michael@0: //
michael@0: //  SkTRefArray.h
michael@0: //  core
michael@0: //
michael@0: //  Created by Mike Reed on 7/17/12.
michael@0: //  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
michael@0: //
michael@0: 
michael@0: #ifndef SkTRefArray_DEFINED
michael@0: #define SkTRefArray_DEFINED
michael@0: 
michael@0: #include "SkRefCnt.h"
michael@0: #include <new>
michael@0: 
michael@0: /**
michael@0:  *  Wrapper to manage thread-safe sharing of an array of T objects. The array
michael@0:  *  cannot be grown or shrunk.
michael@0:  */
michael@0: template <typename T> class SkTRefArray : public SkRefCnt {
michael@0:     /*
michael@0:      *  Shared factory to allocate the space needed for our instance plus N
michael@0:      *  T entries at the end. We call our constructor, but not the constructors
michael@0:      *  for the elements. Those are called by the proper Create method.
michael@0:      */
michael@0:     static SkTRefArray<T>* Alloc(int count) {
michael@0:         // space for us, and our [count] elements
michael@0:         size_t size = sizeof(SkTRefArray<T>) + count * sizeof(T);
michael@0:         SkTRefArray<T>* obj = (SkTRefArray<T>*)sk_malloc_throw(size);
michael@0: 
michael@0:         SkNEW_PLACEMENT(obj, SkTRefArray<T>);
michael@0:         obj->fCount = count;
michael@0:         return obj;
michael@0:     }
michael@0: 
michael@0: public:
michael@0:     /**
michael@0:      *  Return a new array with 'count' elements, initialized to their default
michael@0:      *  value. To change them to some other value, use writableBegin/End or
michael@0:      *  writableAt(), but do that before this array is given to another thread.
michael@0:      */
michael@0:     static SkTRefArray<T>* Create(int count) {
michael@0:         SkTRefArray<T>* obj = Alloc(count);
michael@0:         T* array = const_cast<T*>(obj->begin());
michael@0:         for (int i = 0; i < count; ++i) {
michael@0:             SkNEW_PLACEMENT(&array[i], T);
michael@0:         }
michael@0:         return obj;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Return a new array with 'count' elements, initialized from the provided
michael@0:      *  src array. To change them to some other value, use writableBegin/End or
michael@0:      *  writableAt(), but do that before this array is given to another thread.
michael@0:      */
michael@0:     static SkTRefArray<T>* Create(const T src[], int count) {
michael@0:         SkTRefArray<T>* obj = Alloc(count);
michael@0:         T* array = const_cast<T*>(obj->begin());
michael@0:         for (int i = 0; i < count; ++i) {
michael@0:             SkNEW_PLACEMENT_ARGS(&array[i], T, (src[i]));
michael@0:         }
michael@0:         return obj;
michael@0:     }
michael@0: 
michael@0:     int count() const { return fCount; }
michael@0:     const T* begin() const { return (const T*)(this + 1); }
michael@0:     const T* end() const { return this->begin() + fCount; }
michael@0:     const T& at(int index) const {
michael@0:         SkASSERT((unsigned)index < (unsigned)fCount);
michael@0:         return this->begin()[index];
michael@0:     }
michael@0:     const T& operator[](int index) const { return this->at(index); }
michael@0: 
michael@0:     // For the writable methods, we assert that we are the only owner if we
michael@0:     // call these, since other owners are not informed if we change an element.
michael@0: 
michael@0:     T* writableBegin() {
michael@0:         SkASSERT(this->unique());
michael@0:         return (T*)(this + 1);
michael@0:     }
michael@0:     T* writableEnd() {
michael@0:         return this->writableBegin() + fCount;
michael@0:     }
michael@0:     T& writableAt(int index) {
michael@0:         SkASSERT((unsigned)index < (unsigned)fCount);
michael@0:         return this->writableBegin()[index];
michael@0:     }
michael@0: 
michael@0: protected:
michael@0:     virtual void internal_dispose() const SK_OVERRIDE {
michael@0:         T* array = const_cast<T*>(this->begin());
michael@0:         int n = fCount;
michael@0: 
michael@0:         for (int i = 0; i < n; ++i) {
michael@0:             array->~T();
michael@0:             array += 1;
michael@0:         }
michael@0: 
michael@0:         this->internal_dispose_restore_refcnt_to_1();
michael@0:         this->~SkTRefArray<T>();
michael@0:         sk_free((void*)this);
michael@0:     }
michael@0: 
michael@0: private:
michael@0:     int fCount;
michael@0: 
michael@0:     // hide this
michael@0:     virtual ~SkTRefArray() {}
michael@0: 
michael@0:     typedef SkRefCnt INHERITED;
michael@0: };
michael@0: 
michael@0: #endif