michael@0: // AST walker module for Mozilla Parser API compatible trees
michael@0: 
michael@0: (function(mod) {
michael@0:   if (typeof exports == "object" && typeof module == "object") return mod(exports); // CommonJS
michael@0:   if (typeof define == "function" && define.amd) return define(["exports"], mod); // AMD
michael@0:   mod((this.acorn || (this.acorn = {})).walk = {}); // Plain browser env
michael@0: })(function(exports) {
michael@0:   "use strict";
michael@0: 
michael@0:   // A simple walk is one where you simply specify callbacks to be
michael@0:   // called on specific nodes. The last two arguments are optional. A
michael@0:   // simple use would be
michael@0:   //
michael@0:   //     walk.simple(myTree, {
michael@0:   //         Expression: function(node) { ... }
michael@0:   //     });
michael@0:   //
michael@0:   // to do something with all expressions. All Parser API node types
michael@0:   // can be used to identify node types, as well as Expression,
michael@0:   // Statement, and ScopeBody, which denote categories of nodes.
michael@0:   //
michael@0:   // The base argument can be used to pass a custom (recursive)
michael@0:   // walker, and state can be used to give this walked an initial
michael@0:   // state.
michael@0:   exports.simple = function(node, visitors, base, state) {
michael@0:     if (!base) base = exports.base;
michael@0:     function c(node, st, override) {
michael@0:       var type = override || node.type, found = visitors[type];
michael@0:       base[type](node, st, c);
michael@0:       if (found) found(node, st);
michael@0:     }
michael@0:     c(node, state);
michael@0:   };
michael@0: 
michael@0:   // A recursive walk is one where your functions override the default
michael@0:   // walkers. They can modify and replace the state parameter that's
michael@0:   // threaded through the walk, and can opt how and whether to walk
michael@0:   // their child nodes (by calling their third argument on these
michael@0:   // nodes).
michael@0:   exports.recursive = function(node, state, funcs, base) {
michael@0:     var visitor = funcs ? exports.make(funcs, base) : base;
michael@0:     function c(node, st, override) {
michael@0:       visitor[override || node.type](node, st, c);
michael@0:     }
michael@0:     c(node, state);
michael@0:   };
michael@0: 
michael@0:   function makeTest(test) {
michael@0:     if (typeof test == "string")
michael@0:       return function(type) { return type == test; };
michael@0:     else if (!test)
michael@0:       return function() { return true; };
michael@0:     else
michael@0:       return test;
michael@0:   }
michael@0: 
michael@0:   function Found(node, state) { this.node = node; this.state = state; }
michael@0: 
michael@0:   // Find a node with a given start, end, and type (all are optional,
michael@0:   // null can be used as wildcard). Returns a {node, state} object, or
michael@0:   // undefined when it doesn't find a matching node.
michael@0:   exports.findNodeAt = function(node, start, end, test, base, state) {
michael@0:     test = makeTest(test);
michael@0:     try {
michael@0:       if (!base) base = exports.base;
michael@0:       var c = function(node, st, override) {
michael@0:         var type = override || node.type;
michael@0:         if ((start == null || node.start <= start) &&
michael@0:             (end == null || node.end >= end))
michael@0:           base[type](node, st, c);
michael@0:         if (test(type, node) &&
michael@0:             (start == null || node.start == start) &&
michael@0:             (end == null || node.end == end))
michael@0:           throw new Found(node, st);
michael@0:       };
michael@0:       c(node, state);
michael@0:     } catch (e) {
michael@0:       if (e instanceof Found) return e;
michael@0:       throw e;
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   // Find the innermost node of a given type that contains the given
michael@0:   // position. Interface similar to findNodeAt.
michael@0:   exports.findNodeAround = function(node, pos, test, base, state) {
michael@0:     test = makeTest(test);
michael@0:     try {
michael@0:       if (!base) base = exports.base;
michael@0:       var c = function(node, st, override) {
michael@0:         var type = override || node.type;
michael@0:         if (node.start > pos || node.end < pos) return;
michael@0:         base[type](node, st, c);
michael@0:         if (test(type, node)) throw new Found(node, st);
michael@0:       };
michael@0:       c(node, state);
michael@0:     } catch (e) {
michael@0:       if (e instanceof Found) return e;
michael@0:       throw e;
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   // Find the outermost matching node after a given position.
michael@0:   exports.findNodeAfter = function(node, pos, test, base, state) {
michael@0:     test = makeTest(test);
michael@0:     try {
michael@0:       if (!base) base = exports.base;
michael@0:       var c = function(node, st, override) {
michael@0:         if (node.end < pos) return;
michael@0:         var type = override || node.type;
michael@0:         if (node.start >= pos && test(type, node)) throw new Found(node, st);
michael@0:         base[type](node, st, c);
michael@0:       };
michael@0:       c(node, state);
michael@0:     } catch (e) {
michael@0:       if (e instanceof Found) return e;
michael@0:       throw e;
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   // Find the outermost matching node before a given position.
