simple visitor API and code to figure out scope and references

lib/ast.js

@@ -8,12 +8,14 @@ function DEFNODE(type, props, methods, base) {
     for (var i = props.length; --i >= 0;) {
         code += "this." + props[i] + " = props." + props[i] + ";";
     }
-    if (methods && methods.initialize)
+    var proto = base && new base;
+    if (proto && proto.initialize || (methods && methods.initialize))
         code += "this.initialize();";
     code += " } }";
     var ctor = new Function(code)();
-    if (base) {
-        ctor.prototype = new base;
+    if (proto) {
+        ctor.prototype = proto;
+        ctor.BASE = base;
     }
     ctor.prototype.CTOR = ctor;
     ctor.PROPS = props || null;
@@ -30,45 +32,69 @@ function DEFNODE(type, props, methods, base) {
 };
 
 var AST_Token = DEFNODE("Token", "type value line col pos endpos nlb comments_before", {
-
 }, null);
 
 var AST_Node = DEFNODE("Node", "start end", {
-    clone: function() {
-        return new this.CTOR(this);
+    _walk: function(visitor) {
+        return visitor._visit(this);
+    },
+    walk: function(visitor) {
+        return this._walk(visitor); // not sure the indirection will be any help
     }
 }, null);
 
-var AST_Directive = DEFNODE("Directive", "value", {
-
+var AST_Debugger = DEFNODE("Debugger", null, {
 });
 
-var AST_Debugger = DEFNODE("Debugger", null, {
-
+var AST_Directive = DEFNODE("Directive", "value", {
 });
 
 /* -----[ loops ]----- */
 
 var AST_LabeledStatement = DEFNODE("LabeledStatement", "label statement", {
-
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.label._walk(visitor);
+            this.statement._walk(visitor);
+        });
+    }
 });
 
 var AST_Statement = DEFNODE("Statement", "body", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.body._walk(visitor);
+        });
+    }
 });
 
 var AST_SimpleStatement = DEFNODE("SimpleStatement", null, {
-
 }, AST_Statement);
 
 var AST_BlockStatement = DEFNODE("BlockStatement", null, {
-
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            var a = this.body, i = 0, n = a.length;
+            while (i < n) {
+                a[i++]._walk(visitor);
+            }
+        });
+    }
 }, AST_Statement);
 
 var AST_EmptyStatement = DEFNODE("EmptyStatement", null, {
-
+    _walk: function(visitor) {
+        return visitor._visit(this);
+    }
 }, AST_Statement);
 
 var AST_DWLoop = DEFNODE("DWLoop", "condition", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.condition._walk(visitor);
+            this.body._walk(visitor);
+        });
+    }
 }, AST_Statement);
 
 var AST_Do = DEFNODE("Do", null, {
@@ -78,189 +104,376 @@ var AST_While = DEFNODE("While", null, {
 }, AST_DWLoop);
 
 var AST_For = DEFNODE("For", "init condition step", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            if (this.init) this.init._walk(visitor);
+            if (this.condition) this.condition._walk(visitor);
+            if (this.step) this.step._walk(visitor);
+        });
+    }
 }, AST_Statement);
 
 var AST_ForIn = DEFNODE("ForIn", "init name object", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            if (this.init) this.init._walk(visitor);
+            if (this.name) this.name._walk(visitor);
+            if (this.object) this.object._walk(visitor);
+        });
+    }
 }, AST_Statement);
 
 var AST_With = DEFNODE("With", "expression", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+            this.body._walk(visitor);
+        });
+    }
 }, AST_Statement);
 
-/* -----[ functions ]----- */
+/* -----[ scope and functions ]----- */
 
-var AST_Scope = DEFNODE("Scope", "identifiers", {
-}, AST_Statement);
+var AST_Scope = DEFNODE("Scope", null, {
+    initialize: function() {
+        this.labels = {};
+        this.variables = {};
+        this.functions = {};
+        this.uses_with = false;
+        this.uses_eval = false;
+        this.parent_scope = null;
+    }
+}, AST_BlockStatement);
 
 var AST_Toplevel = DEFNODE("Toplevel", null, {
-
 }, AST_Scope);
 
 var AST_Lambda = DEFNODE("Lambda", "name argnames", {
+    initialize: function() {
+        AST_Scope.prototype.initialize.call(this);
+        this.uses_arguments = false;
+    },
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            if (this.name) this.name._walk(visitor);
+            this.argnames.forEach(function(arg){
+                arg._walk(visitor);
+            });
+            this.body._walk(visitor);
+        });
+    }
 }, AST_Scope);
 
 var AST_Function = DEFNODE("Function", null, {
-
 }, AST_Lambda);
 
 var AST_Defun = DEFNODE("Defun", null, {
-
-}, AST_Function);
+}, AST_Lambda);
 
