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Allow _cmp to return NAN, and handle comparisons with NAN properly. #317

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Allow _cmp to return NAN, and handle comparisons with NAN properly. #317

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4 changes: 4 additions & 0 deletions doc/source/reference/embedding/the_stack.rst
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Expand Up @@ -102,3 +102,7 @@ The following functions convert a squirrel value in the stack to a C value::
The function sq_cmp compares 2 values from the stack and returns their relation (like strcmp() in ANSI C).::

SQInteger sq_cmp(HSQUIRRELVM v);

The function sq_cmpex works like sq_cmp, but reports error conditions and sets alwaysfalse to SQTrue if the comparison would always return false, as is the case with floating-point NAN.::

SQRESULT sq_cmpex(HSQUIRRELVM v,SQInteger *res,SQBool *alwaysfalse);
2 changes: 2 additions & 0 deletions doc/source/reference/language/metamethods.rst
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Expand Up @@ -198,6 +198,8 @@ returns an integer as follow:
| < 0 | if ``this`` < ``other`` |
+-----------+----------------------------+

can also return a floating-point NAN value, which results in ``< > <= >=`` returning false and ``<=>`` returning NAN.

^^^^^^^^^^^^^^^^^^^^^^^^
_call
^^^^^^^^^^^^^^^^^^^^^^^^
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1 change: 1 addition & 0 deletions include/squirrel.h
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Expand Up @@ -235,6 +235,7 @@ SQUIRREL_API SQInteger sq_gettop(HSQUIRRELVM v);
SQUIRREL_API void sq_settop(HSQUIRRELVM v,SQInteger newtop);
SQUIRREL_API SQRESULT sq_reservestack(HSQUIRRELVM v,SQInteger nsize);
SQUIRREL_API SQInteger sq_cmp(HSQUIRRELVM v);
SQUIRREL_API SQRESULT sq_cmpex(HSQUIRRELVM v, SQInteger *res, SQBool *alwaysfalse);
SQUIRREL_API void sq_move(HSQUIRRELVM dest,HSQUIRRELVM src,SQInteger idx);

/*object creation handling*/
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14 changes: 12 additions & 2 deletions squirrel/sqapi.cpp
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Expand Up @@ -859,10 +859,20 @@ void sq_remove(HSQUIRRELVM v, SQInteger idx)
SQInteger sq_cmp(HSQUIRRELVM v)
{
SQInteger res;
v->ObjCmp(stack_get(v, -1), stack_get(v, -2),res);
bool alwaysfalse;
v->ObjCmp(stack_get(v, -1), stack_get(v, -2),res,alwaysfalse);
return res;
}

SQRESULT sq_cmpex(HSQUIRRELVM v, SQInteger *res, SQBool *alwaysfalse)
{
if (!res || !alwaysfalse) return SQ_ERROR;
bool af;
SQRESULT result = v->ObjCmp(stack_get(v, -1), stack_get(v, -2), *res, af) ? SQ_OK : SQ_ERROR;
*alwaysfalse = af ? SQTrue : SQFalse;
return result;
}

SQRESULT sq_newslot(HSQUIRRELVM v, SQInteger idx, SQBool bstatic)
{
sq_aux_paramscheck(v, 3);
Expand Down Expand Up @@ -1197,7 +1207,7 @@ SQRESULT sq_tailcall(HSQUIRRELVM v, SQInteger nparams)
{
return sq_throwerror(v, _SC("generators cannot be tail called"));
}

SQInteger stackbase = (v->_top - nparams) - v->_stackbase;
if (!v->TailCall(clo, stackbase, nparams)) {
return SQ_ERROR;
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3 changes: 2 additions & 1 deletion squirrel/sqbaselib.cpp
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Expand Up @@ -784,7 +784,8 @@ static SQInteger array_find(HSQUIRRELVM v)
static bool _sort_compare(HSQUIRRELVM v, SQArray *arr, SQObjectPtr &a,SQObjectPtr &b,SQInteger func,SQInteger &ret)
{
if(func < 0) {
if(!v->ObjCmp(a,b,ret)) return false;
bool alwaysfalse;
if(!v->ObjCmp(a,b,ret,alwaysfalse)) return false;
}
else {
SQInteger top = sq_gettop(v);
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32 changes: 23 additions & 9 deletions squirrel/sqvm.cpp
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Expand Up @@ -204,9 +204,14 @@ bool SQVM::NEG_OP(SQObjectPtr &trg,const SQObjectPtr &o)
}

