lexer/parser: split out `null` and `undefined` from `BOOL` token

also made explicit AST nodes `Bool`, `Null`, and `Undefined`

lib/coffee-script/grammar.js

@@ -64,13 +64,12 @@
         return new Literal($1);
       }), o('DEBUGGER', function() {
         return new Literal($1);
+      }), o('UNDEFINED', function() {
+        return new Undefined;
+      }), o('NULL', function() {
+        return new Null;
       }), o('BOOL', function() {
-        var val;
+        return new Bool($1);
-        val = new Literal($1);
-        if ($1 === 'undefined') {
-          val.isUndefined = true;
-        }
-        return val;
       })
     ],
     Assign: [

lib/coffee-script/lexer.js

@@ -43,7 +43,7 @@
     };
 
     Lexer.prototype.identifierToken = function() {
-      var colon, forcedIdentifier, id, input, match, prev, tag, _ref2, _ref3;
+      var colon, forcedIdentifier, id, input, match, originalId, prev, tag, _ref2, _ref3;
       if (!(match = IDENTIFIER.exec(this.chunk))) {
         return 0;
       }
@@ -87,6 +87,7 @@
         }
       }
       if (!forcedIdentifier) {
+        originalId = id;
         if (__indexOf.call(COFFEE_ALIASES, id) >= 0) {
           id = COFFEE_ALIAS_MAP[id];
         }
@@ -102,9 +103,12 @@
               return 'LOGIC';
             case 'true':
             case 'false':
-            case 'null':
+              id = originalId;
-            case 'undefined':
               return 'BOOL';
+            case 'undefined':
+              return 'UNDEFINED';
+            case 'null':
+              return 'NULL';
             case 'break':
             case 'continue':
               return 'STATEMENT';
@@ -775,15 +779,15 @@
 
   RELATION = ['IN', 'OF', 'INSTANCEOF'];
 
-  BOOL = ['TRUE', 'FALSE', 'NULL', 'UNDEFINED'];
+  BOOL = ['TRUE', 'FALSE'];
 
-  NOT_REGEX = ['NUMBER', 'REGEX', 'BOOL', '++', '--', ']'];
+  NOT_REGEX = ['NUMBER', 'REGEX', 'BOOL', 'NULL', 'UNDEFINED', '++', '--', ']'];
 
   NOT_SPACED_REGEX = NOT_REGEX.concat(')', '}', 'THIS', 'IDENTIFIER', 'STRING');
 
   CALLABLE = ['IDENTIFIER', 'STRING', 'REGEX', ')', ']', '}', '?', '::', '@', 'THIS', 'SUPER'];
 
-  INDEXABLE = CALLABLE.concat('NUMBER', 'BOOL');
+  INDEXABLE = CALLABLE.concat('NUMBER', 'BOOL', 'NULL', 'UNDEFINED');
 
   LINE_BREAK = ['INDENT', 'OUTDENT', 'TERMINATOR'];
 

lib/coffee-script/nodes.js

@@ -466,7 +466,7 @@
 
     Literal.prototype.compileNode = function(o) {
       var code, _ref2;
-      code = this.isUndefined ? o.level >= LEVEL_ACCESS ? '(void 0)' : 'void 0' : this.value === 'this' ? ((_ref2 = o.scope.method) != null ? _ref2.bound : void 0) ? o.scope.method.context : this.value : this.value.reserved ? "\"" + this.value + "\"" : this.value;
+      code = this.value === 'this' ? ((_ref2 = o.scope.method) != null ? _ref2.bound : void 0) ? o.scope.method.context : this.value : this.value.reserved ? "\"" + this.value + "\"" : this.value;
       if (this.isStatement()) {
         return "" + this.tab + code + ";";
       } else {
@@ -482,6 +482,79 @@
 
   })(Base);
 