 /* -----[ JUMPS ]----- */
 
 var AST_Jump = DEFNODE("Jump", null, {
-
 });
 
 var AST_Exit = DEFNODE("Exit", "value", {
+    _walk: function(visitor) {
+        return visitor._visit(this, this.value && function(){
+            this.value._walk(visitor);
+        });
+    }
 }, AST_Jump);
 
 var AST_Return = DEFNODE("Return", null, {
-
 }, AST_Exit);
 
 var AST_Throw = DEFNODE("Throw", null, {
-
 }, AST_Exit);
 
 var AST_LoopControl = DEFNODE("LoopControl", "label", {
+    _walk: function(visitor) {
+        return visitor._visit(this, this.label && function(){
+            this.label._walk(visitor);
+        });
+    }
 }, AST_Jump);
 
 var AST_Break = DEFNODE("Break", null, {
-
 }, AST_LoopControl);
 
 var AST_Continue = DEFNODE("Continue", null, {
-
 }, AST_LoopControl);
 
 /* -----[ IF ]----- */
 
 var AST_If = DEFNODE("If", "condition consequent alternative", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.condition._walk(visitor);
+            this.consequent._walk(visitor);
+            if (this.alternative) this.alternative._walk(visitor);
+        });
+    }
 });
 
 /* -----[ SWITCH ]----- */
 
 var AST_Switch = DEFNODE("Switch", "expression", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+            this.body._walk(visitor);
+        });
+    }
 }, AST_Statement);
 
 var AST_SwitchBlock = DEFNODE("SwitchBlock", null, {
 }, AST_BlockStatement);
 
-var AST_SwitchBranch = DEFNODE("SwitchBranch", "body", {
-});
+var AST_SwitchBranch = DEFNODE("SwitchBranch", null, {
+}, AST_BlockStatement);
 
 var AST_Default = DEFNODE("Default", null, {
-
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            AST_BlockStatement.prototype._walk.call(this, visitor);
+        });
+    }
 }, AST_SwitchBranch);
 
 var AST_Case = DEFNODE("Case", "expression", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+            AST_BlockStatement.prototype._walk.call(this, visitor);
+        });
+    }
 }, AST_SwitchBranch);
 
 /* -----[ EXCEPTIONS ]----- */
 
 var AST_Try = DEFNODE("Try", "btry bcatch bfinally", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.btry._walk(visitor);
+            if (this.bcatch) this.bcatch._walk(visitor);
+            if (this.bfinally) this.bfinally._walk(visitor);
+        });
+    }
 });
 
-var AST_Catch = DEFNODE("Catch", "argname body", {
-});
+// XXX: this is wrong according to ECMA-262 (12.4).  the catch block
+// should introduce another scope, as the argname should be visible
+// only inside the catch block.  However, doing it this way because of
+// IE which simply introduces the name in the surrounding scope.  If
+// we ever want to fix this then AST_Catch should inherit from
+// AST_Scope.
+var AST_Catch = DEFNODE("Catch", "argname", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.argname._walk(visitor);
+            this.body._walk(visitor);
+        });
+    }
+}, AST_BlockStatement);
 
-var AST_Finally = DEFNODE("Finally", "body", {
-});
+var AST_Finally = DEFNODE("Finally", null, {
+}, AST_BlockStatement);
 
 /* -----[ VAR/CONST ]----- */
 
 var AST_Definitions = DEFNODE("Definitions", "definitions", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.definitions.forEach(function(def){
+                def._walk(visitor);
+            });
+        });
+    }
 });
 
 var AST_Var = DEFNODE("Var", null, {
-
 }, AST_Definitions);
 
 var AST_Const = DEFNODE("Const", null, {
-
 }, AST_Definitions);
 
 var AST_VarDef = DEFNODE("VarDef", "name value", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.name._walk(visitor);
+            if (this.value) this.value._walk(visitor);
+        });
+    }
 });
 
 /* -----[ OTHER ]----- */
 
 var AST_Call = DEFNODE("Call", "expression args", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+            this.args.forEach(function(arg){
+                arg._walk(visitor);
+            });
+        });
+    }
 });
 
 var AST_New = DEFNODE("New", null, {
-
 }, AST_Call);
 
 var AST_Seq = DEFNODE("Seq", "first second", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.first._walk(visitor);
+            this.second._walk(visitor);
+        });
+    }
 });
 
 var AST_PropAccess = DEFNODE("PropAccess", "expression property", {
-
 });
 
 var AST_Dot = DEFNODE("Dot", null, {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+        });
+    }
 }, AST_PropAccess);
 
 var AST_Sub = DEFNODE("Sub", null, {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+            this.property._walk(visitor);
+        });
+    }
 }, AST_PropAccess);
 
 var AST_Unary = DEFNODE("Unary", "operator expression", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.expression._walk(visitor);
+        });
+    }
 });
 
 var AST_UnaryPrefix = DEFNODE("UnaryPrefix", null, {
-
 }, AST_Unary);
 
 var AST_UnaryPostfix = DEFNODE("UnaryPostfix", null, {
-
 }, AST_Unary);
 
 var AST_Binary = DEFNODE("Binary", "left operator right", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.left._walk(visitor);
+            this.right._walk(visitor);
+        });
+    }
 });
 
 var AST_Conditional = DEFNODE("Conditional", "condition consequent alternative", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.condition._walk(visitor);
+            this.consequent._walk(visitor);
+            this.alternative._walk(visitor);
+        });
+    }
 });
 
 var AST_Assign = DEFNODE("Assign", "left operator right", {
-
 }, AST_Binary);
 
