/************************************************************
 Copyright (c) 1994 by Silicon Graphics Computer Systems, Inc.

 Permission to use, copy, modify, and distribute this
 software and its documentation for any purpose and without
 fee is hereby granted, provided that the above copyright
 notice appear in all copies and that both that copyright
 notice and this permission notice appear in supporting
 documentation, and that the name of Silicon Graphics not be 
 used in advertising or publicity pertaining to distribution 
 of the software without specific prior written permission.
 Silicon Graphics makes no representation about the suitability 
 of this software for any purpose. It is provided "as is"
 without any express or implied warranty.
 
 SILICON GRAPHICS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS 
 SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 
 AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
 GRAPHICS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL 
 DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, 
 DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 
 OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION  WITH
 THE USE OR PERFORMANCE OF THIS SOFTWARE.

 ********************************************************/

#include "xkbcomp.h"
#include "tokens.h"
#include "expr.h"

#include <ctype.h>

/***====================================================================***/

char *
exprOpText(unsigned type)
{
static char buf[32];

     switch (type) {
	case ExprValue:
	    strcpy(buf,"literal");
	    break;
	case ExprIdent:
	    strcpy(buf,"identifier");
	    break;
	case ExprActionDecl:
	    strcpy(buf,"action declaration");
	    break;
	case ExprFieldRef:
	    strcpy(buf,"field reference");
	    break;
	case ExprArrayRef:
	    strcpy(buf,"array reference");
	    break;
	case ExprKeysymList:
	    strcpy(buf,"list of keysyms");
	    break;
	case ExprActionList:
	    strcpy(buf,"list of actions");
	    break;
	case OpAdd:
	    strcpy(buf,"addition");
	    break;
	case OpSubtract:
	    strcpy(buf,"subtraction");
	    break;
	case OpMultiply:
	    strcpy(buf,"multiplication");
	    break;
	case OpDivide:
	    strcpy(buf,"division");
	    break;
	case OpAssign:
	    strcpy(buf,"assignment");
	    break;
	case OpNot:
	    strcpy(buf,"logical not");
	    break;
	case OpNegate:
	    strcpy(buf,"arithmetic negation");
	    break;
	case OpInvert:
	    strcpy(buf,"bitwise inversion");
	    break;
	case OpUnaryPlus:
	    strcpy(buf,"plus sign");
	    break;
	default:
	    sprintf(buf,"illegal(%d)",type);
	    break;
     }
     return buf;
}

char *
exprTypeText(unsigned type)
{
static char buf[20];

     switch (type) {
	case TypeUnknown:
	    strcpy(buf,"unknown");
	    break;
	case TypeBoolean:
	    strcpy(buf,"boolean");
	    break;
	case TypeInt:
	    strcpy(buf,"int");
	    break;
	case TypeString:
	    strcpy(buf,"string");
	    break;
	case TypeAction:
	    strcpy(buf,"action");
	    break;
	case TypeKeyName:
	    strcpy(buf,"keyname");
	    break;
	default:
	    sprintf(buf,"illegal(%d)",type);
	    break;
     }
     return buf;
}

int
ExprResolveLhs(	ExprDef *	expr,
		ExprResult *	elem_rtrn,
		ExprResult *	field_rtrn,
		ExprDef **	index_rtrn)
{
    switch (expr->op) {
	case ExprIdent:
	    elem_rtrn->str=  NULL;
	    field_rtrn->str= XkbAtomGetString(NULL,expr->value.str);
	    *index_rtrn= NULL;
	    return True;
	case ExprFieldRef:
	    elem_rtrn->str= XkbAtomGetString(NULL,expr->value.field.element);
	    field_rtrn->str= XkbAtomGetString(NULL,expr->value.field.field);
	    *index_rtrn= NULL;
	    return True;
	case ExprArrayRef:
	    elem_rtrn->str= XkbAtomGetString(NULL,expr->value.array.element);
	    field_rtrn->str= XkbAtomGetString(NULL,expr->value.array.field);
	    *index_rtrn= expr->value.array.entry;
	    return True;
    }
    WSGO1("Unexpected operator %d in ResolveLhs\n",expr->op);
    return False;
}

