/*********************************************************************** A JavaScript tokenizer / parser / beautifier / compressor. https://github.com/mishoo/UglifyJS2 -------------------------------- (C) --------------------------------- Author: Mihai Bazon http://mihai.bazon.net/blog Distributed under the BSD license: Copyright 2012 (c) Mihai Bazon 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. ***********************************************************************/ // The layout of the compressor follows the code generator (see // output.js). Basically each node will have a "squeeze" method // that will apply all known compression rules for that node, and // return a new node (or the original node if there was no // compression). We can't quite use the TreeWalker for this // because it's too simplistic. // The Compressor object is for storing the options and for // maintaining various internal state that might be useful for // squeezing nodes. function Compressor(options, false_by_default) { options = defaults(options, { sequences : !false_by_default, properties : !false_by_default, dead_code : !false_by_default, drop_debugger : !false_by_default, unsafe : !false_by_default, conditionals : !false_by_default, comparations : !false_by_default, evaluate : !false_by_default, booleans : !false_by_default, loops : !false_by_default, unused_func : !false_by_default, unused_vars : !false_by_default, hoist_funs : !false_by_default, hoist_vars : !false_by_default, if_return : !false_by_default, join_vars : !false_by_default, cascade : !false_by_default, warnings : true }); var stack = []; function in_boolean_context() { var i = stack.length, self = stack[--i]; while (i > 0) { var p = stack[--i]; if ((p instanceof AST_If && p.condition === self) || (p instanceof AST_Conditional && p.condition === self) || (p instanceof AST_DWLoop && p.condition === self) || (p instanceof AST_For && p.condition === self) || (p instanceof AST_UnaryPrefix && p.operator == "!" && p.expression === self)) { return true; } if (!(p instanceof AST_Binary && (p.operator == "&&" || p.operator == "||"))) return false; self = p; } }; function find_parent(type) { for (var i = stack.length; --i >= 0;) { var x = stack[i]; if (x instanceof type) return x; } }; return { option : function(key) { return options[key] }, push_node : function(node) { stack.push(node) }, pop_node : function() { return stack.pop() }, stack : function() { return stack }, self : function() { return stack[stack.length - 1] }, parent : function(n) { return stack[stack.length - 2 - (n || 0)]; }, warn : function() { if (options.warnings) AST_Node.warn.apply(AST_Node, arguments); }, in_boolean_context: in_boolean_context, find_parent: find_parent, }; }; (function(undefined){ AST_Node.DEFMETHOD("squeeze", function(){ return this; }); AST_Node.DEFMETHOD("optimize", function(){ return this; }); AST_Node.DEFMETHOD("equivalent_to", function(node){ // XXX: this is a rather expensive way to test two node's equivalence: return this.print_to_string() == node.print_to_string(); }); function make_node(ctor, orig, props) { if (!props) props = {}; if (!props.start) props.start = orig.start; if (!props.end) props.end = orig.end; return new ctor(props); }; function SQUEEZE(nodetype, squeeze) { nodetype.DEFMETHOD("squeeze", function(compressor){ compressor.push_node(this); var new_node = squeeze(this, compressor); compressor.pop_node(); return new_node !== undefined ? new_node : this; }); }; function do_list(array, compressor, splice_blocks) { return MAP(array, function(node, i){ node = node.squeeze(compressor, array, i); if (splice_blocks) { if (node instanceof AST_BlockStatement) { return MAP.splice(eliminate_spurious_blocks(node.body)); } if (node instanceof AST_EmptyStatement) return MAP.skip; } return node; }); }; function eliminate_spurious_blocks(statements) { return statements.reduce(function(a, stat){ if (stat instanceof AST_BlockStatement) { a.push.apply(a, eliminate_spurious_blocks(stat.body)); } else if (!(stat instanceof AST_EmptyStatement)) { a.push(stat); } return a; }, []); }; function as_statement_array(thing) { if (thing === null) return []; if (thing instanceof AST_BlockStatement) return thing.body; if (thing instanceof AST_EmptyStatement) return []; if (thing instanceof AST_StatementBase) return [ thing ]; throw new Error("Can't convert thing to statement array"); }; function is_empty(thing) { if (thing === null) return true; if (thing instanceof AST_EmptyStatement) return true; if (thing instanceof AST_BlockStatement) return thing.body.length == 0; return false; }; function tighten_body(statements, compressor) { var CHANGED; statements = do_list(statements, compressor, true); do { CHANGED = false; if (compressor.option("dead_code")) { statements = eliminate_dead_code(statements, compressor); } if (compressor.option("if_return")) { statements = handle_if_return(statements, compressor); } if (compressor.option("sequences")) { statements = sequencesize(statements, compressor); } if (compressor.option("join_vars")) { statements = join_consecutive_vars(statements, compressor); } statements = eliminate_spurious_blocks(statements); } while (CHANGED); return statements; function handle_if_return(statements, compressor) { var self = compressor.self(); var in_lambda = self instanceof AST_Lambda; var last = statements.length - 1; var ret = []; loop: for (var i = statements.length; --i >= 0;) { var stat = statements[i]; switch (true) { case (in_lambda && stat instanceof AST_Return && !stat.value && ret.length == 0): CHANGED = true; // note, ret.length is probably always zero // because we drop unreachable code before this // step. nevertheless, it's good to check. continue loop; case stat instanceof AST_If: // compressor.warn("Current if: {code}", { // code: stat.condition.print_to_string() // }); if (stat.body instanceof AST_Return) { //--- // pretty silly case, but: // if (foo()) return; return; ==> foo(); return; if (((in_lambda && ret.length == 0) || (ret[0] instanceof AST_Return && !ret[0].value)) && !stat.body.value && !stat.alternative) { CHANGED = true; var cond = make_node(AST_SimpleStatement, stat.condition, { body: stat.condition }).optimize(compressor); ret.unshift(cond); continue loop; } //--- // if (foo()) return x; return y; ==> return foo() ? x : y; if (ret[0] instanceof AST_Return && stat.body.value && ret[0].value && !stat.alternative) { CHANGED = true; stat = stat.clone(); stat.alternative = ret[0]; ret[0] = stat.squeeze(compressor); continue loop; } //--- // if (foo()) return x; [ return ; ] ==> return foo() ? x : undefined; if ((ret.length == 0 || ret[0] instanceof AST_Return) && stat.body.value && !stat.alternative && in_lambda) { CHANGED = true; stat = stat.clone(); stat.alternative = ret[0] || make_node(AST_Return, stat, { value: make_node(AST_Undefined, stat) }); ret[0] = stat.squeeze(compressor); continue loop; } //--- // if (foo()) return; [ else x... ]; y... ==> if (!foo()) { x...; y... } if (!stat.body.value && in_lambda) { CHANGED = true; stat = stat.clone(); stat.condition = stat.condition.negate(compressor); stat.body = make_node(AST_BlockStatement, stat, { body: as_statement_array(stat.alternative).concat(ret) }); stat.alternative = null; ret = [ stat.squeeze(compressor) ]; continue loop; } //--- if (ret.length == 1 && in_lambda && ret[0] instanceof AST_SimpleStatement && (!stat.alternative || stat.alternative instanceof AST_SimpleStatement)) { CHANGED = true; ret.push(make_node(AST_Return, ret[0], { value: make_node(AST_Undefined, ret[0]) }).squeeze(compressor)); ret = as_statement_array(stat.alternative).concat(ret); ret.unshift(stat); continue loop; } } var ab = aborts(stat.body); if (ab && ((ab instanceof AST_Return && !ab.value && in_lambda) || (ab instanceof AST_Continue && self === ab.target()))) { CHANGED = true; var body = tighten_body(as_statement_array(stat.body).slice(0, -1), compressor); stat = stat.clone(); stat.condition = stat.condition.negate(compressor); stat.body = make_node(AST_BlockStatement, stat, { body: ret }); stat.alternative = make_node(AST_BlockStatement, stat, { body: body }); ret = [ stat.squeeze(compressor) ]; continue loop; } var ab = aborts(stat.alternative); if (ab && ((ab instanceof AST_Return && !ab.value && in_lambda) || (ab instanceof AST_Continue && self === ab.target()))) { CHANGED = true; stat = stat.clone(); stat.body = make_node(AST_BlockStatement, stat.body, { body: tighten_body(as_statement_array(stat.body).concat(ret), compressor) }); stat.alternative = make_node(AST_BlockStatement, stat.alternative, { body: tighten_body(as_statement_array(stat.alternative).slice(0, -1), compressor) }); ret = [ stat.squeeze(compressor) ]; continue loop; } ret.unshift(stat); break; default: ret.unshift(stat); break; } } return ret; }; function eliminate_dead_code(statements, compressor) { var has_quit = false; return statements.reduce(function(a, stat){ if (has_quit) { extract_declarations_from_unreachable_code(compressor, stat, a); } else { a.push(stat); if (stat instanceof AST_Jump) { has_quit = true; } } return a; }, []); }; function sequencesize(statements, compressor) { if (statements.length < 2) return statements; var seq = [], ret = []; function push_seq() { seq = AST_Seq.from_array(seq); if (seq) ret.push(make_node(AST_SimpleStatement, seq, { body: seq })); seq = []; }; statements.forEach(function(stat){ if (stat instanceof AST_SimpleStatement) seq.push(stat.body); else push_seq(), ret.push(stat); }); push_seq(); ret = sequencesize_2(ret, compressor); CHANGED = ret.length != statements.length; return ret; }; function sequencesize_2(statements, compressor) { function cons_seq(right) { ret.pop(); var left = prev.body; if (left instanceof AST_Seq) { left.add(right); } else { left = AST_Seq.cons(left, right); } return left.optimize(compressor); }; var ret = [], prev = null; statements.forEach(function(stat){ if (prev) { if (stat instanceof AST_For && stat.init && !(stat.init instanceof AST_Definitions)) { stat.init = cons_seq(stat.init); } else if (stat instanceof AST_For && !stat.init) { stat.init = prev.body; ret.pop(); } else if (stat instanceof AST_If) { stat.condition = cons_seq(stat.condition); } else if (stat instanceof AST_With) { stat.expression = cons_seq(stat.expression); } else if (stat instanceof AST_Exit && stat.value) { stat.value = cons_seq(stat.value); } else if (stat instanceof AST_Exit) { stat.value = cons_seq(make_node(AST_Undefined, stat)); } else if (stat instanceof AST_Switch) { stat.expression = cons_seq(stat.expression); } } ret.push(stat); prev = stat instanceof AST_SimpleStatement ? stat : null; }); return ret; }; function join_consecutive_vars(statements, compressor) { var prev = null; return statements.reduce(function(a, stat){ if (stat instanceof AST_Definitions && prev && prev.TYPE == stat.TYPE) { prev.definitions = prev.definitions.concat(stat.definitions); CHANGED = true; } else if (stat instanceof AST_For && prev instanceof AST_Definitions && (!stat.init || stat.init.TYPE == prev.TYPE)) { CHANGED = true; a.pop(); if (stat.init) { stat.init.definitions = prev.definitions.concat(stat.init.definitions); } else { stat.init = prev; } a.push(stat); prev = stat; } else { prev = stat; a.push(stat); } return a; }, []); }; }; function extract_declarations_from_unreachable_code(compressor, stat, target) { compressor.warn("Dropping unreachable code [{file}:{line},{col}]", stat.start); stat.walk(new TreeWalker(function(node){ if (node instanceof AST_Definitions) { compressor.warn("Declarations in unreachable code! [{file}:{line},{col}]", node.start); node = node.clone(); node.remove_initializers(); target.push(node); return true; } if (node instanceof AST_Defun) { target.push(node); return true; } if (node instanceof AST_Scope) { return true; } })); }; /* -----[ boolean/negation helpers ]----- */ // methods to determine whether an expression has a boolean result type (function (def){ var unary_bool = [ "!", "delete" ]; var binary_bool = [ "in", "instanceof", "==", "!