public override Expression VisitUnaryExpression([NotNull] RuleEngineParser.UnaryExpressionContext context)
{
var primaryExpressionContext = context.primaryExpression();
if (primaryExpressionContext != null)
{
return(VisitPrimaryExpression(primaryExpressionContext));
}
var expression = VisitUnaryExpression(context.unaryExpression());
var operatorSign = context.GetChild(0).GetText();
switch (operatorSign)
{
case "+":
return(expression);
case "-":
var leftExpression = Expression.Convert(Expression.Constant(0), expression.Type);
return(Expression.Subtract(leftExpression, expression));
case "!":
return(Expression.Not(expression));
default:
throw new NotSupportedException($"Not support operator '{operatorSign}'.");
}
}
/// <summary>
/// Visit a parse tree produced by <see cref="RuleEngineParser.unaryExpression"/>.
/// <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 VisitUnaryExpression([NotNull] RuleEngineParser.UnaryExpressionContext context)
{
return(VisitChildren(context));
}