01bdceb869
A change made in the spirit of not being weird. C++ containers typically expose their capacities to non-test code, with a function "capacity." Change-Id: Icc7e175a20aff53ef9e144ac9620ced29ef5e95a Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325657 Auto-Submit: John Stiles <johnstiles@google.com> Reviewed-by: Mike Klein <mtklein@google.com> Commit-Queue: John Stiles <johnstiles@google.com>
662 lines
19 KiB
C++
662 lines
19 KiB
C++
/*
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* Copyright 2011 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkTArray_DEFINED
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#define SkTArray_DEFINED
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#include "include/core/SkMath.h"
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#include "include/core/SkTypes.h"
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#include "include/private/SkMalloc.h"
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#include "include/private/SkSafe32.h"
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#include "include/private/SkTLogic.h"
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#include "include/private/SkTemplates.h"
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#include <string.h>
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#include <memory>
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#include <new>
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#include <utility>
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/** SkTArray<T> implements a typical, mostly std::vector-like array.
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Each T will be default-initialized on allocation, and ~T will be called on destruction.
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MEM_MOVE controls the behavior when a T needs to be moved (e.g. when the array is resized)
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- true: T will be bit-copied via memcpy.
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- false: T will be moved via move-constructors.
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Modern implementations of std::vector<T> will generally provide similar performance
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characteristics when used with appropriate care. Consider using std::vector<T> in new code.
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*/
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template <typename T, bool MEM_MOVE = false> class SkTArray {
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public:
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/**
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* Creates an empty array with no initial storage
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*/
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SkTArray() { this->init(); }
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/**
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* Creates an empty array that will preallocate space for reserveCount
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* elements.
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*/
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explicit SkTArray(int reserveCount) { this->init(0, reserveCount); }
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/**
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* Copies one array to another. The new array will be heap allocated.
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*/
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SkTArray(const SkTArray& that) {
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this->init(that.fCount);
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this->copy(that.fItemArray);
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}
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SkTArray(SkTArray&& that) {
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if (that.fOwnMemory) {
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fItemArray = that.fItemArray;
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fCount = that.fCount;
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fAllocCount = that.fAllocCount;
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fOwnMemory = true;
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fReserved = that.fReserved;
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that.fItemArray = nullptr;
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that.fCount = 0;
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that.fAllocCount = 0;
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that.fOwnMemory = true;
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that.fReserved = false;
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} else {
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this->init(that.fCount);
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that.move(fItemArray);
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that.fCount = 0;
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}
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}
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/**
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* Creates a SkTArray by copying contents of a standard C array. The new
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* array will be heap allocated. Be careful not to use this constructor
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* when you really want the (void*, int) version.
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*/
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SkTArray(const T* array, int count) {
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this->init(count);
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this->copy(array);
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}
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SkTArray& operator=(const SkTArray& that) {
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if (this == &that) {
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return *this;
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}
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for (int i = 0; i < fCount; ++i) {
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fItemArray[i].~T();
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}
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fCount = 0;
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this->checkRealloc(that.count());
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fCount = that.count();
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this->copy(that.fItemArray);
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return *this;
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}
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SkTArray& operator=(SkTArray&& that) {
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if (this == &that) {
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return *this;
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}
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for (int i = 0; i < fCount; ++i) {
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fItemArray[i].~T();
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}
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fCount = 0;
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this->checkRealloc(that.count());
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fCount = that.count();
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that.move(fItemArray);
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that.fCount = 0;
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return *this;
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}
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~SkTArray() {
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for (int i = 0; i < fCount; ++i) {
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fItemArray[i].~T();
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}
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if (fOwnMemory) {
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sk_free(fItemArray);
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}
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}
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/**
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* Resets to count() == 0 and resets any reserve count.
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*/
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void reset() {
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this->pop_back_n(fCount);
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fReserved = false;
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}
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/**
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* Resets to count() = n newly constructed T objects and resets any reserve count.
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*/
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void reset(int n) {
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SkASSERT(n >= 0);
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for (int i = 0; i < fCount; ++i) {
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fItemArray[i].~T();
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}
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// Set fCount to 0 before calling checkRealloc so that no elements are moved.