michael@0:   exports.findNodeBefore = function(node, pos, test, base, state) {
michael@0:     test = makeTest(test);
michael@0:     if (!base) base = exports.base;
michael@0:     var max;
michael@0:     var c = function(node, st, override) {
michael@0:       if (node.start > pos) return;
michael@0:       var type = override || node.type;
michael@0:       if (node.end <= pos && (!max || max.node.end < node.end) && test(type, node))
michael@0:         max = new Found(node, st);
michael@0:       base[type](node, st, c);
michael@0:     };
michael@0:     c(node, state);
michael@0:     return max;
michael@0:   };
michael@0: 
michael@0:   // Used to create a custom walker. Will fill in all missing node
michael@0:   // type properties with the defaults.
michael@0:   exports.make = function(funcs, base) {
michael@0:     if (!base) base = exports.base;
michael@0:     var visitor = {};
michael@0:     for (var type in base) visitor[type] = base[type];
michael@0:     for (var type in funcs) visitor[type] = funcs[type];
michael@0:     return visitor;
michael@0:   };
michael@0: 
michael@0:   function skipThrough(node, st, c) { c(node, st); }
michael@0:   function ignore(_node, _st, _c) {}
michael@0: 
michael@0:   // Node walkers.
michael@0: 
michael@0:   var base = exports.base = {};
michael@0:   base.Program = base.BlockStatement = function(node, st, c) {
michael@0:     for (var i = 0; i < node.body.length; ++i)
michael@0:       c(node.body[i], st, "Statement");
michael@0:   };
michael@0:   base.Statement = skipThrough;
michael@0:   base.EmptyStatement = ignore;
michael@0:   base.ExpressionStatement = function(node, st, c) {
michael@0:     c(node.expression, st, "Expression");
michael@0:   };
michael@0:   base.IfStatement = function(node, st, c) {
michael@0:     c(node.test, st, "Expression");
michael@0:     c(node.consequent, st, "Statement");
michael@0:     if (node.alternate) c(node.alternate, st, "Statement");
michael@0:   };
michael@0:   base.LabeledStatement = function(node, st, c) {
michael@0:     c(node.body, st, "Statement");
michael@0:   };
michael@0:   base.BreakStatement = base.ContinueStatement = ignore;
michael@0:   base.WithStatement = function(node, st, c) {
michael@0:     c(node.object, st, "Expression");
michael@0:     c(node.body, st, "Statement");
michael@0:   };
michael@0:   base.SwitchStatement = function(node, st, c) {
michael@0:     c(node.discriminant, st, "Expression");
michael@0:     for (var i = 0; i < node.cases.length; ++i) {
michael@0:       var cs = node.cases[i];
michael@0:       if (cs.test) c(cs.test, st, "Expression");
michael@0:       for (var j = 0; j < cs.consequent.length; ++j)
michael@0:         c(cs.consequent[j], st, "Statement");
michael@0:     }
michael@0:   };
michael@0:   base.ReturnStatement = function(node, st, c) {
michael@0:     if (node.argument) c(node.argument, st, "Expression");
michael@0:   };
michael@0:   base.ThrowStatement = function(node, st, c) {
michael@0:     c(node.argument, st, "Expression");
michael@0:   };
michael@0:   base.TryStatement = function(node, st, c) {
michael@0:     c(node.block, st, "Statement");
michael@0:     if (node.handler) c(node.handler.body, st, "ScopeBody");
michael@0:     if (node.finalizer) c(node.finalizer, st, "Statement");
michael@0:   };
michael@0:   base.WhileStatement = function(node, st, c) {
michael@0:     c(node.test, st, "Expression");
michael@0:     c(node.body, st, "Statement");
michael@0:   };
michael@0:   base.DoWhileStatement = base.WhileStatement;
michael@0:   base.ForStatement = function(node, st, c) {
michael@0:     if (node.init) c(node.init, st, "ForInit");
michael@0:     if (node.test) c(node.test, st, "Expression");
michael@0:     if (node.update) c(node.update, st, "Expression");
michael@0:     c(node.body, st, "Statement");
michael@0:   };
michael@0:   base.ForInStatement = function(node, st, c) {
michael@0:     c(node.left, st, "ForInit");
michael@0:     c(node.right, st, "Expression");
michael@0:     c(node.body, st, "Statement");
michael@0:   };
michael@0:   base.ForInit = function(node, st, c) {
michael@0:     if (node.type == "VariableDeclaration") c(node, st);
michael@0:     else c(node, st, "Expression");
michael@0:   };
michael@0:   base.DebuggerStatement = ignore;
michael@0: 
michael@0:   base.FunctionDeclaration = function(node, st, c) {
michael@0:     c(node, st, "Function");
michael@0:   };
michael@0:   base.VariableDeclaration = function(node, st, c) {
