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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkTInternalSList_DEFINED
#define SkTInternalSList_DEFINED
#include "SkTInternalLList.h" // for SkPtrWrapper
/**
* This macro creates the methods required by the SkTInternalSList class.
* It should be instantiated in the private block of the class you want to put
* into an SkTInternalSList.
* For most use cases you should use SK_DECLARE_INTERNAL_SLIST_INTERFACE and not
* this macro. If you care about the field name, or want to re-use an existing
* field, then you can use this macro to declare the methods pointing to a
* specific field.
* Unlike SK_DECLARE_INTERNAL_SLIST_INTERFACE this does not declare the field
* itself.
* It also makes SkTInternalSList<ClassName> a friend to give it access to the
* methods.
*/
#define SK_DECLARE_INTERNAL_SLIST_ADAPTER(ClassName, field) \
ClassName* getSListNext() { \
return this->field; \
} \
void setSListNext(ClassName* next) { \
this->field = next; \
} \
friend class SkTInternalSList<ClassName>
/**
* This macro declares an fSListNext that auto initializes to NULL and then
* uses SK_DECLARE_INTERNAL_SLIST_ADAPTER to add the methods needed by
* SkTInternalSList.
* It should be instantiated in the private block of the class you want to put
* into an SkTInternalSList.
*/
#define SK_DECLARE_INTERNAL_SLIST_INTERFACE(ClassName) \
SK_DECLARE_INTERNAL_SLIST_ADAPTER(ClassName, fSListNext); \
SkPtrWrapper<ClassName> fSListNext
/**
* An implementation of an intrusive singly linked list.
* The type T must have a methods getSListNext and setSListNext that are visible
* to the list. The easiest way to do this is with
* SK_DECLARE_INTERNAL_SLIST_INTERFACE.
* The list does not maintain ownership of any of its elements, or ever delete
* them.
*/
template<typename T> class SkTInternalSList {
public:
SkTInternalSList() : fHead(NULL), fCount(0) {}
/**
* Push an item onto the head of the list.
* This method is *not* thread safe.
*/
void push(T* entry) {
SkASSERT(entry->getSListNext() == NULL);
entry->setSListNext(fHead);
fHead = entry;
++fCount;
}
/**
* Takes all the items from another list and pushes them into this list.
* No ordering guarantees are made, the other list will be emptied.
* This method is *not* thread safe.
*/
void pushAll(SkTInternalSList<T>* other) {
if (this->isEmpty()) {
this->swap(other);
return;
}
while (!other->isEmpty()) {
this->push(other->pop());
}
}
/**
* Pop an item from the head of the list.
* Returns NULL if the list is empty.
* This method is *not* thread safe.
*/
T* pop() {
if (NULL == fHead) {
return NULL;
}
T* result = fHead;
fHead = result->getSListNext();
result->setSListNext(NULL);
--fCount;
return result;
}
T* head() const {
return fHead;
}
/**
* Returns true if the list has no elements.
*/
bool isEmpty() const {
return NULL == fHead;
}
/**
* Swaps the contents of this list with another one.
* This method is *not* thread safe.
*/
void swap(SkTInternalSList<T>* other) {
SkTSwap(fHead, other->fHead);
SkTSwap(fCount, other->fCount);
}
/**
* Returns the count of elements in the list.
*/
int getCount() const {
return fCount;
}
private:
T* fHead;
int fCount;
};
#endif
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