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fCount = 0;
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this->checkRealloc(n);
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fCount = n;
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for (int i = 0; i < fCount; ++i) {
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new (fItemArray + i) T;
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}
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fReserved = false;
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}
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/**
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* Resets to a copy of a C array and resets any reserve count.
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*/
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void reset(const T* array, int count) {
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for (int i = 0; i < fCount; ++i) {
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fItemArray[i].~T();
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}
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fCount = 0;
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this->checkRealloc(count);
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fCount = count;
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this->copy(array);
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fReserved = false;
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}
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/**
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* Ensures there is enough reserved space for n additional elements. The is guaranteed at least
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* until the array size grows above n and subsequently shrinks below n, any version of reset()
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* is called, or reserve() is called again.
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*/
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void reserve(int n) {
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SkASSERT(n >= 0);
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if (n > 0) {
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this->checkRealloc(n);
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fReserved = fOwnMemory;
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} else {
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fReserved = false;
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}
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}
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void removeShuffle(int n) {
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SkASSERT(n < fCount);
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int newCount = fCount - 1;
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fCount = newCount;
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fItemArray[n].~T();
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if (n != newCount) {
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this->move(n, newCount);
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}
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}
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/**
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* Number of elements in the array.
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*/
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int count() const { return fCount; }
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/**
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* Is the array empty.
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*/
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bool empty() const { return !fCount; }
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/**
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* Adds 1 new default-initialized T value and returns it by reference. Note
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* the reference only remains valid until the next call that adds or removes
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* elements.
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*/
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T& push_back() {
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void* newT = this->push_back_raw(1);
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return *new (newT) T;
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}
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/**
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* Version of above that uses a copy constructor to initialize the new item
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*/
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T& push_back(const T& t) {
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void* newT = this->push_back_raw(1);
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return *new (newT) T(t);
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}
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/**
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* Version of above that uses a move constructor to initialize the new item
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*/
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T& push_back(T&& t) {
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void* newT = this->push_back_raw(1);
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return *new (newT) T(std::move(t));
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}
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/**
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* Construct a new T at the back of this array.
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*/
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template<class... Args> T& emplace_back(Args&&... args) {
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void* newT = this->push_back_raw(1);
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return *new (newT) T(std::forward<Args>(args)...);
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}
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/**
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* Allocates n more default-initialized T values, and returns the address of
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* the start of that new range. Note: this address is only valid until the
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* next API call made on the array that might add or remove elements.
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*/
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T* push_back_n(int n) {
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SkASSERT(n >= 0);
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void* newTs = this->push_back_raw(n);
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for (int i = 0; i < n; ++i) {
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new (static_cast<char*>(newTs) + i * sizeof(T)) T;
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}
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return static_cast<T*>(newTs);
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}
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/**
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* Version of above that uses a copy constructor to initialize all n items
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* to the same T.
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*/
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T* push_back_n(int n, const T& t) {
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SkASSERT(n >= 0);
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void* newTs = this->push_back_raw(n);
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for (int i = 0; i < n; ++i) {
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new (static_cast<char*>(newTs) + i * sizeof(T)) T(t);
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}
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return static_cast<T*>(newTs);
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}
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/**
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* Version of above that uses a copy constructor to initialize the n items
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* to separate T values.
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*/
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T* push_back_n(int n, const T t[]) {
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SkASSERT(n >= 0);
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this->checkRealloc(n);
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for (int i = 0; i < n; ++i) {
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new (fItemArray + fCount + i) T(t[i]);
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}
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fCount += n;
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return fItemArray + fCount - n;
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}
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/**
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* Version of above that uses the move constructor to set n items.
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*/
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T* move_back_n(int n, T* t) {
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SkASSERT(n >= 0);
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this->checkRealloc(n);
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for (int i = 0; i < n; ++i) {
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new (fItemArray + fCount + i) T(std::move(t[i]));
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}
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fCount += n;
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return fItemArray + fCount - n;
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}
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/**
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* Removes the last element. Not safe to call when count() == 0.
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*/
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void pop_back() {
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SkASSERT(fCount > 0);
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--fCount;
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fItemArray[fCount].~T();
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this->checkRealloc(0);
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}
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/**
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* Removes the last n elements. Not safe to call when count() < n.
