skia2/include/private/SkMacros.h
Hal Canary 50dbc0949f SkTypes: more into SkMacros
Change-Id: I4c9a2d81a1bc4ccebc78eea56c0de116b98d415e
Reviewed-on: https://skia-review.googlesource.com/134330
Commit-Queue: Hal Canary <halcanary@google.com>
Auto-Submit: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
2018-06-12 20:24:43 +00:00

68 lines
2.3 KiB
C

/*
* Copyright 2018 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkMacros_DEFINED
#define SkMacros_DEFINED
/*
* Usage: SK_MACRO_CONCAT(a, b) to construct the symbol ab
*
* SK_MACRO_CONCAT_IMPL_PRIV just exists to make this work. Do not use directly
*
*/
#define SK_MACRO_CONCAT(X, Y) SK_MACRO_CONCAT_IMPL_PRIV(X, Y)
#define SK_MACRO_CONCAT_IMPL_PRIV(X, Y) X ## Y
/*
* Usage: SK_MACRO_APPEND_LINE(foo) to make foo123, where 123 is the current
* line number. Easy way to construct
* unique names for local functions or
* variables.
*/
#define SK_MACRO_APPEND_LINE(name) SK_MACRO_CONCAT(name, __LINE__)
/**
* For some classes, it's almost always an error to instantiate one without a name, e.g.
* {
* SkAutoMutexAcquire(&mutex);
* <some code>
* }
* In this case, the writer meant to hold mutex while the rest of the code in the block runs,
* but instead the mutex is acquired and then immediately released. The correct usage is
* {
* SkAutoMutexAcquire lock(&mutex);
* <some code>
* }
*
* To prevent callers from instantiating your class without a name, use SK_REQUIRE_LOCAL_VAR
* like this:
* class classname {
* <your class>
* };
* #define classname(...) SK_REQUIRE_LOCAL_VAR(classname)
*
* This won't work with templates, and you must inline the class' constructors and destructors.
* Take a look at SkAutoFree and SkAutoMalloc in this file for examples.
*/
#define SK_REQUIRE_LOCAL_VAR(classname) \
static_assert(false, "missing name for " #classname)
////////////////////////////////////////////////////////////////////////////////
// Can be used to bracket data types that must be dense, e.g. hash keys.
#if defined(__clang__) // This should work on GCC too, but GCC diagnostic pop didn't seem to work!
#define SK_BEGIN_REQUIRE_DENSE _Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic error \"-Wpadded\"")
#define SK_END_REQUIRE_DENSE _Pragma("GCC diagnostic pop")
#else
#define SK_BEGIN_REQUIRE_DENSE
#define SK_END_REQUIRE_DENSE
#endif
#define SK_INIT_TO_AVOID_WARNING = 0
#endif // SkMacros_DEFINED