private static Expression GetParseDateTimeToStringOrNull(Expression dateValue, Type sqlFunctionsType)
{
if (!TryGetDatePartMethod <DateTime?>(sqlFunctionsType, out var datePartMethod))
{
return(null);
}
dateValue = dateValue.GetConversionTo <DateTime?>();
var dateTimePattern = CultureInfo
.CurrentCulture
.DateTimeFormat
.SortableDateTimePattern
.Replace("mm", "mi") // Minutes
.Replace('T', ' ') // Date-Time separator
.Replace("'", null)
.ToLowerInvariant();
Expression valueConcatenation = null;
var datePartStartIndex = 0;
var stringConcat = StringExpressionExtensions.GetConcatMethod(parameterCount: 2);
for (var i = 0; i < dateTimePattern.Length; ++i)
{
if (char.IsLetter(dateTimePattern[i]))
{
continue;
}
var datePartNameCall = GetDatePartCall(
datePartMethod,
dateTimePattern,
datePartStartIndex,
i,
dateValue,
sqlFunctionsType);
var added = Expression.Call(
stringConcat,
datePartNameCall,
dateTimePattern[i].ToString().ToConstantExpression());
valueConcatenation = (valueConcatenation != null)
? Expression.Call(stringConcat, valueConcatenation, added) : added;
datePartStartIndex = i + 1;
}
var finalDatePartNameCall = GetDatePartCall(
datePartMethod,
dateTimePattern,
datePartStartIndex,
dateTimePattern.Length,
dateValue,
sqlFunctionsType);
// ReSharper disable once AssignNullToNotNullAttribute
return(Expression.Call(stringConcat, valueConcatenation, finalDatePartNameCall));
}
private static Expression GetStringValueConversion(
Expression sourceValue,
Expression fallbackValue,
Type nonNullableTargetEnumType)
{
if (sourceValue.Type != typeof(string))
{
sourceValue = ToStringConverter.GetConversion(sourceValue);
}
var underlyingEnumType = Enum.GetUnderlyingType(nonNullableTargetEnumType);
var isNumericTest = GetIsNumericTest(sourceValue);
var numericConversion = GetNumericStringToEnumConversion(
sourceValue,
fallbackValue,
nonNullableTargetEnumType,
underlyingEnumType);
var nameMatchingConversion = GetStringToEnumConversion(
sourceValue,
fallbackValue,
nonNullableTargetEnumType);
var numericOrNameConversion = Expression.Condition(
isNumericTest,
numericConversion,
nameMatchingConversion);
var convertedValueOrDefault = Expression.Condition(
StringExpressionExtensions.GetIsNullOrWhiteSpaceCall(sourceValue),
fallbackValue,
numericOrNameConversion);
return(convertedValueOrDefault);
}