forked from OSchip/llvm-project
38 lines
1.6 KiB
Markdown
38 lines
1.6 KiB
Markdown
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# clang pseudoparser
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This directory implements an approximate heuristic parser for C++, based on the
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clang lexer, the C++ grammar, and the GLR parsing algorithm.
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It parses a file in isolation, without reading its included headers.
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The result is a strict syntactic tree whose structure follows the C++ grammar.
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There is no semantic analysis, apart from guesses to disambiguate the parse.
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Disambiguation can optionally be guided by an AST or a symbol index.
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For now, the best reference on intended scope is the [design proposal],
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with further discussion on the [RFC].
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## Dependencies between pseudoparser and clang
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Dependencies are limited because they don't make sense, but also to avoid
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placing a burden on clang mantainers.
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The pseudoparser reuses the clang lexer (clangLex and clangBasic libraries) but
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not the higher-level libraries (Parse, Sema, AST, Frontend...).
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When the pseudoparser should be used together with an AST (e.g. to guide
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disambiguation), this is a separate "bridge" library that depends on both.
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Clang does not depend on the pseudoparser at all. If this seems useful in future
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it should be discussed by RFC.
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## Parity between pseudoparser and clang
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The pseudoparser aims to understand real-world code, and particularly the
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languages and extensions supported by Clang.
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However we don't try to keep these in lockstep: there's no expectation that
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Clang parser changes are accompanied by pseudoparser changes or vice versa.
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[design proposal]: https://docs.google.com/document/d/1eGkTOsFja63wsv8v0vd5JdoTonj-NlN3ujGF0T7xDbM/edit
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[RFC]: https://discourse.llvm.org/t/rfc-a-c-pseudo-parser-for-tooling/59217/49
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