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1//===--- ExpectedTypes.h - Simplified C++ types -----------------*- 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-exception6//7//===----------------------------------------------------------------------===//8// A simplified model of C++ types that can be used to check whether they are9// convertible between each other for the purposes of code completion ranking10// without looking at the ASTs. Note that we don't aim to fully mimic the C++11// conversion rules, merely try to have a model that gives useful improvements12// to the code completion ranking.13//14// We define an encoding of AST types as opaque strings, which can be stored in15// the index. Similar types (such as `int` and `long`) are folded together,16// forming equivalence classes with the same encoding.17//===----------------------------------------------------------------------===//18#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_EXPECTEDTYPES_H19#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_EXPECTEDTYPES_H20 21#include "clang/AST/Type.h"22#include "llvm/ADT/StringRef.h"23#include <optional>24 25namespace clang {26class CodeCompletionResult;27 28namespace clangd {29/// A representation of a type that can be computed based on clang AST and30/// compared for equality. The encoding is stable between different ASTs, this31/// allows the representation to be stored in the index and compared with types32/// coming from a different AST later.33/// OpaqueType is a strongly-typedefed std::string, you can get the underlying34/// string with raw().35class OpaqueType {36public:37 /// Create a type from a code completion result.38 static std::optional<OpaqueType>39 fromCompletionResult(ASTContext &Ctx, const CodeCompletionResult &R);40 /// Construct an instance from a clang::QualType. This is usually a41 /// PreferredType from a clang's completion context.42 static std::optional<OpaqueType> fromType(ASTContext &Ctx, QualType Type);43 44 /// Get the raw byte representation of the type. You can only rely on the45 /// types being equal iff their raw representation is the same. The particular46 /// details of the used encoding might change over time and one should not47 /// rely on it.48 llvm::StringRef raw() const { return Data; }49 50 friend bool operator==(const OpaqueType &L, const OpaqueType &R) {51 return L.Data == R.Data;52 }53 friend bool operator!=(const OpaqueType &L, const OpaqueType &R) {54 return !(L == R);55 }56 57private:58 static std::optional<OpaqueType> encode(ASTContext &Ctx, QualType Type);59 explicit OpaqueType(std::string Data);60 61 std::string Data;62};63} // namespace clangd64} // namespace clang65#endif66