/* Copyright (C) 1989, 1991, 1993, 1994 Aladdin Enterprises. All rights reserved. */

/* ansi2knr.c */
/* Convert ANSI function declarations to K&R syntax */

/*
ansi2knr is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
to anyone for the consequences of using it or for whether it serves any
particular purpose or works at all, unless he says so in writing.  Refer
to the GNU General Public License for full details.

Everyone is granted permission to copy, modify and redistribute
ansi2knr, but only under the conditions described in the GNU
General Public License.  A copy of this license is supposed to have been
given to you along with ansi2knr so you can know your rights and
responsibilities.  It should be in a file named COPYLEFT.  Among other
things, the copyright notice and this notice must be preserved on all
copies.
*/

/*
 * Usage:
	ansi2knr [-Ovarargs=convert] input_file [output_file]
 * If no output_file is supplied, output goes to stdout.
 * There are no error messages.
 *
 * ansi2knr recognizes function definitions by seeing a non-keyword
 * identifier at the left margin, followed by a left parenthesis,
 * with a right parenthesis as the last character on the line.
 * It will recognize a multi-line header provided that the last character
 * of the last line of the header is a right parenthesis,
 * and no intervening line ends with a left brace or a semicolon.
 * These algorithms ignore whitespace and comments, except that
 * the function name must be the first thing on the line.
 * The following constructs will confuse it:
 *	- Any other construct that starts at the left margin and
 *	    follows the above syntax (such as a macro or function call).
 *	- Macros that tinker with the syntax of the function header.
 *
 * If the -Ovarargs=convert switch is supplied, ansi2knr will attempt to
 * convert a ... argument to va_alist and va_dcl.  If this switch is not
 * supplied, ansi2knr will simply drop any such arguments.
 */

/*
 * The original and principal author of ansi2knr is L. Peter Deutsch
 * <ghost@aladdin.com>.  Other authors are noted in the change history
 * that follows (in reverse chronological order):
	lpd 94-07-16 added some conditionals to help GNU `configure',
		suggested by Francois Pinard <pinard@iro.umontreal.ca>;
		properly erase prototype args in function parameters,
		contributed by Jim Avera <jima@netcom.com>;
		correct error in writeblanks (it shouldn't erase EOLs)
	lpd 89-xx-xx original version
 */

/* Most of the conditionals here are to make ansi2knr work with */
/* the GNU configure machinery. */

#ifdef HAVE_CONFIG_H
# ifdef CONFIG_BROKETS
/*
   We use <config.h> instead of "config.h" so that a compilation
   using -I. -I$srcdir will use ./config.h rather than $srcdir/config.h
   (which it would do because it found this file in $srcdir).
 */
#  include <config.h>
# else
#  include "config.h"
# endif
#endif

#include <stdio.h>
#include <ctype.h>

#ifdef HAVE_CONFIG_H

/*
   For properly autoconfiguring ansi2knr, use AC_CONFIG_HEADER(config.h).
   This will define HAVE_CONFIG_H and so, activate the following lines.
 */

# if STDC_HEADERS || HAVE_STRING_H
#  include <string.h>
# else
#  include <strings.h>
# endif

#else /* not HAVE_CONFIG_H */

/*
   Without AC_CONFIG_HEADER, merely use <string.h> as in the original
   Ghostscript distribution.  This loses on older BSD systems.
 */

# include <string.h>

#endif /* not HAVE_CONFIG_H */

#ifdef STDC_HEADERS
# include <stdlib.h>
#else
/*
   malloc and free should be declared in stdlib.h,
   but if you've got a K&R compiler, they probably aren't.
 */
char *malloc();
void free();
#endif

/* Scanning macros */
#define isidchar(ch) (isalnum(ch) || (ch) == '_')
#define isidfirstchar(ch) (isalpha(ch) || (ch) == '_')

/* Forward references */
char *skipspace();
void writeblanks();
int test1();
int convert1();

