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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
9107916b11
The intent of this approach is to eliminate recursion limits as a barrier for the parser. While it may not be urgent to address, I want to avoid pouring effort into a parser approach that we don't think will be usable long-term. Right now this is passing a minor set of tests. It's intended to be enough to show how I'm thinking about flow control for the parser. I'm manually switching back and forth because it seemed like the easiest approach that avoids duplicating tests.
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_TOOLCHAIN_PARSER_PARSER_STATE_H_
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#define CARBON_TOOLCHAIN_PARSER_PARSER_STATE_H_
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#include <cstdint>
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#include <iterator>
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#include "common/ostream.h"
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#include "llvm/ADT/StringRef.h"
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namespace Carbon {
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class ParserState {
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// Note that this must be declared earlier in the class so that its type can
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// be used, for example in the conversion operator.
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enum class StateEnum : uint8_t {
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#define CARBON_PARSER_STATE(Name) Name,
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#include "toolchain/parser/parser_state.def"
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};
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public:
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// `clang-format` has a bug with spacing around `->` returns in macros. See
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// https://bugs.llvm.org/show_bug.cgi?id=48320 for details.
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#define CARBON_PARSER_STATE(Name) \
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static constexpr auto Name()->ParserState { \
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return ParserState(StateEnum::Name); \
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}
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#include "toolchain/parser/parser_state.def"
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// The default constructor is deleted because objects of this type should
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// always be constructed using the above factory functions for each unique
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// kind.
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ParserState() = delete;
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friend auto operator==(ParserState lhs, ParserState rhs) -> bool {
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return lhs.state_ == rhs.state_;
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}
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friend auto operator!=(ParserState lhs, ParserState rhs) -> bool {
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return lhs.state_ != rhs.state_;
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}
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// Gets a friendly name for the token for logging or debugging.
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[[nodiscard]] auto name() const -> llvm::StringRef;
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// Enable conversion to our private enum, including in a `constexpr` context,
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// to enable usage in `switch` and `case`. The enum remains private and
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// nothing else should be using this function.
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// NOLINTNEXTLINE(google-explicit-constructor)
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constexpr operator StateEnum() const { return state_; }
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void Print(llvm::raw_ostream& out) const { out << name(); }
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private:
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constexpr explicit ParserState(StateEnum k) : state_(k) {}
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StateEnum state_;
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};
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// We expect the parse node kind to fit compactly into 8 bits.
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static_assert(sizeof(ParserState) == 1, "ParserState objects include padding!");
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} // namespace Carbon
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#endif // CARBON_TOOLCHAIN_PARSER_PARSER_STATE_H_
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