class Array

# File lib/reduce_to_hash.rb, line 2
def reduce_to_hash(sym_or_hash = nil, &block)
  raise ArgumentError.new('Either block or symbol(s) required') if block.nil? and sym_or_hash.nil?
  raise ArgumentError.new('Block and symbol(s) cannot be used together') unless block.nil? or sym_or_hash.nil?

  if block
    self.reduce({}) do |memo, item|
      mapped = block.call(item)
      if mapped.nil?
        memo
      else
        memo.merge(mapped)
      end
    end

  elsif sym_or_hash.respond_to? :keys
    raise ArgumentError.new('Mapping hash must have single k=>v pair') if sym_or_hash.keys.length != 1

    key = sym_or_hash.keys.first
    val = sym_or_hash.values.first
    self.reduce({}) { |memo, item| memo.merge({rth_extract(item, key) => rth_extract(item, val)}) }

  else
    self.reduce({}) { |memo, item| memo.merge({rth_extract(item, sym_or_hash) => item}) }

  end
end

# File lib/reduce_to_hash.rb, line 31
def rth_extract(item, key)
  if item.is_a? Hash
    item[key]
  else
    item.send(key)
  end
end