92 lines
2.9 KiB
TypeScript
92 lines
2.9 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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import { isPosixPathSeparator } from "./_util.ts";
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import { resolve } from "./resolve.ts";
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import { assertArgs } from "../_common/relative.ts";
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/**
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* Return the relative path from `from` to `to` based on current working directory.
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*
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* @param from path in current working directory
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* @param to path in current working directory
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*/
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export function relative(from: string, to: string): string {
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assertArgs(from, to);
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from = resolve(from);
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to = resolve(to);
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if (from === to) return "";
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// Trim any leading backslashes
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let fromStart = 1;
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const fromEnd = from.length;
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for (; fromStart < fromEnd; ++fromStart) {
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if (!isPosixPathSeparator(from.charCodeAt(fromStart))) break;
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}
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const fromLen = fromEnd - fromStart;
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// Trim any leading backslashes
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let toStart = 1;
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const toEnd = to.length;
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for (; toStart < toEnd; ++toStart) {
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if (!isPosixPathSeparator(to.charCodeAt(toStart))) break;
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}
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const toLen = toEnd - toStart;
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// Compare paths to find the longest common path from root
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const length = fromLen < toLen ? fromLen : toLen;
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let lastCommonSep = -1;
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let i = 0;
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for (; i <= length; ++i) {
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if (i === length) {
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if (toLen > length) {
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if (isPosixPathSeparator(to.charCodeAt(toStart + i))) {
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// We get here if `from` is the exact base path for `to`.
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// For example: from='/foo/bar'; to='/foo/bar/baz'
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return to.slice(toStart + i + 1);
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} else if (i === 0) {
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// We get here if `from` is the root
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// For example: from='/'; to='/foo'
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return to.slice(toStart + i);
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}
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} else if (fromLen > length) {
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if (isPosixPathSeparator(from.charCodeAt(fromStart + i))) {
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// We get here if `to` is the exact base path for `from`.
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// For example: from='/foo/bar/baz'; to='/foo/bar'
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lastCommonSep = i;
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} else if (i === 0) {
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// We get here if `to` is the root.
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// For example: from='/foo'; to='/'
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lastCommonSep = 0;
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}
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}
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break;
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}
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const fromCode = from.charCodeAt(fromStart + i);
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const toCode = to.charCodeAt(toStart + i);
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if (fromCode !== toCode) break;
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else if (isPosixPathSeparator(fromCode)) lastCommonSep = i;
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}
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let out = "";
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// Generate the relative path based on the path difference between `to`
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// and `from`
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for (i = fromStart + lastCommonSep + 1; i <= fromEnd; ++i) {
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if (i === fromEnd || isPosixPathSeparator(from.charCodeAt(i))) {
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if (out.length === 0) out += "..";
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else out += "/..";
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}
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}
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// Lastly, append the rest of the destination (`to`) path that comes after
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// the common path parts
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if (out.length > 0) return out + to.slice(toStart + lastCommonSep);
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else {
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toStart += lastCommonSep;
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if (isPosixPathSeparator(to.charCodeAt(toStart))) ++toStart;
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return to.slice(toStart);
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}
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}
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