text: /*
   * Copyright 2012-present Facebook, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #pragma once
  
  #include <boost/filesystem.hpp>
  
  namespace folly {
  namespace fs {
  
  // Functions defined in this file are meant to extend the
  // boost::filesystem library; functions will be named according to boost's
  // naming conventions instead of ours.  For convenience, import the
  // boost::filesystem namespace into folly::fs.
  using namespace ::boost::filesystem;
  
  /**
   * Check whether "path" starts with "prefix".
   * That is, if prefix has n path elements, then the first n elements of
   * path must be the same as prefix.
   *
   * There is a special case if prefix ends with a slash:
   * /foo/bar/ is not a prefix of /foo/bar, but both /foo/bar and /foo/bar/
   * are prefixes of /foo/bar/baz.
   */
  bool starts_with(const path& p, const path& prefix);
  
  /**
   * If "path" starts with "prefix", return "path" with "prefix" removed.
   * Otherwise, throw filesystem_error.
   */
  path remove_prefix(const path& p, const path& prefix);
  
  /**
   * Canonicalize the parent path, leaving the filename (last component)
   * unchanged.  You may use this before creating a file instead of
   * boost::filesystem::canonical, which requires that the entire path exists.
   */
  path canonical_parent(const path& p, const path& basePath = current_path());
  
  /**
   * Get the path to the current executable.
   *
   * Note that this is not reliable and not recommended in general; it may not be
   * implemented on your platform (in which case it will throw), the executable
   * might have been moved or replaced while running, and applications comprising
   * of multiple executables should use some form of configuration system to
   * find the other executables rather than relying on relative paths from one
   * to another.
   *
   * So this should only be used for tests, logging, or other innocuous purposes.
   */
  path executable_path();
  
  } // namespace fs
  } // namespace folly
  