| // Copyright (c) 2016 The WebM project authors. All Rights Reserved. |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the LICENSE file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| #ifndef SRC_RECURSIVE_PARSER_H_ |
| #define SRC_RECURSIVE_PARSER_H_ |
| |
| #include <cassert> |
| #include <cstdint> |
| #include <memory> |
| #include <utility> |
| |
| #include "src/element_parser.h" |
| #include "webm/callback.h" |
| #include "webm/reader.h" |
| #include "webm/status.h" |
| |
| namespace webm { |
| |
| // Lazily instantiates a parser of type T, and uses that parser to handle all |
| // parsing operations. The parser is allocated when Init is called. This class |
| // is intended to be used with recursive elements, where a parser needs to |
| // recursively instantiate parsers of the same type. |
| template <typename T> |
| class RecursiveParser : public ElementParser { |
| public: |
| RecursiveParser() = default; |
| |
| RecursiveParser(RecursiveParser&&) = default; |
| RecursiveParser& operator=(RecursiveParser&&) = default; |
| |
| RecursiveParser(const RecursiveParser&) = delete; |
| RecursiveParser& operator=(const RecursiveParser&) = delete; |
| |
| Status Init(const ElementMetadata& metadata, |
| std::uint64_t max_size) override { |
| assert(metadata.size == kUnknownElementSize || metadata.size <= max_size); |
| |
| if (!impl_) { |
| impl_.reset(new T); |
| } |
| |
| return impl_->Init(metadata, max_size); |
| } |
| |
| void InitAfterSeek(const Ancestory& child_ancestory, |
| const ElementMetadata& child_metadata) override { |
| if (!impl_) { |
| impl_.reset(new T); |
| } |
| |
| impl_->InitAfterSeek(child_ancestory, child_metadata); |
| } |
| |
| Status Feed(Callback* callback, Reader* reader, |
| std::uint64_t* num_bytes_read) override { |
| assert(callback != nullptr); |
| assert(reader != nullptr); |
| assert(num_bytes_read != nullptr); |
| assert(impl_ != nullptr); |
| |
| return impl_->Feed(callback, reader, num_bytes_read); |
| } |
| |
| decltype(std::declval<T>().value()) value() const { |
| assert(impl_ != nullptr); |
| |
| return impl_->value(); |
| } |
| |
| decltype(std::declval<T>().mutable_value()) mutable_value() { |
| assert(impl_ != nullptr); |
| |
| return impl_->mutable_value(); |
| } |
| |
| private: |
| std::unique_ptr<T> impl_; |
| }; |
| |
| } // namespace webm |
| |
| #endif // SRC_RECURSIVE_PARSER_H_ |