64 lines
1.9 KiB
C++
64 lines
1.9 KiB
C++
#ifndef PRESULT_H
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#define PRESULT_H
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#include "expected.h"
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#include "source_error.h"
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#include <optional>
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/// Returns from the CURRENT function, the one this macro is used in,
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/// if PResult contains an error
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#define RETURN_IF_ERR(presult) \
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do { \
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auto&& return_if_err_temp_ = (presult); \
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if (!return_if_err_temp_) { \
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return PError(return_if_err_temp_.error()); \
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} \
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} while (0)
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/// Works the same as RETURN_IF_ERR but can also assign the unwrapped result
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/// to a variable if successful
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#define ASSIGN_OR_RETURN_IF_ERR(var, presult) \
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do { \
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auto&& assign_or_return_if_err_temp_ = (presult); \
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if (!assign_or_return_if_err_temp_) { \
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return PError(assign_or_return_if_err_temp_.error()); \
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} else { \
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var = *assign_or_return_if_err_temp_; \
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} \
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} while (0)
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using PError = tl::unexpected<SourceError>;
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/// Holds either an AST node or an error
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/// The value MUST be checked before usage, e.g. using RETURN_IF_ERR
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template<typename T>
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struct PResult : tl::expected<T, SourceError> {
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using tl::expected<T, SourceError>::expected;
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/// Implicit conversion from PResult<U> to PResult<T>
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/// if U is convertible to T
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template<typename U, class V = std::enable_if_t<std::is_convertible<std::decay_t<U>, T>::value>>
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PResult(PResult<U> presult) :
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tl::expected<T, SourceError>(presult ? PResult<T>(*presult) : PError(presult.error())) {}
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};
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/// Alternative to PResult that is returned from parseLibrary* functions
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/// that only consume one token so they can fail without affecting
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/// the parser state
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template<typename T>
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struct POptResult : public PResult<T> {
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using PResult<T>::PResult;
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std::optional<T> optional() {
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if (*this) {
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return **this;
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} else {
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return std::nullopt;
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}
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}
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};
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#endif // PRESULT_H
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