Chris@63: // Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
Chris@63: // Licensed under the MIT License:
Chris@63: //
Chris@63: // Permission is hereby granted, free of charge, to any person obtaining a copy
Chris@63: // of this software and associated documentation files (the "Software"), to deal
Chris@63: // in the Software without restriction, including without limitation the rights
Chris@63: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
Chris@63: // copies of the Software, and to permit persons to whom the Software is
Chris@63: // furnished to do so, subject to the following conditions:
Chris@63: //
Chris@63: // The above copyright notice and this permission notice shall be included in
Chris@63: // all copies or substantial portions of the Software.
Chris@63: //
Chris@63: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Chris@63: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Chris@63: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
Chris@63: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Chris@63: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
Chris@63: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
Chris@63: // THE SOFTWARE.
Chris@63: 
Chris@63: #ifndef KJ_ARRAY_H_
Chris@63: #define KJ_ARRAY_H_
Chris@63: 
Chris@63: #if defined(__GNUC__) && !KJ_HEADER_WARNINGS
Chris@63: #pragma GCC system_header
Chris@63: #endif
Chris@63: 
Chris@63: #include "common.h"
Chris@63: #include <string.h>
Chris@63: #include <initializer_list>
Chris@63: 
Chris@63: namespace kj {
Chris@63: 
Chris@63: // =======================================================================================
Chris@63: // ArrayDisposer -- Implementation details.
Chris@63: 
Chris@63: class ArrayDisposer {
Chris@63:   // Much like Disposer from memory.h.
Chris@63: 
Chris@63: protected:
Chris@63:   // Do not declare a destructor, as doing so will force a global initializer for
Chris@63:   // HeapArrayDisposer::instance.
Chris@63: 
Chris@63:   virtual void disposeImpl(void* firstElement, size_t elementSize, size_t elementCount,
Chris@63:                            size_t capacity, void (*destroyElement)(void*)) const = 0;
Chris@63:   // Disposes of the array.  `destroyElement` invokes the destructor of each element, or is nullptr
Chris@63:   // if the elements have trivial destructors.  `capacity` is the amount of space that was
Chris@63:   // allocated while `elementCount` is the number of elements that were actually constructed;
Chris@63:   // these are always the same number for Array<T> but may be different when using ArrayBuilder<T>.
Chris@63: 
Chris@63: public:
Chris@63: 
Chris@63:   template <typename T>
Chris@63:   void dispose(T* firstElement, size_t elementCount, size_t capacity) const;
Chris@63:   // Helper wrapper around disposeImpl().
Chris@63:   //
Chris@63:   // Callers must not call dispose() on the same array twice, even if the first call throws
Chris@63:   // an exception.
Chris@63: 
Chris@63: private:
Chris@63:   template <typename T, bool hasTrivialDestructor = __has_trivial_destructor(T)>
Chris@63:   struct Dispose_;
Chris@63: };
Chris@63: 
Chris@63: class ExceptionSafeArrayUtil {
Chris@63:   // Utility class that assists in constructing or destroying elements of an array, where the
Chris@63:   // constructor or destructor could throw exceptions.  In case of an exception,
Chris@63:   // ExceptionSafeArrayUtil's destructor will call destructors on all elements that have been
Chris@63:   // constructed but not destroyed.  Remember that destructors that throw exceptions are required
Chris@63:   // to use UnwindDetector to detect unwind and avoid exceptions in this case.  Therefore, no more
Chris@63:   // than one exception will be thrown (and the program will not terminate).
Chris@63: 
Chris@63: public:
Chris@63:   inline ExceptionSafeArrayUtil(void* ptr, size_t elementSize, size_t constructedElementCount,
Chris@63:                                 void (*destroyElement)(void*))
Chris@63:       : pos(reinterpret_cast<byte*>(ptr) + elementSize * constructedElementCount),
Chris@63:         elementSize(elementSize), constructedElementCount(constructedElementCount),
Chris@63:         destroyElement(destroyElement) {}
Chris@63:   KJ_DISALLOW_COPY(ExceptionSafeArrayUtil);
Chris@63: 
Chris@63:   inline ~ExceptionSafeArrayUtil() noexcept(false) {
Chris@63:     if (constructedElementCount > 0) destroyAll();
Chris@63:   }
Chris@63: 
Chris@63:   void construct(size_t count, void (*constructElement)(void*));
Chris@63:   // Construct the given number of elements.
Chris@63: 
Chris@63:   void destroyAll();
Chris@63:   // Destroy all elements.  Call this immediately before ExceptionSafeArrayUtil goes out-of-scope
Chris@63:   // to ensure that one element throwing an exception does not prevent the others from being
Chris@63:   // destroyed.
Chris@63: 
Chris@63:   void release() { constructedElementCount = 0; }
Chris@63:   // Prevent ExceptionSafeArrayUtil's destructor from destroying the constructed elements.
Chris@63:   // Call this after you've successfully finished constructing.
