decomment.c   [plain text]


/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.0 (the 'License').  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License."
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * decomment.c
 *
 * Removes all comments and (optionally) whitespace from an input file. 
 * Writes result on stdout.
 */
 
#import <stdio.h>
#import <libc.h>

/*
 * State of input scanner.
 */
typedef enum {
	IS_NORMAL,
	IS_SLASH,		// encountered opening '/'
	IS_IN_COMMENT,		// within / * * / comment
	IS_STAR,		// encountered closing '*'
	IS_IN_END_COMMENT	// within / / comment
} input_state_t;

static volatile void usage(char **argv);

int main(int argc, char **argv)
{
	int fd;
	char bufchar;
	int bytes_read;
	input_state_t input_state = IS_NORMAL;
	int exit_code = 0;
	int remove_whitespace = 0;
	int arg;
	
	if(argc < 2)
		usage(argv);
	for(arg=2; arg<argc; arg++) {
		switch(argv[arg][0]) {
		    case 'r':
		    	remove_whitespace++;
			break;
		    default:
		    	usage(argv);
		}
	}	
	
	fd = open(argv[1], O_RDONLY, 0);
	if(fd <= 0) {
		fprintf(stderr, "Error opening %s\n", argv[1]);
		perror("open");
		exit(1);
	}
	for(;;) {
		bytes_read = read(fd, &bufchar, 1);
		if(bytes_read <= 0) {
			if(bytes_read < 0) {
				fprintf(stderr, "Error reading %s\n", argv[1]);
				perror("read");
				exit_code = 1;
			}
			break;
		}
		
		switch(input_state) {
		
		    case IS_NORMAL:
		    	if(bufchar == '/') {
			   	/*
				 * Might be start of a comment.
				 */
				input_state = IS_SLASH;
			}
			else {
				if(!(remove_whitespace && isspace(bufchar))) {
					putchar(bufchar);
				}
			}
			break;
			
		    case IS_SLASH:
		    	switch(bufchar) {
			    case '*':
			    	/*
				 * Start of normal comment.
				 */
				input_state = IS_IN_COMMENT;
				break;
				
			    case '/':
			    	/*
				 * Start of 'to-end-of-line' comment.
				 */
				input_state = IS_IN_END_COMMENT;
				break;
				
			    default:
			    	/*
				 * Not the start of comment. Emit the '/'
				 * we skipped last char in case we were
				 * entering a comment this time, then the
				 * current char.
				 */
				putchar('/');
				if(!(remove_whitespace && isspace(bufchar))) {
					putchar(bufchar);
				}
				input_state = IS_NORMAL;
				break;
			}
			break;
			
		    case IS_IN_COMMENT:
		    	if(bufchar == '*') {
			    	/*
				 * Maybe ending comment...
				 */
			    	input_state = IS_STAR;
			}
		    	break;
	
	
		    case IS_STAR:
		    	switch(bufchar) {
			    case '/':
				/*
				 * End of normal comment.
				 */
				input_state = IS_NORMAL;
				break;
				
			    case '*':
			    	/*
				 * Still could be one char away from end
				 * of comment.
				 */
				break;
				
			    default:
			    	/*
				 * Still inside comment, no end in sight.
				 */
				input_state = IS_IN_COMMENT;
				break;
			}
			break;
			
		    case IS_IN_END_COMMENT:
		    	if(bufchar == '\n') {
				/*
				 * End of comment. Emit the newline if 
				 * appropriate.
				 */
				if(!remove_whitespace) {
					putchar(bufchar);
				}
				input_state = IS_NORMAL;
			}
			break;
		
		} /* switch input_state */
	} 	  /* main read loop */
	
	/*
	 * Done.
	 */
	return(exit_code);
}

static volatile void usage(char **argv)
{
	printf("usage: %s infile [r(emove whitespace)]\n", argv[0]);
	exit(1);
}