public override VfpExpression Visit(VfpCaseExpression expression)
{
Debug.Assert(expression.When.Count == expression.Then.Count);
Write("ICASE(");
for (var index = 0; index < expression.When.Count; index++)
{
if (index > 0)
{
Write(",");
}
expression.When[index].Accept(this);
Write(",");
expression.Then[index].Accept(this);
}
if (expression.Else != null && !(expression.Else is VfpNullExpression))
{
Write(",");
expression.Else.Accept(this);
}
Write(")");
return(expression);
}
private static bool IsEmptyCaseExpression(VfpCaseExpression expression)
{
if (expression == null || expression.When.Count != 1 || expression.Then.Count != 1)
{
return(false);
}
if (!(expression.When.First() is VfpIsEmptyExpression))
{
return(false);
}
if (!(expression.Then[0] is VfpConstantExpression constant1) || constant1.ConstantKind != PrimitiveTypeKind.Boolean || !(bool)constant1.Value)
{
return(false);
}
if (!(expression.Else is VfpConstantExpression constant2) || constant2.ConstantKind != PrimitiveTypeKind.Boolean || (bool)constant2.Value)
{
return(false);
}
return(true);
}
private static bool IsExpectedCaseExpression(VfpCaseExpression expression)
{
if (expression == null || expression.When.Count != 2 || expression.Then.Count != 2)
{
return(false);
}
var constant1 = expression.Then[0] as VfpConstantExpression;
if (constant1 == null || constant1.ConstantKind != PrimitiveTypeKind.Boolean)
{
return(false);
}
var constant2 = expression.Then[1] as VfpConstantExpression;
if (constant2 == null || constant2.ConstantKind != PrimitiveTypeKind.Boolean)
{
return(false);
}
if (!(bool)constant1.Value)
{
return(false);
}
if ((bool)constant2.Value)
{
return(false);
}
return(true);
}
public virtual VfpExpression Visit(VfpCaseExpression expression)
{
return(new VfpCaseExpression(expression.ResultType,
VisitVfpExpressionList(expression.When),
VisitVfpExpressionList(expression.Then),
expression.Else.Accept(this)));
}
public override VfpExpression Visit(VfpCaseExpression expression)
{
if (!_canRewrite || !NullGatherer.Gather(expression).Any())
{
return(expression);
}
return(expression.Cast(expression.ResultType));
}
private static bool IsComparisonCaseExpression(VfpCaseExpression expression)
{
if (expression == null || expression.When.Count != 2 || expression.Then.Count != 2)
{
return(false);
}
if (!(expression.Then[0] is VfpConstantExpression constant1) || constant1.ConstantKind != PrimitiveTypeKind.Boolean || !(bool)constant1.Value)
{
return(false);
}
if (!(expression.Then[1] is VfpConstantExpression constant2) || constant2.ConstantKind != PrimitiveTypeKind.Boolean || (bool)constant2.Value)
{
return(false);
}
return(true);
}
private static bool IsExpectedCaseExpression(VfpCaseExpression expression) => IsComparisonCaseExpression(expression) || IsEmptyCaseExpression(expression) || IsNotAndIsEmptyCaseExpression(expression);
public override VfpExpression Visit(VfpCaseExpression expression)
{
return(IsExpectedCaseExpression(expression) ? base.Visit(expression.When[0]) : base.Visit(expression));
}
