Xenia-Canary/src/xenia/base/fs.cc

/**
 ******************************************************************************
 * Xenia : Xbox 360 Emulator Research Project                                 *
 ******************************************************************************
 * Copyright 2015 Ben Vanik. All rights reserved.                             *
 * Released under the BSD license - see LICENSE in the root for more details. *
 ******************************************************************************
 */

#include "xenia/base/fs.h"

#include <string>
#include <vector>
#include <algorithm>

namespace xe {
namespace fs {

std::string CanonicalizePath(const std::string& original_path) {
  char path_sep('\\');
  std::string path(xe::fix_path_separators(original_path, path_sep));

  std::vector<std::string::size_type> path_breaks;

  std::string::size_type pos(path.find_first_of(path_sep));
  std::string::size_type pos_n(std::string::npos);

  while (pos != std::string::npos) {
    if ((pos_n = path.find_first_of(path_sep, pos + 1)) == std::string::npos) {
      pos_n = path.size();
    }

    auto diff(pos_n - pos);
    switch (diff) {
      case 0:
        pos_n = std::string::npos;
        break;
      case 1:
        // Duplicate separators
        path.erase(pos, 1);
        pos_n -= 1;
        break;
      case 2:
        // Potential marker for current directory
        if (path[pos + 1] == '.') {
          path.erase(pos, 2);
          pos_n -= 2;
        } else {
          path_breaks.push_back(pos);
        }
        break;
      case 3:
        // Potential marker for parent directory
        if (path[pos + 1] == '.' && path[pos + 2] == '.') {
          if (path_breaks.empty()) {
            // Ensure we don't override the device name
            std::string::size_type loc(path.find_first_of(':'));
            auto req(pos + 3);
            if (loc == std::string::npos || loc > req) {
              path.erase(0, req);
              pos_n -= req;
            } else {
              path.erase(loc + 1, req - (loc + 1));
              pos_n -= req - (loc + 1);
            }
          } else {
            auto last(path_breaks.back());
            auto last_diff((pos + 3) - last);
            path.erase(last, last_diff);
            pos_n = last;
            // Also remove path reference
            path_breaks.erase(path_breaks.end() - 1);
          }
        } else {
          path_breaks.push_back(pos);
        }
        break;

      default:
        path_breaks.push_back(pos);
        break;
    }

    pos = pos_n;
  }

  // Remove trailing seperator
  if (!path.empty() && path.back() == path_sep) {
    path.erase(path.size() - 1);
  }

  // Final sanity check for dead paths
  if ((path.size() == 1 && (path[0] == '.' || path[0] == path_sep)) ||
      (path.size() == 2 && path[0] == '.' && path[1] == '.')) {
    return "";
  }

  return path;
}

WildcardFlags WildcardFlags::FIRST(true, false);
WildcardFlags WildcardFlags::LAST(false, true);

WildcardFlags::WildcardFlags() : FromStart(false), ToEnd(false) {}

WildcardFlags::WildcardFlags(bool start, bool end)
    : FromStart(start), ToEnd(end) {}

WildcardRule::WildcardRule(const std::string& str_match,
                           const WildcardFlags& flags)
    : match(str_match), rules(flags) {
  std::transform(match.begin(), match.end(), match.begin(), tolower);
}

bool WildcardRule::Check(const std::string& str_lower,
                         std::string::size_type& offset) const {
  if (match.empty()) {
    return true;
  }

  if ((str_lower.size() - offset) < match.size()) {
    return false;
  }

  std::string::size_type result(str_lower.find(match, offset));

  if (result != std::string::npos) {
    if (rules.FromStart && result != offset) {
      return false;
    }

    if (rules.ToEnd && result != (str_lower.size() - match.size())) {
      return false;
    }

    offset = (result + match.size());
    return true;
  }

  return false;
}

void WildcardEngine::PreparePattern(const std::string& pattern) {
  rules.clear();

  WildcardFlags flags(WildcardFlags::FIRST);
  size_t n = 0;
  size_t last = 0;
  while ((n = pattern.find_first_of('*', last)) != pattern.npos) {
    if (last != n) {
      std::string str_str(pattern.substr(last, n - last));
      rules.push_back(WildcardRule(str_str, flags));
    }
    last = n + 1;
    flags = WildcardFlags();
  }
  if (last != pattern.size()) {
    std::string str_str(pattern.substr(last));
    rules.push_back(WildcardRule(str_str, WildcardFlags::LAST));
  }
}

void WildcardEngine::SetRule(const std::string& pattern) {
  PreparePattern(pattern);
}

bool WildcardEngine::Match(const std::string& str) const {
  std::string str_lc;
  std::transform(str.begin(), str.end(), std::back_inserter(str_lc), tolower);

  std::string::size_type offset(0);
  for (const auto& rule : rules) {
    if (!(rule.Check(str_lc, offset))) {
      return false;
    }
  }

  return true;
}

}  // namespace fs
}  // namespace xe