Chris@63: 
Chris@63: private:
Chris@63:   byte* pos;
Chris@63:   size_t elementSize;
Chris@63:   size_t constructedElementCount;
Chris@63:   void (*destroyElement)(void*);
Chris@63: };
Chris@63: 
Chris@63: class DestructorOnlyArrayDisposer: public ArrayDisposer {
Chris@63: public:
Chris@63:   static const DestructorOnlyArrayDisposer instance;
Chris@63: 
Chris@63:   void disposeImpl(void* firstElement, size_t elementSize, size_t elementCount,
Chris@63:                    size_t capacity, void (*destroyElement)(void*)) const override;
Chris@63: };
Chris@63: 
Chris@63: class NullArrayDisposer: public ArrayDisposer {
Chris@63:   // An ArrayDisposer that does nothing.  Can be used to construct a fake Arrays that doesn't
Chris@63:   // actually own its content.
Chris@63: 
Chris@63: public:
Chris@63:   static const NullArrayDisposer instance;
Chris@63: 
Chris@63:   void disposeImpl(void* firstElement, size_t elementSize, size_t elementCount,
Chris@63:                    size_t capacity, void (*destroyElement)(void*)) const override;
Chris@63: };
Chris@63: 
Chris@63: // =======================================================================================
Chris@63: // Array
Chris@63: 
Chris@63: template <typename T>
Chris@63: class Array {
Chris@63:   // An owned array which will automatically be disposed of (using an ArrayDisposer) in the
Chris@63:   // destructor.  Can be moved, but not copied.  Much like Own<T>, but for arrays rather than
Chris@63:   // single objects.
Chris@63: 
Chris@63: public:
Chris@63:   inline Array(): ptr(nullptr), size_(0), disposer(nullptr) {}
Chris@63:   inline Array(decltype(nullptr)): ptr(nullptr), size_(0), disposer(nullptr) {}
Chris@63:   inline Array(Array&& other) noexcept
Chris@63:       : ptr(other.ptr), size_(other.size_), disposer(other.disposer) {
Chris@63:     other.ptr = nullptr;
Chris@63:     other.size_ = 0;
Chris@63:   }
Chris@63:   inline Array(Array<RemoveConstOrDisable<T>>&& other) noexcept
Chris@63:       : ptr(other.ptr), size_(other.size_), disposer(other.disposer) {
Chris@63:     other.ptr = nullptr;
Chris@63:     other.size_ = 0;
Chris@63:   }
Chris@63:   inline Array(T* firstElement, size_t size, const ArrayDisposer& disposer)
Chris@63:       : ptr(firstElement), size_(size), disposer(&disposer) {}
Chris@63: 
Chris@63:   KJ_DISALLOW_COPY(Array);
Chris@63:   inline ~Array() noexcept { dispose(); }
Chris@63: 
Chris@63:   inline operator ArrayPtr<T>() {
Chris@63:     return ArrayPtr<T>(ptr, size_);
Chris@63:   }
Chris@63:   inline operator ArrayPtr<const T>() const {
Chris@63:     return ArrayPtr<T>(ptr, size_);
Chris@63:   }
Chris@63:   inline ArrayPtr<T> asPtr() {
Chris@63:     return ArrayPtr<T>(ptr, size_);
Chris@63:   }
Chris@63:   inline ArrayPtr<const T> asPtr() const {
Chris@63:     return ArrayPtr<T>(ptr, size_);
Chris@63:   }
Chris@63: 
Chris@63:   inline size_t size() const { return size_; }
Chris@63:   inline T& operator[](size_t index) const {
Chris@63:     KJ_IREQUIRE(index < size_, "Out-of-bounds Array access.");
Chris@63:     return ptr[index];
Chris@63:   }
Chris@63: 
Chris@63:   inline const T* begin() const { return ptr; }
Chris@63:   inline const T* end() const { return ptr + size_; }
Chris@63:   inline const T& front() const { return *ptr; }
Chris@63:   inline const T& back() const { return *(ptr + size_ - 1); }
Chris@63:   inline T* begin() { return ptr; }
Chris@63:   inline T* end() { return ptr + size_; }
Chris@63:   inline T& front() { return *ptr; }
Chris@63:   inline T& back() { return *(ptr + size_ - 1); }
Chris@63: 
Chris@63:   inline ArrayPtr<T> slice(size_t start, size_t end) {
Chris@63:     KJ_IREQUIRE(start <= end && end <= size_, "Out-of-bounds Array::slice().");
Chris@63:     return ArrayPtr<T>(ptr + start, end - start);
Chris@63:   }
Chris@63:   inline ArrayPtr<const T> slice(size_t start, size_t end) const {
Chris@63:     KJ_IREQUIRE(start <= end && end <= size_, "Out-of-bounds Array::slice().");
Chris@63:     return ArrayPtr<const T>(ptr + start, end - start);
Chris@63:   }
Chris@63: 
Chris@63:   inline ArrayPtr<const byte> asBytes() const { return asPtr().asBytes(); }
Chris@63:   inline ArrayPtr<PropagateConst<T, byte>> asBytes() { return asPtr().asBytes(); }
Chris@63:   inline ArrayPtr<const char> asChars() const { return asPtr().asChars(); }
Chris@63:   inline ArrayPtr<PropagateConst<T, char>> asChars() { return asPtr().asChars(); }
Chris@63: 
Chris@63:   inline Array<PropagateConst<T, byte>> releaseAsBytes() {
Chris@63:     // Like asBytes() but transfers ownership.
