clang-tools  9.0.0
Quality.h
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1 //===--- Quality.h - Ranking alternatives for ambiguous queries --*- 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 /// Some operations such as code completion produce a set of candidates.
10 /// Usually the user can choose between them, but we should put the best options
11 /// at the top (they're easier to select, and more likely to be seen).
12 ///
13 /// This file defines building blocks for ranking candidates.
14 /// It's used by the features directly and also in the implementation of
15 /// indexes, as indexes also need to heuristically limit their results.
16 ///
17 /// The facilities here are:
18 /// - retrieving scoring signals from e.g. indexes, AST, CodeCompletionString
19 /// These are structured in a way that they can be debugged, and are fairly
20 /// consistent regardless of the source.
21 /// - compute scores from scoring signals. These are suitable for sorting.
22 /// - sorting utilities like the TopN container.
23 /// These could be split up further to isolate dependencies if we care.
24 ///
25 //===----------------------------------------------------------------------===//
26 
27 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_QUALITY_H
28 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_QUALITY_H
29 
30 #include "ExpectedTypes.h"
31 #include "FileDistance.h"
32 #include "clang/Sema/CodeCompleteConsumer.h"
33 #include "llvm/ADT/ArrayRef.h"
34 #include "llvm/ADT/StringRef.h"
35 #include "llvm/ADT/StringSet.h"
36 #include <algorithm>
37 #include <functional>
38 #include <vector>
39 
40 namespace llvm {
41 class raw_ostream;
42 } // namespace llvm
43 
44 namespace clang {
45 class CodeCompletionResult;
46 
47 namespace clangd {
48 
49 struct Symbol;
50 class URIDistance;
51 
52 // Signals structs are designed to be aggregated from 0 or more sources.
53 // A default instance has neutral signals, and sources are merged into it.
54 // They can be dumped for debugging, and evaluate()d into a score.
55 
56 /// Attributes of a symbol that affect how much we like it.
58  bool Deprecated = false;
59  bool ReservedName = false; // __foo, _Foo are usually implementation details.
60  // FIXME: make these findable once user types _.
61  bool ImplementationDetail = false;
62  unsigned References = 0;
63 
65  Unknown = 0,
75  } Category = Unknown;
76 
77  void merge(const CodeCompletionResult &SemaCCResult);
78  void merge(const Symbol &IndexResult);
79 
80  // Condense these signals down to a single number, higher is better.
81  float evaluate() const;
82 };
83 llvm::raw_ostream &operator<<(llvm::raw_ostream &,
84  const SymbolQualitySignals &);
85 
86 /// Attributes of a symbol-query pair that affect how much we like it.
88  /// The name of the symbol (for ContextWords). Must be explicitly assigned.
89  llvm::StringRef Name;
90  /// 0-1+ fuzzy-match score for unqualified name. Must be explicitly assigned.
91  float NameMatch = 1;
92  /// Lowercase words relevant to the context (e.g. near the completion point).
93  llvm::StringSet<>* ContextWords = nullptr;
94  bool Forbidden = false; // Unavailable (e.g const) or inaccessible (private).
95  /// Whether fixits needs to be applied for that completion or not.
96  bool NeedsFixIts = false;
97  bool InBaseClass = false; // A member from base class of the accessed class.
98 
99  URIDistance *FileProximityMatch = nullptr;
100  /// These are used to calculate proximity between the index symbol and the
101  /// query.
102  llvm::StringRef SymbolURI;
103  /// FIXME: unify with index proximity score - signals should be
104  /// source-independent.
105  /// Proximity between best declaration and the query. [0-1], 1 is closest.
106  float SemaFileProximityScore = 0;
107 
108  // Scope proximity is only considered (both index and sema) when this is set.
109  ScopeDistance *ScopeProximityMatch = nullptr;
110  llvm::Optional<llvm::StringRef> SymbolScope;
111  // A symbol from sema should be accessible from the current scope.
112  bool SemaSaysInScope = false;
113 
114  // An approximate measure of where we expect the symbol to be used.
120  } Scope = GlobalScope;
121 
122  enum QueryType {
125  } Query = Generic;
126 
127  CodeCompletionContext::Kind Context = CodeCompletionContext::CCC_Other;
128 
129  // Whether symbol is an instance member of a class.
130  bool IsInstanceMember = false;
131 
132  // Whether clang provided a preferred type in the completion context.
133  bool HadContextType = false;
134  // Whether a source completion item or a symbol had a type information.
135  bool HadSymbolType = false;
136  // Whether the item matches the type expected in the completion context.