+  exports.Undefined = (function(_super) {
+
+    __extends(Undefined, _super);
+
+    function Undefined() {
+      return Undefined.__super__.constructor.apply(this, arguments);
+    }
+
+    Undefined.prototype.isAssignable = NO;
+
+    Undefined.prototype.isComplex = NO;
+
+    Undefined.prototype.compileNode = function(o) {
+      if (o.level >= LEVEL_ACCESS) {
+        return '(void 0)';
+      } else {
+        return 'void 0';
+      }
+    };
+
+    return Undefined;
+
+  })(Base);
+
+  exports.Null = (function(_super) {
+
+    __extends(Null, _super);
+
+    function Null() {
+      return Null.__super__.constructor.apply(this, arguments);
+    }
+
+    Null.prototype.isAssignable = NO;
+
+    Null.prototype.isComplex = NO;
+
+    Null.prototype.compileNode = function() {
+      return "null";
+    };
+
+    return Null;
+
+  })(Base);
+
+  exports.Bool = (function(_super) {
+
+    __extends(Bool, _super);
+
+    Bool.prototype.isAssignable = NO;
+
+    Bool.prototype.isComplex = NO;
+
+    Bool.prototype.compileNode = function() {
+      switch (this.val) {
+        case 'yes':
+        case 'on':
+          return 'true';
+        case 'no':
+        case 'off':
+          return 'false';
+        default:
+          return this.val;
+      }
+    };
+
+    function Bool(val) {
+      this.val = val;
+    }
+
+    return Bool;
+
+  })(Base);
+
   exports.Return = Return = (function(_super) {
 
     __extends(Return, _super);

lib/coffee-script/rewriter.js

@@ -332,7 +332,7 @@
 
   IMPLICIT_FUNC = ['IDENTIFIER', 'SUPER', ')', 'CALL_END', ']', 'INDEX_END', '@', 'THIS'];
 
-  IMPLICIT_CALL = ['IDENTIFIER', 'NUMBER', 'STRING', 'JS', 'REGEX', 'NEW', 'PARAM_START', 'CLASS', 'IF', 'TRY', 'SWITCH', 'THIS', 'BOOL', 'UNARY', 'SUPER', '@', '->', '=>', '[', '(', '{', '--', '++'];
+  IMPLICIT_CALL = ['IDENTIFIER', 'NUMBER', 'STRING', 'JS', 'REGEX', 'NEW', 'PARAM_START', 'CLASS', 'IF', 'TRY', 'SWITCH', 'THIS', 'BOOL', 'NULL', 'UNDEFINED', 'UNARY', 'SUPER', '@', '->', '=>', '[', '(', '{', '--', '++'];
 
   IMPLICIT_UNSPACED_CALL = ['+', '-'];
 

src/grammar.coffee

@@ -127,10 +127,9 @@ grammar =
     o 'JS',                                     -> new Literal $1
     o 'REGEX',                                  -> new Literal $1
     o 'DEBUGGER',                               -> new Literal $1
-    o 'BOOL',                                   ->
+    o 'UNDEFINED',                              -> new Undefined
-      val = new Literal $1
+    o 'NULL',                                   -> new Null
-      val.isUndefined = yes if $1 is 'undefined'
+    o 'BOOL',                                   -> new Bool $1
-      val
   ]
 
   # Assignment of a variable, property, or index to a value.

src/lexer.coffee

@@ -115,12 +115,17 @@ exports.Lexer = class Lexer
         @error "reserved word \"#{id}\""
 
     unless forcedIdentifier
+      originalId = id
       id  = COFFEE_ALIAS_MAP[id] if id in COFFEE_ALIASES
       tag = switch id
         when '!'                 then 'UNARY'
         when '==', '!='          then 'COMPARE'
         when '&&', '||'          then 'LOGIC'
-        when 'true', 'false', 'null', 'undefined' then 'BOOL'
+        when 'true', 'false'
+          id = originalId
+          'BOOL'
+        when 'undefined'         then 'UNDEFINED'
+        when 'null'              then 'NULL'
         when 'break', 'continue' then 'STATEMENT'
         else  tag
 
