84 lines
3.7 KiB
C
84 lines
3.7 KiB
C
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// Copyright 2018 The NXT Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef BACKEND_ERROR_H_
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#define BACKEND_ERROR_H_
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#include "common/Result.h"
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namespace backend {
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// This is the content of an error value for MaybeError or ResultOrError, split off to its own
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// file to avoid having all files including headers like <string> and <vector>
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class ErrorData;
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// MaybeError and ResultOrError are meant to be used as return value for function that are not
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// expected to, but might fail. The handling of error is potentially much slower than successes.
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using MaybeError = Result<void, ErrorData*>;
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template <typename T>
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using ResultOrError = Result<T, ErrorData*>;
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// Returning a success is done like so:
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// return {}; // for Error
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// return SomethingOfTypeT; // for ResultOrError<T>
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//
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// Returning an error is done via:
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// NXT_RETURN_ERROR("My error message");
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#define NXT_RETURN_ERROR(EXPR) return MakeError(EXPR, __FILE__, __func__, __LINE__)
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#define NXT_CONCAT1(x, y) x##y
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#define NXT_CONCAT2(x, y) NXT_CONCAT1(x, y)
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#define NXT_LOCAL_VAR NXT_CONCAT2(_localVar, __LINE__)
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// When Errors aren't handled explicitly, calls to functions returning errors should be
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// wrapped in an NXT_TRY. It will return the error if any, otherwise keep executing
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// the current function.
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#define NXT_TRY(EXPR) \
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{ \
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auto NXT_LOCAL_VAR = EXPR; \
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if (NXT_UNLIKELY(NXT_LOCAL_VAR.IsError())) { \
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ErrorData* error = NXT_LOCAL_VAR.AcquireError(); \
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AppendBacktrace(error, __FILE__, __func__, __LINE__); \
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return {error}; \
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} \
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} \
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for (;;) \
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break
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// NXT_TRY_ASSIGN is the same as NXT_TRY for ResultOrError and assigns the success value, if
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// any, to VAR.
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#define NXT_TRY_ASSIGN(VAR, EXPR) \
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{ \
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auto NXT_LOCAL_VAR = EXPR; \
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if (NXT_UNLIKELY(NXT_LOCAL_VAR.IsError())) { \
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ErrorData* error = NXT_LOCAL_VAR.AcquireError(); \
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AppendBacktrace(error, __FILE__, __func__, __LINE__); \
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return {error}; \
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} \
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VAR = NXT_LOCAL_VAR.AcquireSuccess(); \
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} \
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for (;;) \
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break
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// Implementation detail of NXT_TRY and NXT_TRY_ASSIGN's adding to the Error's backtrace.
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void AppendBacktrace(ErrorData* error, const char* file, const char* function, int line);
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// Implementation detail of NXT_RETURN_ERROR
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ErrorData* MakeError(const char* message, const char* file, const char* function, int line);
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} // namespace backend
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#endif // BACKEND_ERROR_H_
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