Chris@63:     static_assert(sizeof(T) == sizeof(byte),
Chris@63:         "releaseAsBytes() only possible on arrays with byte-size elements (e.g. chars).");
Chris@63:     Array<PropagateConst<T, byte>> result(
Chris@63:         reinterpret_cast<PropagateConst<T, byte>*>(ptr), size_, *disposer);
Chris@63:     ptr = nullptr;
Chris@63:     size_ = 0;
Chris@63:     return result;
Chris@63:   }
Chris@63:   inline Array<PropagateConst<T, char>> releaseAsChars() {
Chris@63:     // Like asChars() but transfers ownership.
Chris@63:     static_assert(sizeof(T) == sizeof(PropagateConst<T, char>),
Chris@63:         "releaseAsChars() only possible on arrays with char-size elements (e.g. bytes).");
Chris@63:     Array<PropagateConst<T, char>> result(
Chris@63:         reinterpret_cast<PropagateConst<T, char>*>(ptr), size_, *disposer);
Chris@63:     ptr = nullptr;
Chris@63:     size_ = 0;
Chris@63:     return result;
Chris@63:   }
Chris@63: 
Chris@63:   inline bool operator==(decltype(nullptr)) const { return size_ == 0; }
Chris@63:   inline bool operator!=(decltype(nullptr)) const { return size_ != 0; }
Chris@63: 
Chris@63:   inline Array& operator=(decltype(nullptr)) {
Chris@63:     dispose();
Chris@63:     return *this;
Chris@63:   }
Chris@63: 
Chris@63:   inline Array& operator=(Array&& other) {
Chris@63:     dispose();
Chris@63:     ptr = other.ptr;
Chris@63:     size_ = other.size_;
Chris@63:     disposer = other.disposer;
Chris@63:     other.ptr = nullptr;
Chris@63:     other.size_ = 0;
Chris@63:     return *this;
Chris@63:   }
Chris@63: 
Chris@63: private:
Chris@63:   T* ptr;
Chris@63:   size_t size_;
Chris@63:   const ArrayDisposer* disposer;
Chris@63: 
Chris@63:   inline void dispose() {
Chris@63:     // Make sure that if an exception is thrown, we are left with a null ptr, so we won't possibly
Chris@63:     // dispose again.
Chris@63:     T* ptrCopy = ptr;
Chris@63:     size_t sizeCopy = size_;
Chris@63:     if (ptrCopy != nullptr) {
Chris@63:       ptr = nullptr;
Chris@63:       size_ = 0;
Chris@63:       disposer->dispose(ptrCopy, sizeCopy, sizeCopy);
Chris@63:     }
Chris@63:   }
Chris@63: 
Chris@63:   template <typename U>
Chris@63:   friend class Array;
Chris@63: };
Chris@63: 
Chris@63: static_assert(!canMemcpy<Array<char>>(), "canMemcpy<>() is broken");
Chris@63: 
Chris@63: namespace _ {  // private
Chris@63: 
Chris@63: class HeapArrayDisposer final: public ArrayDisposer {
Chris@63: public:
Chris@63:   template <typename T>
Chris@63:   static T* allocate(size_t count);
Chris@63:   template <typename T>
Chris@63:   static T* allocateUninitialized(size_t count);
Chris@63: 
Chris@63:   static const HeapArrayDisposer instance;
Chris@63: 
Chris@63: private:
Chris@63:   static void* allocateImpl(size_t elementSize, size_t elementCount, size_t capacity,
Chris@63:                             void (*constructElement)(void*), void (*destroyElement)(void*));
Chris@63:   // Allocates and constructs the array.  Both function pointers are null if the constructor is
Chris@63:   // trivial, otherwise destroyElement is null if the constructor doesn't throw.
Chris@63: 
Chris@63:   virtual void disposeImpl(void* firstElement, size_t elementSize, size_t elementCount,
Chris@63:                            size_t capacity, void (*destroyElement)(void*)) const override;
Chris@63: 
Chris@63:   template <typename T, bool hasTrivialConstructor = __has_trivial_constructor(T),
Chris@63:                         bool hasNothrowConstructor = __has_nothrow_constructor(T)>
Chris@63:   struct Allocate_;
Chris@63: };
Chris@63: 
Chris@63: }  // namespace _ (private)
Chris@63: 
Chris@63: template <typename T>
Chris@63: inline Array<T> heapArray(size_t size) {
Chris@63:   // Much like `heap<T>()` from memory.h, allocates a new array on the heap.
