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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { CHAR_COLON } from "../_common/constants.ts";import { normalizeString } from "../_common/normalize_string.ts";import { assertPath } from "../_common/assert_path.ts";import { isPathSeparator, isWindowsDeviceRoot } from "./_util.ts";
/** * Resolves path segments into a `path` * @param pathSegments to process to path */export function resolve(...pathSegments: string[]): string {  let resolvedDevice = "";  let resolvedTail = "";  let resolvedAbsolute = false;
  for (let i = pathSegments.length - 1; i >= -1; i--) {    let path: string;    // deno-lint-ignore no-explicit-any    const { Deno } = globalThis as any;    if (i >= 0) {      path = pathSegments[i]!;    } else if (!resolvedDevice) {      if (typeof Deno?.cwd !== "function") {        throw new TypeError("Resolved a drive-letter-less path without a CWD.");      }      path = Deno.cwd();    } else {      if (        typeof Deno?.env?.get !== "function" || typeof Deno?.cwd !== "function"      ) {        throw new TypeError("Resolved a relative path without a CWD.");      }      path = Deno.cwd();
      // Verify that a cwd was found and that it actually points      // to our drive. If not, default to the drive's root.      if (        path === undefined ||        path.slice(0, 3).toLowerCase() !== `${resolvedDevice.toLowerCase()}\\`      ) {        path = `${resolvedDevice}\\`;      }    }
    assertPath(path);
    const len = path.length;
    // Skip empty entries    if (len === 0) continue;
    let rootEnd = 0;    let device = "";    let isAbsolute = false;    const code = path.charCodeAt(0);
    // Try to match a root    if (len > 1) {      if (isPathSeparator(code)) {        // Possible UNC root
        // If we started with a separator, we know we at least have an        // absolute path of some kind (UNC or otherwise)        isAbsolute = true;
        if (isPathSeparator(path.charCodeAt(1))) {          // Matched double path separator at beginning          let j = 2;          let last = j;          // Match 1 or more non-path separators          for (; j < len; ++j) {            if (isPathSeparator(path.charCodeAt(j))) break;          }          if (j < len && j !== last) {            const firstPart = path.slice(last, j);            // Matched!            last = j;            // Match 1 or more path separators            for (; j < len; ++j) {              if (!isPathSeparator(path.charCodeAt(j))) break;            }            if (j < len && j !== last) {              // Matched!              last = j;              // Match 1 or more non-path separators              for (; j < len; ++j) {                if (isPathSeparator(path.charCodeAt(j))) break;              }              if (j === len) {                // We matched a UNC root only                device = `\\\\${firstPart}\\${path.slice(last)}`;                rootEnd = j;              } else if (j !== last) {                // We matched a UNC root with leftovers
                device = `\\\\${firstPart}\\${path.slice(last, j)}`;                rootEnd = j;              }            }          }        } else {          rootEnd = 1;        }      } else if (isWindowsDeviceRoot(code)) {        // Possible device root
        if (path.charCodeAt(1) === CHAR_COLON) {          device = path.slice(0, 2);          rootEnd = 2;          if (len > 2) {            if (isPathSeparator(path.charCodeAt(2))) {              // Treat separator following drive name as an absolute path              // indicator              isAbsolute = true;              rootEnd = 3;            }          }        }      }    } else if (isPathSeparator(code)) {      // `path` contains just a path separator      rootEnd = 1;      isAbsolute = true;    }
    if (      device.length > 0 &&      resolvedDevice.length > 0 &&      device.toLowerCase() !== resolvedDevice.toLowerCase()    ) {      // This path points to another device so it is not applicable      continue;    }
    if (resolvedDevice.length === 0 && device.length > 0) {      resolvedDevice = device;    }    if (!resolvedAbsolute) {      resolvedTail = `${path.slice(rootEnd)}\\${resolvedTail}`;      resolvedAbsolute = isAbsolute;    }
    if (resolvedAbsolute && resolvedDevice.length > 0) break;  }
  // At this point the path should be resolved to a full absolute path,  // but handle relative paths to be safe (might happen when Deno.cwd()  // fails)
  // Normalize the tail path  resolvedTail = normalizeString(    resolvedTail,    !resolvedAbsolute,    "\\",    isPathSeparator,  );
  return resolvedDevice + (resolvedAbsolute ? "\\" : "") + resolvedTail || ".";}