path: root/lib/ast.js

/***********************************************************************

  A JavaScript tokenizer / parser / beautifier / compressor.
  https://github.com/mishoo/UglifyJS2

  -------------------------------- (C) ---------------------------------

                           Author: Mihai Bazon
                         <mihai.bazon@gmail.com>
                       http://mihai.bazon.net/blog

  Distributed under the BSD license:

    Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com>

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

        * Redistributions of source code must retain the above
          copyright notice, this list of conditions and the following
          disclaimer.

        * Redistributions in binary form must reproduce the above
          copyright notice, this list of conditions and the following
          disclaimer in the documentation and/or other materials
          provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
    OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
    TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
    THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    SUCH DAMAGE.

 ***********************************************************************/

var NODE_HIERARCHY = {};

function DEFNODE(type, props, methods, base) {
    if (arguments.length < 4) base = AST_Node;
    if (!props) props = [];
    else props = props.split(/\s+/);
    var self_props = props;
    if (base && base.PROPS)
        props = props.concat(base.PROPS);
    var code = "return function AST_" + type + "(props){ if (props) { ";
    for (var i = props.length; --i >= 0;) {
        code += "this." + props[i] + " = props." + props[i] + ";";
    }
    var proto = base && new base;
    if (proto && proto.initialize || (methods && methods.initialize))
        code += "this.initialize();";
    code += " } }";
    var ctor = new Function(code)();
    if (proto) {
        ctor.prototype = proto;
        ctor.BASE = base;
    }
    ctor.prototype.CTOR = ctor;
    ctor.PROPS = props || null;
    ctor.SELF_PROPS = self_props;
    if (type) {
        ctor.prototype.TYPE = ctor.TYPE = type;
    }
    if (methods) for (i in methods) if (HOP(methods, i)) {
        ctor.prototype[i] = methods[i];
    }
    ctor.DEFMETHOD = function(name, method) {
        this.prototype[name] = method;
    };
    NODE_HIERARCHY[type] = {
        def: ctor,
        base: base
    };
    return ctor;
};

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);
    },
    $documentation: "Base class of all AST nodes",
    _walk: function(visitor) {
        return visitor._visit(this);
    },
    walk: function(visitor) {
        return this._walk(visitor); // not sure the indirection will be any help
    }
}, null);

AST_Node.warn_function = null;
AST_Node.warn = function(txt, props) {
    if (AST_Node.warn_function)
        AST_Node.warn_function(string_template(txt, props));
};

/* -----[ statements ]----- */

var AST_StatementBase = DEFNODE("StatementBase", null, {
});

var AST_Statement = DEFNODE("Statement", "body", {
    $documentation: "Base class of all statements",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.body._walk(visitor);
        });
    }
}, AST_StatementBase);

var AST_Debugger = DEFNODE("Debugger", null, {
    $documentation: "Represents a debugger statement"
}, AST_StatementBase);

var AST_Directive = DEFNODE("Directive", "value", {
    $documentation: "Represents a directive, like \"use strict\";"
}, AST_StatementBase);

var AST_SimpleStatement = DEFNODE("SimpleStatement", null, {
    $documentation: "A statement consisting of an expression, i.e. a = 1 + 2."
}, AST_Statement);

var AST_BlockStatement = DEFNODE("BlockStatement", null, {
    $documentation: "A block statement.",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.body.forEach(function(stat){
                stat._walk(visitor);
            });
        });
    }
}, AST_Statement);

function walk_body(node, visitor) {
    if (node.body instanceof Array) node.body.forEach(function(stat){
        stat._walk(visitor);
    });
    else if (node.body instanceof AST_Statement) node.body._walk(visitor);
};

var AST_Block = DEFNODE("Block", null, {
    $documentation: "A block of statements (usually always bracketed)",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            walk_body(this, visitor);
        });
    }
}, AST_Statement);

