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std/path/windows/relative.ts

Deno standard library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { CHAR_BACKWARD_SLASH } from "../_common/constants.ts";import { resolve } from "./resolve.ts";import { assertArgs } from "../_common/relative.ts";
/** * Return the relative path from `from` to `to` based on current working directory. * * An example in windws, for instance: * from = 'C:\\orandea\\test\\aaa' * to = 'C:\\orandea\\impl\\bbb' * The output of the function should be: '..\\..\\impl\\bbb' * * @param from path in current working directory * @param to path in current working directory */export function relative(from: string, to: string): string { assertArgs(from, to);
const fromOrig = resolve(from); const toOrig = resolve(to);
if (fromOrig === toOrig) return "";
from = fromOrig.toLowerCase(); to = toOrig.toLowerCase();
if (from === to) return "";
// Trim any leading backslashes let fromStart = 0; let fromEnd = from.length; for (; fromStart < fromEnd; ++fromStart) { if (from.charCodeAt(fromStart) !== CHAR_BACKWARD_SLASH) break; } // Trim trailing backslashes (applicable to UNC paths only) for (; fromEnd - 1 > fromStart; --fromEnd) { if (from.charCodeAt(fromEnd - 1) !== CHAR_BACKWARD_SLASH) break; } const fromLen = fromEnd - fromStart;
// Trim any leading backslashes let toStart = 0; let toEnd = to.length; for (; toStart < toEnd; ++toStart) { if (to.charCodeAt(toStart) !== CHAR_BACKWARD_SLASH) break; } // Trim trailing backslashes (applicable to UNC paths only) for (; toEnd - 1 > toStart; --toEnd) { if (to.charCodeAt(toEnd - 1) !== CHAR_BACKWARD_SLASH) break; } const toLen = toEnd - toStart;
// Compare paths to find the longest common path from root const length = fromLen < toLen ? fromLen : toLen; let lastCommonSep = -1; let i = 0; for (; i <= length; ++i) { if (i === length) { if (toLen > length) { if (to.charCodeAt(toStart + i) === CHAR_BACKWARD_SLASH) { // We get here if `from` is the exact base path for `to`. // For example: from='C:\\foo\\bar'; to='C:\\foo\\bar\\baz' return toOrig.slice(toStart + i + 1); } else if (i === 2) { // We get here if `from` is the device root. // For example: from='C:\\'; to='C:\\foo' return toOrig.slice(toStart + i); } } if (fromLen > length) { if (from.charCodeAt(fromStart + i) === CHAR_BACKWARD_SLASH) { // We get here if `to` is the exact base path for `from`. // For example: from='C:\\foo\\bar'; to='C:\\foo' lastCommonSep = i; } else if (i === 2) { // We get here if `to` is the device root. // For example: from='C:\\foo\\bar'; to='C:\\' lastCommonSep = 3; } } break; } const fromCode = from.charCodeAt(fromStart + i); const toCode = to.charCodeAt(toStart + i); if (fromCode !== toCode) break; else if (fromCode === CHAR_BACKWARD_SLASH) lastCommonSep = i; }
// We found a mismatch before the first common path separator was seen, so // return the original `to`. if (i !== length && lastCommonSep === -1) { return toOrig; }
let out = ""; if (lastCommonSep === -1) lastCommonSep = 0; // Generate the relative path based on the path difference between `to` and // `from` for (i = fromStart + lastCommonSep + 1; i <= fromEnd; ++i) { if (i === fromEnd || from.charCodeAt(i) === CHAR_BACKWARD_SLASH) { if (out.length === 0) out += ".."; else out += "\\.."; } }
// Lastly, append the rest of the destination (`to`) path that comes after // the common path parts if (out.length > 0) { return out + toOrig.slice(toStart + lastCommonSep, toEnd); } else { toStart += lastCommonSep; if (toOrig.charCodeAt(toStart) === CHAR_BACKWARD_SLASH) ++toStart; return toOrig.slice(toStart, toEnd); }}