137  bool TypeMatchesPreferred = false;
138 
139  void merge(const CodeCompletionResult &SemaResult);
140  void merge(const Symbol &IndexResult);
141 
142  // Condense these signals down to a single number, higher is better.
143  float evaluate() const;
144 };
145 llvm::raw_ostream &operator<<(llvm::raw_ostream &,
146  const SymbolRelevanceSignals &);
147 
148 /// Combine symbol quality and relevance into a single score.
149 float evaluateSymbolAndRelevance(float SymbolQuality, float SymbolRelevance);
150 
151 /// TopN<T> is a lossy container that preserves only the "best" N elements.
152 template <typename T, typename Compare = std::greater<T>> class TopN {
153 public:
154  using value_type = T;
155  TopN(size_t N, Compare Greater = Compare())
156  : N(N), Greater(std::move(Greater)) {}
157 
158  // Adds a candidate to the set.
159  // Returns true if a candidate was dropped to get back under N.
160  bool push(value_type &&V) {
161  bool Dropped = false;
162  if (Heap.size() >= N) {
163  Dropped = true;
164  if (N > 0 && Greater(V, Heap.front())) {
165  std::pop_heap(Heap.begin(), Heap.end(), Greater);
166  Heap.back() = std::move(V);
167  std::push_heap(Heap.begin(), Heap.end(), Greater);
168  }
169  } else {
170  Heap.push_back(std::move(V));
171  std::push_heap(Heap.begin(), Heap.end(), Greater);
172  }
173  assert(Heap.size() <= N);
174  assert(std::is_heap(Heap.begin(), Heap.end(), Greater));
175  return Dropped;
176  }
177 
178  // Returns candidates from best to worst.
179  std::vector<value_type> items() && {
180  std::sort_heap(Heap.begin(), Heap.end(), Greater);
181  assert(Heap.size() <= N);
182  return std::move(Heap);
183  }
184 
185 private:
186  const size_t N;
187  std::vector<value_type> Heap; // Min-heap, comparator is Greater.
188  Compare Greater;
189 };
190 
191 /// Returns a string that sorts in the same order as (-Score, Tiebreak), for
192 /// LSP. (The highest score compares smallest so it sorts at the top).
193 std::string sortText(float Score, llvm::StringRef Tiebreak = "");
194 
196  uint32_t NumberOfParameters = 0;
197  uint32_t NumberOfOptionalParameters = 0;
198  CodeCompleteConsumer::OverloadCandidate::CandidateKind Kind =
199  CodeCompleteConsumer::OverloadCandidate::CandidateKind::CK_Function;
200 };
201 llvm::raw_ostream &operator<<(llvm::raw_ostream &,
202  const SignatureQualitySignals &);
203 
204 } // namespace clangd
205 } // namespace clang
206 
207 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_QUALITY_H
Some operations such as code completion produce a set of candidates.
llvm::Optional< llvm::StringRef > SymbolScope
Definition: Quality.h:110
TopN(size_t N, Compare Greater=Compare())
Definition: Quality.h:155
std::string sortText(float Score, llvm::StringRef Name)
Returns a string that sorts in the same order as (-Score, Tiebreak), for LSP.
Definition: Quality.cpp:481
Attributes of a symbol that affect how much we like it.
Definition: Quality.h:57
llvm::StringRef Name
The name of the symbol (for ContextWords). Must be explicitly assigned.
Definition: Quality.h:89
BindArgumentKind Kind
llvm::Optional< float > Score
bool push(value_type &&V)
Definition: Quality.h:160
const Symbol * IndexResult
A context is an immutable container for per-request data that must be propagated through layers that ...
Definition: Context.h:69
llvm::StringRef SymbolURI
These are used to calculate proximity between the index symbol and the query.
Definition: Quality.h:102
float evaluateSymbolAndRelevance(float SymbolQuality, float SymbolRelevance)
Combine symbol quality and relevance into a single score.
Definition: Quality.cpp:463
The class presents a C++ symbol, e.g.
Definition: Symbol.h:36
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
unsigned References
Support lookups like FileDistance, but the lookup keys are symbol scopes.
Definition: FileDistance.h:116
const CodeCompletionResult * SemaResult
std::vector< value_type > items() &&
Definition: Quality.h:179
llvm::raw_ostream & operator<<(llvm::raw_ostream &OS, const CodeCompletion &C)
Attributes of a symbol-query pair that affect how much we like it.
Definition: Quality.h:87
TopN<T> is a lossy container that preserves only the "best" N elements.
Definition: Quality.h:152