Add hexadecimal, binary and unsigned integer literals

grammar.coffee

@@ -435,7 +435,12 @@ module.exports = grammar
       @_expression,
       @initializer_list)
 
-    number_literal: -> /\d+(\.\d+)?/
+    number_literal: -> token(choice(
+      /\d+(\.\d+)?/,
+      /\d+u/,
+      seq("0x", /[0-9a-fA-f]+/),
+      seq("0b", /[01]+/),
+    ))
 
     char_literal: -> token(seq(
       "'",

grammar_test/expressions.txt

@@ -1,3 +1,18 @@
+============================================
+Number literals
+============================================
+
+int a = 0xAC00;
+int b = 0.123;
+int c = 0b1010001;
+
+---
+
+(translation_unit
+  (declaration (identifier) (init_declarator (identifier) (number_literal)))
+  (declaration (identifier) (init_declarator (identifier) (number_literal)))
+  (declaration (identifier) (init_declarator (identifier) (number_literal))))
+
 ============================================
 Identifiers
 ============================================