зеркало из https://github.com/mozilla/gecko-dev.git
Bug 989460 - Part 1: Add MacroArgs.h for macros related to implementing variadic macros. r=Waldo
This also converts MOZ_RELEASE_ASSERT and MOZ_BEGIN_NESTED_ENUM_CLASS to use the new helper macros.
This commit is contained in:
Birunthan Mohanathas
Родитель
a33ed136f3
Коммит
accb4d62ef
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@ -12,6 +12,7 @@
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#include "mozilla/Attributes.h"
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#include "mozilla/Compiler.h"
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#include "mozilla/Likely.h"
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#include "mozilla/MacroArgs.h"
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#include <stddef.h>
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#include <stdio.h>
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@ -295,30 +296,13 @@ __declspec(noreturn) __inline void MOZ_NoReturn() {}
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MOZ_REALLY_CRASH(); \
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} \
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} while (0)
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/* And now, helper macrology up the wazoo. */
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/*
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* Count the number of arguments passed to MOZ_ASSERT, very carefully
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* tiptoeing around an MSVC bug where it improperly expands __VA_ARGS__ as a
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* single token in argument lists. See these URLs for details:
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*
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* http://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement
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* http://cplusplus.co.il/2010/07/17/variadic-macro-to-count-number-of-arguments/#comment-644
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*/
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#define MOZ_COUNT_ASSERT_ARGS_IMPL2(_1, _2, count, ...) \
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count
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#define MOZ_COUNT_ASSERT_ARGS_IMPL(args) \
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MOZ_COUNT_ASSERT_ARGS_IMPL2 args
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#define MOZ_COUNT_ASSERT_ARGS(...) \
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MOZ_COUNT_ASSERT_ARGS_IMPL((__VA_ARGS__, 2, 1, 0))
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/* Pick the right helper macro to invoke. */
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#define MOZ_ASSERT_CHOOSE_HELPER2(count) MOZ_ASSERT_HELPER##count
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#define MOZ_ASSERT_CHOOSE_HELPER1(count) MOZ_ASSERT_CHOOSE_HELPER2(count)
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#define MOZ_ASSERT_CHOOSE_HELPER(count) MOZ_ASSERT_CHOOSE_HELPER1(count)
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/* The actual macros. */
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#define MOZ_ASSERT_GLUE(x, y) x y
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#define MOZ_RELEASE_ASSERT_GLUE(a, b) a b
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#define MOZ_RELEASE_ASSERT(...) \
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MOZ_ASSERT_GLUE(MOZ_ASSERT_CHOOSE_HELPER(MOZ_COUNT_ASSERT_ARGS(__VA_ARGS__)), \
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(__VA_ARGS__))
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MOZ_RELEASE_ASSERT_GLUE( \
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MOZ_PASTE_PREFIX_AND_ARG_COUNT(MOZ_ASSERT_HELPER, __VA_ARGS__), \
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(__VA_ARGS__))
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#ifdef DEBUG
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# define MOZ_ASSERT(...) MOZ_RELEASE_ASSERT(__VA_ARGS__)
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#else
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@ -0,0 +1,105 @@
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* Implements various macros meant to ease the use of variadic macros.
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*/
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#ifndef mozilla_MacroArgs_h
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#define mozilla_MacroArgs_h
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/*
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* MOZ_PASTE_PREFIX_AND_ARG_COUNT(aPrefix, ...) counts the number of variadic
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* arguments and prefixes it with |aPrefix|. For example:
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*
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* MOZ_PASTE_PREFIX_AND_ARG_COUNT(, foo, 42) expands to 2
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* MOZ_PASTE_PREFIX_AND_ARG_COUNT(A, foo, 42, bar) expands to A3
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*
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* You must pass in between 1 and 50 (inclusive) variadic arguments, past
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* |aPrefix|. It is not legal to do
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*
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* MOZ_PASTE_PREFIX_AND_ARG_COUNT(prefix)
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*
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* (that is, pass in 0 variadic arguments). To ensure that a compile-time
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* error occurs when these constraints are violated, use the
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* MOZ_STATIC_ASSERT_VALID_ARG_COUNT macro with the same variaidc arguments
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* wherever this macro is used.
