//When an expression is parsed in Algo.
public override object VisitExpr([NotNull] algoParser.ExprContext context)
{
//Is it an addition?
if (context.ADD_OP() != null)
{
//Yes. Evaluate the left hand expression.
AlgoValue left = (AlgoValue)VisitExpr(context.expr());
//Evaluate the right hand term.
AlgoValue right = (AlgoValue)VisitTerm(context.term());
//Perform an add operation, based on type.
return(AlgoOperators.Add(context, left, right));
}
else if (context.TAKE_OP() != null)
{
//Take operation.
//Evaluate the left hand expression.
AlgoValue left = (AlgoValue)VisitExpr(context.expr());
//Evaluate the right hand term.
AlgoValue right = (AlgoValue)VisitTerm(context.term());
//Perform a take operation, based on type.
return(AlgoOperators.Sub(context, left, right));
}
else
{
//No, just a term, evaluate.
return((AlgoValue)VisitTerm(context.term()));
}
}
//When a variable is modified using a postfix operator.
public override object VisitStat_setvar_postfix([NotNull] algoParser.Stat_setvar_postfixContext context)
{
//Get variable name.
AlgoValue oldValue = Particles.ParseParticleBlock(this, context, context.IDENTIFIER(), context.particle());
if (oldValue == null)
{
Error.Fatal(context, "No value returned to modify with operator.");
return(null);
}
//Switch on the operator type.
int toAdd = 0;
if (context.postfix_op().ADD_PFOP() != null)
{
//Increment.
toAdd = 1;
}
else
{
//Decrement.
toAdd = -1;
}
//Apply the operator.
AlgoValue newValue = null;
switch (oldValue.Type)
{
case AlgoValueType.Integer:
case AlgoValueType.Float:
case AlgoValueType.Rational:
newValue = AlgoOperators.Add(context, oldValue, new AlgoValue()
{
Type = AlgoValueType.Integer,
Value = new BigInteger(toAdd)
});
break;
default:
Error.Fatal(context, "Cannot increment a variable of type " + oldValue.Type.ToString() + ".");
return(null);
}
//Set the variable value.
oldValue.Value = newValue.Value;
oldValue.Type = newValue.Type;
return(null);
}
//When a variable value is changed by a self modifying operator.
public override object VisitStat_setvar_op([NotNull] algoParser.Stat_setvar_opContext context)
{
//Get variable reference.
AlgoValue oldValue = Particles.ParseParticleBlock(this, context, context.IDENTIFIER(), context.particle());
if (oldValue == null)
{
Error.Fatal(context, "No value returned to modify with operator.");
return(null);
}
//Does, evaluate the expression to set the value.
AlgoValue value = (AlgoValue)VisitExpr(context.expr());
//Switching on selfmod value.
AlgoValue newValue;
if (context.selfmod_op().ADDFROM_OP() != null)
{
//Attempt to add.
newValue = AlgoOperators.Add(context, oldValue, value);
}
else if (context.selfmod_op().DIVFROM_OP() != null)
{
//Attempt to divide.
newValue = AlgoOperators.Div(context, oldValue, value);
}
else if (context.selfmod_op().MULFROM_OP() != null)
{
//Attempt to multiply.
newValue = AlgoOperators.Mul(context, oldValue, value);
}
else if (context.selfmod_op().TAKEFROM_OP() != null)
{
//Attempt to subtract.
newValue = AlgoOperators.Sub(context, oldValue, value);
}
else
{
//Invalid operator type, oopsie! Implemented in parser but not here.
Error.Fatal(context, "Invalid operator given for self modifying variable, implemented in parser but not in interpreter.");
return(null);
}
//Set the value of the variable.
oldValue.Value = newValue.Value;
oldValue.Type = newValue.Type;
return(null);
}