feat: Add common to std/path (denoland#4527)

std/path/common.ts

@@ -0,0 +1,38 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { SEP } from "./constants.ts";
+
+/** Determines the common path from a set of paths, using an optional separator,
+ * which defaults to the OS default separator.
+ *
+ * import { common } from "https://deno.land/std/path/mod.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}`;
+}

std/path/common_test.ts

@@ -0,0 +1,47 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+const { test } = Deno;
+import { assertEquals } from "../testing/asserts.ts";
+
+import { common } from "./mod.ts";
+
+test({
+ name: "path - common - basic usage",
+ fn() {
+ const actual = common(
+ [
+ "file:https://deno/cli/js/deno.ts",
+ "file:https://deno/std/path/mod.ts",
+ "file:https://deno/cli/js/main.ts",
+ ],
+ "/"
+ );
+ assertEquals(actual, "file:https://deno/");
+ },
+});
+
+test({
+ name: "path - common - no shared",
+ fn() {
+ const actual = common(
+ ["file:https://deno/cli/js/deno.ts", "https://deno.land/std/path/mod.ts"],
+ "/"
+ );
+ assertEquals(actual, "");
+ },
+});
+
+test({
+ name: "path - common - windows sep",
+ fn() {
+ const actual = common(
+ [
+ "c:\\deno\\cli\\js\\deno.ts",
+ "c:\\deno\\std\\path\\mod.ts",
+ "c:\\deno\\cli\\js\\main.ts",
+ ],
+ "\\"
+ );
+ assertEquals(actual, "c:\\deno\\");
+ },
+});

std/path/mod.ts

@@ -1,5 +1,5 @@
 // Copyright the Browserify authors. MIT License.
-// Ported from https://github.com/browserify/path-browserify/
+// Ported mostly from https://github.com/browserify/path-browserify/
 
 import * as _win32 from "./win32.ts";
 import * as _posix from "./posix.ts";
@@ -10,20 +10,23 @@ const path = isWindows ? _win32 : _posix;
 
 export const win32 = _win32;
 export const posix = _posix;
-export const resolve = path.resolve;
-export const normalize = path.normalize;
-export const isAbsolute = path.isAbsolute;
-export const join = path.join;
-export const relative = path.relative;
-export const toNamespacedPath = path.toNamespacedPath;
-export const dirname = path.dirname;
-export const basename = path.basename;
-export const extname = path.extname;
-export const format = path.format;
-export const parse = path.parse;
-export const sep = path.sep;
-export const delimiter = path.delimiter;
+export const {
+ resolve,
+ normalize,
+ isAbsolute,
+ join,
+ relative,
+ toNamespacedPath,
+ dirname,
+ basename,
+ extname,
+ format,
+ parse,
+ sep,
+ delimiter,
+} = path;
 
+export { common } from "./common.ts";
 export { EOL, SEP, SEP_PATTERN, isWindows } from "./constants.ts";
 export * from "./interface.ts";
 export * from "./glob.ts";