/// <summary>
/// Exit a parse tree produced by <see cref="algoParser.stat_try_catch"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitStat_try_catch([NotNull] algoParser.Stat_try_catchContext context)
{
}
/// <summary>
/// Visit a parse tree produced by <see cref="algoParser.stat_try_catch"/>.
/// <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 VisitStat_try_catch([NotNull] algoParser.Stat_try_catchContext context)
{
return(VisitChildren(context));
}
//When a try/catch block is executed.
public override object VisitStat_try_catch([NotNull] algoParser.Stat_try_catchContext context)
{
//Turn on execution catch mode.
AlgoRuntimeInformation.CatchExceptions = true;
//Loop over the statements, execute all.
bool foundError = false;
string errorMessage = "";
Scopes.AddScope();
foreach (var statement in context.block()[0].statement())
{
//Execute statement.
AlgoValue returned = null;
try
{
returned = (AlgoValue)VisitStatement(statement);
}
catch (Exception e)
{
//C# error somewhere up the heirarchy, 90% means an error has been thrown.
foundError = true;
errorMessage = "Internal Language Error: " + e.Message;
}
//Check if an error has been found.
if (AlgoRuntimeInformation.ExceptionCaught())
{
//Yep, break out to the catch block.
foundError = true;
errorMessage = AlgoRuntimeInformation.GetExceptionMessage();
AlgoRuntimeInformation.CatchExceptions = false;
break;
}
//If something was actually returned, return it up.
if (returned != null)
{
AlgoRuntimeInformation.CatchExceptions = false;
Scopes.RemoveScope();
return(returned);
}
}
Scopes.RemoveScope();
//Turn off error catching.
AlgoRuntimeInformation.CatchExceptions = false;
//Done executing try statements, did an error come back?
if (!foundError)
{
return(null);
}
//Yep, get the identifier to use for the error message, check it doesn't exist.
if (Scopes.VariableExists(context.IDENTIFIER().GetText()))
{
Error.Fatal(context, "A variable already exists named '" + context.IDENTIFIER().GetText() + "', cannot use for catch parameter.");
return(null);
}
//Create it, assign it the caught value.
Scopes.AddScope();
Scopes.AddVariable(context.IDENTIFIER().GetText(), new AlgoValue()
{
Type = AlgoValueType.String,
Value = errorMessage
}, context);
//Execute what's in the catch scope.
foreach (var statement in context.block()[1].statement())
{
AlgoValue returned = (AlgoValue)VisitStatement(statement);
if (returned != null)
{
Scopes.RemoveScope();
return(returned);
}
}
//Finished!
return(null);
}
