text: /*
   *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include "rtc_base/stringutils.h"
  
  namespace rtc {
  
  size_t strcpyn(char* buffer,
                 size_t buflen,
                 const char* source,
                 size_t srclen /* = SIZE_UNKNOWN */) {
    if (buflen <= 0)
      return 0;
  
    if (srclen == SIZE_UNKNOWN) {
      srclen = strlen(source);
    }
    if (srclen >= buflen) {
      srclen = buflen - 1;
    }
    memcpy(buffer, source, srclen);
    buffer[srclen] = 0;
    return srclen;
  }
  
  void replace_substrs(const char* search,
                       size_t search_len,
                       const char* replace,
                       size_t replace_len,
                       std::string* s) {
    size_t pos = 0;
    while ((pos = s->find(search, pos, search_len)) != std::string::npos) {
      s->replace(pos, search_len, replace, replace_len);
      pos += replace_len;
    }
  }
  
  bool starts_with(const char* s1, const char* s2) {
    return strncmp(s1, s2, strlen(s2)) == 0;
  }
  
  bool ends_with(const char* s1, const char* s2) {
    size_t s1_length = strlen(s1);
    size_t s2_length = strlen(s2);
  
    if (s2_length > s1_length) {
      return false;
    }
  
    const char* start = s1 + (s1_length - s2_length);
    return strncmp(start, s2, s2_length) == 0;
  }
  
  static const char kWhitespace[] = " \n\r\t";
  
  std::string string_trim(const std::string& s) {
    std::string::size_type first = s.find_first_not_of(kWhitespace);
    std::string::size_type last = s.find_last_not_of(kWhitespace);
  
    if (first == std::string::npos || last == std::string::npos) {
      return std::string("");
    }
  
    return s.substr(first, last - first + 1);
  }
  
  std::string ToHex(const int i) {
    char buffer[50];
    snprintf(buffer, sizeof(buffer), "%x", i);
  
    return std::string(buffer);
  }
  
  std::string LeftPad(char padding, unsigned length, std::string s) {
    if (s.length() >= length)
      return s;
    return std::string(length - s.length(), padding) + s;
  }
  
  }  // namespace rtc
  