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-exception
6//
7//===----------------------------------------------------------------------===//
8// A simplified model of C++ types that can be used to check whether they are
9// convertible between each other for the purposes of code completion ranking
10// 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 improvements
12// to the code completion ranking.
13//
14// We define an encoding of AST types as opaque strings, which can be stored in
15// 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_H
19#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_EXPECTEDTYPES_H
20
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 and
30/// compared for equality. The encoding is stable between different ASTs, this
31/// allows the representation to be stored in the index and compared with types
32/// coming from a different AST later.
33/// OpaqueType is a strongly-typedefed std::string, you can get the underlying
34/// 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 a
41 /// 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 the
45 /// types being equal iff their raw representation is the same. The particular
46 /// details of the used encoding might change over time and one should not
47 /// 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 clangd
64} // namespace clang
65#endif
66

source code of clang-tools-extra/clangd/ExpectedTypes.h