=", "===", "!==", "<", "<=", ">=", ">" ]; def(AST_Node, function(){ return false }); def(AST_UnaryPrefix, function(){ return member(this.operator, unary_bool); }); def(AST_Binary, function(){ return member(this.operator, binary_bool) || ( (this.operator == "&&" || this.operator == "||") && this.left.is_boolean() && this.right.is_boolean() ); }); def(AST_Conditional, function(){ return this.consequent.is_boolean() && this.alternative.is_boolean(); }); def(AST_Assign, function(){ return this.operator == "=" && this.right.is_boolean(); }); def(AST_Seq, function(){ return this.cdr.is_boolean(); }); def(AST_True, function(){ return true }); def(AST_False, function(){ return true }); })(function(node, func){ node.DEFMETHOD("is_boolean", func); }); // methods to determine if an expression has a string result type (function (def){ def(AST_Node, function(){ return false }); def(AST_String, function(){ return true }); def(AST_UnaryPrefix, function(){ return this.operator == "typeof"; }); def(AST_Binary, function(){ return this.operator == "+" && (this.left.is_string() || this.right.is_string()); }); def(AST_Assign, function(){ return this.operator == "=" && this.right.is_string(); }); })(function(node, func){ node.DEFMETHOD("is_string", func); }); function best_of(ast1, ast2) { return ast1.print_to_string().length > ast2.print_to_string().length ? ast2 : ast1; }; // methods to evaluate a constant expression (function (def){ // The evaluate method returns an array with one or two // elements. If the node has been successfully reduced to a // constant, then the second element tells us the value; // otherwise the second element is missing. The first element // of the array is always an AST_Node descendant; when // evaluation was successful it's a node that represents the // constant; otherwise it's the original node. AST_Node.DEFMETHOD("evaluate", function(compressor){ if (!compressor.option("evaluate")) return [ this ]; try { var val = this._eval(), ast; switch (typeof val) { case "string": ast = make_node(AST_String, this, { value: val }); break; case "number": ast = make_node(isNaN(val) ? AST_NaN : AST_Number, this, { value: val }).optimize(compressor); break; case "boolean": ast = make_node(val ? AST_True : AST_False, this); break; case "undefined": ast = make_node(AST_Undefined, this).optimize(compressor); break; default: if (val === null) { ast = make_node(AST_Null, this); break; } throw new Error(string_template("Can't handle constant of type: {type}", { type: typeof val })); } return [ best_of(ast, this), val ]; } catch(ex) { if (ex !== def) throw ex; return [ this ]; } }); def(AST_Statement, function(){ throw new Error("Cannot evaluate a statement"); }); function ev(node) { return node._eval(); }; def(AST_Node, function(){ throw def; // not constant }); def(AST_Constant, function(){ return this.getValue(); }); def(AST_UnaryPrefix, function(){ var e = this.expression; switch (this.operator) { case "!": return !ev(e); case "typeof": return typeof ev(e); case "void": return void ev(e); case "~": return ~ev(e); case "-": return -ev(e); case "+": return +ev(e); } throw def; }); def(AST_Binary, function(){ var left = this.left, right = this.right; switch (this.operator) { case "&&" : return ev(left) && ev(right); case "||" : return ev(left) || ev(right); case "|" : return ev(left) | ev(right); case "&" : return ev(left) & ev(right); case "^" : return ev(left) ^ ev(right); case "+" : return ev(left) + ev(right); case "*" : return ev(left) * ev(right); case "/" : return ev(left) / ev(right); case "%" : return ev(left) % ev(right); case "-" : return ev(left) - ev(right); case "<<" : return ev(left) << ev(right); case ">>" : return ev(left) >> ev(right); case ">>>" : return ev(left) >>> ev(right); case "==" : return ev(left) == ev(right); case "===" : return ev(left) === ev(right); case "!=" : return ev(left) != ev(right); case "!==" : return ev(left) !== ev(right); case "<" : return ev(left) < ev(right); case "<=" : return ev(left) <= ev(right); case ">" : return ev(left) > ev(right); case ">=" : return ev(left) >= ev(right); case "in" : return ev(left) in ev(right); case "instanceof" : return ev(left) instanceof ev(right); } throw def; }); def(AST_Conditional, function(){ return ev(this.condition) ? ev(this.consequent) : ev(this.alternative); }); })(function(node, func){ node.DEFMETHOD("_eval", func); }); // method to negate an expression (function(def){ function basic_negation(exp) { return make_node(AST_UnaryPrefix, exp, { operator: "!", expression: exp }); }; def(AST_Node, function(){ return basic_negation(this); }); def(AST_Statement, function(){ throw new Error("Cannot negate a statement"); }); def(AST_Function, function(){ return basic_negation(this); }); def(AST_UnaryPrefix, function(){ if (this.operator == "!") return this.expression; return basic_negation(this); }); def(AST_Seq, function(compressor){ var self = this.clone(); self.cdr = self.cdr.negate(compressor); return self; }); def(AST_Conditional, function(compressor){ var self = this.clone(); self.consequent = self.consequent.negate(compressor); self.alternative = self.alternative.negate(compressor); return best_of(basic_negation(this), self); }); def(AST_Binary, function(compressor){ var self = this.clone(), op = this.operator; if (compressor.option("comparations")) switch (op) { case "<=" : self.operator = ">" ; return self; case "<" : self.operator = ">=" ; return self; case ">=" : self.operator = "<" ; return self; case ">" : self.operator = "<=" ; return self; } switch (op) { case "==" : self.operator = "!