/*
* States = 0,1,2, ..., numStates-1
* numStates-2 = Start
* numStates-1 = final
*/
nfa::nfa (string regex) {
num_states = 2; // start & final
alphabet.insert (EPSILON);
// initialize the transitions vector & push start & final states
transitions.resize (2);
transitions[0].resize (MAX_ALPHABET);
transitions[1].resize (MAX_ALPHABET);
// base regular expression
if (regex.length () == 1) {
alphabet.insert (regex[0]);
transitions[0][regex[0]].insert (1);
return;
}
// complex regular expression [DEAL WITH ISSUES IF your 0->1 e-transtion creates]
// epsilon transition
transitions[0][EPSILON].insert (1);
// create the nfa for the nfa
build_nfa (regex);
}
int main(int argc, char** argv) {
// read all used flags
while (1) {
static struct option long_options[] = {
{"invert-match", no_argument, 0, 'v'},
{"line-regexp", no_argument, 0, 'x'},
{"count", no_argument, 0, 'c'},
{"help", no_argument, &display_help, 1},
{"version", no_argument, 0, 'V'},
{"cache-limit", required_argument, 0, OPTION_CACHE_LIMIT},
{0, 0, 0, 0}
};
int option_index = 0;
int c = getopt_long(argc, argv, "vxcV", long_options, &option_index);
if (c == -1) break;
switch (c) {
case 'v': invert_match = true; break;
case 'x': whole_lines = true; break;
case 'c': count_matches = true; break;
case OPTION_CACHE_LIMIT:
cache_mem_limit = parse_size_in_kb(optarg);
if (cache_mem_limit == -1U) {
print_usage(argv[0]);
return 2;
}
break;
case 'V':
display_version = true;
break;
case 0: break;
default:
print_usage(argv[0]);
return 2;
}
}
if (display_help) {
printf(help_message, argv[0]);
return 0;
}
if (display_version) {
printf(version_message);
return 0;
}
// check if there is exactly one regular expression
if (optind != argc-1) {
print_usage(argv[0]);
return 2;
}
char* regex = argv[optind];
// parse the regular expression to abstract syntax tree
struct syntree* tree;
tree = parse(regex, strlen(regex));
// build nfa for the regular expression
struct nfa* nfa;
nfa = build_nfa(tree, whole_lines);
free_tree(tree);
// initialize simulation state
sim_init(&state, nfa, invert_match, cache_mem_limit);
// initialize buffer
uintptr_t buffer_size = 65536;
buffer_init(&buffer, STDIN_FILENO, STDOUT_FILENO, buffer_size);
// main matching loop
uintmax_t match_count = 0;
bool new_line = true;
bool some_match = false;
intptr_t res = buffer_next(&buffer);
if (!count_matches) buffer_mark(&buffer);
while (res == 1) {
// save next input byte to ch
uint_fast8_t ch = buffer_get(&buffer);
if (ch == '\n') {
// handle the end of line here
new_line = true;
// simulate the special line end character
if (!state.dfa_state->accept) sim_step(&state, CHAR_INPUT_END);
if (sim_is_match(&state)) {
// the last line matched, either print it or count it
some_match = true;
if (count_matches) {
++match_count;
} else {
int_fast8_t res = buffer_print(&buffer, true);
if (res != 1) die(2, (res == -1) ? errno : 0,
"Error writing to stdout");
}
}
// reset simulation state
state.dfa_state = state.after_begin;
// read next character from input
res = buffer_next(&buffer);
if (!count_matches) buffer_mark(&buffer);
} else {
new_line = false;
// simulate only if there was no match on the current line
if (!state.dfa_state->accept) {
// if the character is not valid ASCII, no transitions will take place
if (ch > MAX_CHAR) state.dfa_state = state.before_begin;
// otherwise do the simulation
else sim_step(&state, ch);
}
// read next character from input
res = buffer_next(&buffer);
}
}
if (res == -1) die(2, errno, "Error reading from stdin");
// check if there is no \n at the end of the input
// if it is the case, behave as if it was there
if (!new_line) {
if (!state.dfa_state->accept) sim_step(&state, CHAR_INPUT_END);
if (sim_is_match(&state)) {
some_match = true;
if (count_matches) {
++match_count;
} else {
int_fast8_t res = buffer_print(&buffer, false);
puts("");
if (res != 1) die(2, (res == -1) ? errno : 0,
"Error writing to stdout");
}
}
}
// if -c is used, print the count of matches
if (count_matches) {
printf("%" PRIuMAX "\n", match_count);
}
// clean up
buffer_cleanup(&buffer);
sim_cleanup(&state);
free_nfa(nfa);
// return status is based on whether there was a match or not
return some_match ? 0 : 1;
}