rexml: REXML::Element#[] accepts String or Symbol as attribute name

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57003 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -251,6 +251,12 @@ with all sufficient information, see the ChangeLog file or Redmine
   * Readline.quoting_detection_proc and Readline.quoting_detection_proc=
     [Feature #12659]
 
+* REXML
+
+  * REXML::Element#[]: If String or Symbol is specified, attribute
+    value is returned. Otherwise, Nth child is returned. This is
+    backward compatible change.
+
 * set
 
   * New methods: Set#compare_by_identity and Set#compare_by_identity?.

lib/rexml/element.rb

@@ -551,6 +551,30 @@ module REXML
     # Attributes                                    #
     #################################################
 
+    # Fetches an attribute value or a child.
+    #
+    # If String or Symbol is specified, it's treated as attribute
+    # name. Attribute value as String or +nil+ is returned. This case
+    # is shortcut of +attributes[name]+.
+    #
+    # If Integer is specified, it's treated as the index of
+    # child. It returns Nth child.
+    #
+    #   doc = REXML::Document.new("<a attr='1'><b/><c/></a>")
+    #   doc.root["attr"]             # => "1"
+    #   doc.root.attributes["attr"]  # => "1"
+    #   doc.root[1]                  # => <c/>
+    def [](name_or_index)
+      case name_or_index
+      when String
+        attributes[name_or_index]
+      when Symbol
+        attributes[name_or_index.to_s]
+      else
+        super
+      end
+    end
+
     def attribute( name, namespace=nil )
       prefix = nil
       if namespaces.respond_to? :key

test/rexml/test_element.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: false
+
+require "test/unit/testcase"
+require "rexml/document"
+
+module REXMLTests
+  class ElementTester < Test::Unit::TestCase
+    def test_array_reference_string
+      doc = REXML::Document.new("<language name='Ruby'/>")
+      assert_equal("Ruby", doc.root["name"])
+    end
+
+    def test_array_reference_symbol
+      doc = REXML::Document.new("<language name='Ruby'/>")
+      assert_equal("Ruby", doc.root[:name])
+    end
+  end
+end