="; return self; case "!=" : self.operator = "=="; return self; case "===": self.operator = "!=="; return self; case "!==": self.operator = "==="; return self; case "&&": self.operator = "||"; self.left = self.left.negate(compressor); self.right = self.right.negate(compressor); return best_of(basic_negation(this), self); case "||": self.operator = "&&"; self.left = self.left.negate(compressor); self.right = self.right.negate(compressor); return best_of(basic_negation(this), self); } return basic_negation(this); }); })(function(node, func){ node.DEFMETHOD("negate", function(compressor){ return func.call(this, compressor); }); }); // determine if expression has side effects (function(def){ def(AST_Node, function(){ return true }); def(AST_EmptyStatement, function(){ return false }); def(AST_Constant, function(){ return false }); def(AST_This, function(){ return false }); def(AST_Function, function(){ return false }); def(AST_BlockStatement, function(){ for (var i = this.body.length; --i >= 0;) { if (this.body[i].has_side_effects()) return true; } return false; }); def(AST_SimpleStatement, function(){ return this.body.has_side_effects(); }); def(AST_Binary, function(){ return this.left.has_side_effects() || this.right.has_side_effects(); }); def(AST_Assign, function(){ return true }); def(AST_Conditional, function(){ return this.condition.has_side_effects() || this.consequent.has_side_effects() || this.alternative.has_side_effects(); }); def(AST_Unary, function(){ return this.operator == "delete" || this.operator == "++" || this.operator == "--" || this.expression.has_side_effects(); }); def(AST_SymbolRef, function(){ return false }); def(AST_Object, function(){ for (var i = this.properties.length; --i >= 0;) if (this.properties[i].has_side_effects()) return true; return false; }); def(AST_ObjectProperty, function(){ return this.value.has_side_effects(); }); def(AST_Array, function(){ for (var i = this.elements.length; --i >= 0;) if (this.elements[i].has_side_effects()) return true; return false; }); def(AST_Dot, function(){ return this.expression.has_side_effects(); }); def(AST_Sub, function(){ return this.expression.has_side_effects() || this.property.has_side_effects(); }); def(AST_Seq, function(){ return this.car.has_side_effects() || this.cdr.has_side_effects(); }); })(function(node, func){ node.DEFMETHOD("has_side_effects", func); }); // tell me if a statement aborts function aborts(thing) { return thing && thing.aborts(); }; (function(def){ def(AST_StatementBase, function(){ return null }); def(AST_Jump, function(){ return this }); def(AST_BlockStatement, function(){ var n = this.body.length; return n > 0 && aborts(this.body[n - 1]); }); })(function(node, func){ node.DEFMETHOD("aborts", func); }); /* -----[ node squeezers ]----- */ SQUEEZE(AST_Directive, function(self, compressor){ if (self.hoisted || self.scope.has_directive(self.value) !== self.scope) { return new AST_EmptyStatement(self); } return self; }); SQUEEZE(AST_Debugger, function(self, compressor){ if (compressor.option("drop_debugger")) return new AST_EmptyStatement(self); }); SQUEEZE(AST_LabeledStatement, function(self, compressor){ self = self.clone(); self.body = self.body.squeeze(compressor); return self.label.references.length == 0 ? self.body : self; }); SQUEEZE(AST_Statement, function(self, compressor){ self = self.clone(); self.body = self.body.squeeze(compressor); return self; }); SQUEEZE(AST_BlockStatement, function(self, compressor){ self = self.clone(); self.body = tighten_body(self.body, compressor); return self.optimize(compressor); }); AST_BlockStatement.DEFMETHOD("optimize", function(compressor){ switch (this.body.length) { case 1: return this.body[0]; case 0: return make_node(AST_EmptyStatement, this); } return this; }); SQUEEZE(AST_Block, function(self, compressor){ self = self.clone(); self.body = tighten_body(self.body, compressor); return self; }); SQUEEZE(AST_Scope, function(self, compressor){ self = self.clone(); self.hoist_declarations(compressor); self.body = tighten_body(self.body, compressor); return self; }); AST_Scope.DEFMETHOD("drop_unused_vars", function(compressor){ if (compressor.option("unused_vars")) { var self = this; var tw = new TreeWalker(function(node){ if (node !== self) { if (node instanceof AST_Scope) return true; // don't go in nested scopes if (node instanceof AST_Definitions) { if (!(tw.parent() instanceof AST_ForIn)) { var a = node.definitions; for (var i = a.length; --i >= 0;) { var def = a[i]; var sym = def.name; if (sym.unreferenced()) { var warn = { name: sym.name, file: sym.start.file, line: sym.start.line, col: sym.start.col }; if (def.value && def.value.has_side_effects()) { compressor.warn("Side effects in initialization of unreferenced variable {name} [{file}:{line},{col}]", warn); } else { compressor.warn("Dropping unreferenced variable {name} [{file}:{line},{col}]", warn); a.splice(i, 1); } } } } return true; } if (!(node instanceof AST_Statement)) { return true; // pointless to visit expressions } } }); this.walk(tw); } }); AST_Scope.DEFMETHOD("hoist_declarations", function(compressor){ var hoist_funs = compressor.option("hoist_funs"); var hoist_vars = compressor.option("hoist_vars"); this.drop_unused_vars(compressor); if (hoist_funs || hoist_vars) { var self = this; var hoisted = []; var defuns = {}; var vars = {}, vars_found = 0, vardecl = []; var tw = new TreeWalker(function(node){ if (node !