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*/
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void pop_back_n(int n) {
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SkASSERT(n >= 0);
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SkASSERT(fCount >= n);
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fCount -= n;
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for (int i = 0; i < n; ++i) {
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fItemArray[fCount + i].~T();
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}
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this->checkRealloc(0);
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}
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/**
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* Pushes or pops from the back to resize. Pushes will be default
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* initialized.
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*/
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void resize_back(int newCount) {
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SkASSERT(newCount >= 0);
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if (newCount > fCount) {
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this->push_back_n(newCount - fCount);
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} else if (newCount < fCount) {
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this->pop_back_n(fCount - newCount);
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}
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}
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/** Swaps the contents of this array with that array. Does a pointer swap if possible,
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otherwise copies the T values. */
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void swap(SkTArray& that) {
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using std::swap;
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if (this == &that) {
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return;
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}
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if (fOwnMemory && that.fOwnMemory) {
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swap(fItemArray, that.fItemArray);
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swap(fCount, that.fCount);
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swap(fAllocCount, that.fAllocCount);
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} else {
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// This could be more optimal...
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SkTArray copy(std::move(that));
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that = std::move(*this);
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*this = std::move(copy);
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}
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}
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T* begin() {
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return fItemArray;
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}
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const T* begin() const {
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return fItemArray;
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}
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T* end() {
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return fItemArray ? fItemArray + fCount : nullptr;
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}
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const T* end() const {
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return fItemArray ? fItemArray + fCount : nullptr;
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}
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T* data() { return fItemArray; }
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const T* data() const { return fItemArray; }
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size_t size() const { return (size_t)fCount; }
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void resize(size_t count) { this->resize_back((int)count); }
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/**
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* Get the i^th element.
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*/
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T& operator[] (int i) {
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SkASSERT(i < fCount);
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SkASSERT(i >= 0);
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return fItemArray[i];
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}
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const T& operator[] (int i) const {
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SkASSERT(i < fCount);
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SkASSERT(i >= 0);
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return fItemArray[i];
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}
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T& at(int i) { return (*this)[i]; }
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const T& at(int i) const { return (*this)[i]; }
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/**
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* equivalent to operator[](0)
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*/
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T& front() { SkASSERT(fCount > 0); return fItemArray[0];}
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const T& front() const { SkASSERT(fCount > 0); return fItemArray[0];}
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/**
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* equivalent to operator[](count() - 1)
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*/
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T& back() { SkASSERT(fCount); return fItemArray[fCount - 1];}
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const T& back() const { SkASSERT(fCount > 0); return fItemArray[fCount - 1];}
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/**
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* equivalent to operator[](count()-1-i)
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*/
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T& fromBack(int i) {
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SkASSERT(i >= 0);
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SkASSERT(i < fCount);
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return fItemArray[fCount - i - 1];
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}
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const T& fromBack(int i) const {
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SkASSERT(i >= 0);
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SkASSERT(i < fCount);
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return fItemArray[fCount - i - 1];
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}
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bool operator==(const SkTArray<T, MEM_MOVE>& right) const {
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int leftCount = this->count();
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if (leftCount != right.count()) {
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return false;
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}
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for (int index = 0; index < leftCount; ++index) {
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if (fItemArray[index] != right.fItemArray[index]) {
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return false;
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}
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}
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return true;
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}
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bool operator!=(const SkTArray<T, MEM_MOVE>& right) const {
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return !(*this == right);
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}
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int capacity() const {
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return fAllocCount;
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}
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protected:
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/**
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* Creates an empty array that will use the passed storage block until it
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* is insufficiently large to hold the entire array.
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*/
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template <int N>
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SkTArray(SkAlignedSTStorage<N,T>* storage) {
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this->initWithPreallocatedStorage(0, storage->get(), N);
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}
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/**
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* Copy another array, using preallocated storage if preAllocCount >=
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* array.count(). Otherwise storage will only be used when array shrinks
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* to fit.
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*/
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template <int N>
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SkTArray(const SkTArray& array, SkAlignedSTStorage<N,T>* storage) {
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this->initWithPreallocatedStorage(array.fCount, storage->get(), N);
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this->copy(array.fItemArray);
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}
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/**
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* Move another array, using preallocated storage if preAllocCount >=
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* array.count(). Otherwise storage will only be used when array shrinks
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* to fit.
