1 //===--- VariantValue.h - Polymorphic value type -*- C++ -*-===/
2 //                     The LLVM Compiler Infrastructure
3 //
4 // This file is distributed under the University of Illinois Open Source
5 // License. See LICENSE.TXT for details.
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// \brief Polymorphic value type.
11 ///
12 /// Supports all the types required for dynamic Matcher construction.
13 ///  Used by the registry to construct matchers in a generic way.
14 ///
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_CLANG_ASTMATCHERS_DYNAMIC_VARIANTVALUE_H
18 #define LLVM_CLANG_ASTMATCHERS_DYNAMIC_VARIANTVALUE_H
19 
20 #include "clang/ASTMatchers/ASTMatchers.h"
21 #include "clang/ASTMatchers/ASTMatchersInternal.h"
22 #include "llvm/ADT/IntrusiveRefCntPtr.h"
23 #include "llvm/ADT/Optional.h"
24 #include "llvm/ADT/Twine.h"
25 #include <memory>
26 #include <vector>
27 
28 namespace clang {
29 namespace ast_matchers {
30 namespace dynamic {
31 
32 /// \brief Kind identifier.
33 ///
34 /// It supports all types that VariantValue can contain.
35 class ArgKind {
36  public:
37   enum Kind {
38     AK_Matcher,
39     AK_Unsigned,
40     AK_String
41   };
42   /// \brief Constructor for non-matcher types.
ArgKind(Kind K)43   ArgKind(Kind K) : K(K) { assert(K != AK_Matcher); }
44 
45   /// \brief Constructor for matcher types.
ArgKind(ast_type_traits::ASTNodeKind MatcherKind)46   ArgKind(ast_type_traits::ASTNodeKind MatcherKind)
47       : K(AK_Matcher), MatcherKind(MatcherKind) {}
48 
getArgKind()49   Kind getArgKind() const { return K; }
getMatcherKind()50   ast_type_traits::ASTNodeKind getMatcherKind() const {
51     assert(K == AK_Matcher);
52     return MatcherKind;
53   }
54 
55   /// \brief Determines if this type can be converted to \p To.
56   ///
57   /// \param To the requested destination type.
58   ///
59   /// \param Specificity value corresponding to the "specificity" of the
60   ///   convertion.
61   bool isConvertibleTo(ArgKind To, unsigned *Specificity) const;
62 
63   bool operator<(const ArgKind &Other) const {
64     if (K == AK_Matcher && Other.K == AK_Matcher)
65       return MatcherKind < Other.MatcherKind;
66     return K < Other.K;
67   }
68 
69   /// \brief String representation of the type.
70   std::string asString() const;
71 
72 private:
73   Kind K;
74   ast_type_traits::ASTNodeKind MatcherKind;
75 };
76 
77 using ast_matchers::internal::DynTypedMatcher;
78 
79 /// \brief A variant matcher object.
80 ///
81 /// The purpose of this object is to abstract simple and polymorphic matchers
82 /// into a single object type.
83 /// Polymorphic matchers might be implemented as a list of all the possible
84 /// overloads of the matcher. \c VariantMatcher knows how to select the
85 /// appropriate overload when needed.
86 /// To get a real matcher object out of a \c VariantMatcher you can do:
87 ///  - getSingleMatcher() which returns a matcher, only if it is not ambiguous
88 ///    to decide which matcher to return. Eg. it contains only a single
89 ///    matcher, or a polymorphic one with only one overload.
90 ///  - hasTypedMatcher<T>()/getTypedMatcher<T>(): These calls will determine if
91 ///    the underlying matcher(s) can unambiguously return a Matcher<T>.
92 class VariantMatcher {
93   /// \brief Methods that depend on T from hasTypedMatcher/getTypedMatcher.
94   class MatcherOps {
95   public:
MatcherOps(ast_type_traits::ASTNodeKind NodeKind)96     MatcherOps(ast_type_traits::ASTNodeKind NodeKind) : NodeKind(NodeKind) {}
97 
98     bool canConstructFrom(const DynTypedMatcher &Matcher,
99                           bool &IsExactMatch) const;
100 
101     /// \brief Convert \p Matcher the destination type and return it as a new
102     /// DynTypedMatcher.
103     virtual DynTypedMatcher
104     convertMatcher(const DynTypedMatcher &Matcher) const = 0;
105 
106     /// \brief Constructs a variadic typed matcher from \p InnerMatchers.