var AST_EmptyStatement = DEFNODE("EmptyStatement", null, {
    $documentation: "The empty statement (empty block or simply a semicolon).",
    _walk: function(visitor) {
        return visitor._visit(this);
    }
}, AST_Statement);

var AST_StatementWithBody = DEFNODE("StatementWithBody", null, {
    $documentation: "Base class for all statements that contain one nested body: `For`, `ForIn`, `Do`, `While`, `With`."
}, AST_Statement);

var AST_LabeledStatement = DEFNODE("LabeledStatement", "label", {
    $documentation: "Statement with a label",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.label._walk(visitor);
            this.body._walk(visitor);
        });
    }
}, AST_StatementWithBody);

var AST_DWLoop = DEFNODE("DWLoop", "condition", {
    $documentation: "Base class for do/while statements.",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.condition._walk(visitor);
            this.body._walk(visitor);
        });
    }
}, AST_StatementWithBody);

var AST_Do = DEFNODE("Do", null, {
    $documentation: "A `do` statement"
}, AST_DWLoop);

var AST_While = DEFNODE("While", null, {
    $documentation: "A `while` statement"
}, AST_DWLoop);

var AST_For = DEFNODE("For", "init condition step", {
    $documentation: "A `for` statement",
    _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);
            this.body._walk(visitor);
        });
    }
}, AST_StatementWithBody);

var AST_ForIn = DEFNODE("ForIn", "init name object", {
    $documentation: "A `for ... in` statement",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.init._walk(visitor);
            this.object._walk(visitor);
            this.body._walk(visitor);
        });
    }
}, AST_StatementWithBody);

var AST_With = DEFNODE("With", "expression", {
    $documentation: "A `with` statement",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.expression._walk(visitor);
            this.body._walk(visitor);
        });
    }
}, AST_StatementWithBody);

/* -----[ scope and functions ]----- */

var AST_Scope = DEFNODE("Scope", "variables functions uses_with uses_eval parent_scope enclosed cname", {
    $documentation: "Base class for all statements introducing a lexical scope",
}, AST_Block);

var AST_Toplevel = DEFNODE("Toplevel", null, {
    $documentation: "The toplevel scope"
}, AST_Scope);

var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments", {
    $documentation: "Base class for functions",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            if (this.name) this.name._walk(visitor);
            this.argnames.forEach(function(arg){
                arg._walk(visitor);
            });
            walk_body(this, visitor);
        });
    }
}, AST_Scope);

var AST_Function = DEFNODE("Function", null, {
    $documentation: "A function expression"
}, AST_Lambda);

var AST_Defun = DEFNODE("Defun", null, {
    $documentation: "A function definition"
}, AST_Lambda);

/* -----[ JUMPS ]----- */

var AST_Jump = DEFNODE("Jump", null, {
    $documentation: "Base class for “jumps” (for now that's `return`, `throw`, `break` and `continue`)"
}, AST_Statement);

var AST_Exit = DEFNODE("Exit", "value", {
    $documentation: "Base class for “exits” (`return` and `throw`)",
    _walk: function(visitor) {
        return visitor._visit(this, this.value && function(){
            this.value._walk(visitor);
        });
    }
}, AST_Jump);

var AST_Return = DEFNODE("Return", null, {
    $documentation: "A `return` statement"
}, AST_Exit);

var AST_Throw = DEFNODE("Throw", null, {
    $documentation: "A `throw` statement"
}, AST_Exit);

var AST_LoopControl = DEFNODE("LoopControl", "label", {
    $documentation: "Base class for loop control statements (`break` and `continue`)",
    _walk: function(visitor) {
        return visitor._visit(this, this.label && function(){
            this.label._walk(visitor);
        });
    }
}, AST_Jump);

var AST_Break = DEFNODE("Break", null, {
    $documentation: "A `break` statement"
}, AST_LoopControl);

var AST_Continue = DEFNODE("Continue", null, {
    $documentation: "A `continue` statement"
}, AST_LoopControl);