== self) { if (node instanceof AST_Directive && (hoist_funs || hoist_vars) && !node.hoisted) { hoisted.unshift(node.clone()); node.hoisted = true; } if (node instanceof AST_Defun && hoist_funs && !node.hoisted) { hoisted.push(node.clone()); node.hoisted = true; defuns[node.name.name] = true; } if (node instanceof AST_Var && hoist_vars && !node.hoisted) { node.definitions.forEach(function(def){ vars[def.name.name] = def; ++vars_found; }); vardecl.push(node); } if (node instanceof AST_Scope) return true; } }); self.walk(tw); if (vars_found > 0 && vardecl.length > 1) { vardecl.forEach(function(v){ v.hoisted = true }); var node = make_node(AST_Var, self, { definitions: Object.keys(vars).map(function(name){ var def = vars[name].clone(); def.value = null; return def; }) }); hoisted.unshift(node); } self.body = hoisted.concat(self.body); } }); SQUEEZE(AST_SimpleStatement, function(self, compressor){ self = self.clone(); self.body = self.body.squeeze(compressor); return self.optimize(compressor); }); AST_SimpleStatement.DEFMETHOD("optimize", function(compressor){ if (!this.body.has_side_effects()) { compressor.warn("Dropping side-effect-free statement [{file}:{line},{col}]", this.start); return make_node(AST_EmptyStatement, this); } return this; }); SQUEEZE(AST_EmptyStatement, function(self, compressor){ return self; }); SQUEEZE(AST_DWLoop, function(self, compressor){ self = self.clone(); self.condition = self.condition.squeeze(compressor); self.body = self.body.squeeze(compressor); return self.optimize(compressor); }); AST_DWLoop.DEFMETHOD("optimize", function(compressor){ var self = this; var cond = self.condition.evaluate(compressor); self.condition = cond[0]; if (!compressor.option("loops")) return self; if (cond.length == 2) { if (cond[1]) { return make_node(AST_For, self, { body: self.body }); } else if (self instanceof AST_While) { if (compressor.option("dead_code")) { var a = []; extract_declarations_from_unreachable_code(compressor, self.body, a); return make_node(AST_BlockStatement, self, { body: a }).optimize(compressor); } } else { return self.body; } } return self; }); // while(cond){ ... } ==> for(;cond;){ ... } // // not helpful, it seems (output is a bit bigger after gzip) // // AST_While.DEFMETHOD("optimize", function(compressor){ // var self = AST_DWLoop.prototype.optimize.call(this, compressor); // if (self instanceof AST_While) { // self = make_node(AST_For, self, { // condition: self.condition, // body: self.body // }).optimize(compressor); // } // return self; // }); SQUEEZE(AST_For, function(self, compressor){ self = self.clone(); if (self.init) self.init = self.init.squeeze(compressor); if (self.condition) self.condition = self.condition.squeeze(compressor); if (self.step) self.step = self.step.squeeze(compressor); self.body = self.body.squeeze(compressor); return self.optimize(compressor); }); AST_For.DEFMETHOD("optimize", function(compressor){ var cond = this.condition; if (cond) { cond = cond.evaluate(compressor); this.condition = cond[0]; } if (!compressor.option("loops")) return this; if (cond) { if (cond.length == 2 && !cond[1]) { if (compressor.option("dead_code")) { var a = []; if (this.init instanceof AST_Statement) { a.push(this.init); } else if (this.init) { a.push(make_node(AST_SimpleStatement, this.init, { body: this.init })); } extract_declarations_from_unreachable_code(compressor, this.body, a); return make_node(AST_BlockStatement, this, { body: a }); } } } return this; }); SQUEEZE(AST_ForIn, function(self, compressor){ self = self.clone(); self.init = self.init.squeeze(compressor); self.object = self.object.squeeze(compressor); self.body = self.body.squeeze(compressor); return self; }); SQUEEZE(AST_With, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); self.body = self.body.squeeze(compressor); }); SQUEEZE(AST_Exit, function(self, compressor){ self = self.clone(); if (self.value) self.value = self.value.squeeze(compressor); return self; }); SQUEEZE(AST_LoopControl, function(self, compressor){ self = self.clone(); if (self.label) self.label = self.label.squeeze(compressor); return self; }); SQUEEZE(AST_If, function(self, compressor){ self = self.clone(); self.condition = self.condition.squeeze(compressor); self.body = self.body.squeeze(compressor); if (self.alternative) self.alternative = self.alternative.squeeze(compressor); return self.optimize(compressor); }); AST_If.DEFMETHOD("optimize", function(compressor){ var self = this; if (!compressor.option("conditionals")) return self; // if condition can be statically determined, warn and drop // one of the blocks. note, statically determined implies // “has no side effects”; also it doesn't work for cases like // `x && true`, though it probably should. var cond = self.condition.evaluate(compressor); self.condition = cond[0]; if (cond.length == 2) { if (cond[1]) { compressor.warn("Condition always true [{file}:{line},{col}]", self.condition.start); if (compressor.option("dead_code")) { var a = []; if (self.alternative) { extract_declarations_from_unreachable_code(compressor, self.alternative, a); } a.push(self.body); return make_node(AST_BlockStatement, self, { body: a }); } } else { compressor.warn("Condition always false [{file}:{line},{col}]", self.condition.start); if (compressor.option("dead_code")) { var a = []; extract_declarations_from_unreachable_code(compressor, self.body, a); if (self.alternative) a.push(self.alternative); return make_node(AST_BlockStatement, self, { body: a }); } } } if (is_empty(self.alternative)) self.alternative = null; var negated = self.condition.negate(compressor).optimize(compressor); var negated_is_best = best_of(self.condition, negated) === negated; if (self.alternative && negated_is_best) { negated_is_best = false; // because we already do the switch here. self.condition = negated; var tmp = self.body; self.body = self.alternative || new AST_EmptyStatement(); self.alternative = tmp; } if (is_empty(self.body) && is_empty(self.alternative)) { return make_node(AST_SimpleStatement, self.condition, { body: self.condition }); } if (self.body instanceof AST_SimpleStatement && self.alternative instanceof AST_SimpleStatement) { return make_node(AST_SimpleStatement, self, { body: make_node(AST_Conditional, self, { condition : self.condition, consequent : self.body.body, alternative : self.alternative.body }).optimize(compressor) }); } if (is_empty(self.alternative) && self.body instanceof AST_SimpleStatement) { if (negated_is_best) return make_node(AST_SimpleStatement, self, { body: make_node(AST_Binary, self, { operator : "||", left : negated, right : self.body.body }).optimize(compressor) }); return make_node(AST_SimpleStatement, self, { body: make_node(AST_Binary, self, { operator : "&&", left : self.condition, right : self.body.body }).optimize(compressor) }); } if (self.body instanceof AST_EmptyStatement && self.alternative && self.alternative instanceof AST_SimpleStatement) { return make_node(AST_SimpleStatement, self, { body: make_node(AST_Binary, self, { operator : "||", left : self.condition, right : self.alternative.body }).optimize(compressor) }); } if (self.body instanceof AST_Exit && self.alternative instanceof AST_Exit && self.body.TYPE == self.alternative.TYPE) { return make_node(self.body.CTOR, self, { value: make_node(AST_Conditional, self, { condition : self.condition, consequent : self.body.value, alternative : self.alternative.value || make_node(AST_Undefined, self).optimize(compressor) }).optimize(compressor) }); } if (self.body instanceof AST_If && !self.body.alternative && !self.alternative) { self.condition = make_node(AST_Binary, self.condition, { operator: "&&", left: self.condition, right: self.body.condition }).optimize(compressor); self.body = self.body.body; } if (aborts(self.body)) { if (self.alternative) { var alt = self.alternative; self.alternative = null; return make_node(AST_BlockStatement, self, { body: [ self, alt ] }).optimize(compressor); } } if (aborts(self.alternative)) { var body = self.body; self.body = self.alternative; self.condition = negated_is_best ? negated : self.condition.negate(compressor).optimize(compressor); self.alternative = null; return make_node(AST_BlockStatement, self, { body: [ self, body ] }).optimize(compressor); } return self; }); SQUEEZE(AST_Switch, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); self.body = self.body.squeeze(compressor); return self.optimize(compressor); }); AST_Switch.DEFMETHOD("optimize", function(compressor){ var last_branch = this.body.body[this.body.body.length - 1]; if (last_branch) { var stat = last_branch.body[last_branch.body.length - 1]; // last statement if (stat instanceof AST_Break && !stat.label) last_branch.body.pop(); } return this; }); SQUEEZE(AST_Case, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); self.body = tighten_body(self.body, compressor); return self; }); SQUEEZE(AST_Try, function(self, compressor){ self = self.clone(); self.body = tighten_body(self.body, compressor); if (self.bcatch) self.bcatch = self.bcatch.squeeze(compressor); if (self.bfinally) self.bfinally = self.bfinally.squeeze(compressor); return self; }); AST_Definitions.DEFMETHOD("remove_initializers", function(){ this.definitions = this.definitions.map(function(def){ def = def.clone(); def.value = null; return def; }); }); AST_Definitions.DEFMETHOD("to_assignments", function(){ var assignments = this.definitions.reduce(function(a, def){ if (def.value) { var name = make_node(AST_SymbolRef, def.name, def.name); a.push(make_node(AST_Assign, def, { operator : "=", left : name, right : def.value })); } return a; }, []); if (assignments.length == 0) return null; return (function seq(list){ var first = list[0]; if (list.length == 1) return first; return make_node(AST_Seq, first, { car: first, cdr: seq(list.slice(1)) }); })(assignments); }); SQUEEZE(AST_Definitions, function(self, compressor){ if (self.definitions.length == 0) return make_node(AST_EmptyStatement, self); if (self.hoisted) { var seq = self.to_assignments(); var p = compressor.parent(); if (seq) seq = seq.squeeze(compressor); if (p instanceof AST_ForIn && p.init === self) { if (seq == null) return self.definitions[0].name; //XXX: is this fine? return seq; } if (p instanceof AST_For && p.init === self) { return seq; } if (!seq) return make_node(AST_EmptyStatement, self); return make_node(AST_SimpleStatement, self, { body: seq }); } self = self.clone(); self.definitions = do_list(self.definitions, compressor); return self; }); SQUEEZE(AST_VarDef, function(self, compressor){ self = self.clone(); if (self.value) self.value = self.value.squeeze(compressor); return self; }); SQUEEZE(AST_Lambda, function(self, compressor){ if (self.hoisted) return make_node(AST_EmptyStatement, self); self = self.clone(); if (self.name) self.name = self.name.squeeze(compressor); self.argnames = do_list(self.argnames, compressor); self.hoist_declarations(compressor); self.body = tighten_body(self.body, compressor); return self.optimize(compressor); }); AST_Function.DEFMETHOD("optimize", function(compressor){ if (compressor.option("unused_func")) { if (this.name && this.name.unreferenced()) { this.name = null; } } return this; }); AST_Defun.DEFMETHOD("optimize", function(compressor){ if (compressor.option("unused_func")) { if (this.name.unreferenced() && !