 /* -----[ LITERALS ]----- */
 
 var AST_Array = DEFNODE("Array", "elements", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.elements.forEach(function(el){
+                el._walk(visitor);
+            });
+        });
+    }
 });
 
 var AST_Object = DEFNODE("Object", "properties", {
+    _walk: function(visitor) {
+        return visitor._visit(this, function(){
+            this.properties.forEach(function(prop){
+                prop._walk(visitor);
+            });
+        });
+    }
 });
 
-var AST_ObjectProperty = DEFNODE("ObjectProperty");
+var AST_ObjectProperty = DEFNODE("ObjectProperty", "key value");
 
-var AST_ObjectKeyVal = DEFNODE("ObjectKeyval", "key value", {
+var AST_ObjectKeyVal = DEFNODE("ObjectKeyval", null, {
 }, AST_ObjectProperty);
 
-var AST_ObjectSetter = DEFNODE("ObjectSetter", "name func", {
+var AST_ObjectSetter = DEFNODE("ObjectSetter", null, {
 }, AST_ObjectProperty);
 
-var AST_ObjectGetter = DEFNODE("ObjectGetter", "name func", {
+var AST_ObjectGetter = DEFNODE("ObjectGetter", null, {
 }, AST_ObjectProperty);
 
-var AST_Symbol = DEFNODE("Symbol", "name", {
+var AST_Symbol = DEFNODE("Symbol", "scope name", {
 });
 
-var AST_This = DEFNODE("This", null, {
-
+var AST_SymbolDeclaration = DEFNODE("SymbolDeclaration", "references", {
+    initialize: function() {
+        this.references = [];
+    }
 }, AST_Symbol);
 
-var AST_SymbolRef = DEFNODE("SymbolRef", "scope symbol", {
+var AST_SymbolVar = DEFNODE("SymbolVar", null, {
+    $documentation: "Symbol defining a variable or constant"
+}, AST_SymbolDeclaration);
 
-}, AST_Symbol);
+var AST_SymbolFunarg = DEFNODE("SymbolFunarg", null, {
+    $documentation: "Symbol naming a function argument"
+}, AST_SymbolVar);
+
+var AST_SymbolDefun = DEFNODE("SymbolDefun", null, {
+    $documentation: "Symbol defining a function"
+}, AST_SymbolDeclaration);
+
+var AST_SymbolLambda = DEFNODE("SymbolLambda", null, {
+    $documentation: "Symbol naming a function expression"
+}, AST_SymbolDeclaration);
+
+var AST_SymbolCatch = DEFNODE("SymbolCatch", null, {
+    $documentation: "Symbol naming the exception in catch"
+}, AST_SymbolDeclaration);
 
 var AST_Label = DEFNODE("Label", null, {
+    $documentation: "Symbol naming a label (declaration)"
+}, AST_SymbolDeclaration);
 
+var AST_SymbolRef = DEFNODE("SymbolRef", "symbol", {
+    $documentation: "Reference to some symbol (not definition/declaration)",
+    reference: function(symbol) {
+        if (symbol) {
+            this.symbol = symbol;
+            symbol.references.push(this);
+            this.global = symbol.scope.parent_scope == null;
+        } else {
+            this.undeclared = true;
+            this.global = true;
+        }
+    }
+}, AST_Symbol);
+
+var AST_LabelRef = DEFNODE("LabelRef", null, {
+    $documentation: "Reference to a label symbol"
 }, AST_SymbolRef);
 
+var AST_This = DEFNODE("This", null, {
+}, AST_Symbol);
+
 var AST_Constant = DEFNODE("Constant", null, {
     getValue: function() {
         return this.value;
@@ -268,11 +481,9 @@ var AST_Constant = DEFNODE("Constant", null, {
 });
 
 var AST_String = DEFNODE("String", "value", {
-
 }, AST_Constant);
 
 var AST_Number = DEFNODE("Number", "value", {
-
 }, AST_Constant);
 
 var AST_RegExp = DEFNODE("Regexp", "pattern mods", {
@@ -282,7 +493,6 @@ var AST_RegExp = DEFNODE("Regexp", "pattern mods", {
 }, AST_Constant);
 
 var AST_Atom = DEFNODE("Atom", null, {
-
 }, AST_Constant);
 
 var AST_Null = DEFNODE("Null", null, {
@@ -300,3 +510,21 @@ var AST_False = DEFNODE("False", null, {
 var AST_True = DEFNODE("True", null, {
     value: true
 }, AST_Atom);
+
+/* -----[ TreeWalker ]----- */
+
+function TreeWalker(callback) {
+    this.visit = callback;
+    this.stack = [];
+};
+TreeWalker.prototype = {
+    _visit: function(node, descend) {
+        this.stack.push(node);
+        var ret = this.visit(node, descend);
+        if (!ret && descend) {
+            descend.call(node);
+        }
+        this.stack.pop(node);
+        return ret;
+    }
+};