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*/
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template <int N>
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SkTArray(SkTArray&& array, SkAlignedSTStorage<N,T>* storage) {
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this->initWithPreallocatedStorage(array.fCount, storage->get(), N);
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array.move(fItemArray);
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array.fCount = 0;
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}
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/**
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* Copy a C array, using preallocated storage if preAllocCount >=
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* count. Otherwise storage will only be used when array shrinks
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* to fit.
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*/
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template <int N>
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SkTArray(const T* array, int count, SkAlignedSTStorage<N,T>* storage) {
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this->initWithPreallocatedStorage(count, storage->get(), N);
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this->copy(array);
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}
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private:
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void init(int count = 0, int reserveCount = 0) {
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SkASSERT(count >= 0);
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SkASSERT(reserveCount >= 0);
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fCount = count;
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if (!count && !reserveCount) {
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fAllocCount = 0;
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fItemArray = nullptr;
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fOwnMemory = true;
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fReserved = false;
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} else {
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fAllocCount = std::max(count, std::max(kMinHeapAllocCount, reserveCount));
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fItemArray = (T*)sk_malloc_throw((size_t)fAllocCount, sizeof(T));
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fOwnMemory = true;
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fReserved = reserveCount > 0;
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}
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}
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void initWithPreallocatedStorage(int count, void* preallocStorage, int preallocCount) {
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SkASSERT(count >= 0);
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SkASSERT(preallocCount > 0);
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SkASSERT(preallocStorage);
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fCount = count;
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fItemArray = nullptr;
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fReserved = false;
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if (count > preallocCount) {
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fAllocCount = std::max(count, kMinHeapAllocCount);
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fItemArray = (T*)sk_malloc_throw(fAllocCount, sizeof(T));
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fOwnMemory = true;
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} else {
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fAllocCount = preallocCount;
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fItemArray = (T*)preallocStorage;
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fOwnMemory = false;
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}
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}
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/** In the following move and copy methods, 'dst' is assumed to be uninitialized raw storage.
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* In the following move methods, 'src' is destroyed leaving behind uninitialized raw storage.
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*/
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void copy(const T* src) {
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// Some types may be trivially copyable, in which case we *could* use memcopy; but
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// MEM_MOVE == true implies that the type is trivially movable, and not necessarily
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// trivially copyable (think sk_sp<>). So short of adding another template arg, we
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// must be conservative and use copy construction.
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for (int i = 0; i < fCount; ++i) {
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new (fItemArray + i) T(src[i]);
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}
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}
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template <bool E = MEM_MOVE> std::enable_if_t<E, void> move(int dst, int src) {
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memcpy(&fItemArray[dst], &fItemArray[src], sizeof(T));
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}
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template <bool E = MEM_MOVE> std::enable_if_t<E, void> move(void* dst) {
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sk_careful_memcpy(dst, fItemArray, fCount * sizeof(T));
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}
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template <bool E = MEM_MOVE> std::enable_if_t<!E, void> move(int dst, int src) {
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new (&fItemArray[dst]) T(std::move(fItemArray[src]));
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fItemArray[src].~T();
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}
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template <bool E = MEM_MOVE> std::enable_if_t<!E, void> move(void* dst) {
|
|
for (int i = 0; i < fCount; ++i) {
|
|
new (static_cast<char*>(dst) + sizeof(T) * (size_t)i) T(std::move(fItemArray[i]));
|
|
fItemArray[i].~T();
|
|
}
|
|
}
|
|
|
|
static constexpr int kMinHeapAllocCount = 8;
|
|
|
|
// Helper function that makes space for n objects, adjusts the count, but does not initialize
|
|
// the new objects.
|
|
void* push_back_raw(int n) {
|
|
this->checkRealloc(n);
|
|
void* ptr = fItemArray + fCount;
|
|
fCount += n;
|
|
return ptr;
|
|
}
|
|
|
|
void checkRealloc(int delta) {
|
|
SkASSERT(fCount >= 0);
|
|
SkASSERT(fAllocCount >= 0);
|
|
SkASSERT(-delta <= fCount);
|
|
|
|
// Move into 64bit math temporarily, to avoid local overflows
|
|
int64_t newCount = fCount + delta;
|
|
|
|
// We allow fAllocCount to be in the range [newCount, 3*newCount]. We also never shrink
|
|
// when we're currently using preallocated memory, would allocate less than
|
|
// kMinHeapAllocCount, or a reserve count was specified that has yet to be exceeded.
