1 //===-- Regex.h - Regular Expression matcher implementation -*- 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 // This file implements a POSIX regular expression matcher.  Both Basic and
10 // Extended POSIX regular expressions (ERE) are supported.  EREs were extended
11 // to support backreferences in matches.
12 // This implementation also supports matching strings with embedded NUL chars.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_SUPPORT_REGEX_H
17 #define LLVM_SUPPORT_REGEX_H
18 
19 #include "llvm/ADT/BitmaskEnum.h"
20 #include <string>
21 
22 struct llvm_regex;
23 
24 namespace llvm {
25   class StringRef;
26   template<typename T> class SmallVectorImpl;
27 
28   class Regex {
29   public:
30     enum RegexFlags : unsigned {
31       NoFlags = 0,
32       /// Compile for matching that ignores upper/lower case distinctions.
33       IgnoreCase = 1,
34       /// Compile for newline-sensitive matching. With this flag '[^' bracket
35       /// expressions and '.' never match newline. A ^ anchor matches the
36       /// null string after any newline in the string in addition to its normal
37       /// function, and the $ anchor matches the null string before any
38       /// newline in the string in addition to its normal function.
39       Newline = 2,
40       /// By default, the POSIX extended regular expression (ERE) syntax is
41       /// assumed. Pass this flag to turn on basic regular expressions (BRE)
42       /// instead.
43       BasicRegex = 4,
44 
45       LLVM_MARK_AS_BITMASK_ENUM(BasicRegex)
46     };
47 
48     Regex();
49     /// Compiles the given regular expression \p Regex.
50     ///
51     /// \param Regex - referenced string is no longer needed after this
52     /// constructor does finish.  Only its compiled form is kept stored.
53     Regex(StringRef Regex, RegexFlags Flags = NoFlags);
54     Regex(StringRef Regex, unsigned Flags);
55     Regex(const Regex &) = delete;
56     Regex &operator=(Regex regex) {
57       std::swap(preg, regex.preg);
58       std::swap(error, regex.error);
59       return *this;
60     }
61     Regex(Regex &&regex);
62     ~Regex();
63 
64     /// isValid - returns the error encountered during regex compilation, if
65     /// any.
66     bool isValid(std::string &Error) const;
67     bool isValid() const { return !error; }
68 
69     /// getNumMatches - In a valid regex, return the number of parenthesized
70     /// matches it contains.  The number filled in by match will include this
71     /// many entries plus one for the whole regex (as element 0).
72     unsigned getNumMatches() const;
73 
74     /// matches - Match the regex against a given \p String.
75     ///
76     /// \param Matches - If given, on a successful match this will be filled in
77     /// with references to the matched group expressions (inside \p String),
78     /// the first group is always the entire pattern.
79     ///
80     /// \param Error - If non-null, any errors in the matching will be recorded
81     /// as a non-empty string. If there is no error, it will be an empty string.
82     ///
83     /// This returns true on a successful match.
84     bool match(StringRef String, SmallVectorImpl<StringRef> *Matches = nullptr,
85                std::string *Error = nullptr) const;
86 
87     /// sub - Return the result of replacing the first match of the regex in
88     /// \p String with the \p Repl string. Backreferences like "\0" in the
89     /// replacement string are replaced with the appropriate match substring.
90     ///
91     /// Note that the replacement string has backslash escaping performed on
92     /// it. Invalid backreferences are ignored (replaced by empty strings).
93     ///
94     /// \param Error If non-null, any errors in the substitution (invalid
95     /// backreferences, trailing backslashes) will be recorded as a non-empty
96     /// string. If there is no error, it will be an empty string.
97     std::string sub(StringRef Repl, StringRef String,
98                     std::string *Error = nullptr) const;
99 
100     /// If this function returns true, ^Str$ is an extended regular
101     /// expression that matches Str and only Str.
102     static bool isLiteralERE(StringRef Str);
103 
104     /// Turn String into a regex by escaping its special characters.
105     static std::string escape(StringRef String);
106 
107   private:
108     struct llvm_regex *preg;
109     int error;
110   };
111 }
112 
113 #endif // LLVM_SUPPORT_REGEX_H
114