96 lines
2.9 KiB
C++
96 lines
2.9 KiB
C++
// Copyright (c) 2016 The WebM project authors. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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#ifndef SRC_BOOL_PARSER_H_
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#define SRC_BOOL_PARSER_H_
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#include <cassert>
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#include <cstdint>
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#include "src/element_parser.h"
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#include "src/parser_utils.h"
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#include "webm/callback.h"
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#include "webm/element.h"
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#include "webm/reader.h"
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#include "webm/status.h"
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namespace webm {
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// Parses a boolean from a byte stream. EBML does not have a boolean type, but
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// the Matroska spec defines some unsigned integer elements that have a range of
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// [0, 1]. The BoolParser parses these unsigned integer elements into
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// true/false, and reports a Status::kInvalidElementValue error if the integer
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// is outside of its permitted range.
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class BoolParser : public ElementParser {
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public:
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explicit BoolParser(bool default_value = false)
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: default_value_(default_value) {}
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Status Init(const ElementMetadata& metadata,
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std::uint64_t max_size) override {
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assert(metadata.size == kUnknownElementSize || metadata.size <= max_size);
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// Booleans are really just unsigned integers with a range limit of 0-1.
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// Unsigned integers can't be encoded with more than 8 bytes.
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if (metadata.size > 8) {
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return Status(Status::kInvalidElementSize);
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}
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size_ = num_bytes_remaining_ = static_cast<int>(metadata.size);
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value_ = default_value_;
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return Status(Status::kOkCompleted);
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}
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Status Feed(Callback* callback, Reader* reader,
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std::uint64_t* num_bytes_read) override {
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assert(callback != nullptr);
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assert(reader != nullptr);
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assert(num_bytes_read != nullptr);
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std::uint64_t uint_value = 0;
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const Status status = AccumulateIntegerBytes(num_bytes_remaining_, reader,
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&uint_value, num_bytes_read);
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num_bytes_remaining_ -= static_cast<int>(*num_bytes_read);
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// Only the last byte should have a value, and it should only be 0 or 1.
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if ((num_bytes_remaining_ != 0 && uint_value != 0) || uint_value > 1) {
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return Status(Status::kInvalidElementValue);
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}
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if (size_ > 0) {
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value_ = uint_value == 1;
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}
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return status;
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}
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// Gets the parsed bool. This must not be called until the parse had been
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// successfully completed.
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bool value() const {
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assert(num_bytes_remaining_ == 0);
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return value_;
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}
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// Gets the parsed bool. This must not be called until the parse had been
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// successfully completed.
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bool* mutable_value() {
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assert(num_bytes_remaining_ == 0);
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return &value_;
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}
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private:
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bool value_;
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bool default_value_;
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int num_bytes_remaining_ = -1;
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int size_;
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};
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} // namespace webm
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#endif // SRC_BOOL_PARSER_H_
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