sourcemap-codec - npm Package Compare versions

Comparing version 1.4.7 to 1.4.8

CHANGELOG.md

 # sourcemap-codec changelog
 
+## 1.4.8
+
+* Performance boost ([#80](https://github.com/Rich-Harris/sourcemap-codec/pull/80))
+
 ## 1.4.7
@@ -4,0 +8,0 @@

dist/sourcemap-codec.es.js

@@ -7,26 +7,24 @@ var charToInteger = {};
 function decode(mappings) {
-    var generatedCodeColumn = 0; // first field
-    var sourceFileIndex = 0; // second field
-    var sourceCodeLine = 0; // third field
-    var sourceCodeColumn = 0; // fourth field
-    var nameIndex = 0; // fifth field
     var decoded = [];
     var line = [];
-    var segment = [];
-    for (var i = 0, j = 0, shift = 0, value = 0, len = mappings.length; i < len; i++) {
+    var segment = [
+        0,
+        0,
+        0,
+        0,
+        0,
+    ];
+    var j = 0;
+    for (var i = 0, shift = 0, value = 0; i < mappings.length; i++) {
         var c = mappings.charCodeAt(i);
         if (c === 44) { // ","
-            if (segment.length)
-                line.push(segment);
-            segment = [];
+            segmentify(line, segment, j);
             j = 0;
         }
         else if (c === 59) { // ";"
-            if (segment.length)
-                line.push(segment);
-            segment = [];
+            segmentify(line, segment, j);
             j = 0;
             decoded.push(line);
             line = [];
-            generatedCodeColumn = 0;
+            segment[0] = 0;
         }
@@ -48,26 +46,5 @@ else {
                 if (shouldNegate) {
-                    value = -value;
-                    if (value === 0)
-                        value = -0x80000000;
+                    value = value === 0 ? -0x80000000 : -value;
                 }
-                if (j == 0) {
-                    generatedCodeColumn += value;
-                    segment.push(generatedCodeColumn);
-                }
-                else if (j === 1) {
-                    sourceFileIndex += value;
-                    segment.push(sourceFileIndex);
-                }
-                else if (j === 2) {
-                    sourceCodeLine += value;
-                    segment.push(sourceCodeLine);
-                }
-                else if (j === 3) {
-                    sourceCodeColumn += value;
-                    segment.push(sourceCodeColumn);
-                }
-                else if (j === 4) {
-                    nameIndex += value;
-                    segment.push(nameIndex);
-                }
+                segment[j] += value;
                 j++;
@@ -78,7 +55,21 @@ value = shift = 0; // reset
     }
-    if (segment.length)
-        line.push(segment);
+    segmentify(line, segment, j);
     decoded.push(line);
     return decoded;
 }
+function segmentify(line, segment, j) {
+    // This looks ugly, but we're creating specialized arrays with a specific
+    // length. This is much faster than creating a new array (which v8 expands to
+    // a capacity of 17 after pushing the first item), or slicing out a subarray
+    // (which is slow). Length 4 is assumed to be the most frequent, followed by
+    // length 5 (since not everything will have an associated name), followed by
+    // length 1 (it's probably rare for a source substring to not have an
+    // associated segment data).
+    if (j === 4)
+        line.push([segment[0], segment[1], segment[2], segment[3]]);
+    else if (j === 5)
+        line.push([segment[0], segment[1], segment[2], segment[3], segment[4]]);
+    else if (j === 1)
+        line.push([segment[0]]);
+}
 function encode(decoded) {
@@ -85,0 +76,0 @@ var sourceFileIndex = 0; // second field

dist/sourcemap-codec.umd.js

@@ -13,26 +13,24 @@ (function (global, factory) {
 	function decode(mappings) {
-	    var generatedCodeColumn = 0; // first field
-	    var sourceFileIndex = 0; // second field
-	    var sourceCodeLine = 0; // third field
-	    var sourceCodeColumn = 0; // fourth field
-	    var nameIndex = 0; // fifth field
 	    var decoded = [];
 	    var line = [];
-	    var segment = [];
-	    for (var i = 0, j = 0, shift = 0, value = 0, len = mappings.length; i < len; i++) {
+	    var segment = [
+	        0,
+	        0,
+	        0,
+	        0,
+	        0,
+	    ];
+	    var j = 0;
+	    for (var i = 0, shift = 0, value = 0; i < mappings.length; i++) {
 	        var c = mappings.charCodeAt(i);
 	        if (c === 44) { // ","
-	            if (segment.length)
-	                line.push(segment);
-	            segment = [];
+	            segmentify(line, segment, j);
 	            j = 0;
 	        }
 	        else if (c === 59) { // ";"
-	            if (segment.length)
-	                line.push(segment);
-	            segment = [];
+	            segmentify(line, segment, j);
 	            j = 0;
 	            decoded.push(line);
 	            line = [];
-	            generatedCodeColumn = 0;
+	            segment[0] = 0;
 	        }
@@ -54,26 +52,5 @@ else {
 	                if (shouldNegate) {
-	                    value = -value;
-	                    if (value === 0)
-	                        value = -0x80000000;
+	                    value = value === 0 ? -0x80000000 : -value;
 	                }
-	                if (j == 0) {
-	                    generatedCodeColumn += value;
-	                    segment.push(generatedCodeColumn);
-	                }
-	                else if (j === 1) {
-	                    sourceFileIndex += value;
-	                    segment.push(sourceFileIndex);
-	                }
-	                else if (j === 2) {
-	                    sourceCodeLine += value;
-	                    segment.push(sourceCodeLine);
-	                }
-	                else if (j === 3) {
-	                    sourceCodeColumn += value;
-	                    segment.push(sourceCodeColumn);
-	                }
-	                else if (j === 4) {
-	                    nameIndex += value;
-	                    segment.push(nameIndex);
-	                }
+	                segment[j] += value;
 	                j++;
@@ -84,7 +61,21 @@ value = shift = 0; // reset
 	    }
-	    if (segment.length)
-	        line.push(segment);
+	    segmentify(line, segment, j);
 	    decoded.push(line);
 	    return decoded;
 	}
+	function segmentify(line, segment, j) {
+	    // This looks ugly, but we're creating specialized arrays with a specific
+	    // length. This is much faster than creating a new array (which v8 expands to
+	    // a capacity of 17 after pushing the first item), or slicing out a subarray
+	    // (which is slow). Length 4 is assumed to be the most frequent, followed by
+	    // length 5 (since not everything will have an associated name), followed by
+	    // length 1 (it's probably rare for a source substring to not have an
+	    // associated segment data).
+	    if (j === 4)
+	        line.push([segment[0], segment[1], segment[2], segment[3]]);
+	    else if (j === 5)
+	        line.push([segment[0], segment[1], segment[2], segment[3], segment[4]]);
+	    else if (j === 1)
+	        line.push([segment[0]]);
+	}
 	function encode(decoded) {
@@ -91,0 +82,0 @@ var sourceFileIndex = 0; // second field

package.json

 {
   "name": "sourcemap-codec",
-  "version": "1.4.7",
+  "version": "1.4.8",
   "description": "Encode/decode sourcemap mappings",
@@ -5,0 +5,0 @@ "main": "dist/sourcemap-codec.umd.js",

No alert changes

Worsened metrics

Total package byte prevSize

31802

decreased by-2.46%

Lines of code

259

decreased by-6.5%

No dependency changes