support #__PURE__ in ESTree

bin/uglifyjs

@@ -314,16 +314,43 @@ function run() {
     try {
         if (options.parse) {
             if (options.parse.acorn) {
+                var annotations = Object.create(null);
                 files = convert_ast(function(toplevel, name) {
-                    return require("acorn").parse(files[name], {
+                    var content = files[name];
+                    var list = annotations[name] = [];
+                    var prev = -1;
+                    return require("acorn").parse(content, {
                         allowHashBang: true,
                         ecmaVersion: "latest",
                         locations: true,
+                        onComment: function(block, text, start, end) {
+                            var match = /[@#]__PURE__/.exec(text);
+                            if (!match) {
+                                if (start != prev) return;
+                                match = [ list[prev] ];
+                            }
+                            while (/\s/.test(content[end])) end++;
+                            list[end] = match[0];
+                            prev = end;
+                        },
+                        preserveParens: true,
                         program: toplevel,
                         sourceFile: name,
                         sourceType: "module",
                     });
                 });
+                files.walk(new UglifyJS.TreeWalker(function(node) {
+                    if (!(node instanceof UglifyJS.AST_Call)) return;
+                    var list = annotations[node.start.file];
+                    var pure = list[node.start.pos];
+                    if (!pure) {
+                        var pos = node.start.parens;
+                        if (pos) for (var i = 0; !pure && i < pos.length; i++) {
+                            pure = list[pos[i]];
+                        }
+                    }
+                    if (pure) node.pure = pure;
+                }));
             } else if (options.parse.spidermonkey) {
                 files = convert_ast(function(toplevel, name) {
                     var obj = JSON.parse(files[name]);

lib/mozilla-ast.js

@@ -446,8 +446,22 @@
                 args.value = val;
                 return new AST_String(args);
               case "number":
-                args.value = val;
+                if (isNaN(val)) return new AST_NaN(args);
-                return new AST_Number(args);
+                var negate, node;
+                if (isFinite(val)) {
+                    negate = 1 / val < 0;
+                    args.value = negate ? -val : val;
+                    node = new AST_Number(args);
+                } else {
+                    negate = val < 0;
+                    node = new AST_Infinity(args);
+                }
+                return negate ? new AST_UnaryPrefix({
+                    start: args.start,
+                    end: args.end,
+                    operator: "-",
+                    expression: node,
+                }) : node;
               case "boolean":
                 return new (val ? AST_True : AST_False)(args);
             }
@@ -532,6 +546,14 @@
                 name: "this",
             });
         },
+        ParenthesizedExpression: function(M) {
+            var node = from_moz(M.expression);
+            if (!node.start.parens) node.start.parens = [];
+            node.start.parens.push(my_start_token(M));
+            if (!node.end.parens) node.end.parens = [];
+            node.end.parens.push(my_end_token(M));
+            return node;
+        },
     };
 
     MOZ_TO_ME.UpdateExpression =
@@ -570,8 +592,8 @@
     map("AssignmentExpression", AST_Assign, "operator=operator, left>left, right>right");
     map("AssignmentPattern", AST_DefaultValue, "left>name, right>value");
     map("ConditionalExpression", AST_Conditional, "test>condition, consequent>consequent, alternate>alternative");
-    map("NewExpression", AST_New, "callee>expression, arguments@args");
+    map("NewExpression", AST_New, "callee>expression, arguments@args, pure=pure");
-    map("CallExpression", AST_Call, "callee>expression, arguments@args");
+    map("CallExpression", AST_Call, "callee>expression, arguments@args, pure=pure");
     map("SequenceExpression", AST_Sequence, "expressions@expressions");
     map("SpreadElement", AST_Spread, "argument>expression");
     map("ObjectExpression", AST_Object, "properties@properties");

lib/output.js

@@ -1456,7 +1456,7 @@ function OutputStream(options) {
             parent = output.parent(level++);
             if (parent instanceof AST_Call && parent.expression === node) return;
         } while (parent instanceof AST_PropAccess && parent.expression === node);
-        output.print("/*" + self.pure + "*/");
+        output.print(typeof self.pure == "string" ? "/*" + self.pure + "*/" : "/*@__PURE__*/");
     }
     function print_call_args(self, output) {
         if (self.expression instanceof AST_Call || self.expression instanceof AST_Lambda) {