(this.parent_scope instanceof AST_Toplevel)) { compressor.warn("Dropping unused function {name} [{file}:{line},{col}]", { name: this.name.name, file: this.start.file, line: this.start.line, col: this.start.col }); return make_node(AST_EmptyStatement, this); } } return this; }); SQUEEZE(AST_Call, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); self.args = do_list(self.args, compressor); return self.optimize(compressor); }); AST_Call.DEFMETHOD("optimize", function(compressor){ if (compressor.option("unsafe")) { var exp = this.expression; if (exp instanceof AST_SymbolRef && exp.undeclared()) { switch (exp.name) { case "Array": if (this.args.length != 1) { return make_node(AST_Array, this, { elements: this.args }).optimize(compressor); } break; case "Object": if (this.args.length == 0) { return make_node(AST_Object, this, { properties: [] }).optimize(compressor); } break; case "String": return make_node(AST_Binary, this, { left: this.args[0], operator: "+", right: make_node(AST_String, this, { value: "" }) }); } } else if (exp instanceof AST_Dot && exp.property == "toString" && this.args.length == 0) { return make_node(AST_Binary, this, { left: exp.expression, operator: "+", right: make_node(AST_String, this, { value: "" }) }); } } return this; }); AST_New.DEFMETHOD("optimize", function(compressor){ if (compressor.option("unsafe")) { var exp = this.expression; if (exp instanceof AST_SymbolRef && exp.undeclared()) { switch (exp.name) { case "Object": case "RegExp": case "Function": case "Error": case "Array": return make_node(AST_Call, this, this).optimize(compressor); } } } return this; }); SQUEEZE(AST_Seq, function(self, compressor){ self = self.clone(); self.car = self.car.squeeze(compressor); self.cdr = self.cdr.squeeze(compressor); return self.optimize(compressor); }); AST_Seq.DEFMETHOD("optimize", function(compressor){ var self = this; if (self.cdr instanceof AST_Seq) self.cdr = self.cdr.optimize(compressor); if (compressor.option("cascade")) { if (self.car instanceof AST_Assign && !self.car.left.has_side_effects() && self.car.left.equivalent_to(self.cdr)) { return self.car; } if (!self.car.has_side_effects() && !self.cdr.has_side_effects() && self.car.equivalent_to(self.cdr)) { return self.car; } } return self; }); SQUEEZE(AST_Dot, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); return self; }); SQUEEZE(AST_Sub, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); var prop = self.property = self.property.squeeze(compressor); if (prop instanceof AST_String && compressor.option("properties")) { prop = prop.getValue(); if (is_identifier(prop)) { self = new AST_Dot(self); self.property = prop; } } return self; }); SQUEEZE(AST_Unary, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); return self; }); SQUEEZE(AST_UnaryPrefix, function(self, compressor){ self = self.clone(); self.expression = self.expression.squeeze(compressor); return self.optimize(compressor); }); AST_UnaryPrefix.DEFMETHOD("optimize", function(compressor){ var self = this; var e = self.expression; if (compressor.option("booleans") && compressor.in_boolean_context()) { switch (self.operator) { case "!": if (e instanceof AST_UnaryPrefix && e.operator == "!") { // !!foo ==> foo, if we're in boolean context return e.expression; } break; case "typeof": // typeof always returns a non-empty string, thus it's // always true in booleans compressor.warn("Boolean expression always true [{file}:{line},{col}]", self.start); return make_node(AST_True, self).optimize(compressor); } } if (e instanceof AST_Binary) { self = best_of(self, e.negate(compressor)); } return self.evaluate(compressor)[0]; }); SQUEEZE(AST_Binary, function(self, compressor){ self = self.clone(); self.left = self.left.squeeze(compressor); self.right = self.right.squeeze(compressor); return self.optimize(compressor); }); AST_Binary.DEFMETHOD("optimize", function(compressor){ if (compressor.option("comparations")) switch (this.operator) { case "===": case "!==": if ((this.left.is_string() && this.right.is_string()) || (this.left.is_boolean() && this.right.is_boolean())) { this.operator = this.operator.substr(0, 2); } // XXX: intentionally falling down to the next case case "==": case "!=": if (this.left instanceof AST_UnaryPrefix && this.left.operator == "typeof" && this.right instanceof AST_String && this.right.value == "undefined") { if (!(this.left.expression instanceof AST_SymbolRef) || !this.left.expression.undeclared()) { this.left = this.left.expression; this.right = make_node(AST_Undefined, this.right).optimize(compressor); if (this.operator.length == 2) this.operator += "="; } } else if (this.left instanceof AST_String && this.left.value == "undefined" && this.right instanceof AST_UnaryPrefix && this.right.operator == "typeof") { if (!(this.right.expression instanceof AST_SymbolRef) || !this.right.expression.undeclared()) { this.left = this.right.expression; this.right = make_node(AST_Undefined, this.left).optimize(compressor); if (this.operator.length == 2) this.operator += "="; } } break; } if (compressor.option("booleans") && compressor.in_boolean_context()) switch (this.operator) { case "&&": var ll = this.left.evaluate(compressor), left = ll[0]; var rr = this.right.evaluate(compressor), right = rr[0]; if ((ll.length == 2 && !ll[1]) || (rr.length == 2 && !rr[1])) { compressor.warn("Boolean && always false [{file}:{line},{col}]", this.start); return make_node(AST_False, this).optimize(compressor); } if (ll.length == 2 && ll[1]) { return rr[0]; } if (rr.length == 2 && rr[1]) { return ll[0]; } break; case "||": var ll = this.left.evaluate(compressor), left = ll[0]; var rr = this.right.evaluate(compressor), right = rr[0]; if ((ll.length == 2 && ll[1]) || (rr.length == 2 && rr[1])) { compressor.warn("Boolean || always true [{file}:{line},{col}]", this.start); return make_node(AST_True, this).optimize(compressor); } if (ll.length == 2 && !ll[1]) { return rr[0]; } if (rr.length == 2 && !rr[1]) { return ll[0]; } break; case "+": var ll = this.left.evaluate(compressor), left = ll[0]; var rr = this.right.evaluate(compressor), right = rr[0]; if ((ll.length == 2 && ll[0] instanceof AST_String && ll[1]) || (rr.length == 2 && rr[0] instanceof AST_String && rr[1])) { compressor.warn("+ in boolean context always true [{file}:{line},{col}]", this.start); return make_node(AST_True, this).optimize(compressor); } break; } var exp = this.evaluate(compressor); if (exp.length == 2) { if (best_of(exp[0], this) !