Chris@63: 
Chris@63:   return Array<T>(_::HeapArrayDisposer::allocate<T>(size), size,
Chris@63:                   _::HeapArrayDisposer::instance);
Chris@63: }
Chris@63: 
Chris@63: template <typename T> Array<T> heapArray(const T* content, size_t size);
Chris@63: template <typename T> Array<T> heapArray(ArrayPtr<T> content);
Chris@63: template <typename T> Array<T> heapArray(ArrayPtr<const T> content);
Chris@63: template <typename T, typename Iterator> Array<T> heapArray(Iterator begin, Iterator end);
Chris@63: template <typename T> Array<T> heapArray(std::initializer_list<T> init);
Chris@63: // Allocate a heap array containing a copy of the given content.
Chris@63: 
Chris@63: template <typename T, typename Container>
Chris@63: Array<T> heapArrayFromIterable(Container&& a) { return heapArray<T>(a.begin(), a.end()); }
Chris@63: template <typename T>
Chris@63: Array<T> heapArrayFromIterable(Array<T>&& a) { return mv(a); }
Chris@63: 
Chris@63: // =======================================================================================
Chris@63: // ArrayBuilder
Chris@63: 
Chris@63: template <typename T>
Chris@63: class ArrayBuilder {
Chris@63:   // Class which lets you build an Array<T> specifying the exact constructor arguments for each
Chris@63:   // element, rather than starting by default-constructing them.
Chris@63: 
Chris@63: public:
Chris@63:   ArrayBuilder(): ptr(nullptr), pos(nullptr), endPtr(nullptr) {}
Chris@63:   ArrayBuilder(decltype(nullptr)): ptr(nullptr), pos(nullptr), endPtr(nullptr) {}
Chris@63:   explicit ArrayBuilder(RemoveConst<T>* firstElement, size_t capacity,
Chris@63:                         const ArrayDisposer& disposer)
Chris@63:       : ptr(firstElement), pos(firstElement), endPtr(firstElement + capacity),
Chris@63:         disposer(&disposer) {}
Chris@63:   ArrayBuilder(ArrayBuilder&& other)
Chris@63:       : ptr(other.ptr), pos(other.pos), endPtr(other.endPtr), disposer(other.disposer) {
Chris@63:     other.ptr = nullptr;
Chris@63:     other.pos = nullptr;
Chris@63:     other.endPtr = nullptr;
Chris@63:   }
Chris@63:   KJ_DISALLOW_COPY(ArrayBuilder);
Chris@63:   inline ~ArrayBuilder() noexcept(false) { dispose(); }
Chris@63: 
Chris@63:   inline operator ArrayPtr<T>() {
Chris@63:     return arrayPtr(ptr, pos);
Chris@63:   }
Chris@63:   inline operator ArrayPtr<const T>() const {
Chris@63:     return arrayPtr(ptr, pos);
Chris@63:   }
Chris@63:   inline ArrayPtr<T> asPtr() {
Chris@63:     return arrayPtr(ptr, pos);
Chris@63:   }
Chris@63:   inline ArrayPtr<const T> asPtr() const {
Chris@63:     return arrayPtr(ptr, pos);
Chris@63:   }
Chris@63: 
Chris@63:   inline size_t size() const { return pos - ptr; }
Chris@63:   inline size_t capacity() const { return endPtr - ptr; }
Chris@63:   inline T& operator[](size_t index) const {
Chris@63:     KJ_IREQUIRE(index < implicitCast<size_t>(pos - ptr), "Out-of-bounds Array access.");
Chris@63:     return ptr[index];
Chris@63:   }
Chris@63: 
Chris@63:   inline const T* begin() const { return ptr; }
Chris@63:   inline const T* end() const { return pos; }
Chris@63:   inline const T& front() const { return *ptr; }
Chris@63:   inline const T& back() const { return *(pos - 1); }
Chris@63:   inline T* begin() { return ptr; }
Chris@63:   inline T* end() { return pos; }
Chris@63:   inline T& front() { return *ptr; }
Chris@63:   inline T& back() { return *(pos - 1); }
Chris@63: 
Chris@63:   ArrayBuilder& operator=(ArrayBuilder&& other) {
Chris@63:     dispose();
Chris@63:     ptr = other.ptr;
Chris@63:     pos = other.pos;
Chris@63:     endPtr = other.endPtr;
Chris@63:     disposer = other.disposer;
Chris@63:     other.ptr = nullptr;
Chris@63:     other.pos = nullptr;
Chris@63:     other.endPtr = nullptr;
Chris@63:     return *this;
Chris@63:   }
Chris@63:   ArrayBuilder& operator=(decltype(nullptr)) {
Chris@63:     dispose();
Chris@63:     return *this;
Chris@63:   }
Chris@63: 
Chris@63:   template <typename... Params>
Chris@63:   T& add(Params&&... params) {
Chris@63:     KJ_IREQUIRE(pos < endPtr, "Added too many elements to ArrayBuilder.");
Chris@63:     ctor(*pos, kj::fwd<Params>(params)...);
Chris@63:     return *pos++;
Chris@63:   }
Chris@63: 
