mirror of
https://git.lyx.org/repos/lyx.git
synced 2024-12-14 01:22:33 +00:00
80 lines
2.8 KiB
C++
80 lines
2.8 KiB
C++
/**
|
|
* \file foreach.h
|
|
* This file is part of LyX, the document processor.
|
|
* Licence details can be found in the file COPYING.
|
|
*
|
|
* \author Matthias Ettrich
|
|
*
|
|
* Full author contact details are available in file CREDITS.
|
|
*
|
|
*/
|
|
|
|
#ifndef FOREACH_H
|
|
#define FOREACH_H
|
|
|
|
// Code stolen from Q_FOREACH, augmented to use a reference to the
|
|
// original container instead of a copy. Copies are cheap (if not
|
|
// mutated) for Qt's containers due to copy-on-write. The are less
|
|
// cheap for Standard containers, that's why the modification.
|
|
// Drawback is that we can't use temporary containers as they
|
|
// will be destroyed before the loop is finished. So always write
|
|
//
|
|
// Container const & container = functionReturningTemporaryOrReference()
|
|
// foreach (ContainerItem const & item, container) {
|
|
// ...
|
|
// }
|
|
//
|
|
// to extend the lifetime of the reference.
|
|
|
|
#if defined(Q_CC_GNU) && !defined(Q_CC_INTEL)
|
|
|
|
/* make use of typeof-extension */
|
|
template <typename T>
|
|
class ForeachContainer {
|
|
public:
|
|
inline ForeachContainer(const T & t) : c(t), brk(0), i(c.begin()), e(c.end()) { }
|
|
const T & c;
|
|
int brk;
|
|
typename T::const_iterator i, e;
|
|
};
|
|
|
|
#define foreach(variable, container) \
|
|
for (ForeachContainer<__typeof__(container)> _container_(container); \
|
|
!_container_.brk && _container_.i != _container_.e; \
|
|
__extension__ ({ ++_container_.brk; ++_container_.i; })) \
|
|
for (variable = *_container_.i;; __extension__ ({--_container_.brk; break;}))
|
|
|
|
#else
|
|
|
|
struct ForeachContainerBase {};
|
|
|
|
template <typename T>
|
|
class ForeachContainer : public ForeachContainerBase {
|
|
public:
|
|
inline ForeachContainer(const T& t): c(t), brk(0), i(c.begin()), e(c.end()){}
|
|
const T & c;
|
|
mutable int brk;
|
|
mutable typename T::const_iterator i, e;
|
|
inline bool condition() const { return (!brk++ && i != e); }
|
|
};
|
|
|
|
template <typename T> inline T *foreachPointer(const T &) { return 0; }
|
|
|
|
template <typename T> inline ForeachContainer<T> foreachContainerNew(const T& t)
|
|
{ return ForeachContainer<T>(t); }
|
|
|
|
template <typename T>
|
|
inline const ForeachContainer<T> *foreachContainer(const ForeachContainerBase *base, const T *)
|
|
{ return static_cast<const ForeachContainer<T> *>(base); }
|
|
|
|
#define foreach(variable, container) \
|
|
for (const ForeachContainerBase &_container_ = foreachContainerNew(container); \
|
|
foreachContainer(&_container_, true ? 0 : foreachPointer(container))->condition(); \
|
|
++foreachContainer(&_container_, true ? 0 : foreachPointer(container))->i) \
|
|
for (variable = *foreachContainer(&_container_, true ? 0 : foreachPointer(container))->i; \
|
|
foreachContainer(&_container_, true ? 0 : foreachPointer(container))->brk; \
|
|
--foreachContainer(&_container_, true ? 0 : foreachPointer(container))->brk)
|
|
#endif
|
|
|
|
#endif // FOREACH_H
|