mirror of https://github.com/roytam1/UXP
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
109 lines
4.8 KiB
109 lines
4.8 KiB
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
|
/* vim: set ts=8 sts=2 et sw=2 tw=80: */ |
|
/* 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/. */ |
|
|
|
/* |
|
* Implements various macros meant to ease the use of variadic macros. |
|
*/ |
|
|
|
#ifndef mozilla_MacroArgs_h |
|
#define mozilla_MacroArgs_h |
|
|
|
// Concatenates pre-processor tokens in a way that can be used with __LINE__. |
|
#define MOZ_CONCAT2(x, y) x ## y |
|
#define MOZ_CONCAT(x, y) MOZ_CONCAT2(x, y) |
|
|
|
/* |
|
* MOZ_PASTE_PREFIX_AND_ARG_COUNT(aPrefix, ...) counts the number of variadic |
|
* arguments and prefixes it with |aPrefix|. For example: |
|
* |
|
* MOZ_PASTE_PREFIX_AND_ARG_COUNT(, foo, 42) expands to 2 |
|
* MOZ_PASTE_PREFIX_AND_ARG_COUNT(A, foo, 42, bar) expands to A3 |
|
* |
|
* You must pass in between 1 and 50 (inclusive) variadic arguments, past |
|
* |aPrefix|. It is not legal to do |
|
* |
|
* MOZ_PASTE_PREFIX_AND_ARG_COUNT(prefix) |
|
* |
|
* (that is, pass in 0 variadic arguments). To ensure that a compile-time |
|
* error occurs when these constraints are violated, use the |
|
* MOZ_STATIC_ASSERT_VALID_ARG_COUNT macro with the same variaidc arguments |
|
* wherever this macro is used. |
|
* |
|
* Passing (__VA_ARGS__, <rest of arguments>) rather than simply calling |
|
* MOZ_MACROARGS_ARG_COUNT_HELPER2(__VA_ARGS__, <rest of arguments>) very |
|
* carefully tiptoes around a MSVC bug where it improperly expands __VA_ARGS__ |
|
* as a single token in argument lists. For details, see: |
|
* |
|
* http://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement |
|
* http://cplusplus.co.il/2010/07/17/variadic-macro-to-count-number-of-arguments/#comment-644 |
|
*/ |
|
#define MOZ_PASTE_PREFIX_AND_ARG_COUNT(aPrefix, ...) \ |
|
MOZ_MACROARGS_ARG_COUNT_HELPER((__VA_ARGS__, \ |
|
aPrefix##50, aPrefix##49, aPrefix##48, aPrefix##47, aPrefix##46, \ |
|
aPrefix##45, aPrefix##44, aPrefix##43, aPrefix##42, aPrefix##41, \ |
|
aPrefix##40, aPrefix##39, aPrefix##38, aPrefix##37, aPrefix##36, \ |
|
aPrefix##35, aPrefix##34, aPrefix##33, aPrefix##32, aPrefix##31, \ |
|
aPrefix##30, aPrefix##29, aPrefix##28, aPrefix##27, aPrefix##26, \ |
|
aPrefix##25, aPrefix##24, aPrefix##23, aPrefix##22, aPrefix##21, \ |
|
aPrefix##20, aPrefix##19, aPrefix##18, aPrefix##17, aPrefix##16, \ |
|
aPrefix##15, aPrefix##14, aPrefix##13, aPrefix##12, aPrefix##11, \ |
|
aPrefix##10, aPrefix##9, aPrefix##8, aPrefix##7, aPrefix##6, \ |
|
aPrefix##5, aPrefix##4, aPrefix##3, aPrefix##2, aPrefix##1, aPrefix##0)) |
|
|
|
#define MOZ_MACROARGS_ARG_COUNT_HELPER(aArgs) \ |
|
MOZ_MACROARGS_ARG_COUNT_HELPER2 aArgs |
|
|
|
#define MOZ_MACROARGS_ARG_COUNT_HELPER2( \ |
|
a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, \ |
|
a11, a12, a13, a14, a15, a16, a17, a18, a19, a20, \ |
|
a21, a22, a23, a24, a25, a26, a27, a28, a29, a30, \ |
|
a31, a32, a33, a34, a35, a36, a37, a38, a39, a40, \ |
|
a41, a42, a43, a44, a45, a46, a47, a48, a49, a50, \ |
|
a51, ...) a51 |
|
|
|
/* |
|
* MOZ_STATIC_ASSERT_VALID_ARG_COUNT ensures that a compile-time error occurs |
|
* when the argument count constraints of MOZ_PASTE_PREFIX_AND_ARG_COUNT are |
|
* violated. Use this macro wherever MOZ_PASTE_PREFIX_AND_ARG_COUNT is used |
|
* and pass it the same variadic arguments. |
|
* |
|
* This macro employs a few dirty tricks to function. To detect the zero |
|
* argument case, |(__VA_ARGS__)| is stringified, sizeof-ed, and compared to |
|
* what it should be in the absence of arguments. |
|
* |
|
* Detecting too many arguments is a little trickier. With a valid argument |
|
* count and a prefix of 1, MOZ_PASTE_PREFIX_AND_ARG_COUNT expands to e.g. 14. |
|
* With a prefix of 0.0, it expands to e.g. 0.04. If there are too many |
|
* arguments, it expands to the first argument over the limit. If this |
|
* exceeding argument is a number, the assertion will fail as there is no |
|
* number than can simultaneously be both > 10 and == 0. If the exceeding |
|
* argument is not a number, a compile-time error should still occur due to |
|
* the operations performed on it. |
|
*/ |
|
#define MOZ_MACROARGS_STRINGIFY_HELPER(x) #x |
|
#define MOZ_STATIC_ASSERT_VALID_ARG_COUNT(...) \ |
|
static_assert( \ |
|
sizeof(MOZ_MACROARGS_STRINGIFY_HELPER((__VA_ARGS__))) != sizeof("()") && \ |
|
(MOZ_PASTE_PREFIX_AND_ARG_COUNT(1, __VA_ARGS__)) > 10 && \ |
|
(int)(MOZ_PASTE_PREFIX_AND_ARG_COUNT(0.0, __VA_ARGS__)) == 0, \ |
|
"MOZ_STATIC_ASSERT_VALID_ARG_COUNT requires 1 to 50 arguments") /* ; */ |
|
|
|
/* |
|
* MOZ_ARGS_AFTER_N expands to its arguments excluding the first |N| |
|
* arguments. For example: |
|
* |
|
* MOZ_ARGS_AFTER_2(a, b, c, d) expands to: c, d |
|
*/ |
|
#define MOZ_ARGS_AFTER_1(a1, ...) __VA_ARGS__ |
|
#define MOZ_ARGS_AFTER_2(a1, a2, ...) __VA_ARGS__ |
|
|
|
/* |
|
* MOZ_ARG_N expands to its |N|th argument. |
|
*/ |
|
#define MOZ_ARG_1(a1, ...) a1 |
|
#define MOZ_ARG_2(a1, a2, ...) a2 |
|
|
|
#endif /* mozilla_MacroArgs_h */
|
|
|