Chris@63:   template <typename Container>
Chris@63:   void addAll(Container&& container) {
Chris@63:     addAll<decltype(container.begin()), !isReference<Container>()>(
Chris@63:         container.begin(), container.end());
Chris@63:   }
Chris@63: 
Chris@63:   template <typename Iterator, bool move = false>
Chris@63:   void addAll(Iterator start, Iterator end);
Chris@63: 
Chris@63:   void removeLast() {
Chris@63:     KJ_IREQUIRE(pos > ptr, "No elements present to remove.");
Chris@63:     kj::dtor(*--pos);
Chris@63:   }
Chris@63: 
Chris@63:   void truncate(size_t size) {
Chris@63:     KJ_IREQUIRE(size <= this->size(), "can't use truncate() to expand");
Chris@63: 
Chris@63:     T* target = ptr + size;
Chris@63:     if (__has_trivial_destructor(T)) {
Chris@63:       pos = target;
Chris@63:     } else {
Chris@63:       while (pos > target) {
Chris@63:         kj::dtor(*--pos);
Chris@63:       }
Chris@63:     }
Chris@63:   }
Chris@63: 
Chris@63:   void resize(size_t size) {
Chris@63:     KJ_IREQUIRE(size <= capacity(), "can't resize past capacity");
Chris@63: 
Chris@63:     T* target = ptr + size;
Chris@63:     if (target > pos) {
Chris@63:       // expand
Chris@63:       if (__has_trivial_constructor(T)) {
Chris@63:         pos = target;
Chris@63:       } else {
Chris@63:         while (pos < target) {
Chris@63:           kj::ctor(*pos++);
Chris@63:         }
Chris@63:       }
Chris@63:     } else {
Chris@63:       // truncate
Chris@63:       if (__has_trivial_destructor(T)) {
Chris@63:         pos = target;
Chris@63:       } else {
Chris@63:         while (pos > target) {
Chris@63:           kj::dtor(*--pos);
Chris@63:         }
Chris@63:       }
Chris@63:     }
Chris@63:   }
Chris@63: 
Chris@63:   Array<T> finish() {
Chris@63:     // We could safely remove this check if we assume that the disposer implementation doesn't
Chris@63:     // need to know the original capacity, as is thes case with HeapArrayDisposer since it uses
Chris@63:     // operator new() or if we created a custom disposer for ArrayBuilder which stores the capacity
Chris@63:     // in a prefix.  But that would make it hard to write cleverer heap allocators, and anyway this
Chris@63:     // check might catch bugs.  Probably people should use Vector if they want to build arrays
Chris@63:     // without knowing the final size in advance.
Chris@63:     KJ_IREQUIRE(pos == endPtr, "ArrayBuilder::finish() called prematurely.");
Chris@63:     Array<T> result(reinterpret_cast<T*>(ptr), pos - ptr, *disposer);
Chris@63:     ptr = nullptr;
Chris@63:     pos = nullptr;
Chris@63:     endPtr = nullptr;
Chris@63:     return result;
Chris@63:   }
Chris@63: 
Chris@63:   inline bool isFull() const {
Chris@63:     return pos == endPtr;
Chris@63:   }
Chris@63: 
Chris@63: private:
Chris@63:   T* ptr;
Chris@63:   RemoveConst<T>* pos;
Chris@63:   T* endPtr;
Chris@63:   const ArrayDisposer* disposer;
Chris@63: 
Chris@63:   inline void dispose() {
Chris@63:     // Make sure that if an exception is thrown, we are left with a null ptr, so we won't possibly
Chris@63:     // dispose again.
Chris@63:     T* ptrCopy = ptr;
Chris@63:     T* posCopy = pos;
Chris@63:     T* endCopy = endPtr;
Chris@63:     if (ptrCopy != nullptr) {
Chris@63:       ptr = nullptr;
Chris@63:       pos = nullptr;
Chris@63:       endPtr = nullptr;
Chris@63:       disposer->dispose(ptrCopy, posCopy - ptrCopy, endCopy - ptrCopy);
Chris@63:     }
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T>
Chris@63: inline ArrayBuilder<T> heapArrayBuilder(size_t size) {
Chris@63:   // Like `heapArray<T>()` but does not default-construct the elements.  You must construct them
Chris@63:   // manually by calling `add()`.
Chris@63: 
Chris@63:   return ArrayBuilder<T>(_::HeapArrayDisposer::allocateUninitialized<RemoveConst<T>>(size),
Chris@63:                          size, _::HeapArrayDisposer::instance);
Chris@63: }
Chris@63: 
Chris@63: // =======================================================================================
Chris@63: // Inline Arrays
Chris@63: 
Chris@63: template <typename T, size_t fixedSize>
Chris@63: class FixedArray {
Chris@63:   // A fixed-width array whose storage is allocated inline rather than on the heap.
