TypoCorrection.h revision 63aae82bb12bbbe9028e597fb77e40fa8d348c12 
1//===--- TypoCorrection.h - Class for typo correction results ---*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the TypoCorrection class, which stores the results of
11// Sema's typo correction (Sema::CorrectTypo).
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CLANG_SEMA_TYPOCORRECTION_H
16#define LLVM_CLANG_SEMA_TYPOCORRECTION_H
17
18#include "clang/AST/DeclCXX.h"
19#include "llvm/ADT/SmallVector.h"
20
21namespace clang {
22
23/// @brief Simple class containing the result of Sema::CorrectTypo
24class TypoCorrection {
25public:
26  // "Distance" for unusable corrections
27  static const unsigned InvalidDistance = ~0U;
28  // The largest distance still considered valid (larger edit distances are
29  // mapped to InvalidDistance by getEditDistance).
30  static const unsigned MaximumDistance = 10000U;
31
32  // Relative weightings of the "edit distance" components. The higher the
33  // weight, the more of a penalty to fitness the component will give (higher
34  // weights mean greater contribution to the total edit distance, with the
35  // best correction candidates having the lowest edit distance).
36  static const unsigned CharDistanceWeight = 100U;
37  static const unsigned QualifierDistanceWeight = 110U;
38  static const unsigned CallbackDistanceWeight = 150U;
39
40  TypoCorrection(const DeclarationName &Name, NamedDecl *NameDecl,
41                 NestedNameSpecifier *NNS=0, unsigned CharDistance=0,
42                 unsigned QualifierDistance=0)
43      : CorrectionName(Name), CorrectionNameSpec(NNS),
44      CharDistance(CharDistance), QualifierDistance(QualifierDistance),
45      CallbackDistance(0) {
46    if (NameDecl)
47      CorrectionDecls.push_back(NameDecl);
48  }
49
50  TypoCorrection(NamedDecl *Name, NestedNameSpecifier *NNS=0,
51                 unsigned CharDistance=0)
52      : CorrectionName(Name->getDeclName()), CorrectionNameSpec(NNS),
53      CharDistance(CharDistance), QualifierDistance(0), CallbackDistance(0) {
54    if (Name)
55      CorrectionDecls.push_back(Name);
56  }
57
58  TypoCorrection(DeclarationName Name, NestedNameSpecifier *NNS=0,
59                 unsigned CharDistance=0)
60      : CorrectionName(Name), CorrectionNameSpec(NNS),
61      CharDistance(CharDistance), QualifierDistance(0), CallbackDistance(0) {}
62
63  TypoCorrection()
64      : CorrectionNameSpec(0), CharDistance(0), QualifierDistance(0),
65      CallbackDistance(0) {}
66
67  /// \brief Gets the DeclarationName of the typo correction
68  DeclarationName getCorrection() const { return CorrectionName; }
69  IdentifierInfo* getCorrectionAsIdentifierInfo() const {
70    return CorrectionName.getAsIdentifierInfo();
71  }
72
73  /// \brief Gets the NestedNameSpecifier needed to use the typo correction
74  NestedNameSpecifier* getCorrectionSpecifier() const {
75    return CorrectionNameSpec;
76  }
77  void setCorrectionSpecifier(NestedNameSpecifier* NNS) {
78    CorrectionNameSpec = NNS;
79  }
80
81  void setQualifierDistance(unsigned ED) {
82    QualifierDistance = ED;
83  }
84
85  void setCallbackDistance(unsigned ED) {
86    CallbackDistance = ED;
87  }
88
89  // Convert the given weighted edit distance to a roughly equivalent number of
90  // single-character edits (typically for comparison to the length of the
91  // string being edited).
92  static unsigned NormalizeEditDistance(unsigned ED) {
93    if (ED > MaximumDistance)
94      return InvalidDistance;
95    return (ED + CharDistanceWeight / 2) / CharDistanceWeight;
96  }
97
98  /// \brief Gets the "edit distance" of the typo correction from the typo.
99  /// If Normalized is true, scale the distance down by the CharDistanceWeight
100  /// to return the edit distance in terms of single-character edits.
101  unsigned getEditDistance(bool Normalized = true) const {
102    if (CharDistance > MaximumDistance || QualifierDistance > MaximumDistance ||
103        CallbackDistance > MaximumDistance)
104      return InvalidDistance;
105    unsigned ED =
106        CharDistance * CharDistanceWeight +
107        QualifierDistance * QualifierDistanceWeight +
108        CallbackDistance * CallbackDistanceWeight;
109    if (ED > MaximumDistance)
110      return InvalidDistance;
111    // Half the CharDistanceWeight is added to ED to simulate rounding since
112    // integer division truncates the value (i.e. round-to-nearest-int instead
113    // of round-to-zero).
114    return Normalized ? NormalizeEditDistance(ED) : ED;
115  }
116
117  /// \brief Gets the pointer to the declaration of the typo correction
118  NamedDecl* getCorrectionDecl() const {
119    return hasCorrectionDecl() ? *(CorrectionDecls.begin()) : 0;
120  }
121  template <class DeclClass>
122  DeclClass *getCorrectionDeclAs() const {
123    return dyn_cast_or_null<DeclClass>(getCorrectionDecl());
124  }
125
126  /// \brief Clears the list of NamedDecls before adding the new one.
