streval.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1982-2010 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                  David Korn <dgk@research.att.com>                   *
*                                                                      *
***********************************************************************/
#pragma prototyped

/*
 * D. G. Korn
 * AT&T Labs
 *
 * arithmetic expression evaluator
 *
 * this version compiles the expression onto a stack
 *	 and has a separate executor
 */

#include	"streval.h"
#include	<ctype.h>
#include	<error.h>
#include	<stak.h>
#include	"FEATURE/externs"
#include	"defs.h"	/* for sh.decomma */

#ifndef ERROR_dictionary
#   define ERROR_dictionary(s)	(s)
#endif
#ifndef SH_DICT
#   define SH_DICT	"libshell"
#endif

#define MAXLEVEL	9
#define SMALL_STACK	12

/*
 * The following are used with tokenbits() macro
 */
#define T_OP		0x3f		/* mask for operator number */
#define T_BINARY	0x40		/* binary operators */
#define T_NOFLOAT	0x80		/* non floating point operator */
#define A_LVALUE	(2*MAXPREC+2)

#define pow2size(x)		((x)<=2?2:(x)<=4?4:(x)<=8?8:(x)<=16?16:(x)<=32?32:64)
#define round(x,size)		(((x)+(size)-1)&~((size)-1))
#define stakpush(v,val,type)	((((v)->offset=round(staktell(),pow2size(sizeof(type)))),\
				stakseek((v)->offset+sizeof(type)), \
				*((type*)stakptr((v)->offset)) = (val)),(v)->offset)
#define roundptr(ep,cp,type)	(((unsigned char*)(ep))+round(cp-((unsigned char*)(ep)),pow2size(sizeof(type))))

static int level;

struct vars				/* vars stacked per invocation */
{
	const char	*expr;		/* current expression */	
	const char	*nextchr;	/* next char in current expression */	
	const char	*errchr; 	/* next char after error	*/
	const char	*errstr;	/* error string			*/
	struct lval	errmsg;	 	/* error message text		*/
	int		offset;		/* offset for pushchr macro	*/
	int		staksize;	/* current stack size needed	*/
	int		stakmaxsize;	/* maximum stack size needed	*/
	unsigned char	paren;	 	/* parenthesis level		*/
	char		infun;	/* incremented by comma inside function	*/
	int		emode;
	Sfdouble_t	(*convert)(const char**,struct lval*,int,Sfdouble_t);
};

typedef Sfdouble_t (*Math_f)(Sfdouble_t,...);
typedef Sfdouble_t (*Math_1f_f)(Sfdouble_t);
typedef int	   (*Math_1i_f)(Sfdouble_t);
typedef Sfdouble_t (*Math_2f_f)(Sfdouble_t,Sfdouble_t);
typedef int        (*Math_2i_f)(Sfdouble_t,Sfdouble_t);
typedef Sfdouble_t (*Math_3f_f)(Sfdouble_t,Sfdouble_t,Sfdouble_t);
typedef int        (*Math_3i_f)(Sfdouble_t,Sfdouble_t,Sfdouble_t);

#define getchr(vp)	(*(vp)->nextchr++)
#define peekchr(vp)	(*(vp)->nextchr)
#define ungetchr(vp)	((vp)->nextchr--)

#if ('a'==97)	/* ASCII encodings */
#   define getop(c)	(((c) >= sizeof(strval_states))? \
				((c)=='|'?A_OR:((c)=='^'?A_XOR:((c)=='~'?A_TILDE:A_REG))):\
				strval_states[(c)])
#else
#   define getop(c)	(isdigit(c)?A_DIG:((c==' '||c=='\t'||c=='\n'||c=='"')?0: \
			(c=='<'?A_LT:(c=='>'?A_GT:(c=='='?A_ASSIGN: \
			(c=='+'?A_PLUS:(c=='-'?A_MINUS:(c=='*'?A_TIMES: \
			(c=='/'?A_DIV:(c=='%'?A_MOD:(c==','?A_COMMA: \
			(c=='&'?A_AND:(c=='!'?A_NOT:(c=='('?A_LPAR: \
			(c==')'?A_RPAR:(c==0?A_EOF:(c==':'?A_COLON: \
			(c=='?'?A_QUEST:(c=='|'?A_OR:(c=='^'?A_XOR: \
			(c=='\''?A_LIT: \
			(c=='.'?A_DOT:(c=='~'?A_TILDE:A_REG)))))))))))))))))))))))
#endif