|
|
bool mustGrow = newCount > fAllocCount;
|
|
bool shouldShrink = fAllocCount > 3 * newCount && fOwnMemory && !fReserved;
|
|
if (!mustGrow && !shouldShrink) {
|
|
return;
|
|
}
|
|
|
|
|
|
// Whether we're growing or shrinking, we leave at least 50% extra space for future growth.
|
|
int64_t newAllocCount = newCount + ((newCount + 1) >> 1);
|
|
// Align the new allocation count to kMinHeapAllocCount.
|
|
static_assert(SkIsPow2(kMinHeapAllocCount), "min alloc count not power of two.");
|
|
newAllocCount = (newAllocCount + (kMinHeapAllocCount - 1)) & ~(kMinHeapAllocCount - 1);
|
|
// At small sizes the old and new alloc count can both be kMinHeapAllocCount.
|
|
if (newAllocCount == fAllocCount) {
|
|
return;
|
|
}
|
|
|
|
fAllocCount = Sk64_pin_to_s32(newAllocCount);
|
|
SkASSERT(fAllocCount >= newCount);
|
|
T* newItemArray = (T*)sk_malloc_throw((size_t)fAllocCount, sizeof(T));
|
|
this->move(newItemArray);
|
|
if (fOwnMemory) {
|
|
sk_free(fItemArray);
|
|
|
|
}
|
|
fItemArray = newItemArray;
|
|
fOwnMemory = true;
|
|
fReserved = false;
|
|
}
|
|
|
|
T* fItemArray;
|
|
int fCount;
|
|
int fAllocCount;
|
|
bool fOwnMemory : 1;
|
|
bool fReserved : 1;
|
|
};
|
|
|
|
template <typename T, bool M> static inline void swap(SkTArray<T, M>& a, SkTArray<T, M>& b) {
|
|
a.swap(b);
|
|
}
|
|
|
|
template<typename T, bool MEM_MOVE> constexpr int SkTArray<T, MEM_MOVE>::kMinHeapAllocCount;
|
|
|
|
/**
|
|
* Subclass of SkTArray that contains a preallocated memory block for the array.
|
|
*/
|
|
template <int N, typename T, bool MEM_MOVE= false>
|
|
class SkSTArray : public SkTArray<T, MEM_MOVE> {
|
|
private:
|
|
using INHERITED = SkTArray<T, MEM_MOVE>;
|
|
|
|
public:
|
|
SkSTArray() : INHERITED(&fStorage) {
|
|
}
|
|
|
|
SkSTArray(const SkSTArray& array)
|
|
: INHERITED(array, &fStorage) {
|
|
}
|
|
|
|
SkSTArray(SkSTArray&& array)
|
|
: INHERITED(std::move(array), &fStorage) {
|
|
}
|
|
|
|
explicit SkSTArray(const INHERITED& array)
|
|
: INHERITED(array, &fStorage) {
|
|
}
|
|
|
|
explicit SkSTArray(INHERITED&& array)
|
|
: INHERITED(std::move(array), &fStorage) {
|
|
}
|
|
|
|
explicit SkSTArray(int reserveCount)
|
|
: INHERITED(reserveCount) {
|
|
}
|
|
|
|
SkSTArray(const T* array, int count)
|
|
: INHERITED(array, count, &fStorage) {
|
|
}
|
|
|
|
SkSTArray& operator=(const SkSTArray& array) {
|
|
INHERITED::operator=(array);
|
|
return *this;
|
|
}
|
|
|
|
SkSTArray& operator=(SkSTArray&& array) {
|
|
INHERITED::operator=(std::move(array));
|
|
return *this;
|
|
}
|
|
|
|
SkSTArray& operator=(const INHERITED& array) {
|
|
INHERITED::operator=(array);
|
|
return *this;
|
|
}
|
|
|
|
SkSTArray& operator=(INHERITED&& array) {
|
|
INHERITED::operator=(std::move(array));
|
|
return *this;
|
|
}
|
|
|
|
private:
|
|
SkAlignedSTStorage<N,T> fStorage;
|
|
};
|
|
|
|
#endif
|