/*

 * Copyright 2009 The Android Open Source Project

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#ifndef sk_tools_Registry_DEFINED

#define sk_tools_Registry_DEFINED

#include "include/core/SkTypes.h"

#include "include/private/base/SkNoncopyable.h"

namespace sk_tools {

/**

 * Template class that registers itself (in the constructor) into a linked-list

 * and provides a function-pointer. This can be used to auto-register a set of

 * services, e.g. a set of image codecs.

 */

template <typename T> class Registry : SkNoncopyable {

public:

    explicit Registry(T value, bool condition = true) : fValue(value) {

        if (condition) {

            this->linkToRegistryHead();

        }

    }

    static const Registry* Head() { return gHead; }

    const Registry* next() const { return fChain; }

    const T& get() const { return fValue; }

    // for (const T& t : sk_tools::Registry<T>::Range()) { process(t); }

    struct Range {

        struct Iterator {

            const Registry* fPtr;

            const T& operator*() { return SkASSERT(fPtr), fPtr->get(); }

            void operator++() { if (fPtr) { fPtr = fPtr->next(); } }

            bool operator!=(const Iterator& other) const { return fPtr != other.fPtr; }

        };

        Iterator begin() const { return Iterator{Registry::Head()}; }

        Iterator end() const { return Iterator{nullptr}; }

    };

private:

    void linkToRegistryHead() {

        fChain = gHead;

        gHead  = this;

    }

    T fValue;

    Registry* fChain;

    static Registry* gHead;

};

// The caller still needs to declare an instance of this somewhere

template <typename T> Registry<T>* Registry<T>::gHead;

}  // namespace sk_tools

#endif