#define seterror(v,msg)		_seterror(v,ERROR_dictionary(msg))
#define ERROR(vp,msg)		return(seterror((vp),msg))

/*
 * set error message string and return(0)
 */
static int _seterror(struct vars *vp,const char *msg)
{
	if(!vp->errmsg.value)
		vp->errmsg.value = (char*)msg;
	vp->errchr = vp->nextchr;
	vp->nextchr = "";
	level = 0;
	return(0);
}


static void arith_error(const char *message,const char *expr, int mode)
{
        level = 0;
	mode = (mode&3)!=0;
        errormsg(SH_DICT,ERROR_exit(mode),message,expr);
}

#if _ast_no_um2fm
static Sfdouble_t U2F(Sfulong_t u)
{
	Sflong_t	s = u;
	Sfdouble_t	f;

	if (s >= 0)
		return s;
	s = u / 2;
	f = s;
	f *= 2;
	if (u & 1)
		f++;
	return f;
}
#else
#define U2F(x)		x
#endif

Sfdouble_t	arith_exec(Arith_t *ep)
{
	register Sfdouble_t num=0,*dp,*sp;
	register unsigned char *cp = ep->code;
	register int c,type=0;
	register char *tp;
	Sfdouble_t small_stack[SMALL_STACK+1];
	const char *ptr = "";
	Math_f fun;
	struct lval node;
	node.emode = ep->emode;
	node.expr = ep->expr;
	node.elen = ep->elen;
	node.value = 0;
	node.nosub = 0;
	if(level++ >=MAXLEVEL)
	{
		arith_error(e_recursive,ep->expr,ep->emode);
		return(0);
	}
	if(ep->staksize < SMALL_STACK)
		sp = small_stack;
	else
		sp = (Sfdouble_t*)stakalloc(ep->staksize*(sizeof(Sfdouble_t)+1));
	tp = (char*)(sp+ep->staksize);
	tp--,sp--;
	while(c = *cp++)
	{
		if(c&T_NOFLOAT)
		{
			if(type==1 || ((c&T_BINARY) && (c&T_OP)!=A_MOD  && tp[-1]==1))
				arith_error(e_incompatible,ep->expr,ep->emode);
		}
		switch(c&T_OP)
		{
		    case A_JMP: case A_JMPZ: case A_JMPNZ:
			c &= T_OP;
			cp = roundptr(ep,cp,short);
			if((c==A_JMPZ && num) || (c==A_JMPNZ &&!num))
				cp += sizeof(short);
			else
				cp = (unsigned char*)ep + *((short*)cp);
			continue;
		    case A_NOTNOT:
			num = (num!=0);
			type=0;
			break;
		    case A_PLUSPLUS:
			node.nosub = 1;
			(*ep->fun)(&ptr,&node,ASSIGN,num+1);
			break;
		    case A_MINUSMINUS:
			node.nosub = 1;
			(*ep->fun)(&ptr,&node,ASSIGN,num-1);
			break;
		    case A_INCR:
			num = num+1;
			node.nosub = 1;
			num = (*ep->fun)(&ptr,&node,ASSIGN,num);
			break;
		    case A_DECR:
			num = num-1;
			node.nosub = 1;
			num = (*ep->fun)(&ptr,&node,ASSIGN,num);
			break;
		    case A_SWAP:
			num = sp[-1];
			sp[-1] = *sp;
			type = tp[-1];
			tp[-1] = *tp;
			break;
		    case A_POP:
			sp--;
			continue;
		    case A_PUSHV:
			cp = roundptr(ep,cp,Sfdouble_t*);
			dp = *((Sfdouble_t**)cp);
			cp += sizeof(Sfdouble_t*);
			c = *(short*)cp;
			cp += sizeof(short);
			node.value = (char*)dp;
			node.flag = c;
			node.isfloat=0;
			node.level = level;
			num = (*ep->fun)(&ptr,&node,VALUE,num);
			if(node.value != (char*)dp)
				arith_error(node.value,ptr,ep->emode);
			*++sp = num;
			type = node.isfloat;
			if(num > LDBL_ULLONG_MAX || num < LDBL_LLONG_MIN)
				type = 1;
			else
			{
				Sfdouble_t d=num;
				if(num > LDBL_LLONG_MAX && num <= LDBL_ULLONG_MAX)
				{
					type = 2;
					d -= LDBL_LLONG_MAX;
				}
				if((Sflong_t)d!=d)
					type = 1;
			}
			*++tp = type;
			c = 0;
			break;
		    case A_ASSIGNOP:
			node.nosub = 1;
			/* FALLTHROUGH */
		    case A_STORE:
			cp = roundptr(ep,cp,Sfdouble_t*);
			dp = *((Sfdouble_t**)cp);
			cp += sizeof(Sfdouble_t*);
			c = *(short*)cp;
			if(c<0)
				c = 0;
			cp += sizeof(short);
			node.value = (char*)dp;
			node.flag = c;