Chris@63: 
Chris@63: public:
Chris@63:   inline size_t size() const { return fixedSize; }
Chris@63:   inline T* begin() { return content; }
Chris@63:   inline T* end() { return content + fixedSize; }
Chris@63:   inline const T* begin() const { return content; }
Chris@63:   inline const T* end() const { return content + fixedSize; }
Chris@63: 
Chris@63:   inline operator ArrayPtr<T>() {
Chris@63:     return arrayPtr(content, fixedSize);
Chris@63:   }
Chris@63:   inline operator ArrayPtr<const T>() const {
Chris@63:     return arrayPtr(content, fixedSize);
Chris@63:   }
Chris@63: 
Chris@63:   inline T& operator[](size_t index) { return content[index]; }
Chris@63:   inline const T& operator[](size_t index) const { return content[index]; }
Chris@63: 
Chris@63: private:
Chris@63:   T content[fixedSize];
Chris@63: };
Chris@63: 
Chris@63: template <typename T, size_t fixedSize>
Chris@63: class CappedArray {
Chris@63:   // Like `FixedArray` but can be dynamically resized as long as the size does not exceed the limit
Chris@63:   // specified by the template parameter.
Chris@63:   //
Chris@63:   // TODO(someday):  Don't construct elements past currentSize?
Chris@63: 
Chris@63: public:
Chris@63:   inline KJ_CONSTEXPR() CappedArray(): currentSize(fixedSize) {}
Chris@63:   inline explicit constexpr CappedArray(size_t s): currentSize(s) {}
Chris@63: 
Chris@63:   inline size_t size() const { return currentSize; }
Chris@63:   inline void setSize(size_t s) { KJ_IREQUIRE(s <= fixedSize); currentSize = s; }
Chris@63:   inline T* begin() { return content; }
Chris@63:   inline T* end() { return content + currentSize; }
Chris@63:   inline const T* begin() const { return content; }
Chris@63:   inline const T* end() const { return content + currentSize; }
Chris@63: 
Chris@63:   inline operator ArrayPtr<T>() {
Chris@63:     return arrayPtr(content, currentSize);
Chris@63:   }
Chris@63:   inline operator ArrayPtr<const T>() const {
Chris@63:     return arrayPtr(content, currentSize);
Chris@63:   }
Chris@63: 
Chris@63:   inline T& operator[](size_t index) { return content[index]; }
Chris@63:   inline const T& operator[](size_t index) const { return content[index]; }
Chris@63: 
Chris@63: private:
Chris@63:   size_t currentSize;
Chris@63:   T content[fixedSize];
Chris@63: };
Chris@63: 
Chris@63: // =======================================================================================
Chris@63: // KJ_MAP
Chris@63: 
Chris@63: #define KJ_MAP(elementName, array) \
Chris@63:   ::kj::_::Mapper<KJ_DECLTYPE_REF(array)>(array) * \
Chris@63:   [&](typename ::kj::_::Mapper<KJ_DECLTYPE_REF(array)>::Element elementName)
Chris@63: // Applies some function to every element of an array, returning an Array of the results,  with
Chris@63: // nice syntax.  Example:
Chris@63: //
Chris@63: //     StringPtr foo = "abcd";
Chris@63: //     Array<char> bar = KJ_MAP(c, foo) -> char { return c + 1; };
Chris@63: //     KJ_ASSERT(str(bar) == "bcde");
Chris@63: 
Chris@63: namespace _ {  // private
Chris@63: 
Chris@63: template <typename T>
Chris@63: struct Mapper {
Chris@63:   T array;
Chris@63:   Mapper(T&& array): array(kj::fwd<T>(array)) {}
Chris@63:   template <typename Func>
Chris@63:   auto operator*(Func&& func) -> Array<decltype(func(*array.begin()))> {
Chris@63:     auto builder = heapArrayBuilder<decltype(func(*array.begin()))>(array.size());
Chris@63:     for (auto iter = array.begin(); iter != array.end(); ++iter) {
Chris@63:       builder.add(func(*iter));
Chris@63:     }
Chris@63:     return builder.finish();
Chris@63:   }
Chris@63:   typedef decltype(*kj::instance<T>().begin()) Element;
Chris@63: };
Chris@63: 
Chris@63: template <typename T, size_t s>
Chris@63: struct Mapper<T(&)[s]> {
Chris@63:   T* array;
Chris@63:   Mapper(T* array): array(array) {}
Chris@63:   template <typename Func>
Chris@63:   auto operator*(Func&& func) -> Array<decltype(func(*array))> {
Chris@63:     auto builder = heapArrayBuilder<decltype(func(*array))>(s);
Chris@63:     for (size_t i = 0; i < s; i++) {
Chris@63:       builder.add(func(array[i]));
Chris@63:     }
Chris@63:     return builder.finish();
Chris@63:   }
Chris@63:   typedef decltype(*array)& Element;
Chris@63: };
Chris@63: 
Chris@63: }  // namespace _ (private)
Chris@63: 
Chris@63: // =======================================================================================
Chris@63: // Inline implementation details
Chris@63: 
Chris@63: template <typename T>
Chris@63: struct ArrayDisposer::Dispose_<T, true> {
Chris@63:   static void dispose(T* firstElement, size_t elementCount, size_t capacity,
Chris@63:                       const ArrayDisposer& disposer) {
