path: remove unnecessary string copies

tniessen · MylesBorins · commit e82a9144edee · 2017-08-15T20:57:21.000-07:00
As the length of `path` is known at this point, there is no point in making an exact copy using `slice`. Backport-PR-URL: #14787 PR-URL: #14438 Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Timothy Gu <timothygu99@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Khaidi Chu <i@2333.moe>
diff --git a/lib/path.js b/lib/path.js
@@ -767,7 +767,9 @@ const win32 = {
         }
       }
     } else if (code === 47/*/*/ || code === 92/*\*/) {
-      return path[0];
+      // `path` contains just a path separator, exit early to avoid
+      // unnecessary work
+      return path;
     }
 
     for (var i = len - 1; i >= offset; --i) {
@@ -1031,23 +1033,23 @@ const win32 = {
               if (len === 3) {
                 // `path` contains just a drive root, exit early to avoid
                 // unnecessary work
-                ret.root = ret.dir = path.slice(0, 3);
+                ret.root = ret.dir = path;
                 return ret;
               }
               rootEnd = 3;
             }
           } else {
             // `path` contains just a drive root, exit early to avoid
             // unnecessary work
-            ret.root = ret.dir = path.slice(0, 2);
+            ret.root = ret.dir = path;
             return ret;
           }
         }
       }
     } else if (code === 47/*/*/ || code === 92/*\*/) {
       // `path` contains just a path separator, exit early to avoid
       // unnecessary work
-      ret.root = ret.dir = path[0];
+      ret.root = ret.dir = path;
       return ret;
     }
 

Original file line number	Diff line number	Diff line change
`@@ -767,7 +767,9 @@ const win32 = {`
`767`	`767`	`}`
`768`	`768`	`}`
`769`	`769`	`} else if (code === 47/// \|\| code === 92/\/) {`
`770`		`- return path[0];`
	`770`	+ // `path` contains just a path separator, exit early to avoid
	`771`	`+ // unnecessary work`
	`772`	`+ return path;`
`771`	`773`	`}`
`772`	`774`
`773`	`775`	`for (var i = len - 1; i >= offset; --i) {`
`@@ -1031,23 +1033,23 @@ const win32 = {`
`1031`	`1033`	`if (len === 3) {`
`1032`	`1034`	// `path` contains just a drive root, exit early to avoid
`1033`	`1035`	`// unnecessary work`
`1034`		`- ret.root = ret.dir = path.slice(0, 3);`
	`1036`	`+ ret.root = ret.dir = path;`
`1035`	`1037`	`return ret;`
`1036`	`1038`	`}`
`1037`	`1039`	`rootEnd = 3;`
`1038`	`1040`	`}`
`1039`	`1041`	`} else {`
`1040`	`1042`	// `path` contains just a drive root, exit early to avoid
`1041`	`1043`	`// unnecessary work`
`1042`		`- ret.root = ret.dir = path.slice(0, 2);`
	`1044`	`+ ret.root = ret.dir = path;`
`1043`	`1045`	`return ret;`
`1044`	`1046`	`}`
`1045`	`1047`	`}`
`1046`	`1048`	`}`
`1047`	`1049`	`} else if (code === 47/// \|\| code === 92/\/) {`
`1048`	`1050`	// `path` contains just a path separator, exit early to avoid
`1049`	`1051`	`// unnecessary work`
`1050`		`- ret.root = ret.dir = path[0];`
	`1052`	`+ ret.root = ret.dir = path;`
`1051`	`1053`	`return ret;`
`1052`	`1054`	`}`
`1053`	`1055`