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Diffstat (limited to 'mfbt/Try.h')
| -rw-r--r-- | mfbt/Try.h | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/mfbt/Try.h b/mfbt/Try.h new file mode 100644 index 0000000000..a650a33ea2 --- /dev/null +++ b/mfbt/Try.h @@ -0,0 +1,41 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_Try_h +#define mozilla_Try_h + +#include "mozilla/Result.h" + +/** + * MOZ_TRY(expr) is the C++ equivalent of Rust's `try!(expr);`. First, it + * evaluates expr, which must produce a Result value. On success, it + * discards the result altogether. On error, it immediately returns an error + * Result from the enclosing function. + */ +#define MOZ_TRY(expr) \ + do { \ + auto mozTryTempResult_ = ::mozilla::ToResult(expr); \ + if (MOZ_UNLIKELY(mozTryTempResult_.isErr())) { \ + return mozTryTempResult_.propagateErr(); \ + } \ + } while (0) + +/** + * MOZ_TRY_VAR(target, expr) is the C++ equivalent of Rust's `target = + * try!(expr);`. First, it evaluates expr, which must produce a Result value. On + * success, the result's success value is assigned to target. On error, + * immediately returns the error result. |target| must be an lvalue. + */ +#define MOZ_TRY_VAR(target, expr) \ + do { \ + auto mozTryVarTempResult_ = (expr); \ + if (MOZ_UNLIKELY(mozTryVarTempResult_.isErr())) { \ + return mozTryVarTempResult_.propagateErr(); \ + } \ + (target) = mozTryVarTempResult_.unwrap(); \ + } while (0) + +#endif // mozilla_Try_h |