Compile-time VerbalExpressions

C++ Regular Expressions made easy

CTVE is a C++17 library that helps construct difficult regular expressions. The regular expressions are build at compile time and can be used with compile time or runtime regular expression libraries.

It is based on the ideas of https://github.com/VerbalExpressions and powered by the wish to use Hana Dusíkovás fantastic compile time regular expression library without having to maintain code sprinkled with dozens of hard to read regular expressions.

Try online: https://godbolt.org/z/9j1x75

Example

#include <ctve.hpp>
#include <ctre.hpp>
#include <iostream>

namespace patterns
{
using namespace ctve;

static constexpr auto url =
    "http"
    + maybe('s')
    + "://"
    + maybe("www.")
    + capture(something_not_in(' ', '/', ':'))
    + maybe(':' + capture(digit.one_or_more()))
    + maybe(capture('/' + anything_not_in(' ')));
}

int main()
{
  auto&& [match, host, port, path] 
      = ctre::match<patterns::url>("https://github.com/mrpi/compile-time-verbal-expressions");
  if (match)
  {
    std::cout << "host: " << std::string_view{host} << '\n';
    std::cout << "port: " << std::string_view{port} << '\n';
    std::cout << "path: " << std::string_view{path} << '\n';
  }
}

Syntax

using namespace ctve; expected in following exampels

Code	Matches	PCRE
find('x')	exactly the given character	(?:x)
find("xyz")	exactly the given character sequence	(?:xzy)
'x'	exactly the given character (handled like find('x') by operator+)	(?:x)
"xyz"	exactly the given character sequence (handled like find("xyz") by operator+)	(?:xzy)
maybe('.')	empty string or a single dot	(?:\.)?
maybe(any_char)	empty string or one char	(?:.)?
digit	a single digit	[\d]
digit.one_or_more()	one or more digits	(?:[\d])+
digit.zero_or_more()	zero or more digits	(?:[\d])*
word_char.at_least(2)	two or more word chars	(?:[\w]){2,}
word_char.at_most(3)	up to three word chars	(?:[\w]){0,3}
whitespace.count(2,3)	two or three whitespace chars	(?:[\s]){2,3}
in(digit, range{'a','f'})	a hexadecimal digit	[\da-f]
anything_not_in(' ', '/')	string without spaces and slashes	[^ /]*
something_not_in(digit, '.')	non empty string without digits and dots	[^\d\\.]+
capture(word_char.count(3))	capture three word chars	((?:[\w]){3})
"Hello" + maybe(whitespace)	"Hello" optionally followed by a whitespace	(?:Hello)(?:[\s])?
find("Hello") \|\| "Hallo"	"Hello" or "Hallo"	(?:Hello)\|(?:Hallo)

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