michael@0:     for (var i = 0; i < node.declarations.length; ++i) {
michael@0:       var decl = node.declarations[i];
michael@0:       if (decl.init) c(decl.init, st, "Expression");
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   base.Function = function(node, st, c) {
michael@0:     c(node.body, st, "ScopeBody");
michael@0:   };
michael@0:   base.ScopeBody = function(node, st, c) {
michael@0:     c(node, st, "Statement");
michael@0:   };
michael@0: 
michael@0:   base.Expression = skipThrough;
michael@0:   base.ThisExpression = ignore;
michael@0:   base.ArrayExpression = function(node, st, c) {
michael@0:     for (var i = 0; i < node.elements.length; ++i) {
michael@0:       var elt = node.elements[i];
michael@0:       if (elt) c(elt, st, "Expression");
michael@0:     }
michael@0:   };
michael@0:   base.ObjectExpression = function(node, st, c) {
michael@0:     for (var i = 0; i < node.properties.length; ++i)
michael@0:       c(node.properties[i].value, st, "Expression");
michael@0:   };
michael@0:   base.FunctionExpression = base.FunctionDeclaration;
michael@0:   base.SequenceExpression = function(node, st, c) {
michael@0:     for (var i = 0; i < node.expressions.length; ++i)
michael@0:       c(node.expressions[i], st, "Expression");
michael@0:   };
michael@0:   base.UnaryExpression = base.UpdateExpression = function(node, st, c) {
michael@0:     c(node.argument, st, "Expression");
michael@0:   };
michael@0:   base.BinaryExpression = base.AssignmentExpression = base.LogicalExpression = function(node, st, c) {
michael@0:     c(node.left, st, "Expression");
michael@0:     c(node.right, st, "Expression");
michael@0:   };
michael@0:   base.ConditionalExpression = function(node, st, c) {
michael@0:     c(node.test, st, "Expression");
michael@0:     c(node.consequent, st, "Expression");
michael@0:     c(node.alternate, st, "Expression");
michael@0:   };
michael@0:   base.NewExpression = base.CallExpression = function(node, st, c) {
michael@0:     c(node.callee, st, "Expression");
michael@0:     if (node.arguments) for (var i = 0; i < node.arguments.length; ++i)
michael@0:       c(node.arguments[i], st, "Expression");
michael@0:   };
michael@0:   base.MemberExpression = function(node, st, c) {
michael@0:     c(node.object, st, "Expression");
michael@0:     if (node.computed) c(node.property, st, "Expression");
michael@0:   };
michael@0:   base.Identifier = base.Literal = ignore;
michael@0: 
michael@0:   // A custom walker that keeps track of the scope chain and the
michael@0:   // variables defined in it.
michael@0:   function makeScope(prev, isCatch) {
michael@0:     return {vars: Object.create(null), prev: prev, isCatch: isCatch};
michael@0:   }
michael@0:   function normalScope(scope) {
michael@0:     while (scope.isCatch) scope = scope.prev;
michael@0:     return scope;
michael@0:   }
michael@0:   exports.scopeVisitor = exports.make({
michael@0:     Function: function(node, scope, c) {
michael@0:       var inner = makeScope(scope);
michael@0:       for (var i = 0; i < node.params.length; ++i)
michael@0:         inner.vars[node.params[i].name] = {type: "argument", node: node.params[i]};
michael@0:       if (node.id) {
michael@0:         var decl = node.type == "FunctionDeclaration";
michael@0:         (decl ? normalScope(scope) : inner).vars[node.id.name] =
michael@0:           {type: decl ? "function" : "function name", node: node.id};
michael@0:       }
michael@0:       c(node.body, inner, "ScopeBody");
michael@0:     },
michael@0:     TryStatement: function(node, scope, c) {
michael@0:       c(node.block, scope, "Statement");
michael@0:       if (node.handler) {
michael@0:         var inner = makeScope(scope, true);
michael@0:         inner.vars[node.handler.param.name] = {type: "catch clause", node: node.handler.param};
michael@0:         c(node.handler.body, inner, "ScopeBody");
michael@0:       }
michael@0:       if (node.finalizer) c(node.finalizer, scope, "Statement");
michael@0:     },
michael@0:     VariableDeclaration: function(node, scope, c) {
michael@0:       var target = normalScope(scope);
michael@0:       for (var i = 0; i < node.declarations.length; ++i) {
michael@0:         var decl = node.declarations[i];
michael@0:         target.vars[decl.id.name] = {type: "var", node: decl.id};
michael@0:         if (decl.init) c(decl.init, scope, "Expression");
michael@0:       }
michael@0:     }
michael@0:   });
michael@0: 
michael@0: });