/* lisp.c */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "struct.h"
#include "lisp.h"
#include "san.h"


struct exp* mk_exp( char* s )	/* safe */
{
    char* str;
    struct exp* ret;
    str = format_wspace( s );
    ret = unsafe_mk_exp( str );
    free( str );
    return ret;
}
struct exp* unsafe_mk_exp( char* s ) /* builds a simple exp, unsafe, s must be stripped and legal */
{
    char* buf;			/* temporarily stores each arg */
    int pos,
	fst,
	skp;
    struct exp* lst,		/* the lst we make */
	* tmp,	  	
	* ret;			/* what we actually return, a pointer to the list */
    ret = exp_alloc();
    lst = exp_alloc();
    fst = pos = skp = 0; 
    buf = malloc( sizeof ( char ) * ( max_args( s ) + 1 ) );
    for ( ; *s++ != ')'; )
	if ( pos && isspace( *s ) )
	{
	    buf[pos] = '\0';
	    pos = 0;
	    if ( !fst )		/* first elem of the lst */
	    {
		exp_car_set( B_NODE, lst,
			     strcpy( malloc( sizeof ( char ) * ( strlen( buf ) + 1 ) ), buf ) );
		fst = 1;
	    }
	    else
	    {
		tmp = exp_alloc();
		exp_car_set( B_NODE, tmp, 
			     strcpy( malloc( sizeof ( char ) * ( strlen( buf ) + 1 ) ), buf ) );
		exp_add( lst, tmp );
	    }
	}
	else if ( *s == '(' )
	{
	    if ( !fst )
	    {
		exp_car_set( L_NODE, lst, unsafe_mk_exp( s ) );
		fst = 1;
	    }
	    else
		exp_add( lst, unsafe_mk_exp( s ) );
	    for ( skp = 1, s++; skp; s++ )
		if ( *s == '(' )
		    skp++;
		else if ( *s == ')' )
		    skp--;
	}
	else
	    buf[pos++] = *s;
    free( buf );
    exp_car_set( L_NODE, ret, lst );
    return ret;
}