vendored parslet, deemed stable enough and better without dependency

lib/parslet/atoms/re.rb

@@ -0,0 +1,38 @@
+# Matches a special kind of regular expression that only ever matches one
+# character at a time. Useful members of this family are: <code>character
+# ranges, \\w, \\d, \\r, \\n, ...</code>
+#
+# Example: 
+#
+#   match('[a-z]')  # matches a-z
+#   match('\s')     # like regexps: matches space characters
+#
+class Parslet::Atoms::Re < Parslet::Atoms::Base
+  attr_reader :match, :re
+  def initialize(match)
+    super()
+
+    @match = match.to_s
+    @re    = Regexp.new(self.match, Regexp::MULTILINE)
+    @error_msgs = {
+      :premature  => "Premature end of input", 
+      :failed     => "Failed to match #{match.inspect[1..-2]}"
+    }
+  end
+
+  def try(source, context, consume_all)
+    return succ(source.consume(1)) if source.matches?(@re)
+    
+    # No string could be read
+    return context.err(self, source, @error_msgs[:premature]) \
+      if source.chars_left < 1
+        
+    # No match
+    return context.err(self, source, @error_msgs[:failed])
+  end
+
+  def to_s_inner(prec)
+    match.inspect[1..-2]
+  end
+end
+