			num = (*ep->fun)(&ptr,&node,ASSIGN,num);
			c=0;
			break;
		    case A_PUSHF:
			cp = roundptr(ep,cp,Math_f);
			*++sp = (Sfdouble_t)(cp-ep->code);
			cp += sizeof(Math_f);
			*++tp = *cp++;
			continue;
		    case A_PUSHN:
			cp = roundptr(ep,cp,Sfdouble_t);
			num = *((Sfdouble_t*)cp);
			cp += sizeof(Sfdouble_t);
			*++sp = num;
			*++tp = type = *cp++;
			break;
		    case A_NOT:
			type=0;
			num = !num;
			break;
		    case A_UMINUS:
			num = -num;
			break;
		    case A_TILDE:
			num = ~((Sflong_t)(num));
			break;
		    case A_PLUS:
			num += sp[-1];
			break;
		    case A_MINUS:
			num = sp[-1] - num;
			break;
		    case A_TIMES:
			num *= sp[-1];
			break;
		    case A_POW:
			num = pow(sp[-1],num);
			break;
		    case A_MOD:
			if(!(Sflong_t)num)
				arith_error(e_divzero,ep->expr,ep->emode);
			if(type==2 || tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) % (Sfulong_t)(num));
			else
				num = (Sflong_t)(sp[-1]) % (Sflong_t)(num);
			break;
		    case A_DIV:
			if(type==1 || tp[-1]==1)
			{
				num = sp[-1]/num;
				type = 1;
			}
			else if((Sfulong_t)(num)==0)
				arith_error(e_divzero,ep->expr,ep->emode);
			else if(type==2 || tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) / (Sfulong_t)(num));
			else
				num = (Sflong_t)(sp[-1]) / (Sflong_t)(num);
			break;
		    case A_LSHIFT:
			if(tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) << (long)(num));
			else
				num = (Sflong_t)(sp[-1]) << (long)(num);
			break;
		    case A_RSHIFT:
			if(tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) >> (long)(num));
			else
				num = (Sflong_t)(sp[-1]) >> (long)(num);
			break;
		    case A_XOR:
			if(type==2 || tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) ^ (Sfulong_t)(num));
			else
				num = (Sflong_t)(sp[-1]) ^ (Sflong_t)(num);
			break;
		    case A_OR:
			if(type==2 || tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) | (Sfulong_t)(num));
			else
				num = (Sflong_t)(sp[-1]) | (Sflong_t)(num);
			break;
		    case A_AND:
			if(type==2 || tp[-1]==2)
				num = U2F((Sfulong_t)(sp[-1]) & (Sfulong_t)(num));
			else
				num = (Sflong_t)(sp[-1]) & (Sflong_t)(num);
			break;
		    case A_EQ:
			num = (sp[-1]==num);
			type=0;
			break;
		    case A_NEQ:
			num = (sp[-1]!=num);
			type=0;
			break;
		    case A_LE:
			num = (sp[-1]<=num);
			type=0;
			break;
		    case A_GE:
			num = (sp[-1]>=num);
			type=0;
			break;
		    case A_GT:
			num = (sp[-1]>num);
			type=0;
			break;
		    case A_LT:
			num = (sp[-1]<num);
			type=0;
			break;
		    case A_CALL1F:
			sp--,tp--;
			fun = *((Math_f*)(ep->code+(int)(*sp)));
			type = 0;
			num = (*((Math_1f_f)fun))(num);
			break;
		    case A_CALL1I:
			sp--,tp--;
			fun = *((Math_f*)(ep->code+(int)(*sp)));
			type = *tp;
			num = (*((Math_1i_f)(uintptr_t)fun))(num);
			break;
		    case A_CALL2F:
			sp-=2,tp-=2;
			fun = *((Math_f*)(ep->code+(int)(*sp)));
			type = 0;
			num = (*((Math_2f_f)fun))(sp[1],num);
			break;
		    case A_CALL2I:
			sp-=2,tp-=2;
			fun = *((Math_f*)(ep->code+(int)(*sp)));
			type = *tp;
			num = (*((Math_2i_f)(uintptr_t)fun))(sp[1],num);
			break;
		    case A_CALL3F:
			sp-=3,tp-=3;
			fun = *((Math_f*)(ep->code+(int)(*sp)));
			type = 0;
			num = (*((Math_3f_f)fun))(sp[1],sp[2],num);
			break;
		}
		if(c&T_BINARY)
			sp--,tp--;
		*sp = num;
		*tp = type;
	}
	if(level>0)
		level--;
	return(num);
}