Bool
SimpleLookup(	XPointer 	priv,
		Atom		elem,
		Atom		field,
		unsigned	type,
		ExprResult *	val_rtrn)
{
LookupEntry *	entry;
register char *	str;

    if ((priv==NULL)||
	(field==None)||(elem!=None)||
	((type!=TypeInt)&&(type!=TypeFloat))) {
	return False;
    }
    str= XkbAtomGetString(NULL,field);
    for (entry=(LookupEntry *)priv;(entry!=NULL)&&(entry->name!=NULL);entry++) {
	if (uStrCaseCmp(str,entry->name)==0) {
	    val_rtrn->uval= entry->result;
	    if (type==TypeFloat)
		val_rtrn->uval*= XkbGeomPtsPerMM;
	    return True;
	}
    }
    return False;
}

Bool
RadioLookup(	XPointer 	priv,
		Atom		elem,
		Atom		field,
		unsigned	type,
		ExprResult *	val_rtrn)
{
register char *	str;
int		rg;

    if ((field==None)||(elem!=None)||(type!=TypeInt))
	return False;
    str= XkbAtomGetString(NULL,field);
    if (str) {
	if (uStrCasePrefix("group",str))
	    str+= strlen("group");
	else if (uStrCasePrefix("radiogroup",str))
	    str+= strlen("radiogroup");
	else if (uStrCasePrefix("rg",str))
	    str+= strlen("rg");
	else if (!isdigit(str[0]))
	    str= NULL;
    }
    if ((!str)||(sscanf(str,"%i",&rg)<1)||(rg<1)||(rg>XkbMaxRadioGroups))
	return False;
    val_rtrn->uval= rg;
    return True;
}

int
TableLookup(	XPointer 	priv,
		Atom		elem,
		Atom		field,
		unsigned	type,
		ExprResult *	val_rtrn)
{
LookupTable *	tbl= (LookupTable *)priv;
register char *	str;

    if ((priv==NULL)||(field==None)||(type!=TypeInt))
	return False;
    str= XkbAtomGetString(NULL,elem);
    while (tbl) {
	if (((str==NULL)&&(tbl->element==NULL))||
	    ((str!=NULL)&&(tbl->element!=NULL)&&
			  (uStrCaseCmp(str,tbl->element)==0))) {
	    break;
	}
	tbl= tbl->nextElement;
    }
    if (tbl==NULL)	/* didn't find a matching element */
	return False;
    priv= (XPointer)tbl->entries;
    return SimpleLookup(priv,(Atom)None,field,type,val_rtrn);
}

static LookupEntry modIndexNames[] = {
	{	"shift",	ShiftMapIndex 	},
	{	"control",	ControlMapIndex	},
	{	"lock",		LockMapIndex	},
	{	"mod1",		Mod1MapIndex	},
	{	"mod2",		Mod2MapIndex	},
	{	"mod3",		Mod3MapIndex	},
	{	"mod4",		Mod4MapIndex	},
	{	"mod5",		Mod5MapIndex	},
	{	"none",		XkbNoModifier	},
	{	NULL,		0		}
};

int
LookupModIndex(	XPointer 	priv,
		Atom		elem,
		Atom		field,
		unsigned	type,
		ExprResult *	val_rtrn)
{
    return SimpleLookup((XPointer)modIndexNames,elem,field,type,val_rtrn);
}

int
LookupModMask(	XPointer 	priv,
		Atom		elem,
		Atom		field,
		unsigned	type,
    		ExprResult *	val_rtrn)
{
char *str;

    if ((elem!=None)||(type!=TypeInt))
	return False;
    str= XkbAtomGetString(NULL,field);
    if (str==NULL)
	 return False;
    if (uStrCaseCmp(str,"all")==0)
	 val_rtrn->uval= 0xff;
    else if (uStrCaseCmp(str,"none")==0)
	 val_rtrn->uval= 0;
    else if (LookupModIndex(priv,elem,field,type,val_rtrn))
	 val_rtrn->uval= (1<<val_rtrn->uval);
    else if (priv != NULL) {
	LookupPriv *lpriv= (LookupPriv *)priv;
	if ((lpriv->chain==NULL)||
	    (!(*lpriv->chain)(lpriv->chainPriv,elem,field,type,val_rtrn)))
	    return False;
    }
    else return False;
    return True;
}

