1 # This backports the Ruby 1.9 String interpolation syntax to Ruby 1.8.
3 # This backport has been shipped with I18n for a number of versions. Meanwhile
4 # Rails has started to rely on it and we are going to move it to ActiveSupport.
5 # See https://rails.lighthouseapp.com/projects/8994/tickets/6013-move-19-string-interpolation-syntax-backport-from-i18n-to-activesupport
7 # Once the above patch has been applied to Rails the following code will be
11 heavily based on Masao Mutoh's gettext String interpolation extension
12 http://github.com/mutoh/gettext/blob/f6566738b981fe0952548c421042ad1e0cdfb31e/lib/gettext/core_ext/string.rb
13 Copyright (C) 2005-2009 Masao Mutoh
14 You may redistribute it and/or modify it under the same license terms as Ruby.
18 raise ArgumentError if ("a %{x}" % {:x=>'b'}) != 'a b'
20 # KeyError is raised by String#% when the string contains a named placeholder
21 # that is not contained in the given arguments hash. Ruby 1.9 includes and
22 # raises this exception natively. We define it to mimic Ruby 1.9's behaviour
24 class KeyError < IndexError
25 def initialize(message = nil)
26 super(message || "key not found")
28 end unless defined?(KeyError)
30 # Extension for String class. This feature is included in Ruby 1.9 or later but not occur TypeError.
32 # String#% method which accept "named argument". The translator can know
33 # the meaning of the msgids using "named argument" instead of %s/%d style.
35 # For older ruby versions, such as ruby-1.8.5
36 alias :bytesize :size unless instance_methods.find {|m| m.to_s == 'bytesize'}
37 alias :interpolate_without_ruby_19_syntax :% # :nodoc:
39 INTERPOLATION_PATTERN = Regexp.union(
40 /%\{(\w+)\}/, # matches placeholders like "%{foo}"
41 /%<(\w+)>(.*?\d*\.?\d*[bBdiouxXeEfgGcps])/ # matches placeholders like "%<foo>.d"
44 INTERPOLATION_PATTERN_WITH_ESCAPE = Regexp.union(
49 # % uses self (i.e. the String) as a format specification and returns the
50 # result of applying it to the given arguments. In other words it interpolates
51 # the given arguments to the string according to the formats the string
54 # There are three ways to use it:
56 # * Using a single argument or Array of arguments.
58 # This is the default behaviour of the String class. See Kernel#sprintf for
59 # more details about the format string.
63 # "%d %s" % [1, "message"]
66 # * Using a Hash as an argument and unformatted, named placeholders.
68 # When you pass a Hash as an argument and specify placeholders with %{foo}
69 # it will interpret the hash values as named arguments.
73 # "%{firstname}, %{lastname}" % {:firstname => "Masao", :lastname => "Mutoh"}
76 # * Using a Hash as an argument and formatted, named placeholders.
78 # When you pass a Hash as an argument and specify placeholders with %<foo>d
79 # it will interpret the hash values as named arguments and format the value
80 # according to the formatting instruction appended to the closing >.
84 # "%<integer>d, %<float>.1f" % { :integer => 10, :float => 43.4 }
87 if args.kind_of?(Hash)
88 dup.gsub(INTERPOLATION_PATTERN_WITH_ESCAPE) do |match|
92 key = ($1 || $2).to_sym
93 raise KeyError unless args.has_key?(key)
94 $3 ? sprintf("%#{$3}", args[key]) : args[key]
97 elsif self =~ INTERPOLATION_PATTERN
98 raise ArgumentError.new('one hash required')
100 result = gsub(/%([{<])/, '%%\1')
101 result.send :'interpolate_without_ruby_19_syntax', args