main.c

/*
 * This file is licensed under BSD 3-Clause.
 * All license information is available in the included COPYING file.
 */

/*
 * main.c
 *
 * Author       : Finn Rayment <finn@rayment.fr>
 * Date created : 21/07/2022
 */

#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <readline/readline.h>
#include <readline/history.h>

#include "y.tab.h"

extern int yyended;
extern int yyrunning;
extern void switch_to_buffer(char *);
extern void clean_buffer();
extern char *argv_parse_redirect(int, char **);
extern void argv_parse_cleanup(void);

void
help(void)
{
	fprintf(stdout, "Usage: calc [OPTION]... [EQUATION]\n");
	fprintf(stdout, "Lightweight command-line calculator.\n\n");
	fprintf(stdout, "    -h               show this help message and exit\n");
	fprintf(stdout, "    -v               print the proram version and exit\n");
	fprintf(stdout, "\n");
	fprintf(stdout, "If no equation is given, then the program will be opened\n"
	                "in interactive mode.\n");
	fprintf(stdout, "\n");
	fprintf(stdout, "Copyright (c) 2022, Finn Rayment\n");
	fprintf(stdout, "This software is licensed under BSD 3-clause.\n");
}

void
version(void)
{
	fprintf(stdout, "calc-%s\n", VERSION);
}

int
main(int argc,
     char **argv)
{
	int c, redirect;
	char *argv_buf, *in, *in2;
	size_t len;

	in = NULL;
	in2 = NULL;
	len = 0;

	while ((c = getopt(argc, argv, "hv")) != -1)
	{
		switch (c)
		{
		case 'h':
			help();
			return EXIT_SUCCESS;
		case 'v':
			version();
			return EXIT_SUCCESS;
		case '?':
			if (isprint(optopt))
				fprintf(stderr, "Unknown option '-%c'.\n", optopt);
			else
				fprintf(stderr, "Unknown option character '\\x%x'.\n", optopt);
			return EXIT_FAILURE;
		default:
			abort();
		}
	}

	redirect = optind < argc;

	if (redirect)
	{
		argv_buf = argv_parse_redirect(argc, argv);
		fprintf(stdout, "> %s\n", argv_buf);
	}

	while (yyrunning)
	{
		if (!redirect)
		{
			in = readline("> ");
			if (!in)
				break; /* eof */
			len = strlen(in);
			/* add a newline to cause input to ask again.
			 * if we don't do this, yyparse() will act like there is an eof. */
			in2 = (char *) malloc((len+2) * sizeof(char));
			memcpy(in2, in, sizeof(char) * len);
			*(in2+len) = '\n';
			*(in2+len+1) = '\0';
			switch_to_buffer(in2);
		}
		yyparse();
		if (!redirect)
		{
			add_history(in);
			clean_buffer();
			free(in2);
			free(in);
			in = NULL;
			in2 = NULL;
		}
	}

	if (redirect)
		argv_parse_cleanup();

	clear_history();

	return EXIT_SUCCESS;
}