Class: Urbane::ActiveSupport::OrderedHash

Inherits:
Hash
  • Object
show all
Defined in:
lib/urbane/vendor/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 # => [:a, :b], this order is guaranteed

ActiveSupport::OrderedHash is namespaced to prevent conflicts with other implementations.

Class Method Summary collapse

Instance Method Summary collapse

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/urbane/vendor/ordered_hash.rb', line 69

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

Class Method Details

.[](*args) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 74

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/urbane/vendor/ordered_hash.rb', line 104

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

#clear ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 175

def clear
  super
  @keys.clear
  self
end

#delete(key) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 109

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/urbane/vendor/ordered_hash.rb', line 117

def delete_if
  super
  sync_keys!
  self
end

#each ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 161

def each
  return to_enum(:each) unless block_given?
  @keys.each {|key| yield [key, self[key]]}
  self
end

#each_key ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 149

def each_key
  return to_enum(:each_key) unless block_given?
  @keys.each { |key| yield key }
  self
end

#each_pair ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 167

def each_pair
  return to_enum(:each_pair) unless block_given?
  @keys.each {|key| yield key, self[key]}
  self
end

#each_value ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 155

def each_value
  return to_enum(:each_value) unless block_given?
  @keys.each { |key| yield self[key]}
  self
end

#encode_with(coder) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 29

def encode_with(coder)
  coder.represent_seq '!omap', map { |k,v| { k => v } }
end

#extractable_options? ⇒ Boolean

Returns true to make sure that this hash is extractable via Array#extract_options!

Returns:

  • (Boolean) 


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# File 'lib/urbane/vendor/ordered_hash.rb', line 52

def extractable_options?
  true
end

#initialize_copy(other) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 98

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

#inspect ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 213

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

#invert ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 209

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

#keys ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 133

def keys
  @keys.dup
end

#merge(other_hash, &block) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 198

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/urbane/vendor/ordered_hash.rb', line 187

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

#nested_under_indifferent_access ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 47

def nested_under_indifferent_access
  self
end

#reject(&block) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 129

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

#reject! ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 123

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/urbane/vendor/ordered_hash.rb', line 203

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

#shift ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 181

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

#to_a ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 145

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

#to_hash ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 141

def to_hash
  self
end

#to_yaml(opts = {}) ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 33

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

#to_yaml_type ⇒ Object

:nodoc:



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# File 'lib/urbane/vendor/ordered_hash.rb', line 25

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

#values ⇒ Object 



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# File 'lib/urbane/vendor/ordered_hash.rb', line 137

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