/* The main program */
int
main(argc, argv)
    int argc;
    char *argv[];
{	FILE *in, *out;
#define bufsize 5000			/* arbitrary size */
	char *buf;
	char *line;
	int convert_varargs = 0;
	if ( argc > 1 && argv[1][0] == '-' )
	  {	if ( !strcmp(argv[1], "-Ovarargs=convert") )
		  {	convert_varargs = 1;
			argc--;
			argv++;
		  }
		else
		  {	fprintf(stderr, "Unrecognized switch: %s\n", argv[1]);
			exit(1);
		  }
	  }
	switch ( argc )
	   {
	default:
		printf("Usage: ansi2knr [-Ovarargs=convert] input_file [output_file]\n");
		exit(0);
	case 2:
		out = stdout;
		break;
	case 3:
		out = fopen(argv[2], "w");
		if ( out == NULL )
		   {	fprintf(stderr, "Cannot open output file %s\n", argv[2]);
			exit(1);
		   }
	   }
	in = fopen(argv[1], "r");
	if ( in == NULL )
	   {	fprintf(stderr, "Cannot open input file %s\n", argv[1]);
		exit(1);
	   }
	fprintf(out, "#line 1 \"%s\"\n", argv[1]);
	buf = malloc(bufsize);
	line = buf;
	while ( fgets(line, (unsigned)(buf + bufsize - line), in) != NULL )
	   {	switch ( test1(buf) )
		   {
		case 2:			/* a function header */
			convert1(buf, out, 1, convert_varargs);
			break;
		case 1:			/* a function */
			convert1(buf, out, 0, convert_varargs);
			break;
		case -1:		/* maybe the start of a function */
			line = buf + strlen(buf);
			if ( line != buf + (bufsize - 1) ) /* overflow check */
				continue;
			/* falls through */
		default:		/* not a function */
			fputs(buf, out);
			break;
		   }
		line = buf;
	   }
	if ( line != buf ) fputs(buf, out);
	free(buf);
	fclose(out);
	fclose(in);
	return 0;
}

/* Skip over space and comments, in either direction. */
char *
skipspace(p, dir)
    register char *p;
    register int dir;			/* 1 for forward, -1 for backward */
{	for ( ; ; )
	   {	while ( isspace(*p) ) p += dir;
		if ( !(*p == '/' && p[dir] == '*') ) break;
		p += dir;  p += dir;
		while ( !(*p == '*' && p[dir] == '/') )
		   {	if ( *p == 0 ) return p;	/* multi-line comment?? */
			p += dir;
		   }
		p += dir;  p += dir;
	   }
	return p;
}

/*
 * Write blanks over part of a string.
 * Don't overwrite end-of-line characters.
 */
void
writeblanks(start, end)
    char *start;
    char *end;
{	char *p;
	for ( p = start; p < end; p++ )
	  if ( *p != '\r' && *p != '\n' ) *p = ' ';
}

/*
 * Test whether the string in buf is a function definition.
 * The string may contain and/or end with a newline.
 * Return as follows:
 *	0 - definitely not a function definition;
 *	1 - definitely a function definition;
 *	2 - definitely a function prototype (NOT USED);
 *	-1 - may be the beginning of a function definition,
 *		append another line and look again.
 * The reason we don't attempt to convert function prototypes is that
 * Ghostscript's declaration-generating macros look too much like
 * prototypes, and confuse the algorithms.
 */
int
test1(buf)
    char *buf;
{	register char *p = buf;
	char *bend;
	char *endfn;
	int contin;
	if ( !isidfirstchar(*p) )
		return 0;		/* no name at left margin */
	bend = skipspace(buf + strlen(buf) - 1, -1);
	switch ( *bend )
	   {
	case ';': contin = 0 /*2*/; break;
	case ')': contin = 1; break;
	case '{': return 0;		/* not a function */
	default: contin = -1;
	   }
	while ( isidchar(*p) ) p++;
	endfn = p;
	p = skipspace(p, 1);
	if ( *p++ != '(' )
		return 0;		/* not a function */
	p = skipspace(p, 1);
	if ( *p == ')' )
		return 0;		/* no parameters */
	/* Check that the apparent function name isn't a keyword. */
	/* We only need to check for keywords that could be followed */
	/* by a left parenthesis (which, unfortunately, is most of them). */
	   {	static char *words[] =
		   {	"asm", "auto", "case", "char", "const", "double",
			"extern", "float", "for", "if", "int", "long",
			"register", "return", "short", "signed", "sizeof",
			"static", "switch", "typedef", "unsigned",
			"void", "volatile", "while", 0
		   };
		char **key = words;
		char *kp;
		int len = endfn - buf;
		while ( (kp = *key) != 0 )
		   {	if ( strlen(kp) == len && !strncmp(kp, buf, len) )
				return 0;	/* name is a keyword */
			key++;
		   }
	   }
	return contin;
}

