1 //===-- Regex.h - Regular Expression matcher implementation -*- 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 implements a POSIX regular expression matcher.  Both Basic and
11 // Extended POSIX regular expressions (ERE) are supported.  EREs were extended
12 // to support backreferences in matches.
13 // This implementation also supports matching strings with embedded NUL chars.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_SUPPORT_REGEX_H
18 #define LLVM_SUPPORT_REGEX_H
19 
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 {
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 
46     /// Compiles the given regular expression \p Regex.
47     Regex(StringRef Regex, unsigned Flags = NoFlags);
48     Regex(const Regex &) = delete;
49     Regex &operator=(Regex regex) {
50       std::swap(preg, regex.preg);
51       std::swap(error, regex.error);
52       return *this;
53     }
Regex(Regex && regex)54     Regex(Regex &&regex) {
55       preg = regex.preg;
56       error = regex.error;
57       regex.preg = nullptr;
58     }
59     ~Regex();
60 
61     /// isValid - returns the error encountered during regex compilation, or
62     /// matching, if any.
63     bool isValid(std::string &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     /// This returns true on a successful match.
77     bool match(StringRef String, SmallVectorImpl<StringRef> *Matches = nullptr);
78 
79     /// sub - Return the result of replacing the first match of the regex in
80     /// \p String with the \p Repl string. Backreferences like "\0" in the
81     /// replacement string are replaced with the appropriate match substring.
82     ///
83     /// Note that the replacement string has backslash escaping performed on
84     /// it. Invalid backreferences are ignored (replaced by empty strings).
85     ///
86     /// \param Error If non-null, any errors in the substitution (invalid
87     /// backreferences, trailing backslashes) will be recorded as a non-empty
88     /// string.
89     std::string sub(StringRef Repl, StringRef String,
90                     std::string *Error = nullptr);
91 
92     /// \brief If this function returns true, ^Str$ is an extended regular
93     /// expression that matches Str and only Str.
94     static bool isLiteralERE(StringRef Str);
95 
96     /// \brief Turn String into a regex by escaping its special characters.
97     static std::string escape(StringRef String);
98 
99   private:
100     struct llvm_regex *preg;
101     int error;
102   };
103 }
104 
105 #endif // LLVM_SUPPORT_REGEX_H
106