/* -----[ IF ]----- */

var AST_If = DEFNODE("If", "condition alternative", {
    $documentation: "A `if` statement",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.condition._walk(visitor);
            this.body._walk(visitor);
            if (this.alternative) this.alternative._walk(visitor);
        });
    }
}, AST_StatementWithBody);

/* -----[ SWITCH ]----- */

var AST_Switch = DEFNODE("Switch", "expression", {
    $documentation: "A `switch` statement",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.expression._walk(visitor);
            this.body._walk(visitor);
        });
    }
}, AST_Statement);

var AST_SwitchBlock = DEFNODE("SwitchBlock", null, {
    $documentation: "The switch block is somewhat special, hence a special node for it",
}, AST_Block);

var AST_SwitchBranch = DEFNODE("SwitchBranch", null, {
    $documentation: "Base class for `switch` branches",
}, AST_Block);

var AST_Default = DEFNODE("Default", null, {
    $documentation: "A `default` switch branch",
}, AST_SwitchBranch);

var AST_Case = DEFNODE("Case", "expression", {
    $documentation: "A `case` switch branch",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.expression._walk(visitor);
            walk_body(this, visitor);
        });
    }
}, AST_SwitchBranch);

/* -----[ EXCEPTIONS ]----- */

var AST_Try = DEFNODE("Try", "bcatch bfinally", {
    $documentation: "A `try` statement",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            walk_body(this, visitor);
            if (this.bcatch) this.bcatch._walk(visitor);
            if (this.bfinally) this.bfinally._walk(visitor);
        });
    }
}, AST_Block);

// 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", {
    $documentation: "A `catch` node; only makes sense as part of a `try` statement",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.argname._walk(visitor);
            walk_body(this, visitor);
        });
    }
}, AST_Block);

var AST_Finally = DEFNODE("Finally", null, {
    $documentation: "A `finally` node; only makes sense as part of a `try` statement"
}, AST_Block);

/* -----[ VAR/CONST ]----- */

var AST_Definitions = DEFNODE("Definitions", "definitions", {
    $documentation: "Base class for `var` or `const` nodes (variable declarations/initializations)",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.definitions.forEach(function(def){
                def._walk(visitor);
            });
        });
    }
}, AST_Statement);

var AST_Var = DEFNODE("Var", null, {
    $documentation: "A `var` statement"
}, AST_Definitions);

var AST_Const = DEFNODE("Const", null, {
    $documentation: "A `const` statement"
}, AST_Definitions);

var AST_VarDef = DEFNODE("VarDef", "name value", {
    $documentation: "A variable declaration; only appears in a AST_Definitions node",
    _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", {
    $documentation: "A function call expression",
    _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, {
    $documentation: "An object instantiation.  Derives from a function call since it has exactly the same properties."
}, AST_Call);

var AST_Seq = DEFNODE("Seq", "first second", {
    $documentation: "A sequence expression (two comma-separated expressions)",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.first._walk(visitor);
            this.second._walk(visitor);
        });
    }
});

var AST_PropAccess = DEFNODE("PropAccess", "expression property", {
    $documentation: "Base class for property access expressions, i.e. `a.foo` or `a[\"foo\"]`"
});

var AST_Dot = DEFNODE("Dot", null, {
    $documentation: "A dotted property access expression",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.expression._walk(visitor);
        });
    }
}, AST_PropAccess);

var AST_Sub = DEFNODE("Sub", null, {
    $documentation: "Index-style property access, i.e. `a[\"foo\"]`",
    _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", {
    $documentation: "Base class for unary expressions",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.expression._walk(visitor);
        });
    }
});

var AST_UnaryPrefix = DEFNODE("UnaryPrefix", null, {
    $documentation: "Unary prefix expression, i.e. `typeof i` or `++i`"
}, AST_Unary);

var AST_UnaryPostfix = DEFNODE("UnaryPostfix", null, {
    $documentation: "Unary postfix expression, i.e. `i++`"
}, AST_Unary);

var AST_Binary = DEFNODE("Binary", "left operator right", {
    $documentation: "Binary expression, i.e. `a + b`",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.left._walk(visitor);
            this.right._walk(visitor);
        });
    }
});

var AST_Conditional = DEFNODE("Conditional", "condition consequent alternative", {
    $documentation: "Conditional expression using the ternary operator, i.e. `a ? b : c`",
    _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", {
    $documentation: "An assignment expression — `a = b + 5`",
}, AST_Binary);