== this) return exp[0]; } var self = this; if (compressor.option("comparations")) { var reverse = function(op) { self.operator = op; var tmp = self.left; self.left = self.right; self.right = tmp; }; switch (self.operator) { case "==": case "!=": var ll = self.left.evaluate(compressor); var rr = self.right.evaluate(compressor); if (ll.length == 2 && typeof ll[1] == "boolean") { compressor.warn("Non-strict equality against boolean: {operator} {value} [{file}:{line},{col}]", { operator : self.operator, value : ll[1], file : self.start.file, line : self.start.line, col : self.start.col }); self.left = make_node(AST_Number, self.left, { value: +ll[1] }); } if (rr.length == 2 && typeof rr[1] == "boolean") { compressor.warn("Non-strict equality against boolean {operator} {value} [{file}:{line},{col}]", { operator : self.operator, value : rr[1], file : self.start.file, line : self.start.line, col : self.start.col }); self.right = make_node(AST_Number, self.right, { value: +rr[1] }); } break; case "<": reverse(">"); break; case "<=": reverse(">="); break; } if (!(compressor.parent() instanceof AST_Binary)) { var negated = make_node(AST_UnaryPrefix, self, { operator: "!", expression: self.negate(compressor) }); self = best_of(self, negated); } } return self; }); SQUEEZE(AST_Assign, function(self, compressor){ self = self.clone(); self.left = self.left.squeeze(compressor); self.right = self.right.squeeze(compressor); return self.optimize(compressor); }); SQUEEZE(AST_SymbolRef, function(self, compressor){ return self.optimize(compressor); }); AST_SymbolRef.DEFMETHOD("optimize", function(compressor){ if (this.undeclared()) switch (this.name) { case "undefined": return make_node(AST_Undefined, this).optimize(compressor); case "NaN": return make_node(AST_NaN, this).optimize(compressor); } return this; }); SQUEEZE(AST_Undefined, function(self, compressor){ return self.optimize(compressor); }); AST_Undefined.DEFMETHOD("optimize", function(compressor){ if (compressor.option("unsafe")) { var scope = compressor.find_parent(AST_Scope); var undef = scope.find_variable("undefined"); if (undef) { var ref = make_node(AST_SymbolRef, this, { name : "undefined", scope : scope, thedef : undef }); ref.reference(); return ref; } } return this; }); var ASSIGN_OPS = [ '+', '-', '/', '*', '%', '>>', '<<', '>>>', '|', '^', '&' ]; AST_Assign.DEFMETHOD("optimize", function(compressor){ if (this.operator == "=" && this.left instanceof AST_SymbolRef && this.right instanceof AST_Binary && this.right.left instanceof AST_SymbolRef && this.right.left.name == this.left.name && member(this.right.operator, ASSIGN_OPS)) { this.operator = this.right.operator + "="; this.right = this.right.right; } return this; }); SQUEEZE(AST_Conditional, function(self, compressor){ self = self.clone(); self.condition = self.condition.squeeze(compressor); self.consequent = self.consequent.squeeze(compressor); self.alternative = self.alternative.squeeze(compressor); return self.optimize(compressor); }); AST_Conditional.DEFMETHOD("optimize", function(compressor){ var self = this; if (!compressor.option("conditionals")) return self; if (self.condition instanceof AST_Seq) { var car = self.condition.car; self.condition = self.condition.cdr; return AST_Seq.cons(car, self.optimize(compressor)).optimize(compressor); } var cond = self.condition.evaluate(compressor); if (cond.length == 2) { if (cond[1]) { compressor.warn("Condition always true [{file}:{line},{col}]", self.start); return self.consequent; } else { compressor.warn("Condition always false [{file}:{line},{col}]", self.start); return self.alternative; } } var negated = cond[0].negate(compressor); if (best_of(cond[0], negated) === negated) { self = make_node(AST_Conditional, self, { condition: negated, consequent: self.alternative, alternative: self.consequent }); } var consequent = self.consequent; var alternative = self.alternative; if (consequent instanceof AST_Assign && alternative instanceof AST_Assign && consequent.operator == alternative.operator && consequent.left.equivalent_to(alternative.left) ) { /* * Stuff like this: * if (foo) exp = something; else exp = something_else; * ==> * exp = foo ? something : something_else; */ self = make_node(AST_Assign, self, { operator: consequent.operator, left: consequent.left, right: make_node(AST_Conditional, self, { condition: self.condition, consequent: consequent.right, alternative: alternative.right }) }); } return self; }); SQUEEZE(AST_Array, function(self, compressor){ self = self.clone(); self.elements = do_list(self.elements, compressor); return self; }); SQUEEZE(AST_Object, function(self, compressor){ self = self.clone(); self.properties = do_list(self.properties, compressor); return self; }); SQUEEZE(AST_ObjectProperty, function(self, compressor){ self = self.clone(); self.value = self.value.squeeze(compressor); return self; }); SQUEEZE(AST_True, function(self, compressor){ return self.optimize(compressor); }); AST_True.DEFMETHOD("optimize", function(compressor){ if (compressor.option("booleans")) return make_node(AST_UnaryPrefix, this, { operator: "!", expression: make_node(AST_Number, this, { value: 0 }) }); return this; }); SQUEEZE(AST_False, function(self, compressor){ return self.optimize(compressor); }); AST_False.DEFMETHOD("optimize", function(compressor){ if (compressor.option("booleans")) return make_node(AST_UnaryPrefix, this, { operator: "!", expression: make_node(AST_Number, this, { value: 1 }) }); return this; }); })();