Regex Light

Acknowledgement

The implementation of regex_light started from this great article: https://www.cs.princeton.edu/courses/archive/spr09/cos333/beautiful.html

Features

• (): You can make parenthesized groups for backward reference
• Small and fast
• Portablity: Similar API to stdlib's regex

$Lang

• C.ASCII

Types

• regex_t
• regmatch_t

Functions

• regcomp() # the 3rd arg will be ignored
• regexec()
• regfree()

Expressions

• any literal character
• . ... any single character
• ^ ... beginning of the input
• $ ... end of the input
• * ... zero or more of previous character
• + ... one or more of previous character
• ? ... zero or one of previous character
• [-] ... specified characters, between the two characters
• () ... group for backward reference in regmatch_t
• \. \^ \$ \* \+ \? \[ \( ... escape special characters treating them literals

Expressions which don't work

• ()* ()+ ()? ... but I want to make them work
• (|) ... group OR group
• \1 \2 ... backreference in pattern

Known issues

assert_match("[-a]", "-", 1, "-");
assert_match("[a-]", "-", 1, "-");
assert_match("((ab)cd)e", "abcde", 3, "abcde", "abcd", "ab"); // can not handle nested PAREN
assert_match("(ab)?c", "c", 2, "c", ""); // ()? doesn't work
assert_match("(ab)*c", "abababc", 2, "abababc", "ab"); // ()* doesn't work
assert_match("(ab)+c", "abababc", 2, "abababc", "ab"); // ()+ doesn't work