include/llvm/Support/Regex.h

   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