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denoland-deno/ext/node/polyfills/path/common.ts
Bartek Iwańczuk b40086fd7d
refactor(core): include_js_files! 'dir' option doesn't change specifiers (#18019)
This commit changes "include_js_files!" macro from "deno_core"
in a way that "dir" option doesn't cause specifiers to be rewritten 
to include it.

Example:
```
include_js_files! {
  dir "js",
  "hello.js",
}
```

The above definition required embedders to use:
`import ... from "internal:<ext_name>/js/hello.js"`. 
But with this change, the "js" directory in which the files are stored
is an implementation detail, which for embedders results in: 
`import ... from "internal:<ext_name>/hello.js"`.

The directory the files are stored in, is an implementation detail and 
in some cases might result in a significant size difference for the 
snapshot. As an example, in "deno_node" extension, we store the 
source code in "polyfills" directory; which resulted in each specifier 
to look like "internal:deno_node/polyfills/<module_name>", but with 
this change it's "internal:deno_node/<module_name>". 

Given that "deno_node" has over 100 files, many of them having 
several import specifiers to the same extension, this change removes
10 characters from each import specifier.
2023-03-05 02:31:38 +00:00

39 lines
1.1 KiB
TypeScript

// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
import { SEP } from "internal:deno_node/path/separator.ts";
/** Determines the common path from a set of paths, using an optional separator,
* which defaults to the OS default separator.
*
* ```ts
* const p = common([
* "./deno/std/path/mod.ts",
* "./deno/std/fs/mod.ts",
* ]);
* console.log(p); // "./deno/std/"
* ```
*/
export function common(paths: string[], sep = SEP): string {
const [first = "", ...remaining] = paths;
if (first === "" || remaining.length === 0) {
return first.substring(0, first.lastIndexOf(sep) + 1);
}
const parts = first.split(sep);
let endOfPrefix = parts.length;
for (const path of remaining) {
const compare = path.split(sep);
for (let i = 0; i < endOfPrefix; i++) {
if (compare[i] !== parts[i]) {
endOfPrefix = i;
}
}
if (endOfPrefix === 0) {
return "";
}
}
const prefix = parts.slice(0, endOfPrefix).join(sep);
return prefix.endsWith(sep) ? prefix : `${prefix}${sep}`;
}