//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()));
}
}
/// <summary>
/// Visit a parse tree produced by <see cref="algoParser.expr"/>.
/// <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 VisitExpr([NotNull] algoParser.ExprContext context)
{
return(VisitChildren(context));
}
/// <summary>
/// Exit a parse tree produced by <see cref="algoParser.expr"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitExpr([NotNull] algoParser.ExprContext context)
{
}