hphp/util/string-holder.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16
  17 #pragma once
  18
  19 #include <stdint.h>
  20 #include <cstddef>
  21
  22 namespace HPHP {
  23 ///////////////////////////////////////////////////////////////////////////////
  24
  25 /**
  26  * For now, use this for StringHolder, instead of something like
  27  * std::default_delete.
  28  */
  29 enum struct FreeType {
  30   NoFree,
  31   Free,
  32   LocalFree,
  33 };
  34
  35 /*
  36  * String holder class for storing a reference to a string that is not
  37  * owned by us. The type indicates whether/how to deallocate the string upon
  38  * destruction.
  39  */
  40 struct StringHolder {
  41   /* implicit */
  42   StringHolder(std::nullptr_t = nullptr)
  43     : m_data(nullptr), m_len(0), m_type(FreeType::NoFree) {}
  44   StringHolder(const char* data, uint32_t len, FreeType t)
  45     : m_data(data), m_len(len), m_type(t) {}
  46   StringHolder(StringHolder&& o) noexcept
  47     : m_data(o.m_data), m_len(o.m_len), m_type(o.m_type) {
  48     o.m_data = nullptr;
  49   }
  50   StringHolder(const StringHolder&) = delete;
  51
  52   ~StringHolder();
  53
  54   StringHolder& operator=(StringHolder&&) noexcept;
  55   StringHolder& operator=(const StringHolder&) = delete;
  56
  57   uint32_t size() const { return m_len; }
  58
  59   // The length is not the size of the buffer, but the useful size of it. For
  60   // example, we could allocate a big buffer, but only uses part of it. The
  61   // capacity of the buffer isn't stored here.
  62   void shrinkTo(uint32_t newLen);
  63
  64   const char* data() const { return m_data; }
  65
  66   operator bool() const { return data() != nullptr; }
  67
  68 private:
  69   const char* m_data;
  70   uint32_t m_len;
  71   FreeType m_type;
  72 };
  73
  74 ///////////////////////////////////////////////////////////////////////////////
  75 }
  76