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