Class: ActiveSupport::OrderedHash

Inherits:
Hash show all
Defined in:
lib/active_support/ordered_hash.rb

Overview

:nodoc:

Direct Known Subclasses

OrderedOptions

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Hash

#as_json, #assert_valid_keys, #deep_merge, #deep_merge!, #diff, #encode_json, #except, #except!, #extract!, #extractable_options?, 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 37

def initialize(*args, &block)
  super
  @keys = []
end

Class Method Details

.[](*args) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 42

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

Instance Method Details

#[]=(key, value) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 72

def []=(key, value)
  @keys << key if !has_key?(key)
  super
end

#clear ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 131

def clear
  super
  @keys.clear
  self
end

#delete(key) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 77

def delete(key)
  if has_key? key
    index = @keys.index(key)
    @keys.delete_at index
  end
  super
end

#delete_if ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 85

def delete_if
  super
  sync_keys!
  self
end

#each ⇒ Object Also known as: each_pair 



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# File 'lib/active_support/ordered_hash.rb', line 125

def each
  @keys.each {|key| yield [key, self[key]]}
end

#each_key ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 117

def each_key
  @keys.each { |key| yield key }
end

#each_value ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 121

def each_value
  @keys.each { |key| yield self[key]}
end

#initialize_copy(other) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 66

def initialize_copy(other)
  super
  # make a deep copy of keys
  @keys = other.keys
end

#inspect ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 169

def inspect
  "#<OrderedHash #{super}>"
end

#invert ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 165

def invert
  OrderedHash[self.to_a.map!{|key_value_pair| key_value_pair.reverse}]
end

#keys ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 101

def keys
  @keys.dup
end

#merge(other_hash, &block) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 154

def merge(other_hash, &block)
  dup.merge!(other_hash, &block)
end

#merge!(other_hash) ⇒ Object Also known as: update 



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# File 'lib/active_support/ordered_hash.rb', line 143

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

#reject(&block) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 97

def reject(&block)
  dup.reject!(&block)
end

#reject! ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 91

def reject!
  super
  sync_keys!
  self
end

#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 159

def replace(other)
  super
  @keys = other.keys
  self
end

#shift ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 137

def shift
  k = @keys.first
  v = delete(k)
  [k, v]
end

#to_a ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 113

def to_a
  @keys.map { |key| [ key, self[key] ] }
end

#to_hash ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 109

def to_hash
  self
end

#to_yaml(opts = {}) ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 14

def to_yaml(opts = {})
  YAML.quick_emit(self, opts) do |out|
    out.seq(taguri, to_yaml_style) do |seq|
      each do |k, v|
        seq.add(k => v)
      end
    end
  end
end

#to_yaml_type ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 10

def to_yaml_type
  "!tag:yaml.org,2002:omap"
end

#values ⇒ Object 



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# File 'lib/active_support/ordered_hash.rb', line 105

def values
  @keys.collect { |key| self[key] }
end