Parser.h revision 360784 
1//===- Parser.h - Matcher expression parser ---------------------*- 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/// \file
10/// Simple matcher expression parser.
11///
12/// The parser understands matcher expressions of the form:
13///   MatcherName(Arg0, Arg1, ..., ArgN)
14/// as well as simple types like strings.
15/// The parser does not know how to process the matchers. It delegates this task
16/// to a Sema object received as an argument.
17///
18/// \code
19/// Grammar for the expressions supported:
20/// <Expression>        := <Literal> | <NamedValue> | <MatcherExpression>
21/// <Literal>           := <StringLiteral> | <Boolean> | <Double> | <Unsigned>
22/// <StringLiteral>     := "quoted string"
23/// <Boolean>           := true | false
24/// <Double>            := [0-9]+.[0-9]* | [0-9]+.[0-9]*[eE][-+]?[0-9]+
25/// <Unsigned>          := [0-9]+
26/// <NamedValue>        := <Identifier>
27/// <MatcherExpression> := <Identifier>(<ArgumentList>) |
28///                        <Identifier>(<ArgumentList>).bind(<StringLiteral>)
29/// <Identifier>        := [a-zA-Z]+
30/// <ArgumentList>      := <Expression> | <Expression>,<ArgumentList>
31/// \endcode
32//
33//===----------------------------------------------------------------------===//
34
35#ifndef LLVM_CLANG_ASTMATCHERS_DYNAMIC_PARSER_H
36#define LLVM_CLANG_ASTMATCHERS_DYNAMIC_PARSER_H
37
38#include "clang/ASTMatchers/ASTMatchersInternal.h"
39#include "clang/ASTMatchers/Dynamic/Registry.h"
40#include "clang/ASTMatchers/Dynamic/VariantValue.h"
41#include "llvm/ADT/ArrayRef.h"
42#include "llvm/ADT/Optional.h"
43#include "llvm/ADT/StringMap.h"
44#include "llvm/ADT/StringRef.h"
45#include <utility>
46#include <vector>
47
48namespace clang {
49namespace ast_matchers {
50namespace dynamic {
51
52class Diagnostics;
53
54/// Matcher expression parser.
55class Parser {
56public:
57  /// Interface to connect the parser with the registry and more.
58  ///
59  /// The parser uses the Sema instance passed into
60  /// parseMatcherExpression() to handle all matcher tokens. The simplest
61  /// processor implementation would simply call into the registry to create
62  /// the matchers.
63  /// However, a more complex processor might decide to intercept the matcher
64  /// creation and do some extra work. For example, it could apply some
65  /// transformation to the matcher by adding some id() nodes, or could detect
66  /// specific matcher nodes for more efficient lookup.
67  class Sema {
68  public:
69    virtual ~Sema();
70
71    /// Process a matcher expression.
72    ///
73    /// All the arguments passed here have already been processed.
74    ///
75    /// \param Ctor A matcher constructor looked up by lookupMatcherCtor.
76    ///
77    /// \param NameRange The location of the name in the matcher source.
78    ///   Useful for error reporting.
79    ///
80    /// \param BindID The ID to use to bind the matcher, or a null \c StringRef
81    ///   if no ID is specified.
82    ///
83    /// \param Args The argument list for the matcher.
84    ///
85    /// \return The matcher objects constructed by the processor, or a null
86    ///   matcher if an error occurred. In that case, \c Error will contain a
87    ///   description of the error.
88    virtual VariantMatcher actOnMatcherExpression(MatcherCtor Ctor,
89                                                  SourceRange NameRange,
90                                                  StringRef BindID,
91                                                  ArrayRef<ParserValue> Args,
92                                                  Diagnostics *Error) = 0;
93
94    /// Look up a matcher by name.
95    ///
96    /// \param MatcherName The matcher name found by the parser.
97    ///
98    /// \return The matcher constructor, or Optional<MatcherCtor>() if not
99    /// found.
100    virtual llvm::Optional<MatcherCtor>
101    lookupMatcherCtor(StringRef MatcherName) = 0;
102
103    /// Compute the list of completion types for \p Context.
104    ///
105    /// Each element of \p Context represents a matcher invocation, going from
106    /// outermost to innermost. Elements are pairs consisting of a reference to
107    /// the matcher constructor and the index of the next element in the
108    /// argument list of that matcher (or for the last element, the index of
109    /// the completion point in the argument list). An empty list requests
110    /// completion for the root matcher.
111    virtual std::vector<ArgKind> getAcceptedCompletionTypes(
112        llvm::ArrayRef<std::pair<MatcherCtor, unsigned>> Context);
113
114    /// Compute the list of completions that match any of
115    /// \p AcceptedTypes.
116    ///
117    /// \param AcceptedTypes All types accepted for this completion.
118    ///
119    /// \return All completions for the specified types.
120    /// Completions should be valid when used in \c lookupMatcherCtor().
121    /// The matcher constructed from the return of \c lookupMatcherCtor()
122    /// should be convertible to some type in \p AcceptedTypes.
123    virtual std::vector<MatcherCompletion>
124    getMatcherCompletions(llvm::ArrayRef<ArgKind> AcceptedTypes);
125  };
126
127  /// Sema implementation that uses the matcher registry to process the
128  ///   tokens.
