1//===--- MatchConsumer.h - MatchConsumer abstraction ------------*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8/// 9/// \file This file defines the *MatchConsumer* abstraction: a computation over 10/// match results, specifically the `ast_matchers::MatchFinder::MatchResult` 11/// class. 12/// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_CLANG_TOOLING_TRANSFORMER_MATCH_CONSUMER_H_ 16#define LLVM_CLANG_TOOLING_TRANSFORMER_MATCH_CONSUMER_H_ 17 18#include "clang/AST/ASTTypeTraits.h" 19#include "clang/ASTMatchers/ASTMatchFinder.h" 20#include "llvm/ADT/StringRef.h" 21#include "llvm/Support/Errc.h" 22#include "llvm/Support/Error.h" 23 24namespace clang { 25namespace transformer { 26/// A failable computation over nodes bound by AST matchers. 27/// 28/// The computation should report any errors though its return value (rather 29/// than terminating the program) to enable usage in interactive scenarios like 30/// clang-query. 31/// 32/// This is a central abstraction of the Transformer framework. 33template <typename T> 34using MatchConsumer = 35 std::function<Expected<T>(const ast_matchers::MatchFinder::MatchResult &)>; 36 37/// Creates an error that signals that a `MatchConsumer` expected a certain node 38/// to be bound by AST matchers, but it was not actually bound. 39inline llvm::Error notBoundError(llvm::StringRef Id) { 40 return llvm::make_error<llvm::StringError>(llvm::errc::invalid_argument, 41 "Id not bound: " + Id); 42} 43 44/// Chooses between the two consumers, based on whether \p ID is bound in the 45/// match. 46template <typename T> 47MatchConsumer<T> ifBound(std::string ID, MatchConsumer<T> TrueC, 48 MatchConsumer<T> FalseC) { 49 return [=](const ast_matchers::MatchFinder::MatchResult &Result) { 50 auto &Map = Result.Nodes.getMap(); 51 return (Map.find(ID) != Map.end() ? TrueC : FalseC)(Result); 52 }; 53} 54 55/// A failable computation over nodes bound by AST matchers, with (limited) 56/// reflection via the `toString` method. 57/// 58/// The computation should report any errors though its return value (rather 59/// than terminating the program) to enable usage in interactive scenarios like 60/// clang-query. 61/// 62/// This is a central abstraction of the Transformer framework. It is a 63/// generalization of `MatchConsumer` and intended to replace it. 64template <typename T> class MatchComputation { 65public: 66 virtual ~MatchComputation() = default; 67 68 /// Evaluates the computation and (potentially) updates the accumulator \c 69 /// Result. \c Result is undefined in the case of an error. `Result` is an 70 /// out parameter to optimize case where the computation involves composing 71 /// the result of sub-computation evaluations. 72 virtual llvm::Error eval(const ast_matchers::MatchFinder::MatchResult &Match, 73 T *Result) const = 0; 74 75 /// Convenience version of `eval`, for the case where the computation is being 76 /// evaluated on its own. 77 llvm::Expected<T> eval(const ast_matchers::MatchFinder::MatchResult &R) const; 78 79 /// Constructs a string representation of the computation, for informational 80 /// purposes. The representation must be deterministic, but is not required to 81 /// be unique. 82 virtual std::string toString() const = 0; 83 84protected: 85 MatchComputation() = default; 86 87 // Since this is an abstract class, copying/assigning only make sense for 88 // derived classes implementing `clone()`. 89 MatchComputation(const MatchComputation &) = default; 90 MatchComputation &operator=(const MatchComputation &) = default; 91}; 92 93template <typename T> 94llvm::Expected<T> MatchComputation<T>::eval( 95 const ast_matchers::MatchFinder::MatchResult &R) const { 96 T Output; 97 if (auto Err = eval(R, &Output)) 98 return std::move(Err); 99 return Output; 100} 101} // namespace transformer 102} // namespace clang 103#endif // LLVM_CLANG_TOOLING_TRANSFORMER_MATCH_CONSUMER_H_ 104