Class: ActiveSupport::OrderedHash
- Inherits:
-
Hash
show all
- Defined in:
- lib/active_support/ordered_hash.rb
Overview
The order of iteration over hashes in Ruby 1.8 is undefined. For example, you do not know the order in which keys
will return keys, or each
yield pairs. ActiveSupport::OrderedHash
implements a hash that preserves insertion order, as in Ruby 1.9:
oh = ActiveSupport::OrderedHash.new
oh[:a] = 1
oh[:b] = 2
oh.keys
ActiveSupport::OrderedHash
is namespaced to prevent conflicts with other implementations.
Constant Summary
Constants inherited
from Hash
Hash::DISALLOWED_XML_TYPES
Class Method Summary
collapse
Instance Method Summary
collapse
Methods inherited from Hash
#as_json, #assert_valid_keys, #deep_dup, #deep_merge, #deep_merge!, #diff, #encode_json, #except, #except!, #extract!, from_trusted_xml, from_xml, #reverse_merge, #reverse_merge!, #slice, #slice!, #stringify_keys, #stringify_keys!, #symbolize_keys, #symbolize_keys!, #to_param, #to_xml, #with_indifferent_access
Constructor Details
#initialize(*args, &block) ⇒ OrderedHash
In MRI the Hash class is core and written in C. In particular, methods are programmed with explicit C function calls and polymorphism is not honored.
For example, []= is crucial in this implementation to maintain the @keys array but hash.c invokes rb_hash_aset() originally. This prevents method reuse through inheritance and forces us to reimplement stuff.
For instance, we cannot use the inherited #merge! because albeit the algorithm itself would work, our []= is not being called at all by the C code.
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# File 'lib/active_support/ordered_hash.rb', line 68
def initialize(*args, &block)
super
@keys = []
end
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Class Method Details
.[](*args) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 73
def self.[](*args)
ordered_hash = new
if (args.length == 1 && args.first.is_a?(Array))
args.first.each do |key_value_pair|
next unless (key_value_pair.is_a?(Array))
ordered_hash[key_value_pair[0]] = key_value_pair[1]
end
return ordered_hash
end
unless (args.size % 2 == 0)
raise ArgumentError.new("odd number of arguments for Hash")
end
args.each_with_index do |val, ind|
next if (ind % 2 != 0)
ordered_hash[val] = args[ind + 1]
end
ordered_hash
end
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Instance Method Details
#[]=(key, value) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 103
def []=(key, value)
@keys << key unless has_key?(key)
super
end
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# File 'lib/active_support/ordered_hash.rb', line 170
def clear
super
@keys.clear
self
end
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#delete(key) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 108
def delete(key)
if has_key? key
index = @keys.index(key)
@keys.delete_at index
end
super
end
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#delete_if ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 116
def delete_if
super
sync_keys!
self
end
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#each ⇒ Object
Also known as:
each_pair
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# File 'lib/active_support/ordered_hash.rb', line 160
def each
return to_enum(:each) unless block_given?
@keys.each {|key| yield [key, self[key]]}
self
end
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# File 'lib/active_support/ordered_hash.rb', line 148
def each_key
return to_enum(:each_key) unless block_given?
@keys.each { |key| yield key }
self
end
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#each_value ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 154
def each_value
return to_enum(:each_value) unless block_given?
@keys.each { |key| yield self[key]}
self
end
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#encode_with(coder) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 28
def encode_with(coder)
coder.represent_seq '!omap', map { |k,v| { k => v } }
end
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Returns true to make sure that this hash is extractable via Array#extract_options!
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# File 'lib/active_support/ordered_hash.rb', line 51
def
true
end
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#initialize_copy(other) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 97
def initialize_copy(other)
super
@keys = other.keys
end
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# File 'lib/active_support/ordered_hash.rb', line 208
def inspect
"#<OrderedHash #{super}>"
end
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# File 'lib/active_support/ordered_hash.rb', line 204
def invert
OrderedHash[self.to_a.map!{|key_value_pair| key_value_pair.reverse}]
end
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# File 'lib/active_support/ordered_hash.rb', line 132
def keys
@keys.dup
end
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#merge(other_hash, &block) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 193
def merge(other_hash, &block)
dup.merge!(other_hash, &block)
end
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#merge!(other_hash) ⇒ Object
Also known as:
update
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# File 'lib/active_support/ordered_hash.rb', line 182
def merge!(other_hash)
if block_given?
other_hash.each { |k, v| self[k] = key?(k) ? yield(k, self[k], v) : v }
else
other_hash.each { |k, v| self[k] = v }
end
self
end
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#nested_under_indifferent_access ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 46
def nested_under_indifferent_access
self
end
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#reject(&block) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 128
def reject(&block)
dup.reject!(&block)
end
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# File 'lib/active_support/ordered_hash.rb', line 122
def reject!
super
sync_keys!
self
end
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#replace(other) ⇒ Object
When replacing with another hash, the initial order of our keys must come from the other hash -ordered or not.
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# File 'lib/active_support/ordered_hash.rb', line 198
def replace(other)
super
@keys = other.keys
self
end
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# File 'lib/active_support/ordered_hash.rb', line 176
def shift
k = @keys.first
v = delete(k)
[k, v]
end
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# File 'lib/active_support/ordered_hash.rb', line 144
def to_a
@keys.map { |key| [ key, self[key] ] }
end
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# File 'lib/active_support/ordered_hash.rb', line 140
def to_hash
self
end
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#to_yaml(opts = {}) ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 32
def to_yaml(opts = {})
if YAML.const_defined?(:ENGINE) && !YAML::ENGINE.syck?
return super
end
YAML.quick_emit(self, opts) do |out|
out.seq(taguri) do |seq|
each do |k, v|
seq.add(k => v)
end
end
end
end
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#to_yaml_type ⇒ Object
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# File 'lib/active_support/ordered_hash.rb', line 24
def to_yaml_type
"!tag:yaml.org,2002:omap"
end
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# File 'lib/active_support/ordered_hash.rb', line 136
def values
@keys.collect { |key| self[key] }
end
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