Class: MultiHash

Inherits:
Object
  • Object
show all
Defined in:
lib/multi_hash_iterator.rb

Overview

Multi Hash allows you to iterate through multiple hashes at the same time. The values will be an array of values from each hash. If a hash contains no value for the key, it will be nil.

Instance Method Summary collapse

Constructor Details

#initialize(*hashes) ⇒ MultiHash

Returns a new instance of MultiHash.



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# File 'lib/multi_hash_iterator.rb', line 7

def initialize *hashes
  @hashes = hashes
  @memo = {}
end

Instance Method Details

#[](key) ⇒ Object 



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# File 'lib/multi_hash_iterator.rb', line 41

def [] key
  @memo[key] ||= @hashes.collect { |h| h[key] }
end

#each ⇒ Object

Enumerate for each key. Returns an enumerator if block is not present



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# File 'lib/multi_hash_iterator.rb', line 15

def each
  return enum_for(:each) unless block_given?

  # iterate through the memo first
  @memo.each do |k, v|
    yield k, v
  end

  count = @hashes.length
  count.times do |i|
    @hashes[i].each do |key, v|
      next if @memo[key]

      values = [].fill(nil, 0, i)
      values << v
      ((i+1)...count).each do |j|
        values << @hashes[j][key]
      end

      yield key, values if block_given?
      @memo[key] = values
    end
  end
end