127  void setCorrectionDecl(NamedDecl *CDecl) {
128    CorrectionDecls.clear();
129    addCorrectionDecl(CDecl);
130  }
131
132  /// \brief Add the given NamedDecl to the list of NamedDecls that are the
133  /// declarations associated with the DeclarationName of this TypoCorrection
134  void addCorrectionDecl(NamedDecl *CDecl);
135
136  std::string getAsString(const LangOptions &LO) const;
137  std::string getQuoted(const LangOptions &LO) const {
138    return "'" + getAsString(LO) + "'";
139  }
140
141  /// \brief Returns whether this TypoCorrection has a non-empty DeclarationName
142  operator bool() const { return bool(CorrectionName); }
143
144  /// \brief Mark this TypoCorrection as being a keyword.
145  /// Since addCorrectionDeclsand setCorrectionDecl don't allow NULL to be
146  /// added to the list of the correction's NamedDecl pointers, NULL is added
147  /// as the only element in the list to mark this TypoCorrection as a keyword.
148  void makeKeyword() {
149    CorrectionDecls.clear();
150    CorrectionDecls.push_back(0);
151  }
152
153  // Check if this TypoCorrection is a keyword by checking if the first
154  // item in CorrectionDecls is NULL.
155  bool isKeyword() const {
156    return !CorrectionDecls.empty() &&
157        CorrectionDecls.front() == 0;
158  }
159
160  // Check if this TypoCorrection is the given keyword.
161  template<std::size_t StrLen>
162  bool isKeyword(const char (&Str)[StrLen]) const {
163    return isKeyword() && getCorrectionAsIdentifierInfo()->isStr(Str);
164  }
165
166  // Returns true if the correction either is a keyword or has a known decl.
167  bool isResolved() const { return !CorrectionDecls.empty(); }
168
169  bool isOverloaded() const {
170    return CorrectionDecls.size() > 1;
171  }
172
173  typedef llvm::SmallVector<NamedDecl*, 1>::iterator decl_iterator;
174  decl_iterator begin() {
175    return isKeyword() ? CorrectionDecls.end() : CorrectionDecls.begin();
176  }
177  decl_iterator end() { return CorrectionDecls.end(); }
178  typedef llvm::SmallVector<NamedDecl*, 1>::const_iterator const_decl_iterator;
179  const_decl_iterator begin() const {
180    return isKeyword() ? CorrectionDecls.end() : CorrectionDecls.begin();
181  }
182  const_decl_iterator end() const { return CorrectionDecls.end(); }
183
184private:
185  bool hasCorrectionDecl() const {
186    return (!isKeyword() && !CorrectionDecls.empty());
187  }
188
189  // Results.
190  DeclarationName CorrectionName;
191  NestedNameSpecifier *CorrectionNameSpec;
192  llvm::SmallVector<NamedDecl*, 1> CorrectionDecls;
193  unsigned CharDistance;
194  unsigned QualifierDistance;
195  unsigned CallbackDistance;
196};
197
198/// @brief Base class for callback objects used by Sema::CorrectTypo to check
199/// the validity of a potential typo correction.
200class CorrectionCandidateCallback {
201 public:
202  static const unsigned InvalidDistance = TypoCorrection::InvalidDistance;
203
204  CorrectionCandidateCallback()
205      : WantTypeSpecifiers(true), WantExpressionKeywords(true),
206        WantCXXNamedCasts(true), WantRemainingKeywords(true),
207        WantObjCSuper(false),
208        IsObjCIvarLookup(false) {}
209
210  virtual ~CorrectionCandidateCallback() {}
211
212  /// \brief Simple predicate used by the default RankCandidate to
213  /// determine whether to return an edit distance of 0 or InvalidDistance.
214  /// This can be overrided by validators that only need to determine if a
215  /// candidate is viable, without ranking potentially viable candidates.
216  /// Only ValidateCandidate or RankCandidate need to be overriden by a
217  /// callback wishing to check the viability of correction candidates.
218  virtual bool ValidateCandidate(const TypoCorrection &candidate) {
219    return true;
220  }
221
222  /// \brief Method used by Sema::CorrectTypo to assign an "edit distance" rank
223  /// to a candidate (where a lower value represents a better candidate), or
224  /// returning InvalidDistance if the candidate is not at all viable. For
225  /// validation callbacks that only need to determine if a candidate is viable,
226  /// the default RankCandidate returns either 0 or InvalidDistance depending
227  /// whether ValidateCandidate returns true or false.
228  virtual unsigned RankCandidate(const TypoCorrection &candidate) {
229    return ValidateCandidate(candidate) ? 0 : InvalidDistance;
230  }
231
232  // Flags for context-dependent keywords.
233  // TODO: Expand these to apply to non-keywords or possibly remove them.
234  bool WantTypeSpecifiers;
235  bool WantExpressionKeywords;
236  bool WantCXXNamedCasts;
237  bool WantRemainingKeywords;
238  bool WantObjCSuper;
239  // Temporary hack for the one case where a CorrectTypoContext enum is used
240  // when looking up results.
241  bool IsObjCIvarLookup;
242};
243
244/// @brief Simple template class for restricting typo correction candidates
245/// to ones having a single Decl* of the given type.
246template <class C>
247class DeclFilterCCC : public CorrectionCandidateCallback {
248 public:
249  virtual bool ValidateCandidate(const TypoCorrection &candidate) {
250    return candidate.getCorrectionDeclAs<C>();
251  }
252};
253
254}
255
256#endif
257