Add number AST node

lib/prattle/ast/number.rb

@@ -0,0 +1,23 @@
+module Prattle
+  module AST
+    class Number < AST::Node
+      Prattle::Parser.register self
+
+      def self.rule_name
+        "number"
+      end
+
+      def initialize(value)
+        @value = value
+      end
+
+      attr_reader :value
+
+      def self.grammar(g)
+        g.number = g.reg(/0|([1-9][0-9]*)/) do |i|
+          Number.new(i.to_i)
+        end
+      end
+    end
+  end
+end

test/ast/test_number.rb

@@ -0,0 +1,20 @@
+require 'test/unit'
+require 'prattle/parser'
+
+class TestNumber < Test::Unit::TestCase
+  def test_parse
+    parser = Prattle::Parser.new("1")
+    node = parser.parse :number
+
+    assert_kind_of Prattle::AST::Number, node
+    assert_equal 1, node.value
+  end
+
+  def test_zero
+    parser = Prattle::Parser.new("0")
+    node = parser.parse :number
+
+    assert_kind_of Prattle::AST::Number, node
+    assert_equal 0, node.value
+  end
+end