Initial release

thirdparty/libwebm/webm_parser/src/bool_parser.h

@@ -0,0 +1,95 @@
+// 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_BOOL_PARSER_H_
+#define SRC_BOOL_PARSER_H_
+
+#include <cassert>
+#include <cstdint>
+
+#include "src/element_parser.h"
+#include "src/parser_utils.h"
+#include "webm/callback.h"
+#include "webm/element.h"
+#include "webm/reader.h"
+#include "webm/status.h"
+
+namespace webm {
+
+// Parses a boolean from a byte stream. EBML does not have a boolean type, but
+// the Matroska spec defines some unsigned integer elements that have a range of
+// [0, 1]. The BoolParser parses these unsigned integer elements into
+// true/false, and reports a Status::kInvalidElementValue error if the integer
+// is outside of its permitted range.
+class BoolParser : public ElementParser {
+ public:
+  explicit BoolParser(bool default_value = false)
+      : default_value_(default_value) {}
+
+  Status Init(const ElementMetadata& metadata,
+              std::uint64_t max_size) override {
+    assert(metadata.size == kUnknownElementSize || metadata.size <= max_size);
+
+    // Booleans are really just unsigned integers with a range limit of 0-1.
+    // Unsigned integers can't be encoded with more than 8 bytes.
+    if (metadata.size > 8) {
+      return Status(Status::kInvalidElementSize);
+    }
+
+    size_ = num_bytes_remaining_ = static_cast<int>(metadata.size);
+    value_ = default_value_;
+
+    return Status(Status::kOkCompleted);
+  }
+
+  Status Feed(Callback* callback, Reader* reader,
+              std::uint64_t* num_bytes_read) override {
+    assert(callback != nullptr);
+    assert(reader != nullptr);
+    assert(num_bytes_read != nullptr);
+
+    std::uint64_t uint_value = 0;
+    const Status status = AccumulateIntegerBytes(num_bytes_remaining_, reader,
+                                                 &uint_value, num_bytes_read);
+    num_bytes_remaining_ -= static_cast<int>(*num_bytes_read);
+
+    // Only the last byte should have a value, and it should only be 0 or 1.
+    if ((num_bytes_remaining_ != 0 && uint_value != 0) || uint_value > 1) {
+      return Status(Status::kInvalidElementValue);
+    }
+
+    if (size_ > 0) {
+      value_ = uint_value == 1;
+    }
+
+    return status;
+  }
+
+  // Gets the parsed bool. This must not be called until the parse had been
+  // successfully completed.
+  bool value() const {
+    assert(num_bytes_remaining_ == 0);
+    return value_;
+  }
+
+  // Gets the parsed bool. This must not be called until the parse had been
+  // successfully completed.
+  bool* mutable_value() {
+    assert(num_bytes_remaining_ == 0);
+    return &value_;
+  }
+
+ private:
+  bool value_;
+  bool default_value_;
+  int num_bytes_remaining_ = -1;
+  int size_;
+};
+
+}  // namespace webm
+
+#endif  // SRC_BOOL_PARSER_H_