xpcom/string/public/nsLiteralString.h
author Phil Ringnalda <philringnalda@gmail.com>
Fri, 04 Jan 2013 21:30:14 -0800
changeset 126826 ea909ce6007b1c67b3bb9ef0d197ef8845399e9c
parent 124059 a0ae1934a4a074c239833e528abb44a0304a279b
child 161495 0a62484ff46bb8ed6d3bb173ab04bc46c62b659b
permissions -rw-r--r--
Back out 5e76dfb1d426 (bug 826635) and 0df74b1a4543:20df426b6111 (bug 826632) for bustage CLOSED TREE

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsLiteralString_h___
#define nsLiteralString_h___

#ifndef nscore_h___
#include "nscore.h"
#endif

#ifndef nsDependentString_h___
#include "nsDependentString.h"
#endif

namespace mozilla {
namespace internal {

// This is the same as sizeof(c) - 1, except it won't compile if c isn't a
// string literal.  This ensures that NS_LITERAL_CSTRING doesn't compile if you
// pass it a char* (or something else for that matter).
template<int n>
inline uint32_t LiteralStringLength(const char (&c)[n])
{
  return n - 1;
}

#if defined(HAVE_CPP_CHAR16_T)
template<int n>
inline uint32_t LiteralWStringLength(const char16_t (&c)[n])
{
  return n - 1;
}
#elif defined(HAVE_CPP_2BYTE_WCHAR_T)
template<int n>
inline uint32_t LiteralWStringLength(const wchar_t (&c)[n])
{
  return n - 1;
}
#endif

} // namespace internal
} // namespace mozilla

#if defined(HAVE_CPP_CHAR16_T) || defined(HAVE_CPP_2BYTE_WCHAR_T)
#if defined(HAVE_CPP_CHAR16_T)
  //PR_STATIC_ASSERT(sizeof(char16_t) == 2);
  #define NS_LL(s)                                u##s
#else
  //PR_STATIC_ASSERT(sizeof(wchar_t) == 2);
  #define NS_LL(s)                                L##s
#endif
  #define NS_MULTILINE_LITERAL_STRING(s)          nsDependentString(reinterpret_cast<const nsAString::char_type*>(s), mozilla::internal::LiteralWStringLength(s))
  #define NS_MULTILINE_LITERAL_STRING_INIT(n,s)   n(reinterpret_cast<const nsAString::char_type*>(s), mozilla::internal::LiteralWStringLength(s))
  #define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)  const nsDependentString n(reinterpret_cast<const nsAString::char_type*>(s), mozilla::internal::LiteralWStringLength(s))
  typedef nsDependentString nsLiteralString;
#else
  #define NS_LL(s)                                s
  #define NS_MULTILINE_LITERAL_STRING(s)          NS_ConvertASCIItoUTF16(s, mozilla::internal::LiteralStringLength(s))
  #define NS_MULTILINE_LITERAL_STRING_INIT(n,s)   n(s, mozilla::internal::LiteralStringLength(s))
  #define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)  const NS_ConvertASCIItoUTF16 n(s, mozilla::internal::LiteralStringLength(s))
  typedef NS_ConvertASCIItoUTF16 nsLiteralString;
#endif

/*
 * Macro arguments used in concatenation or stringification won't be expanded.
 * Therefore, in order for |NS_L(FOO)| to work as expected (which is to expand
 * |FOO| before doing whatever |NS_L| needs to do to it) a helper macro needs
 * to be inserted in between to allow the macro argument to expand.
 * See "3.10.6 Separate Expansion of Macro Arguments" of the CPP manual for a
 * more accurate and precise explanation.
 */

#define NS_L(s)                                   NS_LL(s)

#define NS_LITERAL_STRING(s)                      static_cast<const nsAFlatString&>(NS_MULTILINE_LITERAL_STRING(NS_LL(s)))
#define NS_LITERAL_STRING_INIT(n,s)               NS_MULTILINE_LITERAL_STRING_INIT(n, NS_LL(s))
#define NS_NAMED_LITERAL_STRING(n,s)              NS_NAMED_MULTILINE_LITERAL_STRING(n, NS_LL(s))

#define NS_LITERAL_CSTRING(s)                     static_cast<const nsDependentCString&>(nsDependentCString(s, mozilla::internal::LiteralStringLength(s)))
#define NS_LITERAL_CSTRING_INIT(n,s)              n(s, mozilla::internal::LiteralStringLength(s))
#define NS_NAMED_LITERAL_CSTRING(n,s)             const nsDependentCString n(s, mozilla::internal::LiteralStringLength(s))

typedef nsDependentCString nsLiteralCString;

#endif /* !defined(nsLiteralString_h___) */