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*
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* Passing (__VA_ARGS__, <rest of arguments>) rather than simply calling
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* MOZ_MACROARGS_ARG_COUNT_HELPER2(__VA_ARGS__, <rest of arguments>) very
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* carefully tiptoes around a MSVC bug where it improperly expands __VA_ARGS__
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* as a single token in argument lists. For details, see:
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*
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* http://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement
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* http://cplusplus.co.il/2010/07/17/variadic-macro-to-count-number-of-arguments/#comment-644
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*/
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#define MOZ_PASTE_PREFIX_AND_ARG_COUNT(aPrefix, ...) \
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MOZ_MACROARGS_ARG_COUNT_HELPER((__VA_ARGS__, \
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aPrefix##50, aPrefix##49, aPrefix##48, aPrefix##47, aPrefix##46, \
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aPrefix##45, aPrefix##44, aPrefix##43, aPrefix##42, aPrefix##41, \
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aPrefix##40, aPrefix##39, aPrefix##38, aPrefix##37, aPrefix##36, \
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aPrefix##35, aPrefix##34, aPrefix##33, aPrefix##32, aPrefix##31, \
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aPrefix##30, aPrefix##29, aPrefix##28, aPrefix##27, aPrefix##26, \
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aPrefix##25, aPrefix##24, aPrefix##23, aPrefix##22, aPrefix##21, \
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aPrefix##20, aPrefix##19, aPrefix##18, aPrefix##17, aPrefix##16, \
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aPrefix##15, aPrefix##14, aPrefix##13, aPrefix##12, aPrefix##11, \
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aPrefix##10, aPrefix##9, aPrefix##8, aPrefix##7, aPrefix##6, \
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aPrefix##5, aPrefix##4, aPrefix##3, aPrefix##2, aPrefix##1, aPrefix##0))
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#define MOZ_MACROARGS_ARG_COUNT_HELPER(aArgs) \
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MOZ_MACROARGS_ARG_COUNT_HELPER2 aArgs
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#define MOZ_MACROARGS_ARG_COUNT_HELPER2( \
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a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, \
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a11, a12, a13, a14, a15, a16, a17, a18, a19, a20, \
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a21, a22, a23, a24, a25, a26, a27, a28, a29, a30, \
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a31, a32, a33, a34, a35, a36, a37, a38, a39, a40, \
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a41, a42, a43, a44, a45, a46, a47, a48, a49, a50, \
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a51, ...) a51
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/*
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* MOZ_STATIC_ASSERT_VALID_ARG_COUNT ensures that a compile-time error occurs
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* when the argument count constraints of MOZ_PASTE_PREFIX_AND_ARG_COUNT are
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* violated. Use this macro wherever MOZ_PASTE_PREFIX_AND_ARG_COUNT is used
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* and pass it the same variadic arguments.
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*
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* This macro employs a few dirty tricks to function. To detect the zero
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* argument case, |(__VA_ARGS__)| is stringified, sizeof-ed, and compared to
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* what it should be in the absence of arguments.
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*
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* Detecting too many arguments is a little trickier. With a valid argument
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* count and a prefix of 1, MOZ_PASTE_PREFIX_AND_ARG_COUNT expands to e.g. 14.
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* With a prefix of 0.0, it expands to e.g. 0.04. If there are too many
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* arguments, it expands to the first argument over the limit. If this
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* exceeding argument is a number, the assertion will fail as there is no
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* number than can simultaneously be both > 10 and < 0.1. If the exceeding
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* argument is not a number, a compile-time error will still occur because the
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* exceeding argument is compared to an int and a double.
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*/
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#define MOZ_MACROARGS_STRINGIFY_HELPER(x) #x
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#define MOZ_STATIC_ASSERT_VALID_ARG_COUNT(...) \
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static_assert( \
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sizeof(MOZ_MACROARGS_STRINGIFY_HELPER((__VA_ARGS__))) != sizeof("()") && \
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MOZ_PASTE_PREFIX_AND_ARG_COUNT(1, __VA_ARGS__) > 10 && \
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MOZ_PASTE_PREFIX_AND_ARG_COUNT(0.0, __VA_ARGS__) < 0.1, \
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"MOZ_STATIC_ASSERT_VALID_ARG_COUNT requires 1 to 50 arguments") /* ; */
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/*
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* MOZ_ARGS_AFTER_N expands to its arguments excluding the first |N|
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* arguments. For example:
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*
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* MOZ_ARGS_AFTER_2(a, b, c, d) expands to: c, d
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*/
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#define MOZ_ARGS_AFTER_1(a1, ...) __VA_ARGS__
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#define MOZ_ARGS_AFTER_2(a1, a2, ...) __VA_ARGS__
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/*
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* MOZ_ARG_N expands to its |N|th argument.