int
ExprResolveModIndex(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int	ok= 0;
char		*bogus= NULL;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type!=TypeInt) {
		ERROR1("Found constant of type %s where a modifier mask was expected\n",
						exprTypeText(expr->type));
		return False;
	    }
	    else if ((expr->value.ival>=XkbNumModifiers)||(expr->value.ival<0)){
		ERROR2("Illegal modifier index (%d, must be 0..%d)\n",
					expr->value.ival,XkbNumModifiers-1);
		return False;
	    }
	    val_rtrn->ival= expr->value.ival;
	    return True;
	case ExprIdent:
	    if (LookupModIndex(lookupPriv,(Atom)None,expr->value.str,
				 		(unsigned)TypeInt,val_rtrn)) {
		return True;
	    }
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeInt,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Cannot determine modifier index for \"%s\"\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    break;
	case ExprFieldRef:
	    bogus= "field reference";
	    break;
	case ExprArrayRef:
	    bogus= "array reference";
	    break;
	case ExprActionDecl:
	    bogus= "function";
	    break;
	case OpAdd:
	case OpSubtract:
	case OpMultiply:
	case OpDivide:
	case OpInvert:
	case OpNegate:
	case OpNot:
	case OpUnaryPlus:
	    bogus= "arithmetic operations";
	    break;
	case OpAssign:
	    bogus= "assignment";
	    break;
	default:
	    WSGO1("Unknown operator %d in ResolveModIndex\n",expr->op);
	    return False;
    }
    if (bogus) {
	ERROR1("Modifier index must be a name or number, %s ignored\n",bogus);
	return False;
    }
    return ok;
}

int
ExprResolveModMask(	ExprDef *		expr,
			ExprResult *		val_rtrn,
			IdentLookupFunc		lookup,
			XPointer		lookupPriv)
{
LookupPriv	priv;

    priv.priv= NULL;
    priv.chain= lookup;
    priv.chainPriv= lookupPriv;
    return ExprResolveMask(expr,val_rtrn,LookupModMask,(XPointer)&priv);
}

int
ExprResolveBoolean(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int	ok= 0;
char *	bogus= NULL;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type!=TypeBoolean) {
		ERROR1("Found constant of type %s where boolean was expected\n",
						exprTypeText(expr->type));
		return False;
	    }
	    val_rtrn->ival= expr->value.ival;
	    return True;
	case ExprIdent:
	    bogus= XkbAtomGetString(NULL,expr->value.str);
	    if (bogus) {
		if ((uStrCaseCmp(bogus,"true")==0)||
				(uStrCaseCmp(bogus,"yes")==0)||
				(uStrCaseCmp(bogus,"on")==0)) {
		    val_rtrn->uval= 1;
		    return True;
		}
		else if ((uStrCaseCmp(bogus,"false")==0)||
				(uStrCaseCmp(bogus,"no")==0)||
				(uStrCaseCmp(bogus,"off")==0)) {
		    val_rtrn->uval= 0;
		    return True;
		}
	    }
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeBoolean,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Identifier \"%s\" of type int is unknown\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    return ok;
	case ExprFieldRef:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
			 expr->value.field.element,expr->value.field.field,
			 TypeBoolean,val_rtrn);
	    }
	    if (!ok)
		ERROR2("Default \"%s.%s\" of type boolean is unknown\n",
			XkbAtomText(NULL,expr->value.field.element,XkbMessage),
			XkbAtomText(NULL,expr->value.field.field,XkbMessage));
	    return ok;
	case OpInvert: 
	case OpNot:
	    ok= ExprResolveBoolean(expr,val_rtrn,lookup,lookupPriv);
	    if (ok)
		val_rtrn->uval= !val_rtrn->uval;
	    return ok;
	case OpAdd:	 if (bogus==NULL) 	bogus= "Addition";
	case OpSubtract: if (bogus==NULL)	bogus= "Subtraction";
	case OpMultiply: if (bogus==NULL)	bogus= "Multiplication";
	case OpDivide:   if (bogus==NULL)	bogus= "Division";
	case OpAssign:   if (bogus==NULL)	bogus= "Assignment";
	case OpNegate:	 if (bogus==NULL)	bogus= "Negation";
	    ERROR1("%s of boolean values not permitted\n",bogus);
	    break;
	case OpUnaryPlus:
	    ERROR("Unary \"+\" operator not permitted for boolean values\n");
	    break;
	default:
	    WSGO1("Unknown operator %d in ResolveBoolean\n",expr->op);
	    break;
    }
    return False;
}