@@ -684,7 +689,7 @@ MATH    = ['*', '/', '%']
 RELATION = ['IN', 'OF', 'INSTANCEOF']
 
 # Boolean tokens.
-BOOL = ['TRUE', 'FALSE', 'NULL', 'UNDEFINED']
+BOOL = ['TRUE', 'FALSE']
 
 # Tokens which a regular expression will never immediately follow, but which
 # a division operator might.
@@ -692,7 +697,7 @@ BOOL = ['TRUE', 'FALSE', 'NULL', 'UNDEFINED']
 # See: http://www.mozilla.org/js/language/js20-2002-04/rationale/syntax.html#regular-expressions
 #
 # Our list is shorter, due to sans-parentheses method calls.
-NOT_REGEX = ['NUMBER', 'REGEX', 'BOOL', '++', '--', ']']
+NOT_REGEX = ['NUMBER', 'REGEX', 'BOOL', 'NULL', 'UNDEFINED', '++', '--', ']']
 
 # If the previous token is not spaced, there are more preceding tokens that
 # force a division parse:
@@ -702,7 +707,7 @@ NOT_SPACED_REGEX = NOT_REGEX.concat ')', '}', 'THIS', 'IDENTIFIER', 'STRING'
 # parentheses or bracket following these tokens will be recorded as the start
 # of a function invocation or indexing operation.
 CALLABLE  = ['IDENTIFIER', 'STRING', 'REGEX', ')', ']', '}', '?', '::', '@', 'THIS', 'SUPER']
-INDEXABLE = CALLABLE.concat 'NUMBER', 'BOOL'
+INDEXABLE = CALLABLE.concat 'NUMBER', 'BOOL', 'NULL', 'UNDEFINED'
 
 # Tokens that, when immediately preceding a `WHEN`, indicate that the `WHEN`
 # occurs at the start of a line. We disambiguate these from trailing whens to

src/nodes.coffee

@@ -325,9 +325,7 @@ exports.Literal = class Literal extends Base
     return this if @value is 'continue' and not o?.loop
 
   compileNode: (o) ->
-    code = if @isUndefined
+    code = if @value is 'this'
-      if o.level >= LEVEL_ACCESS then '(void 0)' else 'void 0'
-    else if @value is 'this'
       if o.scope.method?.bound then o.scope.method.context else @value
     else if @value.reserved
       "\"#{@value}\""
@@ -338,6 +336,27 @@ exports.Literal = class Literal extends Base
   toString: ->
     ' "' + @value + '"'
 
+class exports.Undefined extends Base
+  isAssignable: NO
+  isComplex: NO
+  compileNode: (o) ->
+    if o.level >= LEVEL_ACCESS then '(void 0)' else 'void 0'
+
+class exports.Null extends Base
+  isAssignable: NO
+  isComplex: NO
+  compileNode: -> "null"
+
+class exports.Bool extends Base
+  isAssignable: NO
+  isComplex: NO
+  compileNode: ->
+    switch @val
+      when 'yes', 'on' then 'true'
+      when 'no', 'off' then 'false'
+      else @val
+  constructor: (@val) ->
+
 #### Return
 
 # A `return` is a *pureStatement* -- wrapping it in a closure wouldn't

src/rewriter.coffee

@@ -297,7 +297,7 @@ IMPLICIT_FUNC    = ['IDENTIFIER', 'SUPER', ')', 'CALL_END', ']', 'INDEX_END', '@
 # If preceded by an `IMPLICIT_FUNC`, indicates a function invocation.
 IMPLICIT_CALL    = [
   'IDENTIFIER', 'NUMBER', 'STRING', 'JS', 'REGEX', 'NEW', 'PARAM_START', 'CLASS'
-  'IF', 'TRY', 'SWITCH', 'THIS', 'BOOL', 'UNARY', 'SUPER'
+  'IF', 'TRY', 'SWITCH', 'THIS', 'BOOL', 'NULL', 'UNDEFINED', 'UNARY', 'SUPER'
   '@', '->', '=>', '[', '(', '{', '--', '++'
 ]