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69 lines
1.9 KiB
69 lines
1.9 KiB
4 months ago
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/*
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* Copyright 2009 The Android Open Source Project
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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 sk_tools_Registry_DEFINED
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#define sk_tools_Registry_DEFINED
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#include "include/core/SkTypes.h"
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#include "include/private/SkNoncopyable.h"
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namespace sk_tools {
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/** Template class that registers itself (in the constructor) into a linked-list
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and provides a function-pointer. This can be used to auto-register a set of
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services, e.g. a set of image codecs.
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*/
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template <typename T> class Registry : SkNoncopyable {
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public:
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explicit Registry(T value) : fValue(value) {
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#ifdef SK_BUILD_FOR_ANDROID
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// work-around for double-initialization bug
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{
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Registry* reg = gHead;
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while (reg) {
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if (reg == this) {
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return;
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}
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reg = reg->fChain;
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}
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}
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#endif
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fChain = gHead;
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gHead = this;
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}
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static const Registry* Head() { return gHead; }
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const Registry* next() const { return fChain; }
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const T& get() const { return fValue; }
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// for (const T& t : sk_tools::Registry<T>::Range()) { process(t); }
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struct Range {
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struct Iterator {
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const Registry* fPtr;
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const T& operator*() { return SkASSERT(fPtr), fPtr->get(); }
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void operator++() { if (fPtr) { fPtr = fPtr->next(); } }
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bool operator!=(const Iterator& other) const { return fPtr != other.fPtr; }
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};
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Iterator begin() const { return Iterator{Registry::Head()}; }
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Iterator end() const { return Iterator{nullptr}; }
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};
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private:
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T fValue;
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Registry* fChain;
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static Registry* gHead;
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};
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// The caller still needs to declare an instance of this somewhere
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template <typename T> Registry<T>* Registry<T>::gHead;
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} // namespace sk_tools
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#endif
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