Chris@63:     disposer.disposeImpl(const_cast<RemoveConst<T>*>(firstElement),
Chris@63:                          sizeof(T), elementCount, capacity, nullptr);
Chris@63:   }
Chris@63: };
Chris@63: template <typename T>
Chris@63: struct ArrayDisposer::Dispose_<T, false> {
Chris@63:   static void destruct(void* ptr) {
Chris@63:     kj::dtor(*reinterpret_cast<T*>(ptr));
Chris@63:   }
Chris@63: 
Chris@63:   static void dispose(T* firstElement, size_t elementCount, size_t capacity,
Chris@63:                       const ArrayDisposer& disposer) {
Chris@63:     disposer.disposeImpl(firstElement, sizeof(T), elementCount, capacity, &destruct);
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T>
Chris@63: void ArrayDisposer::dispose(T* firstElement, size_t elementCount, size_t capacity) const {
Chris@63:   Dispose_<T>::dispose(firstElement, elementCount, capacity, *this);
Chris@63: }
Chris@63: 
Chris@63: namespace _ {  // private
Chris@63: 
Chris@63: template <typename T>
Chris@63: struct HeapArrayDisposer::Allocate_<T, true, true> {
Chris@63:   static T* allocate(size_t elementCount, size_t capacity) {
Chris@63:     return reinterpret_cast<T*>(allocateImpl(
Chris@63:         sizeof(T), elementCount, capacity, nullptr, nullptr));
Chris@63:   }
Chris@63: };
Chris@63: template <typename T>
Chris@63: struct HeapArrayDisposer::Allocate_<T, false, true> {
Chris@63:   static void construct(void* ptr) {
Chris@63:     kj::ctor(*reinterpret_cast<T*>(ptr));
Chris@63:   }
Chris@63:   static T* allocate(size_t elementCount, size_t capacity) {
Chris@63:     return reinterpret_cast<T*>(allocateImpl(
Chris@63:         sizeof(T), elementCount, capacity, &construct, nullptr));
Chris@63:   }
Chris@63: };
Chris@63: template <typename T>
Chris@63: struct HeapArrayDisposer::Allocate_<T, false, false> {
Chris@63:   static void construct(void* ptr) {
Chris@63:     kj::ctor(*reinterpret_cast<T*>(ptr));
Chris@63:   }
Chris@63:   static void destruct(void* ptr) {
Chris@63:     kj::dtor(*reinterpret_cast<T*>(ptr));
Chris@63:   }
Chris@63:   static T* allocate(size_t elementCount, size_t capacity) {
Chris@63:     return reinterpret_cast<T*>(allocateImpl(
Chris@63:         sizeof(T), elementCount, capacity, &construct, &destruct));
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T>
Chris@63: T* HeapArrayDisposer::allocate(size_t count) {
Chris@63:   return Allocate_<T>::allocate(count, count);
Chris@63: }
Chris@63: 
Chris@63: template <typename T>
Chris@63: T* HeapArrayDisposer::allocateUninitialized(size_t count) {
Chris@63:   return Allocate_<T, true, true>::allocate(0, count);
Chris@63: }
Chris@63: 
Chris@63: template <typename Element, typename Iterator, bool move, bool = canMemcpy<Element>()>
Chris@63: struct CopyConstructArray_;
Chris@63: 
Chris@63: template <typename T, bool move>
Chris@63: struct CopyConstructArray_<T, T*, move, true> {
Chris@63:   static inline T* apply(T* __restrict__ pos, T* start, T* end) {
Chris@63:     memcpy(pos, start, reinterpret_cast<byte*>(end) - reinterpret_cast<byte*>(start));
Chris@63:     return pos + (end - start);
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T>
Chris@63: struct CopyConstructArray_<T, const T*, false, true> {
Chris@63:   static inline T* apply(T* __restrict__ pos, const T* start, const T* end) {
Chris@63:     memcpy(pos, start, reinterpret_cast<const byte*>(end) - reinterpret_cast<const byte*>(start));
Chris@63:     return pos + (end - start);
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T, typename Iterator, bool move>
Chris@63: struct CopyConstructArray_<T, Iterator, move, true> {
Chris@63:   static inline T* apply(T* __restrict__ pos, Iterator start, Iterator end) {
Chris@63:     // Since both the copy constructor and assignment operator are trivial, we know that assignment
Chris@63:     // is equivalent to copy-constructing.  So we can make this case somewhat easier for the
Chris@63:     // compiler to optimize.
Chris@63:     while (start != end) {
Chris@63:       *pos++ = *start++;
Chris@63:     }
Chris@63:     return pos;
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T, typename Iterator>
Chris@63: struct CopyConstructArray_<T, Iterator, false, false> {
Chris@63:   struct ExceptionGuard {
Chris@63:     T* start;
Chris@63:     T* pos;
Chris@63:     inline explicit ExceptionGuard(T* pos): start(pos), pos(pos) {}
Chris@63:     ~ExceptionGuard() noexcept(false) {
Chris@63:       while (pos > start) {
Chris@63:         dtor(*--pos);
Chris@63:       }
Chris@63:     }
Chris@63:   };
Chris@63: 
Chris@63:   static T* apply(T* __restrict__ pos, Iterator start, Iterator end) {
Chris@63:     // Verify that T can be *implicitly* constructed from the source values.