/*
 * This returns operator tokens or A_REG or A_NUM
 */
static int gettok(register struct vars *vp)
{
	register int c,op;
	vp->errchr = vp->nextchr;
	while(1)
	{
		c = getchr(vp);
		switch(op=getop(c))
		{
		    case 0:
			vp->errchr = vp->nextchr;
			continue;
		    case A_EOF:
			vp->nextchr--;
			break;
		    case A_COMMA:
			if(sh.decomma && (c=peekchr(vp))>='0' && c<='9')
			{
				op = A_DIG;
		    		goto keep;
			}
			break;
		    case A_DOT:
			if((c=peekchr(vp))>='0' && c<='9')
				op = A_DIG;
			else
				op = A_REG;
			/*FALL THRU*/
		    case A_DIG: case A_REG: case A_LIT:
		    keep:
			ungetchr(vp);
			break;
		    case A_QUEST:
			if(peekchr(vp)==':')
			{
				getchr(vp);
				op = A_QCOLON;
			}
			break;
		    case A_LT:	case A_GT:
			if(peekchr(vp)==c)
			{
				getchr(vp);
				op -= 2;
				break;
			}
			/* FALL THRU */
		    case A_NOT:	case A_COLON:
			c = '=';
			/* FALL THRU */
		    case A_ASSIGN:
		    case A_TIMES:
		    case A_PLUS:	case A_MINUS:
		    case A_OR:	case A_AND:
			if(peekchr(vp)==c)
			{
				getchr(vp);
				op--;
			}
		}
		return(op);
	}
}

/*   
 * evaluate a subexpression with precedence
 */

static int expr(register struct vars *vp,register int precedence)
{
	register int	c, op;
	int		invalid,wasop=0;
	struct lval	lvalue,assignop;
	const char	*pos;
	Sfdouble_t	d;

