Add string AST node

lib/prattle/ast/string.rb

@@ -0,0 +1,34 @@
+module Prattle
+  module AST
+    class String < AST::Node
+      Prattle::Parser.register self
+
+      def self.rule_name
+        "string"
+      end
+
+      def initialize(value)
+        @value = value
+      end
+
+      attr_reader :value
+
+      def self.grammar(g)
+        escapes = g.str("\\'") { "'"  } \
+          | g.str('\n') { "\n" } \
+          | g.str('\r') { "\r" } \
+          | g.str('\t') { "\t" } \
+          | g.str('\\\\') { "\\" }
+        not_quote = g.many(g.any(escapes, /[^']/)) { |*a| a.join }
+        g.string = g.seq("'", g.t(not_quote), "'") do |str|
+          String.new(str)
+        end
+      end
+
+      def bytecode(g)
+        g.push_literal @value
+        g.string_dup
+      end
+    end
+  end
+end

test/ast/test_string.rb

@@ -0,0 +1,17 @@
+require 'test/unit'
+require 'prattle/parser'
+
+class TestString < Test::Unit::TestCase
+  def test_parse
+    str = "'hello'"
+    parser = Prattle::Parser.new(str)
+    node = parser.parse :string
+
+    assert_kind_of Prattle::AST::String, node
+    assert_equal "hello", node.value
+  end
+
+  def test_run
+    assert_equal "evan", Prattle::AST::String.new("evan").run
+  end
+end