107     /// Will try to convert each inner matcher to the destination type and
108     /// return llvm::None if it fails to do so.
109     llvm::Optional<DynTypedMatcher>
110     constructVariadicOperator(DynTypedMatcher::VariadicOperator Op,
111                               ArrayRef<VariantMatcher> InnerMatchers) const;
112 
113   protected:
114     ~MatcherOps() = default;
115 
116   private:
117     ast_type_traits::ASTNodeKind NodeKind;
118   };
119 
120   /// \brief Payload interface to be specialized by each matcher type.
121   ///
122   /// It follows a similar interface as VariantMatcher itself.
123   class Payload : public RefCountedBaseVPTR {
124   public:
125     ~Payload() override;
126     virtual llvm::Optional<DynTypedMatcher> getSingleMatcher() const = 0;
127     virtual std::string getTypeAsString() const = 0;
128     virtual llvm::Optional<DynTypedMatcher>
129     getTypedMatcher(const MatcherOps &Ops) const = 0;
130     virtual bool isConvertibleTo(ast_type_traits::ASTNodeKind Kind,
131                                  unsigned *Specificity) const = 0;
132   };
133 
134 public:
135   /// \brief A null matcher.
136   VariantMatcher();
137 
138   /// \brief Clones the provided matcher.
139   static VariantMatcher SingleMatcher(const DynTypedMatcher &Matcher);
140 
141   /// \brief Clones the provided matchers.
142   ///
143   /// They should be the result of a polymorphic matcher.
144   static VariantMatcher
145   PolymorphicMatcher(std::vector<DynTypedMatcher> Matchers);
146 
147   /// \brief Creates a 'variadic' operator matcher.
148   ///
149   /// It will bind to the appropriate type on getTypedMatcher<T>().
150   static VariantMatcher
151   VariadicOperatorMatcher(DynTypedMatcher::VariadicOperator Op,
152                           std::vector<VariantMatcher> Args);
153 
154   /// \brief Makes the matcher the "null" matcher.
155   void reset();
156 
157   /// \brief Whether the matcher is null.
isNull()158   bool isNull() const { return !Value; }
159 
160   /// \brief Return a single matcher, if there is no ambiguity.
161   ///
162   /// \returns the matcher, if there is only one matcher. An empty Optional, if
163   /// the underlying matcher is a polymorphic matcher with more than one
164   /// representation.
165   llvm::Optional<DynTypedMatcher> getSingleMatcher() const;
166 
167   /// \brief Determines if the contained matcher can be converted to
168   ///   \c Matcher<T>.
169   ///
170   /// For the Single case, it returns true if it can be converted to
171   /// \c Matcher<T>.
172   /// For the Polymorphic case, it returns true if one, and only one, of the
173   /// overloads can be converted to \c Matcher<T>. If there are more than one
174   /// that can, the result would be ambiguous and false is returned.
175   template <class T>
hasTypedMatcher()176   bool hasTypedMatcher() const {
177     if (!Value) return false;
178     return Value->getTypedMatcher(TypedMatcherOps<T>()).hasValue();
179   }
180 
181   /// \brief Determines if the contained matcher can be converted to \p Kind.
182   ///
183   /// \param Kind the requested destination type.
184   ///
185   /// \param Specificity value corresponding to the "specificity" of the
186   ///   convertion.
isConvertibleTo(ast_type_traits::ASTNodeKind Kind,unsigned * Specificity)187   bool isConvertibleTo(ast_type_traits::ASTNodeKind Kind,
188                        unsigned *Specificity) const {
189     if (Value)
190       return Value->isConvertibleTo(Kind, Specificity);
191     return false;
192   }
193 
194   /// \brief Return this matcher as a \c Matcher<T>.
195   ///
196   /// Handles the different types (Single, Polymorphic) accordingly.
197   /// Asserts that \c hasTypedMatcher<T>() is true.
198   template <class T>
getTypedMatcher()199   ast_matchers::internal::Matcher<T> getTypedMatcher() const {
200     assert(hasTypedMatcher<T>() && "hasTypedMatcher<T>() == false");
201     return Value->getTypedMatcher(TypedMatcherOps<T>())
202         ->template convertTo<T>();
203   }
204 
205   /// \brief String representation of the type of the value.
