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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef FLUTTER_ASSETS_ASSET_MANAGER_H_
#define FLUTTER_ASSETS_ASSET_MANAGER_H_
#include <deque>
#include <memory>
#include <string>
#include <optional>
#include "flutter/assets/asset_resolver.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/memory/ref_counted.h"
namespace flutter {
class AssetManager final : public AssetResolver {
public:
AssetManager();
~AssetManager() override;
//--------------------------------------------------------------------------
/// @brief Adds an asset resolver to the front of the resolver queue.
/// Assets would be loaded from this resolver before any follwing
/// resolvers.
///
/// @return Returns whether this resolver is valid and has been added to
/// the resolver queue.
bool PushFront(std::unique_ptr<AssetResolver> resolver);
//--------------------------------------------------------------------------
/// @brief Adds an asset resolver to the end of the resolver queue.
/// Assets would be loaded from this resolver after any previous
/// resolvers.
///
/// @return Returns whether this resolver is valid and has been added to
/// the resolver queue.
bool PushBack(std::unique_ptr<AssetResolver> resolver);
//--------------------------------------------------------------------------
/// @brief Replaces an asset resolver of the specified `type` with
/// `updated_asset_resolver`. The matching AssetResolver is
/// removed and replaced with `updated_asset_resolvers`.
///
/// AssetResolvers should be updated when the existing resolver
/// becomes obsolete and a newer one becomes available that
/// provides updated access to the same type of assets as the
/// existing one. This update process is meant to be performed
/// at runtime.
///
/// If a null resolver is provided, nothing will be done. If no
/// matching resolver is found, the provided resolver will be
/// added to the end of the AssetManager resolvers queue. The
/// replacement only occurs with the first matching resolver.
/// Any additional matching resolvers are untouched.
///
/// @param[in] updated_asset_resolver The asset resolver to replace the
/// resolver of matching type with.
///
/// @param[in] type The type of AssetResolver to update. Only resolvers of
/// the specified type will be replaced by the updated
/// resolver.
///
void UpdateResolverByType(
std::unique_ptr<AssetResolver> updated_asset_resolver,
AssetResolver::AssetResolverType type);
std::deque<std::unique_ptr<AssetResolver>> TakeResolvers();
// |AssetResolver|
bool IsValid() const override;
// |AssetResolver|
bool IsValidAfterAssetManagerChange() const override;
// |AssetResolver|
AssetResolver::AssetResolverType GetType() const override;
// |AssetResolver|
std::unique_ptr<fml::Mapping> GetAsMapping(
const std::string& asset_name) const override;
// |AssetResolver|
std::vector<std::unique_ptr<fml::Mapping>> GetAsMappings(
const std::string& asset_pattern,
const std::optional<std::string>& subdir) const override;
private:
std::deque<std::unique_ptr<AssetResolver>> resolvers_;
FML_DISALLOW_COPY_AND_ASSIGN(AssetManager);
};
} // namespace flutter
#endif // FLUTTER_ASSETS_ASSET_MANAGER_H_