int
ExprResolveFloat(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int	ok= 0;
ExprResult	leftRtrn,rightRtrn;
ExprDef		*left,*right;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type==TypeString) {
		register char *str;
		str= XkbAtomGetString(NULL,expr->value.str);
		if ((str!=None)&&(strlen(str)==1)) {
		    val_rtrn->uval= str[0]*XkbGeomPtsPerMM;
		    return True;
		}
	    }
	    if ((expr->type!=TypeInt)&&(expr->type!=TypeFloat)) {
		ERROR1("Found constant of type %s, expected a number\n",
						exprTypeText(expr->type));
		return False;
	    }
	    val_rtrn->ival= expr->value.ival;
	    if (expr->type==TypeInt)
		val_rtrn->ival*= XkbGeomPtsPerMM;
	    return True;
	case ExprIdent:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeFloat,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Numeric identifier \"%s\" unknown\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    return ok;
	case ExprFieldRef:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
			 expr->value.field.element,expr->value.field.field,
			 TypeFloat,val_rtrn);
	    }
	    if (!ok)
		ERROR2("Numeric default \"%s.%s\" unknown\n",
			XkbAtomText(NULL,expr->value.field.element,XkbMessage),
			XkbAtomText(NULL,expr->value.field.field,XkbMessage));
	    return ok;
	case OpAdd:
	case OpSubtract:
	case OpMultiply:
	case OpDivide:
	    left= expr->value.binary.left;
	    right= expr->value.binary.right;
	    if (ExprResolveFloat(left,&leftRtrn,lookup,lookupPriv)&&
		ExprResolveFloat(right,&rightRtrn,lookup,lookupPriv)) {
		switch (expr->op) {
		    case OpAdd: 
			val_rtrn->ival= leftRtrn.ival+rightRtrn.ival;
			break;
		    case OpSubtract: 
			val_rtrn->ival= leftRtrn.ival-rightRtrn.ival;
			break;
		    case OpMultiply: 
			val_rtrn->ival= leftRtrn.ival*rightRtrn.ival;
			break;
		    case OpDivide: 
			val_rtrn->ival= leftRtrn.ival/rightRtrn.ival;
			break;
		}
		return True;
	    }
	    return False;
	case OpAssign:
	    WSGO("Assignment operator not implemented yet\n");
	    break;
	case OpNot:
	    left= expr->value.child;
	    if (ExprResolveFloat(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR("The ! operator cannot be applied to a number\n");
	    }
	    return False;
	case OpInvert:
	case OpNegate:
	    left= expr->value.child;
	    if (ExprResolveFloat(left,&leftRtrn,lookup,lookupPriv)) {
		if (expr->op==OpNegate)	
		     val_rtrn->ival= -leftRtrn.ival;
		else val_rtrn->ival= ~leftRtrn.ival;
		return True;
	    }
	    return False;
	case OpUnaryPlus:
	    left= expr->value.child;
	    return ExprResolveFloat(left,val_rtrn,lookup,lookupPriv);
	default:
	    WSGO1("Unknown operator %d in ResolveFloat\n",expr->op);
	    break;
    }
    return False;
}

