2 files changed, 88 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index 98ad75429e..d06a5a32fb 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -7,3 +7,4 @@ require 'active_support/core_ext/string/access'
 require 'active_support/core_ext/string/iterators'
 require 'active_support/core_ext/string/xchar'
 require 'active_support/core_ext/string/behavior'
+require 'active_support/core_ext/string/interpolation'
+\ No newline at end of file
diff --git a/activesupport/lib/active_support/core_ext/string/interpolation.rb b/activesupport/lib/active_support/core_ext/string/interpolation.rb
new file mode 100644
index 0000000000..b21977ecc1
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/string/interpolation.rb
@@ -0,0 +1,87 @@
+if RUBY_VERSION < '1.9'
+
+=begin
+  string.rb - Extension for String.
+
+  Copyright (C) 2005-2009 Masao Mutoh
+
+  You may redistribute it and/or modify it under the same
+  license terms as Ruby.
+=end
+
+# This feature is included in Ruby 1.9 or later but not occur TypeError.
+#
+# String#% method which accepts named arguments. Particularly useful if the
+# string is to be used by a translator because named arguments mean more
+# than %s/%d style.
+class String
+
+  unless instance_methods.find {|m| m.to_s == 'bytesize'}
+    # For older ruby (such as ruby-1.8.5)
+    alias :bytesize :size
+  end
+
+  alias :_old_format_m :% # :nodoc:
+
+  PERCENT_MATCH_RE = Regexp.union(
+      /%%/,
+      /%\{(\w+)\}/,
+      /%<(\w+)>(.*?\d*\.?\d*[bBdiouxXeEfgGcps])/
+  )
+
+  # call-seq:
+  #   %(arg)
+  #   %(hash)
+  #
+  # Format - Uses str as a format specification, and returns the result of applying it to arg.
+  # If the format specification contains more than one substitution, then arg must be
+  # an Array containing the values to be substituted. See Kernel::sprintf for details of the
+  # format string. This is the default behavior of the String class.
+  #   * arg: an Array or other class except Hash.
+  #   * Returns: formatted String
+  # Example:
+  #    "%s, %s" % ["Masao", "Mutoh"]
+  #
+  # Also you can use a Hash as the "named argument". This is recommended way so translators
+  # can understand the meanings of the msgids easily.
+  #   * hash: {:key1 => value1, :key2 => value2, ... }
+  #   * Returns: formatted String
+  # Example:
+  #   For strings.
+  #   "%{firstname}, %{familyname}" % {:firstname => "Masao", :familyname => "Mutoh"}
+  #
+  #   With field type to specify format such as d(decimal), f(float),...
+  #   "%<age>d, %<weight>.1f" % {:age => 10, :weight => 43.4}
+  def %(args)
+    if args.kind_of?(Hash)
+      ret = dup
+      ret.gsub!(PERCENT_MATCH_RE) {|match|
+        if match == '%%'
+          '%'
+        elsif $1
+          key = $1.to_sym
+          args.has_key?(key) ? args[key] : match
+        elsif $2
+          key = $2.to_sym
+          args.has_key?(key) ? sprintf("%#{$3}", args[key]) : match
+        end
+      }
+      ret
+    else
+      ret = gsub(/%([{<])/, '%%\1')
+      begin
+        ret._old_format_m(args)
+      rescue ArgumentError => e
+        if $DEBUG
+          $stderr.puts "  The string:#{ret}"
+          $stderr.puts "  args:#{args.inspect}"
+          puts e.backtrace
+        else
+          raise ArgumentError, e.message
+        end
+      end
+    end
+  end
+end
+
+end
+\ No newline at end of file