/// <summary>
/// Evaluates a given particle, and returns the result.
/// </summary>
public override object VisitParticle([NotNull] algoParser.ParticleContext context)
{
//Get the last result of the particle before this.
AlgoValue current = Particles.GetParticleResult();
if (current == null)
{
Error.Internal("Particle chain started without setting an initial value.");
return(null);
}
//Prepare an "old" scope for swapping.
AlgoScopeCollection oldScope = null;
//What type of particle is it?
//CHILD VARIABLE
if (context.IDENTIFIER() != null)
{
//Sub-variable. Attempt to get from the object.
if (current.Type != AlgoValueType.Object)
{
Error.Fatal(context, "Cannot access children when given variable is not an object, and has no children to access.");
return(null);
}
//Does the sub-variable exist?
AlgoObject curObj = (AlgoObject)current.Value;
AlgoValue newObj = curObj.ObjectScopes.GetVariable(context.IDENTIFIER().GetText());
if (newObj == null)
{
Error.Fatal(context, "No child of the given object exists with name '" + context.IDENTIFIER().GetText() + "'.");
return(null);
}
//Yes, set result and return.
Particles.SetParticleInput(newObj);
return(null);
}
//ARRAY ACCESS
else if (context.array_access_particle() != null)
{
var aap = context.array_access_particle();
//Indexing.
//For each index, iterate over.
AlgoValue currentLV = current;
foreach (var index in aap.literal_params().expr())
{
//Is the current list value a list?
if (currentLV.Type != AlgoValueType.List)
{
Error.Fatal(context, "Cannot index into variable that is not a list or indexable object.");
return(null);
}
//Need to switch scopes for evaluating indexes?
if (Particles.funcArgumentScopes != null)
{
oldScope = Scopes;
Scopes = Particles.funcArgumentScopes;
}
//Evaluate the expression.
AlgoValue indexVal = (AlgoValue)VisitExpr(index);
//Back to normal.
if (Particles.funcArgumentScopes != null)
{
Scopes = oldScope;
}
//Valid?
if (indexVal.Type != AlgoValueType.Integer)
{
Error.Fatal(context, "Index value provided is not an integer. Indexes must be whole integer values.");
return(null);
}
//Is the index outside of the bounds of the array?
if (((List <AlgoValue>)currentLV.Value).Count <= (BigInteger)indexVal.Value)
{
Error.Fatal(context, "Index provided is outside the bounds of the array.");
return(null);
}
//Index into it, set the current value.
currentLV = ((List <AlgoValue>)currentLV.Value)[(int)((BigInteger)indexVal.Value)];
}
//Set result.
Particles.SetParticleInput(currentLV);
return(null);
}
//CHILD FUNCTION
else if (context.functionCall_particle() != null)
{
//Function call.
if (current.Type != AlgoValueType.Object)
{
Error.Fatal(context, "Cannot call a child function on a value with no children (given value was not an object).");
return(null);
}
//Get the child, see if it's a function.
AlgoObject thisObj = current.Value as AlgoObject;
string funcName = context.functionCall_particle().IDENTIFIER().GetText();
AlgoValue childFunc = thisObj.ObjectScopes.GetVariable(funcName);
if (childFunc == null || (childFunc.Type != AlgoValueType.Function && childFunc.Type != AlgoValueType.EmulatedFunction))
{
Error.Fatal(context, "No child function exists with name '" + funcName + "'.");
return(null);
}
//Set the particle result as the function value, call the function call particle.
Particles.SetParticleInput(childFunc);
var result = VisitFunctionCall_particle(context.functionCall_particle());
if (result == null)
{
Particles.ResetParticleInput(); //Returned no result.
}
else
{
//A result came back, set input for the next particle.
Particles.SetParticleInput((AlgoValue)result);
}
return(null);
}
else
{
//Unrecognized!
Error.Internal("Unrecognized particle type to parse, implementation either unfinished or incorrect.");
return(null);
}
}
/// <summary>
/// Visit a parse tree produced by <see cref="algoParser.particle"/>.
/// <para>
/// The default implementation returns the result of calling <see cref="AbstractParseTreeVisitor{Result}.VisitChildren(IRuleNode)"/>
/// on <paramref name="context"/>.
/// </para>
/// </summary>
/// <param name="context">The parse tree.</param>
/// <return>The visitor result.</return>
public virtual Result VisitParticle([NotNull] algoParser.ParticleContext context)
{
return(VisitChildren(context));
}
/// <summary>
/// Exit a parse tree produced by <see cref="algoParser.particle"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitParticle([NotNull] algoParser.ParticleContext context)
{
}
