lazysphere/command/echo.c

#include "command.h"
#include "lslib.h"

#include <stdlib.h>

static struct {
    bool escape_codes;
    bool newline;
} flags;

static void print_with_escape_codes(const char* str) {
    
    size_t index = 0;
    char n;

    while (true) {
        char c = str[index];
        index++;

        if (c == '\0') break;
        if (c != '\\') {
            putchar(c);
            continue;
        }

        n = str[index];
        index++;

        switch (n) {
            case '\\':
                putchar('\\');
                break;
            case 'b':
                putchar('\b');
                break;
            case 'c':
                exit(EXIT_SUCCESS);
            case 'n':
                putchar('\n');
                break;
            case 'r':
                putchar('\r');
                break;
            case 't':
                putchar('\t');
                break;
            case 'v':
                putchar('\v');
                break;
            default:
                putchar(c);
                putchar(n);
        }
    }
}

static int short_arg(char c, char* next) {
    UNUSED(next);
    switch (c) {
        case 'e':
            flags.escape_codes = true;
            break;
        case 'E':
            flags.escape_codes = false;
            break;
        case 'n':
            flags.newline = false;
            break;
        default:
            flags.newline = true;
            flags.escape_codes = false;
            return ARG_IGNORE;
    };
    return ARG_UNUSED;
}

COMMAND(echo) {

    int start, i;

    if (argc < 1) {
        return EXIT_SUCCESS;
    }

    flags.escape_codes = false;
    flags.newline = true;

    start = parse_args(argc, argv, NULL, short_arg, NULL);

    for (i = start; i < argc; i++) {
         if (flags.escape_codes) {
            print_with_escape_codes(argv[i]);
        } else {
            printf("%s", argv[i]);
        }

        if (i + 1 != argc) {
            putchar(' ');
        }
    } 

    if (flags.newline) {
        putchar('\n');
    }

    return EXIT_SUCCESS;
}