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Support casting states to booleans

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- This is so that you can call an A_Jump-type function from inside an if
  statement and do something other than jump if the jump condition was
  met. e.g.

    {
        if (A_Jump(128, "Foo"))
	{
            A_Log("The function would have jumped");
	}
	else
	{
	    A_Log("The function would not have jumped");
	}
    }
This commit is contained in:
Randy Heit 2016-02-18 22:40:04 -06:00
parent aa58c5f519
commit a399f40e5f
2 changed files with 77 additions and 1 deletions
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11
src/thingdef/thingdef_exp.h
View file

@ -390,6 +390,17 @@ public:
ExpEmit Emit(VMFunctionBuilder *build);
};
class FxCastStateToBool : public FxExpression
{
FxExpression *basex;
public:
FxCastStateToBool(FxExpression *x);
~FxCastStateToBool();
FxExpression *Resolve(FCompileContext&);
ExpEmit Emit(VMFunctionBuilder *build);
};
//==========================================================================
//

67
src/thingdef/thingdef_expression.cpp
View file

@ -168,6 +168,11 @@ FxExpression *FxExpression::ResolveAsBoolean(FCompileContext &ctx)
x->ValueType = VAL_Int;
break;
case VAL_State:
x = new FxCastStateToBool(x);
x = x->Resolve(ctx);
break;
default:
ScriptPosition.Message(MSG_ERROR, "Not an integral type");
delete this;
@ -511,6 +516,67 @@ ExpEmit FxFloatCast::Emit(VMFunctionBuilder *build)
//
//==========================================================================
FxCastStateToBool::FxCastStateToBool(FxExpression *x)
: FxExpression(x->ScriptPosition)
{
basex = x;
ValueType = VAL_Int;
}
//==========================================================================
//
//
//
//==========================================================================
FxCastStateToBool::~FxCastStateToBool()
{
SAFE_DELETE(basex);
}
//==========================================================================
//
//
//
//==========================================================================
FxExpression *FxCastStateToBool::Resolve(FCompileContext &ctx)
{
CHECKRESOLVED();
SAFE_RESOLVE(basex, ctx);
assert(basex->ValueType == VAL_State);
assert(!basex->isConstant() && "We shouldn't be able to generate a constant state ref");
return this;
}
//==========================================================================
//
//
//
//==========================================================================
ExpEmit FxCastStateToBool::Emit(VMFunctionBuilder *build)
{
ExpEmit from = basex->Emit(build);
assert(from.RegType == REGT_POINTER);
from.Free(build);
ExpEmit to(build, REGT_INT);
// If from is NULL, produce 0. Otherwise, produce 1.
build->Emit(OP_LI, to.RegNum, 0);
build->Emit(OP_EQA_K, 0, from.RegNum, build->GetConstantAddress(NULL, ATAG_GENERIC));
build->Emit(OP_JMP, 1);
build->Emit(OP_LI, to.RegNum, 1);
return to;
}
//==========================================================================
//
//
//
//==========================================================================
FxPlusSign::FxPlusSign(FxExpression *operand)
: FxExpression(operand->ScriptPosition)
{
@ -753,7 +819,6 @@ FxExpression *FxUnaryNotBoolean::Resolve(FCompileContext& ctx)
{
CHECKRESOLVED();
if (Operand)
{
Operand = Operand->ResolveAsBoolean(ctx);
}