Chris@63:     if (false) implicitCast<T>(*start);
Chris@63: 
Chris@63:     if (noexcept(T(*start))) {
Chris@63:       while (start != end) {
Chris@63:         ctor(*pos++, *start++);
Chris@63:       }
Chris@63:       return pos;
Chris@63:     } else {
Chris@63:       // Crap.  This is complicated.
Chris@63:       ExceptionGuard guard(pos);
Chris@63:       while (start != end) {
Chris@63:         ctor(*guard.pos, *start++);
Chris@63:         ++guard.pos;
Chris@63:       }
Chris@63:       guard.start = guard.pos;
Chris@63:       return guard.pos;
Chris@63:     }
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: template <typename T, typename Iterator>
Chris@63: struct CopyConstructArray_<T, Iterator, true, false> {
Chris@63:   // Actually move-construct.
Chris@63: 
Chris@63:   struct ExceptionGuard {
Chris@63:     T* start;
Chris@63:     T* pos;
Chris@63:     inline explicit ExceptionGuard(T* pos): start(pos), pos(pos) {}
Chris@63:     ~ExceptionGuard() noexcept(false) {
Chris@63:       while (pos > start) {
Chris@63:         dtor(*--pos);
Chris@63:       }
Chris@63:     }
Chris@63:   };
Chris@63: 
Chris@63:   static T* apply(T* __restrict__ pos, Iterator start, Iterator end) {
Chris@63:     // Verify that T can be *implicitly* constructed from the source values.
Chris@63:     if (false) implicitCast<T>(kj::mv(*start));
Chris@63: 
Chris@63:     if (noexcept(T(kj::mv(*start)))) {
Chris@63:       while (start != end) {
Chris@63:         ctor(*pos++, kj::mv(*start++));
Chris@63:       }
Chris@63:       return pos;
Chris@63:     } else {
Chris@63:       // Crap.  This is complicated.
Chris@63:       ExceptionGuard guard(pos);
Chris@63:       while (start != end) {
Chris@63:         ctor(*guard.pos, kj::mv(*start++));
Chris@63:         ++guard.pos;
Chris@63:       }
Chris@63:       guard.start = guard.pos;
Chris@63:       return guard.pos;
Chris@63:     }
Chris@63:   }
Chris@63: };
Chris@63: 
Chris@63: }  // namespace _ (private)
Chris@63: 
Chris@63: template <typename T>
Chris@63: template <typename Iterator, bool move>
Chris@63: void ArrayBuilder<T>::addAll(Iterator start, Iterator end) {
Chris@63:   pos = _::CopyConstructArray_<RemoveConst<T>, Decay<Iterator>, move>::apply(pos, start, end);
Chris@63: }
Chris@63: 
Chris@63: template <typename T>
Chris@63: Array<T> heapArray(const T* content, size_t size) {
Chris@63:   ArrayBuilder<T> builder = heapArrayBuilder<T>(size);
Chris@63:   builder.addAll(content, content + size);
Chris@63:   return builder.finish();
Chris@63: }
Chris@63: 
Chris@63: template <typename T>
Chris@63: Array<T> heapArray(T* content, size_t size) {
Chris@63:   ArrayBuilder<T> builder = heapArrayBuilder<T>(size);
Chris@63:   builder.addAll(content, content + size);
Chris@63:   return builder.finish();
Chris@63: }
Chris@63: 
Chris@63: template <typename T>
Chris@63: Array<T> heapArray(ArrayPtr<T> content) {
Chris@63:   ArrayBuilder<T> builder = heapArrayBuilder<T>(content.size());
Chris@63:   builder.addAll(content);
Chris@63:   return builder.finish();
Chris@63: }
Chris@63: 
Chris@63: template <typename T>
Chris@63: Array<T> heapArray(ArrayPtr<const T> content) {
Chris@63:   ArrayBuilder<T> builder = heapArrayBuilder<T>(content.size());
Chris@63:   builder.addAll(content);
Chris@63:   return builder.finish();
Chris@63: }
Chris@63: 
Chris@63: template <typename T, typename Iterator> Array<T>
Chris@63: heapArray(Iterator begin, Iterator end) {
Chris@63:   ArrayBuilder<T> builder = heapArrayBuilder<T>(end - begin);
Chris@63:   builder.addAll(begin, end);
Chris@63:   return builder.finish();
Chris@63: }
Chris@63: 
Chris@63: template <typename T>
Chris@63: inline Array<T> heapArray(std::initializer_list<T> init) {
Chris@63:   return heapArray<T>(init.begin(), init.end());
Chris@63: }
Chris@63: 
Chris@63: }  // namespace kj
Chris@63: 
Chris@63: #endif  // KJ_ARRAY_H_