#define _RET_SUCCEED(exp) { result = (exp); return true; }
bool SQVM::ObjCmp(const SQObjectPtr &o1,const SQObjectPtr &o2,SQInteger &result)
bool SQVM::ObjCmp(const SQObjectPtr &o1,const SQObjectPtr &o2,SQInteger &result, bool &alwaysfalse)
{
SQObjectType t1 = sq_type(o1), t2 = sq_type(o2);
alwaysfalse = false;
if((t1 == OT_FLOAT && isnan(_float(o1))) || (t2 == OT_FLOAT && isnan(_float(o2)))) {
alwaysfalse = true;
_RET_SUCCEED(0);
}
if(t1 == t2) {
if(_rawval(o1) == _rawval(o2))_RET_SUCCEED(0);
SQObjectPtr res;
Expand All @@ -225,8 +230,12 @@ bool SQVM::ObjCmp(const SQObjectPtr &o1,const SQObjectPtr &o2,SQInteger &result)
if(_delegable(o1)->GetMetaMethod(this, MT_CMP, closure)) {
Push(o1);Push(o2);
if(CallMetaMethod(closure,MT_CMP,2,res)) {
if(sq_type(res) == OT_FLOAT && isnan(_float(res))) {
alwaysfalse = true;
_RET_SUCCEED(0);
}
if(sq_type(res) != OT_INTEGER) {
Raise_Error(_SC("_cmp must return an integer"));
Raise_Error(_SC("_cmp must return an integer or NAN"));
return false;
}
_RET_SUCCEED(_integer(res))
Expand All @@ -236,7 +245,12 @@ bool SQVM::ObjCmp(const SQObjectPtr &o1,const SQObjectPtr &o2,SQInteger &result)
}
//continues through (no break needed)
default:
#ifdef NO_POINTER_CMP
Raise_CompareError(o1,o2);
return false;
#else
_RET_SUCCEED( _userpointer(o1) < _userpointer(o2)?-1:1 );
#endif
}
assert(0);
//if(type(res)!=OT_INTEGER) { Raise_CompareError(o1,o2); return false; }
Expand All @@ -259,7 +273,6 @@ bool SQVM::ObjCmp(const SQObjectPtr &o1,const SQObjectPtr &o2,SQInteger &result)
else if(t1==OT_NULL) {_RET_SUCCEED(-1);}
else if(t2==OT_NULL) {_RET_SUCCEED(1);}
else { Raise_CompareError(o1,o2); return false; }

}
assert(0);
_RET_SUCCEED(0); //cannot happen
Expand All @@ -268,13 +281,14 @@ bool SQVM::ObjCmp(const SQObjectPtr &o1,const SQObjectPtr &o2,SQInteger &result)
bool SQVM::CMP_OP(CmpOP op, const SQObjectPtr &o1,const SQObjectPtr &o2,SQObjectPtr &res)
{
SQInteger r;
if(ObjCmp(o1,o2,r)) {
bool alwaysfalse;
if(ObjCmp(o1,o2,r,alwaysfalse)) {
switch(op) {
case CMP_G: res = (r > 0); return true;
case CMP_GE: res = (r >= 0); return true;
case CMP_L: res = (r < 0); return true;
case CMP_LE: res = (r <= 0); return true;
case CMP_3W: res = r; return true;
case CMP_G: res = (!alwaysfalse && r > 0); return true;
case CMP_GE: res = (!alwaysfalse && r >= 0); return true;
case CMP_L: res = (!alwaysfalse && r < 0); return true;
case CMP_LE: res = (!alwaysfalse && r <= 0); return true;
case CMP_3W: if (alwaysfalse) res = NAN; else res = r; return true;
}
assert(0);
}
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2 changes: 1 addition & 1 deletion squirrel/sqvm.h
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Expand Up @@ -77,7 +77,7 @@ typedef sqvector<CallInfo> CallInfoVec;
bool NewSlotA(const SQObjectPtr &self,const SQObjectPtr &key,const SQObjectPtr &val,const SQObjectPtr &attrs,bool bstatic,bool raw);
bool DeleteSlot(const SQObjectPtr &self, const SQObjectPtr &key, SQObjectPtr &res);
bool Clone(const SQObjectPtr &self, SQObjectPtr &target);
bool ObjCmp(const SQObjectPtr &o1, const SQObjectPtr &o2,SQInteger &res);
bool ObjCmp(const SQObjectPtr &o1, const SQObjectPtr &o2,SQInteger &res,bool &alwaysfalse);
bool StringCat(const SQObjectPtr &str, const SQObjectPtr &obj, SQObjectPtr &dest);
static bool IsEqual(const SQObjectPtr &o1,const SQObjectPtr &o2,bool &res);
bool ToString(const SQObjectPtr &o,SQObjectPtr &res);
Expand Down