	lvalue.value = 0;
	lvalue.fun = 0;
again:
	op = gettok(vp);
	c = 2*MAXPREC+1;
	switch(op)
	{
	    case A_PLUS:
		goto again;
	    case A_EOF:
		if(precedence>2)
			ERROR(vp,e_moretokens);
		return(1);
	    case A_MINUS:
		op =  A_UMINUS;
		goto common;
	    case A_NOT:
		goto common;
	    case A_MINUSMINUS:
		c = A_LVALUE;
		op = A_DECR|T_NOFLOAT;
		goto common;
	    case A_PLUSPLUS:
		c = A_LVALUE;
		op = A_INCR|T_NOFLOAT;
		/* FALL THRU */
	    case A_TILDE:
		op |= T_NOFLOAT;
	    common:
		if(!expr(vp,c))
			return(0);
		stakputc(op);
		break;
	    default:
		vp->nextchr = vp->errchr;
		wasop = 1;
	}
	invalid = wasop;
	while(1)
	{
		assignop.value = 0;
		op = gettok(vp);
		if(op==A_DIG || op==A_REG || op==A_LIT)
		{
			if(!wasop)
				ERROR(vp,e_synbad);
			goto number;
		}
		if(wasop++ && op!=A_LPAR)
			ERROR(vp,e_synbad);
		/* check for assignment operation */
		if(peekchr(vp)== '=' && !(strval_precedence[op]&NOASSIGN))
		{
			if((!lvalue.value || precedence > 3))
				ERROR(vp,e_notlvalue);
			if(precedence==3)
				precedence = 2;
			assignop = lvalue;
			getchr(vp);
			c = 3;
		}
		else
		{
			c = (strval_precedence[op]&PRECMASK);
			if(c==MAXPREC || op==A_POW)
				c++;
			c *= 2;
		}
		/* from here on c is the new precedence level */
		if(lvalue.value && (op!=A_ASSIGN))
		{
			if(vp->staksize++>=vp->stakmaxsize)
				vp->stakmaxsize = vp->staksize;
			stakputc(A_PUSHV);
			stakpush(vp,lvalue.value,char*);
			if(lvalue.flag<0)
				lvalue.flag = 0;
			stakpush(vp,lvalue.flag,short);
			if(vp->nextchr==0)
				ERROR(vp,e_badnum);
			if(!(strval_precedence[op]&SEQPOINT))
				lvalue.value = 0;
			invalid = 0;
		}
		else if(precedence==A_LVALUE)
			ERROR(vp,e_notlvalue);
		if(invalid && op>A_ASSIGN)
			ERROR(vp,e_synbad);
		if(precedence >= c)
			goto done;
		if(strval_precedence[op]&RASSOC)
			c--;
		if((c < (2*MAXPREC+1)) && !(strval_precedence[op]&SEQPOINT))
		{
			wasop = 0;
			if(!expr(vp,c))
				return(0);
		}
		switch(op)
		{
		case A_RPAR:
			if(!vp->paren)
				ERROR(vp,e_paren);
			if(invalid)
				ERROR(vp,e_synbad);
			goto done;

		case A_COMMA:
			wasop = 0;
			if(vp->infun)
				vp->infun++;
			else
			{
				stakputc(A_POP);
				vp->staksize--;
			}
			if(!expr(vp,c))
			{
				stakseek(staktell()-1);
				return(0);
			}
			lvalue.value = 0;
			break;

		case A_LPAR:
		{
			int	infun = vp->infun;
			Sfdouble_t (*fun)(Sfdouble_t,...);
			int nargs = lvalue.nargs;
			fun = lvalue.fun;
			lvalue.fun = 0;
			if(fun)
			{
				if(vp->staksize++>=vp->stakmaxsize)
					vp->stakmaxsize = vp->staksize;
				vp->infun=1;
				stakputc(A_PUSHF);
				stakpush(vp,fun,Math_f);
				stakputc(1);
			}
			else
				vp->infun = 0;
			if(!invalid)
				ERROR(vp,e_synbad);
			vp->paren++;
			if(!expr(vp,1))
				return(0);
			vp->paren--;
			if(fun)
			{
				int  x= (nargs>7)?2:-1;
				nargs &= 7;
				if(vp->infun != nargs)
					ERROR(vp,e_argcount);
				if(vp->staksize+=nargs>=vp->stakmaxsize)
					vp->stakmaxsize = vp->staksize+nargs;
				stakputc(A_CALL1F+nargs+x);
				vp->staksize -= nargs;
			}
			vp->infun = infun;
			if (gettok(vp) != A_RPAR)
				ERROR(vp,e_paren);
			wasop = 0;
			break;
		}

