--- /dev/null
+# heavily based on Masao Mutoh's gettext String interpolation extension
+# http://github.com/mutoh/gettext/blob/f6566738b981fe0952548c421042ad1e0cdfb31e/lib/gettext/core_ext/string.rb
+
+module I18n
+ INTERPOLATION_PATTERN = Regexp.union(
+ /%%/,
+ /%\{(\w+)\}/, # matches placeholders like "%{foo}"
+ /%<(\w+)>(.*?\d*\.?\d*[bBdiouxXeEfgGcps])/ # matches placeholders like "%<foo>.d"
+ )
+
+ class << self
+ def interpolate(string, values)
+ raise ReservedInterpolationKey.new($1.to_sym, string) if string =~ RESERVED_KEYS_PATTERN
+ raise ArgumentError.new('Interpolation values must be a Hash.') unless values.kind_of?(Hash)
+ interpolate_hash(string, values)
+ end
+
+ def interpolate_hash(string, values)
+ string.gsub(INTERPOLATION_PATTERN) do |match|
+ if match == '%%'
+ '%'
+ else
+ key = ($1 || $2).to_sym
+ value = values.key?(key) ? values[key] : raise(MissingInterpolationArgument.new(values, string))
+ value = value.call(values) if value.respond_to?(:call)
+ $3 ? sprintf("%#{$3}", value) : value
+ end
+ end
+ end
+ end
+end