Rmatch

Summary

This is a KISS/YAGNI regex validator. Supports 95% of commonly used regex syntax.

It is faster in matching than the original C reg_exec. Also excluding compilation (reg_comp).
It extracts contents.
Original concept is from Rob Pike and mentioned in the book "Beautiful Code" written by Andy Oram and Greg Wilson.

Supported functions

Support for:

Extracting matched data.
".". Match anything. Does work in combination with greedy matching.
"^". Match must start at beginning.
"+". Match must contain one or more of previous character. Greedy.
"*". Match must contain zero or more of previous character. Greedy.
"[abc]". Match one of these chars. Does NOT work in combination with greedy matching (*+).

Usage matching

rmatch(char * expr, char ** str) is the main function. It returns int[3]. If you have a char * as str argument, don't forget to add the &. The return value contains:

result[0] // 1 if validated. Else 0.
result[1] // match start.
result[2] // match length.

Usage extracting

rmatch_extract(char * expr, char * str) is the main function. It returns char * or NULL. If you have a char * as str argument, don't forget to add the &. You can use it in a loop since it uses the pointer of the input string:

char * str = "testtest";
char * expr = "t.*t";
// Two times it equals to "test"
assert(!strcmp(rmatch_extract(expr, &str), "test"));
assert(!strcmp(rmatch_extract(expr, &str), "test"));
// Third time it equals to NULL
assert(!rmatch_extract(expr, &str));

Other example:

char * str = "testtest";
char * expr = "t.*t";
char * result = NULL;
// Loops until NULL
while((result = rmatch_extract(expr, &str), "test")){
    printf("Found: \"%s\"\n", result);
}
// Be sure last result is invalid
assert(!result);

Tests / examples