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

struct exp* mk_exp( char* s )	/* makes *any* expression */
{
    struct exp* ret,
	* pret,
	* tmp;
    char* buf;
    int simp,
	c,
	fst;
    simp = issimp( s );
    c = fst = 0;
    pret = exp_alloc();
    buf = malloc( sizeof ( char ) * ( max_args( s ) + 1 ) );
    if ( !simp )
	return mk_simp_exp( s );
    else
    {
	for( ; isspace( *s ); s++ );
	for ( ; *s++; )
	{
	    if ( *s == '(' )
	    {
		if ( !fst )
		{
		    ret = mk_exp( s );
		    fst = 1;
		}
		else
		    exp_add( ret, mk_exp( s ) );
		for ( ; *s++ != ')'; ); s++;
	    }
	    else if ( isspace( *s ) && c || *s == ')' )
	    {
		buf[c] = '\0';
		c = 0;
		if ( !fst )
		{
		    ret = exp_alloc();
		    exp_car_set( B_NODE, ret, 
				 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( ret, tmp );
		}
		if ( *s == ')' )
		    break;
	    }
	    else
		buf[c++] = *s;
	}
    }
    exp_car_set( L_NODE, pret, ret );
    free( buf );
    return pret;
}
struct exp* mk_simp_exp( char* s ) /* unsafe */
{
    char* buf;			/* temporarily holds individual args */
    int c,
	fst;
    struct exp* ret, 
	* pret, 
	* tmp;
    pret = exp_alloc();
    buf = malloc( sizeof ( char ) * ( max_args( s ) + 1 ) ); 
    for( ; isspace( *s ); s++ );
    for( c = fst = 0; *s++;  )
	if ( isspace( *s ) && c || *s == ')' )
	{
	    buf[c] = '\0';
	    c = 0;
	    if ( !fst )
	    {
		ret = exp_alloc();
		exp_car_set( B_NODE, ret, 
			     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( ret, tmp );
	    }
	    if ( *s == ')' ) 	/* inelegant piece of crap */
		break;
	}
	else 
	    buf[c++] = *s;
    exp_car_set( L_NODE, pret, ret );
    free( buf );
    return pret;
}
int max_args( char* s )		/* returns the longest argument length */
{
    int c, d;
    c = d = 0;
    for( ; isspace( *s ); s++ );
    for ( ; *s++; )
	if ( *s == '(' )
	    for ( ; *s++ != ')'; ); /* we just skip it */
	else if ( isspace( *s ) || *s == ')' )
	{
	    c = c > d ? c : d;
	    d = 0;
	}
	else
	    d++;
    return c;
}
int issimp( char* s )		/* checks if a list only consists of atoms */
{
    int n;
    n = 0;
    for ( ; *s != ')'; s++ )
        if ( *s == '(' )
            n++;
    return n - 1;
}