protected override async Task <bool> CanLoopAsync(StatementContext context)
{
var variable = context.ResolveVariable(IndexName);
var valueExp = await variable.Evaluate(context);
var value = await valueExp.ReduceToConstantAsync(context);
if (Reverse)
{
var lowerBound = (SqlObject)context.Metadata["lowerBound"];
if (value.LessOrEqualThan(lowerBound).IsTrue)
{
return(false);
}
}
else
{
var upperBound = (SqlObject)context.Metadata["upperBound"];
if (value.GreaterThanOrEqual(upperBound).IsTrue)
{
return(false);
}
}
return(await base.CanLoopAsync(context));
}
protected override async Task AfterLoopAsync(StatementContext context)
{
var variable = context.ResolveVariable(IndexName);
var value = await variable.Evaluate(context);
if (Reverse)
{
variable.SetValue(SqlExpression.Subtract(value, SqlExpression.Constant(SqlObject.BigInt(1))), context);
}
else
{
variable.SetValue(SqlExpression.Add(value, SqlExpression.Constant(SqlObject.BigInt(1))), context);
}
// TODO: resolve the variable from the context and increment
await base.AfterLoopAsync(context);
}