206   ///
207   /// If the underlying matcher is a polymorphic one, the string will show all
208   /// the types.
209   std::string getTypeAsString() const;
210 
211 private:
VariantMatcher(Payload * Value)212   explicit VariantMatcher(Payload *Value) : Value(Value) {}
213 
214   template <typename T> struct TypedMatcherOps;
215 
216   class SinglePayload;
217   class PolymorphicPayload;
218   class VariadicOpPayload;
219 
220   IntrusiveRefCntPtr<const Payload> Value;
221 };
222 
223 template <typename T>
224 struct VariantMatcher::TypedMatcherOps final : VariantMatcher::MatcherOps {
TypedMatcherOpsfinal225   TypedMatcherOps()
226       : MatcherOps(ast_type_traits::ASTNodeKind::getFromNodeKind<T>()) {}
227   typedef ast_matchers::internal::Matcher<T> MatcherT;
228 
229   DynTypedMatcher
convertMatcherfinal230   convertMatcher(const DynTypedMatcher &Matcher) const override {
231     return DynTypedMatcher(Matcher.convertTo<T>());
232   }
233 };
234 
235 /// \brief Variant value class.
236 ///
237 /// Basically, a tagged union with value type semantics.
238 /// It is used by the registry as the return value and argument type for the
239 /// matcher factory methods.
240 /// It can be constructed from any of the supported types. It supports
241 /// copy/assignment.
242 ///
243 /// Supported types:
244 ///  - \c unsigned
245 ///  - \c llvm::StringRef
246 ///  - \c VariantMatcher (\c DynTypedMatcher / \c Matcher<T>)
247 class VariantValue {
248 public:
VariantValue()249   VariantValue() : Type(VT_Nothing) {}
250 
251   VariantValue(const VariantValue &Other);
252   ~VariantValue();
253   VariantValue &operator=(const VariantValue &Other);
254 
255   /// \brief Specific constructors for each supported type.
256   VariantValue(unsigned Unsigned);
257   VariantValue(StringRef String);
258   VariantValue(const VariantMatcher &Matchers);
259 
260   /// \brief Returns true iff this is not an empty value.
261   explicit operator bool() const { return hasValue(); }
hasValue()262   bool hasValue() const { return Type != VT_Nothing; }
263 
264   /// \brief Unsigned value functions.
265   bool isUnsigned() const;
266   unsigned getUnsigned() const;
267   void setUnsigned(unsigned Unsigned);
268 
269   /// \brief String value functions.
270   bool isString() const;
271   const std::string &getString() const;
272   void setString(StringRef String);
273 
274   /// \brief Matcher value functions.
275   bool isMatcher() const;
276   const VariantMatcher &getMatcher() const;
277   void setMatcher(const VariantMatcher &Matcher);
278 
279   /// \brief Determines if the contained value can be converted to \p Kind.
280   ///
281   /// \param Kind the requested destination type.
282   ///
283   /// \param Specificity value corresponding to the "specificity" of the
284   ///   convertion.
285   bool isConvertibleTo(ArgKind Kind, unsigned* Specificity) const;
286 
287   /// \brief Determines if the contained value can be converted to any kind
288   /// in \p Kinds.
289   ///
290   /// \param Kinds the requested destination types.
291   ///
292   /// \param Specificity value corresponding to the "specificity" of the
293   ///   convertion. It is the maximum specificity of all the possible
294   ///   conversions.
295   bool isConvertibleTo(ArrayRef<ArgKind> Kinds, unsigned *Specificity) const;
296 
297   /// \brief String representation of the type of the value.
298   std::string getTypeAsString() const;
299 
300 private:
301   void reset();
302 
303   /// \brief All supported value types.
304   enum ValueType {
305     VT_Nothing,
306     VT_Unsigned,
307     VT_String,
308     VT_Matcher
309   };
310 
311   /// \brief All supported value types.
312   union AllValues {
313     unsigned Unsigned;
314     std::string *String;
315     VariantMatcher *Matcher;
316   };
317 
318   ValueType Type;
319   AllValues Value;
320 };
321 
322 } // end namespace dynamic
323 } // end namespace ast_matchers
324 } // end namespace clang
325 
326 #endif  // LLVM_CLANG_AST_MATCHERS_DYNAMIC_VARIANT_VALUE_H
327