/* -----[ LITERALS ]----- */

var AST_Array = DEFNODE("Array", "elements", {
    $documentation: "An array literal",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.elements.forEach(function(el){
                el._walk(visitor);
            });
        });
    }
});

var AST_Object = DEFNODE("Object", "properties", {
    $documentation: "An object literal",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.properties.forEach(function(prop){
                prop._walk(visitor);
            });
        });
    }
});

var AST_ObjectProperty = DEFNODE("ObjectProperty", "key value", {
    $documentation: "Base class for literal object properties",
    _walk: function(visitor) {
        return visitor._visit(this, function(){
            this.value._walk(visitor);
        });
    }
});

var AST_ObjectKeyVal = DEFNODE("ObjectKeyval", null, {
    $documentation: "A key: value object property",
}, AST_ObjectProperty);

var AST_ObjectSetter = DEFNODE("ObjectSetter", null, {
    $documentation: "An object setter property",
}, AST_ObjectProperty);

var AST_ObjectGetter = DEFNODE("ObjectGetter", null, {
    $documentation: "An object getter property",
}, AST_ObjectProperty);

var AST_Symbol = DEFNODE("Symbol", "scope name global undeclared", {
    $documentation: "Base class for all symbols",
});

var AST_SymbolDeclaration = DEFNODE("SymbolDeclaration", "references", {
    $documentation: "A declaration symbol (symbol in var/const, function name or argument, symbol in catch)",
}, AST_Symbol);

var AST_SymbolVar = DEFNODE("SymbolVar", null, {
    $documentation: "Symbol defining a variable or constant",
}, AST_SymbolDeclaration);

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)",
}, AST_Symbol);

var AST_LabelRef = DEFNODE("LabelRef", null, {
    $documentation: "Reference to a label symbol",
}, AST_SymbolRef);

var AST_This = DEFNODE("This", null, {
    $documentation: "The `this` symbol",
}, AST_Symbol);

var AST_Constant = DEFNODE("Constant", null, {
    $documentation: "Base class for all constants",
    getValue: function() {
        return this.value;
    }
});

var AST_String = DEFNODE("String", "value", {
    $documentation: "A string literal",
}, AST_Constant);

var AST_Number = DEFNODE("Number", "value", {
    $documentation: "A number literal",
}, AST_Constant);

var AST_RegExp = DEFNODE("Regexp", "pattern mods", {
    $documentation: "A regexp literal",
    initialize: function() {
        this.value = new RegExp(this.pattern, this.mods);
    }
}, AST_Constant);

var AST_Atom = DEFNODE("Atom", null, {
    $documentation: "Base class for atoms",
}, AST_Constant);

var AST_Null = DEFNODE("Null", null, {
    $documentation: "The `null` atom",
    value: null
}, AST_Atom);

var AST_Undefined = DEFNODE("Undefined", null, {
    $documentation: "The `undefined` value",
    value: (function(){}())
}, AST_Atom);

var AST_False = DEFNODE("False", null, {
    $documentation: "The `false` atom",
    value: false
}, AST_Atom);

var AST_True = DEFNODE("True", null, {
    $documentation: "The `true` atom",
    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, function(){
            descend.call(node);
        });
        if (!ret && descend) {
            descend.call(node);
        }
        this.stack.pop();
        return ret;
    },
    parent: function(n) {
        return this.stack[this.stack.length - 2 - (n || 0)];
    }
};