int
ExprResolveInteger(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int	ok= 0;
ExprResult	leftRtrn,rightRtrn;
ExprDef		*left,*right;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type==TypeString) {
		register char *str;
		str= XkbAtomGetString(NULL,expr->value.str);
		if (str!=None)
		    switch (strlen(str)) {
			case 0:
			    val_rtrn->uval= 0;
			    return True;
			case 1:
			    val_rtrn->uval= str[0];
			    return True;
			default:
			    break;
		}
	    }
	    if ((expr->type!=TypeInt)&&(expr->type!=TypeFloat)) {
		ERROR1("Found constant of type %s where an int was expected\n",
						exprTypeText(expr->type));
		return False;
	    }
	    val_rtrn->ival= expr->value.ival;
	    if (expr->type==TypeFloat)
		val_rtrn->ival/= XkbGeomPtsPerMM;
	    return True;
	case ExprIdent:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeInt,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Identifier \"%s\" of type int is unknown\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    return ok;
	case ExprFieldRef:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
			 expr->value.field.element,expr->value.field.field,
			 TypeInt,val_rtrn);
	    }
	    if (!ok)
		ERROR2("Default \"%s.%s\" of type int is unknown\n",
			XkbAtomText(NULL,expr->value.field.element,XkbMessage),
			XkbAtomText(NULL,expr->value.field.field,XkbMessage));
	    return ok;
	case OpAdd:
	case OpSubtract:
	case OpMultiply:
	case OpDivide:
	    left= expr->value.binary.left;
	    right= expr->value.binary.right;
	    if (ExprResolveInteger(left,&leftRtrn,lookup,lookupPriv)&&
		ExprResolveInteger(right,&rightRtrn,lookup,lookupPriv)) {
		switch (expr->op) {
		    case OpAdd: 
			val_rtrn->ival= leftRtrn.ival+rightRtrn.ival;
			break;
		    case OpSubtract: 
			val_rtrn->ival= leftRtrn.ival-rightRtrn.ival;
			break;
		    case OpMultiply: 
			val_rtrn->ival= leftRtrn.ival*rightRtrn.ival;
			break;
		    case OpDivide: 
			val_rtrn->ival= leftRtrn.ival/rightRtrn.ival;
			break;
		}
		return True;
	    }
	    return False;
	case OpAssign:
	    WSGO("Assignment operator not implemented yet\n");
	    break;
	case OpNot:
	    left= expr->value.child;
	    if (ExprResolveInteger(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR("The ! operator cannot be applied to an integer\n");
	    }
	    return False;
	case OpInvert:
	case OpNegate:
	    left= expr->value.child;
	    if (ExprResolveInteger(left,&leftRtrn,lookup,lookupPriv)) {
		if (expr->op==OpNegate)	
		     val_rtrn->ival= -leftRtrn.ival;
		else val_rtrn->ival= ~leftRtrn.ival;
		return True;
	    }
	    return False;
	case OpUnaryPlus:
	    left= expr->value.child;
	    return ExprResolveInteger(left,val_rtrn,lookup,lookupPriv);
	default:
	    WSGO1("Unknown operator %d in ResolveInteger\n",expr->op);
	    break;
    }
    return False;
}