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*/
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#define MOZ_ARG_1(a1, ...) a1
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#define MOZ_ARG_2(a1, a2, ...) a2
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#endif /* mozilla_MacroArgs_h */
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@ -10,6 +10,7 @@
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#define mozilla_TypedEnum_h
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#include "mozilla/Attributes.h"
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#include "mozilla/MacroArgs.h"
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#if defined(__cplusplus)
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@ -290,33 +291,12 @@
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# define MOZ_TEMPLATE_ENUM_CLASS_ENUM_TYPE(Name) typename Name::Enum
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#endif
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/*
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* Count the number of arguments passed to MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS,
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* very carefully tiptoeing around an MSVC bug where it improperly expands
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* __VA_ARGS__ as a single token in argument lists. See these URLs for
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* details:
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*
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* http://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement
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* http://cplusplus.co.il/2010/07/17/variadic-macro-to-count-number-of-arguments/#comment-644
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*/
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# define MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS_IMPL2(_1, _2, count, ...) \
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count
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# define MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS_IMPL(args) \
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MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS_IMPL2 args
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# define MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS(...) \
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MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS_IMPL((__VA_ARGS__, 2, 1, 0))
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/* Pick the right helper macro to invoke. */
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# define MOZ_BEGIN_NESTED_ENUM_CLASS_CHOOSE_HELPER2(count) \
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MOZ_BEGIN_NESTED_ENUM_CLASS_HELPER##count
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# define MOZ_BEGIN_NESTED_ENUM_CLASS_CHOOSE_HELPER1(count) \
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MOZ_BEGIN_NESTED_ENUM_CLASS_CHOOSE_HELPER2(count)
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# define MOZ_BEGIN_NESTED_ENUM_CLASS_CHOOSE_HELPER(count) \
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MOZ_BEGIN_NESTED_ENUM_CLASS_CHOOSE_HELPER1(count)
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/* The actual macro. */
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# define MOZ_BEGIN_NESTED_ENUM_CLASS_GLUE(x, y) x y
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# define MOZ_BEGIN_NESTED_ENUM_CLASS_GLUE(a, b) a b
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# define MOZ_BEGIN_NESTED_ENUM_CLASS(...) \
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MOZ_BEGIN_NESTED_ENUM_CLASS_GLUE(MOZ_BEGIN_NESTED_ENUM_CLASS_CHOOSE_HELPER(MOZ_COUNT_BEGIN_ENUM_CLASS_ARGS(__VA_ARGS__)), \
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(__VA_ARGS__))
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MOZ_BEGIN_NESTED_ENUM_CLASS_GLUE( \
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MOZ_PASTE_PREFIX_AND_ARG_COUNT(MOZ_BEGIN_NESTED_ENUM_CLASS_HELPER, \
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__VA_ARGS__), \
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(__VA_ARGS__))
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# define MOZ_BEGIN_ENUM_CLASS(...) MOZ_BEGIN_NESTED_ENUM_CLASS(__VA_ARGS__)
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# define MOZ_END_ENUM_CLASS(Name) \
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@ -36,6 +36,7 @@ EXPORTS.mozilla = [
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'IntegerTypeTraits.h',
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'Likely.h',
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'LinkedList.h',
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'MacroArgs.h',
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'MathAlgorithms.h',
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'Maybe.h',
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'MemoryChecking.h',
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@ -0,0 +1,26 @@
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/MacroArgs.h"
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static_assert(MOZ_PASTE_PREFIX_AND_ARG_COUNT(100, a, b, c) == 1003, "");
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static_assert(MOZ_PASTE_PREFIX_AND_ARG_COUNT(, a, b, c) == 3, "");
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static_assert(MOZ_PASTE_PREFIX_AND_ARG_COUNT(, a) == 1, "");
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static_assert(MOZ_PASTE_PREFIX_AND_ARG_COUNT(, !a) == 1, "");
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static_assert(MOZ_PASTE_PREFIX_AND_ARG_COUNT(, (a, b)) == 1, "");
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static_assert(MOZ_PASTE_PREFIX_AND_ARG_COUNT(, MOZ_ARGS_AFTER_1(a, b, c)) == 2,
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"MOZ_ARGS_AFTER_1(a, b, c) should expand to 'b, c'");
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static_assert(MOZ_ARGS_AFTER_2(a, b, 3) == 3,
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"MOZ_ARGS_AFTER_2(a, b, 3) should expand to '3'");
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static_assert(MOZ_ARG_1(10, 20, 30) == 10, "");
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static_assert(MOZ_ARG_2(10, 20, 30) == 20, "");
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int main()
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{
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}
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@ -17,6 +17,7 @@ CPP_UNIT_TESTS += [
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'TestEnumSet.cpp',
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'TestFloatingPoint.cpp',
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'TestIntegerPrintfMacros.cpp',
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'TestMacroArgs.cpp',
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'TestRollingMean.cpp',
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'TestSHA1.cpp',
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'TestTypedEnum.cpp',
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