kyaa/kyaa.md

kyaa

super hacky macro hacks for parsing arguments in C.

prerequisites

C99 or greater.

standard library headers:

• errno.h
• stdbool.h
• stdio.h
• string.h

tutorial/API

ensure argc and argv are defined. kyaa doesn't actually care if it's in main() or not.

iterate over the arguments with KYAA_LOOP:

int main(int argc, char *argv[]) {
    KYAA_LOOP {
        // i, kyaa_name, kyaa_read_stdin, and kyaa_flag are exposed here.
        // [other code goes here]
    }
    return 0;
}

use KYAA_BEGIN and KYAA_END to begin parsing arguments. put unrelated code above KYAA_BEGIN or below KYAA_END, but not within:

    KYAA_LOOP {
        // [other code goes here]
        KYAA_BEGIN
        // kyaa_arg and kyaa_etc are exposed here.
        // [kyaa code goes here]
        KYAA_END
        // [other code goes here]
    }

use KYAA_FLAG for defining flags that don't take an argument, and KYAA_FLAG_ARG or KYAA_FLAG_LONG for flags that do:

    bool use_feature = false;
    char *log_fn = "logs.txt";
    long my_var = 0;
    KYAA_LOOP {
        // [other code goes here]
        KYAA_BEGIN

        // arguments: short flag, long flag, help description
        KYAA_FLAG("-x", "--enable-feature",
"        enable some feature")
            use_feature = true;

        // same arguments, but kyaa_etc contains the relevant string.
        KYAA_FLAG_ARG("-l", "--log-file",
"        use a given filename for the log file")
            log_fn = kyaa_etc;

        // same arguments, kyaa_etc is set, but kyaa_flag_arg is also set.
        KYAA_FLAG_LONG("-v", "--var",
"        set an integer variable\n"
"        default: 0")
            my_var = kyaa_flag_arg;

        KYAA_END
        // [other code goes here]
    }

kyaa secretly wraps flag handling in if/else statements with {} blocks. do not confuse it for a switch/case method.

kyaa handles -h and --help for printing help text. additional help text may be defined using KYAA_HELP:

    KYAA_LOOP {
        KYAA_BEGIN
        KYAA_HELP(
"  {files...}\n"
"        do things with files.")
        KYAA_END

        do_stuff(kyaa_arg);
    }

kyaa interprets an argument of "-" as a request to enable reading from stdin: kyaa_read_stdin is set to true.

arguments may be passed in three ways, consider:

• -v42
• -v 42
• --var 42

kyaa returns KYAA_OKAY when -h or --help is given, and KYAA_ERROR in the event of invalid flags, missing arguments, or invalid numbers (KYAA_FLAG_LONG). kyaa uses continue for handling arguments.

kyaa prints error messages to stderr, and help text to stdout.

KYAA_ITER may be redefined to avoid name collisions.

TODO

• support --var=42 argument style
• rename overlapping things, e.g. KYAA_FLAG vs kyaa_flag, KYAA_FLAG_ARG vs kyaa_flag_arg, etc.
• move KYAA_FLAG_ARG to kyaa_extend.h or something; write similar macros.