129  class RegistrySema : public Parser::Sema {
130  public:
131    ~RegistrySema() override;
132
133    llvm::Optional<MatcherCtor>
134    lookupMatcherCtor(StringRef MatcherName) override;
135
136    VariantMatcher actOnMatcherExpression(MatcherCtor Ctor,
137                                          SourceRange NameRange,
138                                          StringRef BindID,
139                                          ArrayRef<ParserValue> Args,
140                                          Diagnostics *Error) override;
141
142    std::vector<ArgKind> getAcceptedCompletionTypes(
143        llvm::ArrayRef<std::pair<MatcherCtor, unsigned>> Context) override;
144
145    std::vector<MatcherCompletion>
146    getMatcherCompletions(llvm::ArrayRef<ArgKind> AcceptedTypes) override;
147  };
148
149  using NamedValueMap = llvm::StringMap<VariantValue>;
150
151  /// Parse a matcher expression.
152  ///
153  /// \param MatcherCode The matcher expression to parse.
154  ///
155  /// \param S The Sema instance that will help the parser
156  ///   construct the matchers. If null, it uses the default registry.
157  ///
158  /// \param NamedValues A map of precomputed named values.  This provides
159  ///   the dictionary for the <NamedValue> rule of the grammar.
160  ///   If null, it is ignored.
161  ///
162  /// \return The matcher object constructed by the processor, or an empty
163  ///   Optional if an error occurred. In that case, \c Error will contain a
164  ///   description of the error.
165  ///   The caller takes ownership of the DynTypedMatcher object returned.
166  static llvm::Optional<DynTypedMatcher>
167  parseMatcherExpression(StringRef &MatcherCode, Sema *S,
168                         const NamedValueMap *NamedValues, Diagnostics *Error);
169  static llvm::Optional<DynTypedMatcher>
170  parseMatcherExpression(StringRef &MatcherCode, Sema *S, Diagnostics *Error) {
171    return parseMatcherExpression(MatcherCode, S, nullptr, Error);
172  }
173  static llvm::Optional<DynTypedMatcher>
174  parseMatcherExpression(StringRef &MatcherCode, Diagnostics *Error) {
175    return parseMatcherExpression(MatcherCode, nullptr, Error);
176  }
177
178  /// Parse an expression.
179  ///
180  /// Parses any expression supported by this parser. In general, the
181  /// \c parseMatcherExpression function is a better approach to get a matcher
182  /// object.
183  ///
184  /// \param S The Sema instance that will help the parser
185  ///   construct the matchers. If null, it uses the default registry.
186  ///
187  /// \param NamedValues A map of precomputed named values.  This provides
188  ///   the dictionary for the <NamedValue> rule of the grammar.
189  ///   If null, it is ignored.
190  static bool parseExpression(StringRef &Code, Sema *S,
191                              const NamedValueMap *NamedValues,
192                              VariantValue *Value, Diagnostics *Error);
193  static bool parseExpression(StringRef &Code, Sema *S, VariantValue *Value,
194                              Diagnostics *Error) {
195    return parseExpression(Code, S, nullptr, Value, Error);
196  }
197  static bool parseExpression(StringRef &Code, VariantValue *Value,
198                              Diagnostics *Error) {
199    return parseExpression(Code, nullptr, Value, Error);
200  }
201
202  /// Complete an expression at the given offset.
203  ///
204  /// \param S The Sema instance that will help the parser
205  ///   construct the matchers. If null, it uses the default registry.
206  ///
207  /// \param NamedValues A map of precomputed named values.  This provides
208  ///   the dictionary for the <NamedValue> rule of the grammar.
209  ///   If null, it is ignored.
210  ///
211  /// \return The list of completions, which may be empty if there are no
212  /// available completions or if an error occurred.
213  static std::vector<MatcherCompletion>
214  completeExpression(StringRef &Code, unsigned CompletionOffset, Sema *S,
215                     const NamedValueMap *NamedValues);
216  static std::vector<MatcherCompletion>
217  completeExpression(StringRef &Code, unsigned CompletionOffset, Sema *S) {
218    return completeExpression(Code, CompletionOffset, S, nullptr);
219  }
220  static std::vector<MatcherCompletion>
221  completeExpression(StringRef &Code, unsigned CompletionOffset) {
222    return completeExpression(Code, CompletionOffset, nullptr);
223  }
224
225private:
226  class CodeTokenizer;
227  struct ScopedContextEntry;
228  struct TokenInfo;
229
230  Parser(CodeTokenizer *Tokenizer, Sema *S,
231         const NamedValueMap *NamedValues,
232         Diagnostics *Error);
233
234  bool parseBindID(std::string &BindID);
235  bool parseExpressionImpl(VariantValue *Value);
236  bool parseMatcherExpressionImpl(const TokenInfo &NameToken,
237                                  VariantValue *Value);
238  bool parseIdentifierPrefixImpl(VariantValue *Value);
239
240  void addCompletion(const TokenInfo &CompToken,
241                     const MatcherCompletion &Completion);
242  void addExpressionCompletions();
243
244  std::vector<MatcherCompletion>
245  getNamedValueCompletions(ArrayRef<ArgKind> AcceptedTypes);
246
247  CodeTokenizer *const Tokenizer;
248  Sema *const S;
249  const NamedValueMap *const NamedValues;
250  Diagnostics *const Error;
251
252  using ContextStackTy = std::vector<std::pair<MatcherCtor, unsigned>>;
253
254  ContextStackTy ContextStack;
255  std::vector<MatcherCompletion> Completions;
256};
257
258} // namespace dynamic
259} // namespace ast_matchers
260} // namespace clang
261
262#endif // LLVM_CLANG_AST_MATCHERS_DYNAMIC_PARSER_H
263