/* 
 * uncomment.c
 * Copyright 2002-2003, Kimmo Kulovesi <http://arkku.com/>
 *
 * A program to remove all comments from a C program. Supports
 * C99 and C++ -style doubleslash comments. Should also work on
 * similar languages, like Objective C and Java.
 * 
 * Perverse line continuation with backslashes can sometimes
 * confuse this, but some support is included for that, too.
 */

#include <stdio.h>
#include <stdlib.h>


enum STATE {
    GOT_SLASH,
    CONT_SLASH,
    NORMAL,
    POSSIBLE_CONT_SLASH,
    IN_COMMENT,
    IN_COMMENT_GOT_ASTERISK_BACKSLASH,
    IN_COMMENT_GOT_ASTERISK,
    IN_COMMENT_UNTIL_EOL,
    IN_COMMENT_UNTIL_EOL_GOT_BACKSLASH,
    IN_STRING = '\"',
    IN_CHAR_CONST = '\'',
    IN_STRING_BACKSLASH = '\"' + 1,
    IN_CHAR_CONST_BACKSLASH = '\'' + 1
};


int
main(void)
{
    int c;
    enum STATE state = NORMAL;

    while ((c = getchar()) != EOF) {
	switch (state) {
	case CONT_SLASH:
	case GOT_SLASH:
	    if (c == '*') {
		state = IN_COMMENT;
		break;
	    } else if (c == '/') {
		state = IN_COMMENT_UNTIL_EOL;
		break;

	    } else if (c == '\\' && state != CONT_SLASH) {
		state = POSSIBLE_CONT_SLASH;
		break;
	    }
	    (void) putchar('/');
	    if (state == CONT_SLASH) {
		(void) putchar('\\');
		(void) putchar('\n');
	    }
	    state = NORMAL;

	    /*
	     * FALLTHROUGH 
	     */

	case NORMAL:
	    if (c == '/') {
		state = GOT_SLASH;
		break;
	    }

	    if (c == '\"' || c == '\'')
		state = c;

	    (void) putchar(c);
	    break;

	case POSSIBLE_CONT_SLASH:	/* backslash after a slash */
	    if (c == '\n') {
		state = CONT_SLASH;
	    } else {
		state = NORMAL;
		(void) putchar('/');
		(void) putchar('\\');
	    }
	    break;

	case IN_COMMENT:
	    if (c == '*')
		state = IN_COMMENT_GOT_ASTERISK;
	    break;

	case IN_COMMENT_GOT_ASTERISK_BACKSLASH:
	    if (c == '\n' || c == '*')
		state = IN_COMMENT_GOT_ASTERISK;
	    else
		state = IN_COMMENT;
	    break;

	case IN_COMMENT_GOT_ASTERISK:
	    if (c == '/')
		state = NORMAL;
	    else if (c == '\\')
		state = IN_COMMENT_GOT_ASTERISK_BACKSLASH;
	    else if (c != '*')
		state = IN_COMMENT;
	    break;

	case IN_COMMENT_UNTIL_EOL:
	    if (c == '\\') {
		state = IN_COMMENT_UNTIL_EOL_GOT_BACKSLASH;
	    } else if (c == '\n') {
		(void) putchar('\n');
		state = NORMAL;
	    }
	    break;

	case IN_COMMENT_UNTIL_EOL_GOT_BACKSLASH:
	    if (c != '\\')
		state = IN_COMMENT_UNTIL_EOL;
	    break;

	case IN_STRING:
	case IN_CHAR_CONST:
	    if (c == '\\')
		state++;	/* -> to the matching backslash state */
	    else if (c == state)
		state = NORMAL;
	    (void) putchar(c);
	    break;

	case IN_STRING_BACKSLASH:
	case IN_CHAR_CONST_BACKSLASH:
	    state--;		/* -> to the matching non-backslash state */
	    (void) putchar(c);
	    break;
	}
    }
    return EXIT_SUCCESS;
}