/* Convert a recognized function definition or header to K&R syntax. */
int
convert1(buf, out, header, convert_varargs)
    char *buf;
    FILE *out;
    int header;			/* Boolean */
    int convert_varargs;	/* Boolean */
{	char *endfn;
	register char *p;
	char **breaks;
	unsigned num_breaks = 2;	/* for testing */
	char **btop;
	char **bp;
	char **ap;
	char *vararg = 0;
	/* Pre-ANSI implementations don't agree on whether strchr */
	/* is called strchr or index, so we open-code it here. */
	for ( endfn = buf; *(endfn++) != '('; ) ;
top:	p = endfn;
	breaks = (char **)malloc(sizeof(char *) * num_breaks * 2);
	if ( breaks == 0 )
	   {	/* Couldn't allocate break table, give up */
		fprintf(stderr, "Unable to allocate break table!\n");
		fputs(buf, out);
		return -1;
	   }
	btop = breaks + num_breaks * 2 - 2;
	bp = breaks;
	/* Parse the argument list */
	do
	   {	int level = 0;
		char *lp = NULL;
		char *rp;
		char *end = NULL;
		if ( bp >= btop )
		   {	/* Filled up break table. */
			/* Allocate a bigger one and start over. */
			free((char *)breaks);
			num_breaks <<= 1;
			goto top;
		   }
		*bp++ = p;
		/* Find the end of the argument */
		for ( ; end == NULL; p++ )
		   {	switch(*p)
			   {
			case ',':
				if ( !level ) end = p;
				break;
			case '(':
				if ( !level ) lp = p;
				level++;
				break;
			case ')':
				if ( --level < 0 ) end = p;
				else rp = p;
				break;
			case '/':
				p = skipspace(p, 1) - 1;
				break;
			default:
				;
			   }
		   }
		/* Erase any embedded prototype parameters. */
		if ( lp )
		  writeblanks(lp + 1, rp);
		p--;			/* back up over terminator */
		/* Find the name being declared. */
		/* This is complicated because of procedure and */
		/* array modifiers. */
		for ( ; ; )
		   {	p = skipspace(p - 1, -1);
			switch ( *p )
			   {
			case ']':	/* skip array dimension(s) */
			case ')':	/* skip procedure args OR name */
			   {	int level = 1;
				while ( level )
				 switch ( *--p )
				   {
				case ']': case ')': level++; break;
				case '[': case '(': level--; break;
				case '/': p = skipspace(p, -1) + 1; break;
				default: ;
				   }
			   }
				if ( *p == '(' && *skipspace(p + 1, 1) == '*' )
				   {	/* We found the name being declared */
					while ( !isidfirstchar(*p) )
						p = skipspace(p, 1) + 1;
					goto found;
				   }
				break;
			default: goto found;
			   }
		   }
found:		if ( *p == '.' && p[-1] == '.' && p[-2] == '.' )
		  {	if ( convert_varargs )
			  {	*bp++ = "va_alist";
				vararg = p-2;
			  }
			else
			  {	p++;
				if ( bp == breaks + 1 )	/* sole argument */
				  writeblanks(breaks[0], p);
				else
				  writeblanks(bp[-1] - 1, p);
				bp--;
			  }
		   }
		else
		   {	while ( isidchar(*p) ) p--;
			*bp++ = p+1;
		   }
		p = end;
	   }
	while ( *p++ == ',' );
	*bp = p;
	/* Make a special check for 'void' arglist */
	if ( bp == breaks+2 )
	   {	p = skipspace(breaks[0], 1);
		if ( !strncmp(p, "void", 4) )
		   {	p = skipspace(p+4, 1);
			if ( p == breaks[2] - 1 )
			   {	bp = breaks;	/* yup, pretend arglist is empty */
				writeblanks(breaks[0], p + 1);
			   }
		   }
	   }
	/* Put out the function name and left parenthesis. */
	p = buf;
	while ( p != endfn ) putc(*p, out), p++;
	/* Put out the declaration. */
	if ( header )
	  {	fputs(");", out);
		for ( p = breaks[0]; *p; p++ )
		  if ( *p == '\r' || *p == '\n' )
		    putc(*p, out);
	  }
	else
	  {	for ( ap = breaks+1; ap < bp; ap += 2 )
		  {	p = *ap;
			while ( isidchar(*p) )
			  putc(*p, out), p++;
			if ( ap < bp - 1 )
			  fputs(", ", out);
		  }
		fputs(")  ", out);
		/* Put out the argument declarations */
		for ( ap = breaks+2; ap <= bp; ap += 2 )
		  (*ap)[-1] = ';';
		if ( vararg != 0 )
		  {	*vararg = 0;
			fputs(breaks[0], out);		/* any prior args */
			fputs("va_dcl", out);		/* the final arg */
			fputs(bp[0], out);
		  }
		else
		  fputs(breaks[0], out);
	  }
	free((char *)breaks);
	return 0;
}