int
ExprResolveString(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int		ok= 0;
ExprResult	leftRtrn,rightRtrn;
ExprDef	*	left;
ExprDef *	right;
char *		bogus= NULL;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type!=TypeString) {
		ERROR1("Found constant of type %s, expected a string\n",
						exprTypeText(expr->type));
		return False;
	    }
	    val_rtrn->str= XkbAtomGetString(NULL,expr->value.str);
	    if (val_rtrn->str==NULL) {
		static char *empty= "";
		val_rtrn->str= empty;
	    }
	    return True;
	case ExprIdent:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeString,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Identifier \"%s\" of type string not found\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    return ok;
	case ExprFieldRef:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
			 expr->value.field.element,expr->value.field.field,
			 TypeString,val_rtrn);
	    }
	    if (!ok)
		ERROR2("Default \"%s.%s\" of type string not found\n",
			XkbAtomText(NULL,expr->value.field.element,XkbMessage),
			XkbAtomText(NULL,expr->value.field.field,XkbMessage));
	    return ok;
	case OpAdd:
	    left= expr->value.binary.left;
	    right= expr->value.binary.right;
	    if (ExprResolveString(left,&leftRtrn,lookup,lookupPriv)&&
		ExprResolveString(right,&rightRtrn,lookup,lookupPriv)) {
		int len;
		char *new;
		len= strlen(leftRtrn.str)+strlen(rightRtrn.str)+1;
		new= (char *)uAlloc(len);
		if (new) {
		    sprintf(new,"%s%s",leftRtrn.str,rightRtrn.str);
		    val_rtrn->str= new;
		    return True;
		}
	    }
	    return False;
	case OpSubtract: if (bogus==NULL)	bogus= "Subtraction";
	case OpMultiply: if (bogus==NULL)	bogus= "Multiplication";
	case OpDivide:   if (bogus==NULL)	bogus= "Division";
	case OpAssign:   if (bogus==NULL)	bogus= "Assignment";
	case OpNegate:	 if (bogus==NULL)	bogus= "Negation";
	case OpInvert:	 if (bogus==NULL)	bogus= "Bitwise complement";
	    ERROR1("%s of string values not permitted\n",bogus);
	    return False;
	case OpNot:	 
	    left= expr->value.child;
	    if (ExprResolveString(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR("The ! operator cannot be applied to a string\n");
	    }
	    return False;
	case OpUnaryPlus:
	    left= expr->value.child;
	    if (ExprResolveString(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR("The + operator cannot be applied to a string\n");
	    }
	    return False;
	default:
	    WSGO1("Unknown operator %d in ResolveString\n",expr->op);
	    break;
    }
    return False;
}

int
ExprResolveKeyName(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int		ok= 0;
ExprDef	*	left;
ExprResult 	leftRtrn;
char *		bogus= NULL;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type!=TypeKeyName) {
		ERROR1("Found constant of type %s, expected a key name\n",
						exprTypeText(expr->type));
		return False;
	    }
	    memcpy(val_rtrn->keyName.name,expr->value.keyName,XkbKeyNameLength);
	    return True;
	case ExprIdent:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeString,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Identifier \"%s\" of type string not found\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    return ok;
	case ExprFieldRef:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
			 expr->value.field.element,expr->value.field.field,
			 TypeString,val_rtrn);
	    }
	    if (!ok)
		ERROR2("Default \"%s.%s\" of type key name not found\n",
			XkbAtomText(NULL,expr->value.field.element,XkbMessage),
			XkbAtomText(NULL,expr->value.field.field,XkbMessage));
	    return ok;
	case OpAdd:	 if (bogus==NULL)	bogus= "Addition";
	case OpSubtract: if (bogus==NULL)	bogus= "Subtraction";
	case OpMultiply: if (bogus==NULL)	bogus= "Multiplication";
	case OpDivide:   if (bogus==NULL)	bogus= "Division";
	case OpAssign:   if (bogus==NULL)	bogus= "Assignment";
	case OpNegate:	 if (bogus==NULL)	bogus= "Negation";
	case OpInvert:	 if (bogus==NULL)	bogus= "Bitwise complement";
	    ERROR1("%s of key name values not permitted\n",bogus);
	    return False;
	case OpNot:	 
	    left= expr->value.binary.left;
	    if (ExprResolveString(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR("The ! operator cannot be applied to a key name\n");
	    }
	    return False;
	case OpUnaryPlus:
	    left= expr->value.binary.left;
	    if (ExprResolveString(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR("The + operator cannot be applied to a key name\n");
	    }
	    return False;
	default:
	    WSGO1("Unknown operator %d in ResolveKeyName\n",expr->op);
	    break;
    }
    return False;
}

