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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { assert } from "../../assert/assert.ts";import { assertPath } from "../_common/assert_path.ts";import { isPathSeparator } from "./_util.ts";import { normalize } from "./normalize.ts";
/** * Join all given a sequence of `paths`,then normalizes the resulting path. * @param paths to be joined and normalized */export function join(...paths: string[]): string {  if (paths.length === 0) return ".";
  let joined: string | undefined;  let firstPart: string | null = null;  for (let i = 0; i < paths.length; ++i) {    const path = paths[i]!;    assertPath(path);    if (path.length > 0) {      if (joined === undefined) joined = firstPart = path;      else joined += `\\${path}`;    }  }
  if (joined === undefined) return ".";
  // Make sure that the joined path doesn't start with two slashes, because  // normalize() will mistake it for an UNC path then.  //  // This step is skipped when it is very clear that the user actually  // intended to point at an UNC path. This is assumed when the first  // non-empty string arguments starts with exactly two slashes followed by  // at least one more non-slash character.  //  // Note that for normalize() to treat a path as an UNC path it needs to  // have at least 2 components, so we don't filter for that here.  // This means that the user can use join to construct UNC paths from  // a server name and a share name; for example:  //   path.join('//server', 'share') -> '\\\\server\\share\\')  let needsReplace = true;  let slashCount = 0;  assert(firstPart !== null);  if (isPathSeparator(firstPart.charCodeAt(0))) {    ++slashCount;    const firstLen = firstPart.length;    if (firstLen > 1) {      if (isPathSeparator(firstPart.charCodeAt(1))) {        ++slashCount;        if (firstLen > 2) {          if (isPathSeparator(firstPart.charCodeAt(2))) ++slashCount;          else {            // We matched a UNC path in the first part            needsReplace = false;          }        }      }    }  }  if (needsReplace) {    // Find any more consecutive slashes we need to replace    for (; slashCount < joined.length; ++slashCount) {      if (!isPathSeparator(joined.charCodeAt(slashCount))) break;    }
    // Replace the slashes if needed    if (slashCount >= 2) joined = `\\${joined.slice(slashCount)}`;  }
  return normalize(joined);}