.key(300)   #=> "c"
h.key(999)   #=> nil


# File 'hash.c'

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];
}

#has_key?(key) ⇒ Boolean #include?(key) ⇒ Boolean #key?(key) ⇒ Boolean #member?(key) ⇒ Boolean

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

Overloads:

  • #has_key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #include?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #member?(key) ⇒ Boolean

    Returns:

    • (Boolean)


# File 'hash.c'

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;
}

#keysArray

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"]

Returns:



# File 'hash.c'

static VALUE
rb_hash_keys(VALUE hash)
{
    VALUE ary;

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

    return ary;
}

#lengthFixnum #sizeFixnum

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

Overloads:



# File 'hash.c'

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

#has_key?(key) ⇒ Boolean #include?(key) ⇒ Boolean #key?(key) ⇒ Boolean #member?(key) ⇒ Boolean

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

Overloads:

  • #has_key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #include?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #key?(key) ⇒ Boolean

    Returns:

    • (Boolean)
  • #member?(key) ⇒ Boolean

    Returns:

    • (Boolean)


# File 'hash.c'

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;
}

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

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:

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

    Yields:

    • (key, oldval, newval)


# File 'hash.c'

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

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

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:

  • #merge!(other_hash) ⇒ Hash

    Returns:

  • #update(other_hash) ⇒ Hash

    Returns:

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

    Yields:

    • (key, oldval, newval)

    Returns:

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

    Yields:

    • (key, oldval, newval)

    Returns:



# File 'hash.c'

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);
}

#rassoc(obj) ⇒ Array?

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

Returns:



# File 'hash.c'

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];
}

#rehashHash

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

Returns:



# File 'hash.c'

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

if (RHASH(hash)->iter_lev > 0) {
rb_raise(rb_eRuntimeError, "rehash during iteration");
}

#reject {|key, value| ... } ⇒ Hash #rejectObject

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

Overloads:

  • #reject {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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

#reject! {|key, value| ... } ⇒ Hash? #reject!Object

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

Overloads:

  • #reject! {|key, value| ... } ⇒ Hash?

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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;
}

#replace(other_hash) ⇒ 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}

Returns:



# File 'hash.c'

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;
}

#select {|key, value| ... } ⇒ Hash #selectObject

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:

  • #select {|key, value| ... } ⇒ Hash

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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;
}

#select! {|key, value| ... } ⇒ Hash? #select!Object

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

Overloads:

  • #select! {|key, value| ... } ⇒ Hash?

    Yields:

    • (key, value)

    Returns:



# File 'hash.c'

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;
}

#shiftArray, Object

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"}

Returns:



# File 'hash.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);
}

#lengthFixnum #sizeFixnum

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

Overloads:



# File 'hash.c'

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

#[]=(key) ⇒ Object #store(key, value) ⇒ Object

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'

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);
}

#to_aArray

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]]

Returns:



# File 'hash.c'

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;
}

#to_hashHash

Returns self.

Returns:



# File 'hash.c'

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

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

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:

  • #merge!(other_hash) ⇒ Hash

    Returns:

  • #update(other_hash) ⇒ Hash

    Returns:

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

    Yields:

    • (key, oldval, newval)

    Returns:

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

    Yields:

    • (key, oldval, newval)

    Returns:



# File 'hash.c'

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);
}

#has_value?(value) ⇒ Boolean #value?(value) ⇒ Boolean

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

Overloads:

  • #has_value?(value) ⇒ Boolean

    Returns:

    • (Boolean)
  • #value?(value) ⇒ Boolean

    Returns:

    • (Boolean)


# File 'hash.c'

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];
}

#valuesArray

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]

Returns:



# File 'hash.c'

static VALUE
rb_hash_values(VALUE hash)
{
    VALUE ary;

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

    return ary;
}

#values_at(key, ...) ⇒ Array

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"]

Returns:



# File 'hash.c'

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]));
}