optimize MAP (do_list). Speeds up compress by a couple %

terser · Feb 4, 2023 · 8dc5fc2 · 8dc5fc2
1 parent 627a433
commit 8dc5fc2
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Showing 3 changed files with 33 additions and 43 deletions.
diff --git a/lib/ast.js b/lib/ast.js
@@ -114,7 +114,7 @@ class AST_Token {
     // Return a string summary of the token for node.js console.log
     [Symbol.for("nodejs.util.inspect.custom")](_depth, options) {
         const special = str => options.stylize(str, "special");
-        const quote = this.value.includes("`") ? "'" : "`";
+        const quote = typeof this.value === "string" && this.value.includes("`") ? "'" : "`";
         const value = `${quote}${this.value}${quote}`;
         return `${special("[AST_Token")} ${value} at ${this.line}:${this.col}${special("]")}`;
     }

diff --git a/lib/transform.js b/lib/transform.js
@@ -89,7 +89,7 @@ import {
     AST_Yield,
 } from "./ast.js";
 import {
-    MAP,
+    MAP as do_list,
     noop,
 } from "./utils/index.js";
 
@@ -111,12 +111,6 @@ function def_transform(node, descend) {
     });
 }
 
-function do_list(list, tw) {
-    return MAP(list, function(node) {
-        return node.transform(tw, true);
-    });
-}
-
 def_transform(AST_Node, noop);
 
 def_transform(AST_LabeledStatement, function(self, tw) {

diff --git a/lib/utils/index.js b/lib/utils/index.js
@@ -43,6 +43,8 @@
 
 "use strict";
 
+import { AST_Node } from "../ast.js";
+
 function characters(str) {
     return str.split("");
 }
@@ -96,48 +98,42 @@ function return_this() { return this; }
 function return_null() { return null; }
 
 var MAP = (function() {
-    function MAP(a, f, backwards) {
-        var ret = [], top = [], i;
-        function doit() {
-            var val = f(a[i], i);
-            var is_last = val instanceof Last;
-            if (is_last) val = val.v;
-            if (val instanceof AtTop) {
-                val = val.v;
-                if (val instanceof Splice) {
-                    top.push.apply(top, backwards ? val.v.slice().reverse() : val.v);
-                } else {
-                    top.push(val);
+    function MAP(a, tw) {
+        // Loop but try not to build a new array
+        for (let i = 0; i < a.length; ++i) {
+            let item = a[i];
+            let ret = item.transform(tw, true);
+
+            if (ret !== item) {
+                const a1 = a.slice(0, i);
+
+                // Looks like something was transformed. Change the loop.
+                if (ret instanceof AST_Node) {
+                    a1.push(ret);
+                } else if (ret instanceof Splice) {
+                    a1.push(...ret.v);
                 }
-            } else if (val !== skip) {
-                if (val instanceof Splice) {
-                    ret.push.apply(ret, backwards ? val.v.slice().reverse() : val.v);
-                } else {
-                    ret.push(val);
+
+                while ((item = a[++i])) {
+                    const ret = item.transform(tw, true);
+
+                    if (ret instanceof AST_Node) {
+                        a1.push(ret);
+                    } else if (ret instanceof Splice) {
+                        a1.push(...ret.v);
+                    }
                 }
+
+                return a1;
             }
-            return is_last;
-        }
-        if (Array.isArray(a)) {
-            if (backwards) {
-                for (i = a.length; --i >= 0;) if (doit()) break;
-                ret.reverse();
-                top.reverse();
-            } else {
-                for (i = 0; i < a.length; ++i) if (doit()) break;
-            }
-        } else {
-            for (i in a) if (HOP(a, i)) if (doit()) break;
         }
-        return top.concat(ret);
+
+        return a;
     }
-    MAP.at_top = function(val) { return new AtTop(val); };
+
     MAP.splice = function(val) { return new Splice(val); };
-    MAP.last = function(val) { return new Last(val); };
-    var skip = MAP.skip = {};
-    function AtTop(val) { this.v = val; }
+    MAP.skip = {};
     function Splice(val) { this.v = val; }
-    function Last(val) { this.v = val; }
     return MAP;
 })();