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2a88fb2ecb
- the grammar ambiguity is eliminated by a guard; - modify the guard function signatures, now all parameters are folded in to a single object, avoid a long parameter list (as we will add more parameters in the near future); Reviewed By: sammccall Differential Revision: https://reviews.llvm.org/D130160
65 lines
2.1 KiB
C++
65 lines
2.1 KiB
C++
//===--- Language.h -------------------------------------------- -*- C++-*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef CLANG_PSEUDO_LANGUAGE_H
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#define CLANG_PSEUDO_LANGUAGE_H
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#include "clang-pseudo/Token.h"
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#include "clang-pseudo/grammar/Grammar.h"
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#include "clang-pseudo/grammar/LRTable.h"
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namespace clang {
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namespace pseudo {
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class ForestNode;
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class TokenStream;
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class LRTable;
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struct GuardParams {
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llvm::ArrayRef<const ForestNode *> RHS;
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const TokenStream &Tokens;
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// FIXME: use the index of Tokens.
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SymbolID Lookahead;
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};
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// A guard restricts when a grammar rule can be used.
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//
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// The GLR parser will use the guard to determine whether a rule reduction will
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// be conducted. For example, e.g. a guard may allow the rule
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// `virt-specifier := IDENTIFIER` only if the identifier's text is 'override`.
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//
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// Return true if the guard is satisfied.
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using RuleGuard = llvm::function_ref<bool(const GuardParams &)>;
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// A recovery strategy determines a region of code to skip when parsing fails.
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//
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// For example, given `class-def := CLASS IDENT { body [recover=Brackets] }`,
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// if parsing fails while attempting to parse `body`, we may skip up to the
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// matching `}` and assume everything between was a `body`.
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//
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// The provided index is the token where the skipped region begins.
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// Returns the (excluded) end of the range, or Token::Invalid for no recovery.
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using RecoveryStrategy =
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llvm::function_ref<Token::Index(Token::Index Start, const TokenStream &)>;
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// Specify a language that can be parsed by the pseduoparser.
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struct Language {
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Grammar G;
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LRTable Table;
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// Binding extension ids to corresponding implementations.
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llvm::DenseMap<RuleID, RuleGuard> Guards;
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llvm::DenseMap<ExtensionID, RecoveryStrategy> RecoveryStrategies;
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// FIXME: add clang::LangOptions.
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// FIXME: add default start symbols.
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};
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} // namespace pseudo
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} // namespace clang
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#endif // CLANG_PSEUDO_LANGUAGE_H
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