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// Copyright 2020 The Tint Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SRC_READER_SPIRV_FAIL_STREAM_H_
#define SRC_READER_SPIRV_FAIL_STREAM_H_
#include <ostream>
namespace tint {
namespace reader {
namespace spirv {
/// A FailStream object accumulates values onto a given std::ostream,
/// and can be used to record failure by writing the false value
/// to given a pointer-to-bool.
class FailStream {
public:
/// Creates a new fail stream
/// @param status_ptr where we will write false to indicate failure. Assumed
/// to be a valid pointer to bool.
/// @param out output stream where a message should be written to explain
/// the failure
FailStream(bool* status_ptr, std::ostream* out)
: status_ptr_(status_ptr), out_(out) {}
/// Copy constructor
/// @param other the fail stream to clone
FailStream(const FailStream& other) = default;
/// Converts to a boolean status. A true result indicates success,
/// and a false result indicates failure.
/// @returns the status
operator bool() const { return *status_ptr_; }
/// Returns the current status value. This can be more readable
/// the conversion operator.
/// @returns the status
bool status() const { return *status_ptr_; }
/// Records failure.
/// @returns a FailStream
FailStream& Fail() {
*status_ptr_ = false;
return *this;
}
/// Appends the given value to the message output stream.
/// @param val the value to write to the output stream.
/// @returns this object
template <typename T>
FailStream& operator<<(const T& val) {
*out_ << val;
return *this;
}
private:
bool* status_ptr_;
std::ostream* out_;
};
} // namespace spirv
} // namespace reader
} // namespace tint
#endif // SRC_READER_SPIRV_FAIL_STREAM_H_