str.ion

import libc {...}

struct StrLinesIter {
    next: char const*;
    start: char const*;
    end: char const*;
}

func str_lines(str: char const*): StrLinesIter {
    return {next = str};
}

func str_lines_next(iter: StrLinesIter*): bool {
    if (!*iter.next) {
        return false;
    }
    iter.start = iter.next;
    iter.end = iter.next;
    while (*iter.end && *iter.end != '\n') {
        iter.end++;
    }
    iter.next = *iter.end ? iter.end + 1 : iter.end;
    return true;
}

struct StrWordsIter {
    next: char const*;
    start: char const*;
    end: char const*;
}

func str_words(str: char const*): StrWordsIter {
    return {next = str};
}

func str_words_next(iter: StrWordsIter*): bool {
    iter.start = iter.next;
    while (isspace(*iter.start)) {
        iter.start++;
    }
    if (!*iter.start) {
        return false;
    }
    iter.end = iter.start;
    while (*iter.end && !isspace(*iter.end)) {
        iter.end++;
    }
    iter.next = *iter.end ? iter.end + 1 : iter.end;
    return true;
}

struct StrTokensIter {
    next: char const*;
    delims: char const*;
    start: char const*;
    end: char const*;
}

func str_tokens(str: char const*, delims: char const*): StrTokensIter {
    return {next = str, delims = delims};
}

func str_contains(str: char const*, c: char): bool {
    while (*str) {
        if (*str == c) {
            return true;
        }
        str++;
    }
    return false;
}

func str_tokens_next(iter: StrTokensIter*): bool {
    iter.start = iter.next;
    while (str_contains(iter.delims, *iter.start)) {
        iter.start++;
    }
    if (!*iter.start) {
        return false;
    }
    iter.end = iter.start;
    while (*iter.end && !str_contains(iter.delims, *iter.end)) {
        iter.end++;
    }
    iter.next = *iter.end ? iter.end + 1 : iter.end;
    return true;
}

func main(argc: int, argv: char**): int {
    str := " first\n\n  \nsecond\nthird";
    for (it := str_lines(str); str_lines_next(&it)) {
        printf("'%.*s'\n", it.end - it.start, it.start);
    }
    str = "   first second\r  third\n\t  fourth  ";
    for (it := str_words(str); str_words_next(&it)) {
        printf("'%.*s'\n", it.end - it.start, it.start);
    }
    for (it := str_tokens(str, " \t\n\r"); str_tokens_next(&it)) {
        printf("'%.*s'\n", it.end - it.start, it.start);
    }
    return 0;
}