mfbt/MacroArgs.h
author Andrea Marchesini <amarchesini@mozilla.com>
Wed, 31 Oct 2018 18:30:18 +0100
changeset 500246 544498045a9cfe55968fa6500bffbc3181869fce
parent 410638 bee4404d2f888596ded102cf7599d57cfdbf421a
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1486698 - Update Fetch+Stream implementation to throw when the stream is disturbed or locked, r=bz In this patch, I went through any place in DOM fetch code, where there are ReadableStreams and update the locked, disturbed, readable checks. Because we expose streams more often, we need an extra care in the use of ErrorResult objects. JS streams can now throw exceptions and we need to handle them. This patch also fixes a bug in FileStreamReader::CloseAndRelease() which could be called in case mReader creation fails.

/* -*- 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_ARG_COUNT(...) counts the number of variadic arguments.
 * You must pass in between 0 and 50 (inclusive) variadic arguments.
 * For example:
 *
 *   MOZ_ARG_COUNT() expands to 0
 *   MOZ_ARG_COUNT(a) expands to 1
 *   MOZ_ARG_COUNT(a, b) expands to 2
 *
 * Implementation notes:
 * The `##__VA_ARGS__` form is a GCC extension that removes the comma if
 * __VA_ARGS__ is empty. It is supported by Clang too. MSVC ignores ##,
 * and its default behavior is already to strip the comma when __VA_ARGS__
 * is empty.
 *
 * So MOZ_MACROARGS_ARG_COUNT_HELPER() expands to
 *   (_, 50, 49, ...)
 * MOZ_MACROARGS_ARG_COUNT_HELPER(a) expands to
 *   (_, a, 50, 49, ...)
 * etc.
 */
#define MOZ_ARG_COUNT(...) \
  MOZ_MACROARGS_ARG_COUNT_HELPER2(MOZ_MACROARGS_ARG_COUNT_HELPER(__VA_ARGS__))

#define MOZ_MACROARGS_ARG_COUNT_HELPER(...) (_, ##__VA_ARGS__, \
    50, 49, 48, 47, 46, 45, 44, 43, 42, 41, \
    40, 39, 38, 37, 36, 35, 34, 33, 32, 31, \
    30, 29, 28, 27, 26, 25, 24, 23, 22, 21, \
    20, 19, 18, 17, 16, 15, 14, 13, 12, 11, \
    10, 9,  8,  7,  6,  5,  4,  3,  2,  1, 0)

#define MOZ_MACROARGS_ARG_COUNT_HELPER2(aArgs) \
  MOZ_MACROARGS_ARG_COUNT_HELPER3 aArgs

#define MOZ_MACROARGS_ARG_COUNT_HELPER3(a0, \
   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_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
 *   MOZ_PASTE_PREFIX_AND_ARG_COUNT(A) expands to A0
 *   MOZ_PASTE_PREFIX_AND_ARG_COUNT() expands to 0, but MSVC warns there
 *   aren't enough arguments given.
 *
 * You must pass in between 0 and 50 (inclusive) variadic arguments, past
 * |aPrefix|.
 */
#define MOZ_PASTE_PREFIX_AND_ARG_COUNT_GLUE(a, b) a b
#define MOZ_PASTE_PREFIX_AND_ARG_COUNT(aPrefix, ...) \
  MOZ_PASTE_PREFIX_AND_ARG_COUNT_GLUE( \
    MOZ_CONCAT, (aPrefix, MOZ_ARG_COUNT(__VA_ARGS__)))

/*
 * 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 */