Merge pull request #2594 from yasuyuki/hash

Implement Hash[]

mrbgems/mruby-hash-ext/mrblib/hash.rb

@@ -3,6 +3,58 @@ class Hash
   #  ISO does not define Hash#each_pair, so each_pair is defined in gem.
   alias each_pair each
 
+  ##
+  # call-seq:
+  # Hash[ key, value, ... ] -> new_hash
+  # Hash[ [ [key, value], ... ] ] -> new_hash
+  # Hash[ object ] -> new_hash
+  #
+  # Creates a new hash populated with the given objects.
+  #
+  # Similar to the literal <code>{ _key_ => _value_, ... }</code>. In the first
+  # form, keys and values occur in pairs, so there must be an even number of
+  # arguments.
+  #
+  # The second and third form take a single argument which is either an array
+  # of key-value pairs or an object convertible to a hash.
+  #
+  # Hash["a", 100, "b", 200] #=> {"a"=>100, "b"=>200}
+  # Hash[ [ ["a", 100], ["b", 200] ] ] #=> {"a"=>100, "b"=>200}
+  # Hash["a" => 100, "b" => 200] #=> {"a"=>100, "b"=>200}
+  #
+
+  def self.[](*object)
+    o = object[0]
+    if o.respond_to?(:to_hash)
+      h = Hash.new
+      object[0].to_hash.each { |k, v| h[k] = v }
+      return h
+    elsif o.respond_to?(:to_a)
+      h = Hash.new
+      o.to_a.each do |i|
+        raise ArgumentError, "wrong element type #{i.class} (expected array)" unless i.respond_to?(:to_a)
+        k, v = nil
+        case i.size
+        when 2
+          k = i[0]
+          v = i[1]
+        when 1
+          k = i[0]
+        else
+          raise ArgumentError, "invalid number of elements (#{i.size} for 1..2)"
+        end
+        h[k] = v
+      end
+      return h
+    end
+    raise ArgumentError, 'odd number of arguments for Hash' unless object.length % 2 == 0
+    h = Hash.new
+    0.step(object.length - 2, 2) do |i|
+      h[object[i]] = object[i + 1]
+    end
+    h
+  end
+
   ##
   # call-seq:
   #     hsh.merge!(other_hash)                                 -> hsh

mrbgems/mruby-hash-ext/test/hash.rb

 ##
 # Hash(Ext) Test
 
+assert('Hash.[] Hash') do
+  a = Hash['a_key' => 'a_value']
+
+  assert_equal({'a_key' => 'a_value'}, a)
+end
+
+assert('Hash.[] [ [ ["b_key", "b_value" ] ] ]') do
+  a = Hash[ [ ['b_key', 'b_value'] ] ]
+
+  assert_equal({'b_key' => 'b_value'}, a)
+
+  a = Hash[ [ ] ]
+
+  assert_equal({}, a)
+
+  assert_raise(ArgumentError) do
+    Hash[ [ ['b_key', 'b_value', 'b_over'] ] ]
+  end
+
+  assert_raise(ArgumentError) do
+    Hash[ [ [] ] ]
+  end
+end
+
+assert('Hash.[] "c_key", "c_value"') do
+  a = Hash['c_key', 'c_value', 'd_key', 1]
+
+  assert_equal({'c_key' => 'c_value', 'd_key' => 1}, a)
+
+  a = Hash[]
+
+  assert_equal({}, a)
+
+  assert_raise(ArgumentError) do
+    Hash['d_key']
+  end
+end
+
 assert('Hash#merge!') do
   a = { 'abc_key' => 'abc_value', 'cba_key' => 'cba_value' }
   b = { 'cba_key' => 'XXX',  'xyz_key' => 'xyz_value' }