vendored parslet, deemed stable enough and better without dependency

lib/parslet/rig/rspec.rb

@@ -0,0 +1,59 @@
+RSpec::Matchers.define(:parse) do |input, opts|
+  as = block = nil
+  result = trace = nil
+
+  unless self.respond_to? :failure_message # if RSpec 2.x
+    class << self
+      alias_method :failure_message, :failure_message_for_should
+      alias_method :failure_message_when_negated, :failure_message_for_should_not
+    end
+  end
+
+  match do |parser|
+    begin
+      result = parser.parse(input)
+      block ? 
+        block.call(result) : 
+        (as == result || as.nil?)
+    rescue Parslet::ParseFailed => ex
+      trace = ex.cause.ascii_tree if opts && opts[:trace]
+      false
+    end
+  end
+
+  failure_message do |is|
+    if block
+      "expected output of parsing #{input.inspect}" <<
+      " with #{is.inspect} to meet block conditions, but it didn't"
+    else
+      "expected " << 
+        (as ? 
+          "output of parsing #{input.inspect}"<<
+          " with #{is.inspect} to equal #{as.inspect}, but was #{result.inspect}" : 
+          "#{is.inspect} to be able to parse #{input.inspect}") << 
+        (trace ? 
+          "\n"+trace : 
+          '')
+    end
+  end
+
+  failure_message_when_negated do |is|
+    if block
+      "expected output of parsing #{input.inspect} with #{is.inspect} not to meet block conditions, but it did"
+    else
+      "expected " << 
+        (as ? 
+          "output of parsing #{input.inspect}"<<
+          " with #{is.inspect} not to equal #{as.inspect}" :
+          
+          "#{is.inspect} to not parse #{input.inspect}, but it did")
+    end
+  end
+
+  # NOTE: This has a nodoc tag since the rdoc parser puts this into 
+  # Object, a thing I would never allow. 
+  chain :as do |expected_output, &block|
+    as = expected_output
+    block = block
+  end
+end