		case A_PLUSPLUS:
		case A_MINUSMINUS:
			wasop=0;
			op |= T_NOFLOAT;
			/* FALLTHROUGH */
		case A_ASSIGN:
			if(!lvalue.value)
				ERROR(vp,e_notlvalue);
			if(op==A_ASSIGN)
			{
				stakputc(A_STORE);
				stakpush(vp,lvalue.value,char*);
				stakpush(vp,lvalue.flag,short);
				vp->staksize--;
			}
			else
				stakputc(op);
			lvalue.value = 0;
			break;

		case A_QUEST:
		{
			int offset1,offset2;
			stakputc(A_JMPZ);
			offset1 = stakpush(vp,0,short);
			stakputc(A_POP);
			if(!expr(vp,1))
				return(0);
			if(gettok(vp)!=A_COLON)
				ERROR(vp,e_questcolon);
			stakputc(A_JMP);
			offset2 = stakpush(vp,0,short);
			*((short*)stakptr(offset1)) = staktell();
			stakputc(A_POP);
			if(!expr(vp,3))
				return(0);
			*((short*)stakptr(offset2)) = staktell();
			lvalue.value = 0;
			wasop = 0;
			break;
		}

		case A_COLON:
			ERROR(vp,e_badcolon);
			break;

		case A_QCOLON:
		case A_ANDAND:
		case A_OROR:
		{
			int offset;
			if(op==A_ANDAND)
				op = A_JMPZ;
			else
				op = A_JMPNZ;
			stakputc(op);
			offset = stakpush(vp,0,short);
			stakputc(A_POP);
			if(!expr(vp,c))
				return(0);
			*((short*)stakptr(offset)) = staktell();
			if(op!=A_QCOLON)
				stakputc(A_NOTNOT);
			lvalue.value = 0;
			wasop=0;
			break;
		}
		case A_AND:	case A_OR:	case A_XOR:	case A_LSHIFT:
		case A_RSHIFT:	case A_MOD:
			op |= T_NOFLOAT;
			/* FALL THRU */
		case A_PLUS:	case A_MINUS:	case A_TIMES:	case A_DIV:
		case A_EQ:	case A_NEQ:	case A_LT:	case A_LE:
		case A_GT:	case A_GE:	case A_POW:
			stakputc(op|T_BINARY);
			vp->staksize--;
			break;
		case A_NOT: case A_TILDE:
		default:
			ERROR(vp,e_synbad);
		number:
			wasop = 0;
			if(*vp->nextchr=='L' && vp->nextchr[1]=='\'')
			{
				vp->nextchr++;
				op = A_LIT;
			}
			pos = vp->nextchr;
			lvalue.isfloat = 0;
			lvalue.expr = vp->expr;
			lvalue.emode = vp->emode;
			if(op==A_LIT)
			{
				/* character constants */
				if(pos[1]=='\\' && pos[2]=='\'' && pos[3]!='\'')
				{
					d = '\\';
					vp->nextchr +=2;
				}
				else
					d = chresc(pos+1,(char**)&vp->nextchr);
				/* posix allows the trailing ' to be optional */
				if(*vp->nextchr=='\'')
					vp->nextchr++;
			}
			else
				d = (*vp->convert)(&vp->nextchr, &lvalue, LOOKUP, 0);
			if (vp->nextchr == pos)
			{
				if(vp->errmsg.value = lvalue.value)
					vp->errstr = pos;
				ERROR(vp,op==A_LIT?e_charconst:e_synbad);
			}
			if(op==A_DIG || op==A_LIT)
			{
				stakputc(A_PUSHN);
				if(vp->staksize++>=vp->stakmaxsize)
					vp->stakmaxsize = vp->staksize;
				stakpush(vp,d,Sfdouble_t);
				stakputc(lvalue.isfloat);
			}
	