/***====================================================================***/

int
ExprResolveEnum(ExprDef *expr,ExprResult *val_rtrn,LookupEntry	*values)
{
    if (expr->op!=ExprIdent) {
	ERROR1("Found a %s where an enumerated value was expected\n",
							exprOpText(expr->op));
	return False;
    }
    if (!SimpleLookup((XPointer)values,(Atom)None,expr->value.str,
						(unsigned)TypeInt,val_rtrn)) {
	int	nOut=0;
	ERROR1("Illegal identifier %s (expected one of: ",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	while (values && values->name) {
	    if (nOut!=0)	INFO1(", %s",values->name);
	    else		INFO1("%s",values->name);
	    values++;
	    nOut++;
	}
	INFO(")\n");
	return False;
    }
    return True;
}

int
ExprResolveMask(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int	ok= 0;
ExprResult	leftRtrn,rightRtrn;
ExprDef		*left,*right;
char *		bogus= NULL;

    switch (expr->op) {
	case ExprValue:
	    if (expr->type!=TypeInt) {
		ERROR1("Found constant of type %s where a mask was expected\n",
						exprTypeText(expr->type));
		return False;
	    }
	    val_rtrn->ival= expr->value.ival;
	    return True;
	case ExprIdent:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
				 None,expr->value.str,
				 TypeInt,val_rtrn);
	    }
	    if (!ok)
		ERROR1("Identifier \"%s\" of type int is unknown\n",
				XkbAtomText(NULL,expr->value.str,XkbMessage));
	    return ok;
	case ExprFieldRef:
	    if (lookup) {
		ok= (*lookup)(lookupPriv,
			 expr->value.field.element,expr->value.field.field,
			 TypeInt,val_rtrn);
	    }
	    if (!ok)
		ERROR2("Default \"%s.%s\" of type int is unknown\n",
			XkbAtomText(NULL,expr->value.field.element,XkbMessage),
			XkbAtomText(NULL,expr->value.field.field,XkbMessage));
	    return ok;
	case ExprArrayRef:
	    bogus= "array reference";
	case ExprActionDecl:
	    if (bogus==NULL)
		bogus= "function use";
	    ERROR1("Unexpected %s in mask expression\n",bogus);
	    ACTION("Expression ignored\n");
	    return False;
	case OpAdd:
	case OpSubtract:
	case OpMultiply:
	case OpDivide:
	    left= expr->value.binary.left;
	    right= expr->value.binary.right;
	    if (ExprResolveMask(left,&leftRtrn,lookup,lookupPriv)&&
		ExprResolveMask(right,&rightRtrn,lookup,lookupPriv)) {
		switch (expr->op) {
		    case OpAdd: 
			val_rtrn->ival= leftRtrn.ival|rightRtrn.ival;
			break;
		    case OpSubtract: 
			val_rtrn->ival= leftRtrn.ival&(~rightRtrn.ival);
			break;
		    case OpMultiply: 
		    case OpDivide: 
			ERROR1("Cannot %s masks\n",
					expr->op==OpDivide?"divide":"multiply");
			ACTION("Illegal operation ignored\n");
			return False;
		}
		return True;
	    }
	    return False;
	case OpAssign:
	    WSGO("Assignment operator not implemented yet\n");
	    break;
	case OpInvert:
	    left= expr->value.child;
	    if (ExprResolveInteger(left,&leftRtrn,lookup,lookupPriv)) {
		val_rtrn->ival= ~leftRtrn.ival;
		return True;
	    }
	    return False;
	case OpUnaryPlus:
	case OpNegate:
	case OpNot:
	    left= expr->value.child;
	    if (ExprResolveInteger(left,&leftRtrn,lookup,lookupPriv)) {
		ERROR1("The %s operator cannot be used with a mask\n",
					(expr->op==OpNegate?"-":"!"));
	    }
	    return False;
	default:
	    WSGO1("Unknown operator %d in ResolveMask\n",expr->op);
	    break;
    }
    return False;
}

int
ExprResolveKeySym(	ExprDef *	expr,
			ExprResult *	val_rtrn,
			IdentLookupFunc	lookup,
			XPointer	lookupPriv)
{
int	ok= 0;
KeySym	sym;

    if (expr->op==ExprIdent) {
	char *str;
	str= XkbAtomGetString(NULL,expr->value.str);
	if ((str!=NULL)&&((sym= XStringToKeysym(str))!=NoSymbol)) {
	    val_rtrn->uval= sym;
	    return True;
	}
    }
    ok= ExprResolveInteger(expr,val_rtrn,lookup,lookupPriv);
    if ((ok)&&(val_rtrn->uval<10))
	val_rtrn->uval+= '0';
    return ok;
}