Regular expressions are very useful to describe a formal language. We made a small library that converts a given regular expression into a language (represented by a DFA). Then, several functions helps you to find occurrences of a valid sentence for this language.
int re_compile(t_regex *regex, const char *str);
size_t re_execute(t_regex *regex, const char *str, size_t nmatch, t_rematch *pmatch);
int re_nextmatch(t_regex *regex, const char *str, char **saveptr, t_rematch *match);
int re_fullmatch(t_regex *regex, const char *str);
size_t re_count(t_regex *regex, const char *str);
void re_free(t_regex *regex);# Download & compile the project
git clone https://github.com/lfalkau/libregex
cd libregex
make
# Optionally install it
make install| Character classes | Special characters | Escape sequences | Groups and ranges | Quantifiers |
|---|---|---|---|---|
\c Control character |
\n New line |
\ Escape following character |
. Any character except newline (\n) |
* 0 or more |
\s Whitespace |
\r Carriage return |
(a❘b) a or b |
+ 1 or more |
|
\S Not whitespace |
\t Tab |
(...) Group |
? 0 or 1 (optional) |
|
\d Digit |
\v Vertical tab |
[abc] Single character (a or b or c) |
||
\D Not digit |
\f Form feed |
[^abc] Single character (not a or b or c) |
||
\w Word |
[a-q] Single character range (a or b ... or q) |
|||
\W Not word |
[A-Z] Single character range (A or B ... or Z) |
|||
\x Hexadecimal digit |
[0-9] Single digit from 0 to 9 |
|||
\O Octal digit |