			/* check for function call */
			if(lvalue.fun)
				continue;
			break;
		}
		invalid = 0;
		if(assignop.value)
		{
			if(vp->staksize++>=vp->stakmaxsize)
				vp->stakmaxsize = vp->staksize;
			if(assignop.flag<0)
				assignop.flag = 0;
			stakputc(c&1?A_ASSIGNOP:A_STORE);
			stakpush(vp,assignop.value,char*);
			stakpush(vp,assignop.flag,short);
		}
	}
 done:
	vp->nextchr = vp->errchr;
	return(1);
}

Arith_t *arith_compile(const char *string,char **last,Sfdouble_t(*fun)(const char**,struct lval*,int,Sfdouble_t),int emode)
{
	struct vars cur;
	register Arith_t *ep;
	int offset;
	memset((void*)&cur,0,sizeof(cur));
	cur.emode = emode;
     	cur.expr = cur.nextchr = string;
	cur.convert = fun;
	cur.emode = emode;
	cur.errmsg.value = 0;
	cur.errmsg.emode = emode;
	stakseek(sizeof(Arith_t));
	if(!expr(&cur,0) && cur.errmsg.value)
        {
		if(cur.errstr)
			string = cur.errstr;
		(*fun)( &string , &cur.errmsg, MESSAGE, 0);
		cur.nextchr = cur.errchr;
	}
	stakputc(0);
	offset = staktell();
	ep = (Arith_t*)stakfreeze(0);
	ep->expr = string;
	ep->elen = strlen(string);
	ep->code = (unsigned char*)(ep+1);
	ep->fun = fun;
	ep->emode = emode;
	ep->size = offset - sizeof(Arith_t);
	ep->staksize = cur.stakmaxsize+1;
	if(last)
		*last = (char*)(cur.nextchr);
	return(ep);
}

/*
 * evaluate an integer arithmetic expression in s
 *
 * (Sfdouble_t)(*convert)(char** end, struct lval* string, int type, Sfdouble_t value)
 *     is a user supplied conversion routine that is called when unknown 
 *     chars are encountered.
 * *end points to the part to be converted and must be adjusted by convert to
 * point to the next non-converted character; if typ is MESSAGE then string
 * points to an error message string
 *
 * NOTE: (*convert)() may call strval()
 */

Sfdouble_t strval(const char *s,char **end,Sfdouble_t(*conv)(const char**,struct lval*,int,Sfdouble_t),int emode)
{
	Arith_t *ep;
	Sfdouble_t d;
	char *sp=0;
	int offset;
	if(offset=staktell())
		sp = stakfreeze(1);
	ep = arith_compile(s,end,conv,emode);
	ep->emode = emode;
	d = arith_exec(ep);
	stakset(sp?sp:(char*)ep,offset);
	return(d);
}

#if _mem_name__exception
#undef	_mem_name_exception
#define	_mem_name_exception	1
#undef	exception
#define	exception		_exception
#undef	matherr
#endif

#if _mem_name_exception

#undef	error

#if _BLD_shell && defined(__EXPORT__)
#define extern			__EXPORT__
#endif

#ifndef DOMAIN
#define DOMAIN			_DOMAIN
#endif
#ifndef OVERFLOW
#define OVERFLOW		_OVERFLOW
#endif
#ifndef SING
#define SING			_SING
#endif

    extern int matherr(struct exception *ep)
    {
	const char *message;
	switch(ep->type)
	{
#ifdef DOMAIN
	    case DOMAIN:
		message = ERROR_dictionary(e_domain);
		break;
#endif
#ifdef OVERFLOW
	    case OVERFLOW:
		message = ERROR_dictionary(e_overflow);
		break;
#endif
#ifdef SING
	    case SING:
		message = ERROR_dictionary(e_singularity);
		break;
#endif
	    default:
		return(1);
	}
	level=0;
	errormsg(SH_DICT,ERROR_exit(1),message,ep->name);
	return(0);
    }

#undef	extern

#endif /* _mem_name_exception */