Hash
This class was copied from an old version of ActiveSupport.
# File lib/sass/util/ordered_hash.rb, line 39 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.even? raise ArgumentError.new("odd number of arguments for Hash") end args.each_with_index do |val, ind| next if ind.odd? ordered_hash[val] = args[ind + 1] end ordered_hash end
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.
# File lib/sass/util/ordered_hash.rb, line 34 def initialize(*args) super @keys = [] end
# File lib/sass/util/ordered_hash.rb, line 69 def []=(key, value) @keys << key unless has_key?(key) super end
# File lib/sass/util/ordered_hash.rb, line 140 def clear super @keys.clear self end
# File lib/sass/util/ordered_hash.rb, line 74 def delete(key) if has_key? key index = @keys.index(key) @keys.delete_at index end super end
# File lib/sass/util/ordered_hash.rb, line 82 def delete_if super sync_keys! self end
# File lib/sass/util/ordered_hash.rb, line 126 def each return to_enum(:each) unless block_given? @keys.each {|key| yield [key, self[key]]} self end
# File lib/sass/util/ordered_hash.rb, line 114 def each_key return to_enum(:each_key) unless block_given? @keys.each {|key| yield key} self end
# File lib/sass/util/ordered_hash.rb, line 132 def each_pair return to_enum(:each_pair) unless block_given? @keys.each {|key| yield key, self[key]} self end
# File lib/sass/util/ordered_hash.rb, line 120 def each_value return to_enum(:each_value) unless block_given? @keys.each {|key| yield self[key]} self end
# File lib/sass/util/ordered_hash.rb, line 63 def initialize_copy(other) super # make a deep copy of keys @keys = other.keys end
# File lib/sass/util/ordered_hash.rb, line 183 def inspect "#<OrderedHash #{super}>" end
# File lib/sass/util/ordered_hash.rb, line 179 def invert OrderedHash[to_a.map! {|key_value_pair| key_value_pair.reverse}] end
# File lib/sass/util/ordered_hash.rb, line 163 def merge(other_hash) if block_given? dup.merge!(other_hash) {|k, v1, v2| yield k, v1, v2} else dup.merge!(other_hash) end end
# File lib/sass/util/ordered_hash.rb, line 152 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
# File lib/sass/util/ordered_hash.rb, line 94 def reject dup.reject! {|h, k| yield h, k} end
# File lib/sass/util/ordered_hash.rb, line 88 def reject! super sync_keys! self end
When replacing with another hash, the initial order of our keys must come from the other hash – ordered or not.
# File lib/sass/util/ordered_hash.rb, line 173 def replace(other) super @keys = other.keys self end
# File lib/sass/util/ordered_hash.rb, line 146 def shift k = @keys.first v = delete(k) [k, v] end
# File lib/sass/util/ordered_hash.rb, line 110 def to_a @keys.map {|key| [key, self[key]]} end
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