public static Field GetField(
this ScalarExpression scalarExpression,
string columnName,
ILogger logger,
SchemaFile file
)
{
switch (scalarExpression)
{
case ValueExpression valueExpression:
return(valueExpression.GetField(columnName, logger, file));
case UnaryExpression unaryExpression:
return(unaryExpression.Expression.GetField(columnName, logger, file));
case ParenthesisExpression parenthesisExpression:
return(parenthesisExpression.Expression.GetField(columnName, logger, file));
case ColumnReferenceExpression columnReferenceExpression:
return(columnReferenceExpression.GetField(columnName, logger, file));
case BinaryExpression binaryExpression:
{
// TODO : what if you're working with different types, which one should be reported? (..compute the value)
var first = binaryExpression.FirstExpression.GetField(columnName, logger, file);
var second = binaryExpression.SecondExpression.GetField(columnName, logger, file);
var result = first.Type != FieldType.NotSpecified ? first : second;
return(result.Copy(columnName ?? binaryExpression.GetTokenText()));
}
case ConvertCall convertCall:
{
// TODO : is the result nullable if the column we're converting is nullable?
var isNullable = convertCall.Parameter.GetField(columnName, logger, file).IsNullable;
return(convertCall.DataType.GetField(columnName, isNullable, logger, file));
}
case TryConvertCall tryConvertCall:
{
// TODO : is the result nullable if the column we're converting is nullable?
var isNullable = tryConvertCall.Parameter.GetField(columnName, logger, file).IsNullable;
return(tryConvertCall.DataType.GetField(columnName, isNullable, logger, file));
}
case CastCall castCall:
{
// TODO : is the result nullable if the column we're casting is nullable?
var isNullable = castCall.Parameter.GetField(columnName, logger, file).IsNullable;
return(castCall.DataType.GetField(columnName, isNullable, logger, file));
}
case TryCastCall tryCastCall:
{
// TODO : is the result nullable if the column we're casting is nullable?
var isNullable = tryCastCall.Parameter.GetField(columnName, logger, file).IsNullable;
return(tryCastCall.DataType.GetField(columnName, isNullable, logger, file));
}
case FunctionCall functionCall:
return(functionCall.GetField(columnName, logger, file));
// TODO : consolidate left and right
case LeftFunctionCall leftFunctionCall:
var leftField = leftFunctionCall.Parameters.Last().GetField(columnName, logger, file);
return(new StringField()
{
Name = columnName,
IsNullable = false,
Length = (leftField as StringField)?.Length ?? 0,
Type = FieldType.String,
});
case RightFunctionCall rightFunctionCall:
var rightField = rightFunctionCall.Parameters.Last().GetField(columnName, logger, file);
return(new StringField()
{
Name = columnName,
IsNullable = false,
Length = (rightField as StringField)?.Length ?? 0,
Type = FieldType.String,
});
case SearchedCaseExpression searchedCaseExpression:
{
var columns = searchedCaseExpression
.WhenClauses // TODO : do we care about these boolean expressions?
.Select(x => x.ThenExpression.GetField(columnName, logger, file))
.ToList();
var elseColumn = searchedCaseExpression
.ElseExpression
?.GetField(columnName, logger, file);
if (elseColumn != null)
{
columns.Add(elseColumn);
}
// TODO : compute column type, do not return first..
// https://docs.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-2017#implicit-conversions
return(columns.First());
}
case SimpleCaseExpression simpleCaseExpression:
{
var columns = simpleCaseExpression
.WhenClauses
.Select(x => x.ThenExpression.GetField(columnName, logger, file))
.ToList();
var elseColumn = simpleCaseExpression
.ElseExpression
?.GetField(columnName, logger, file);
if (elseColumn != null)
{
columns.Add(elseColumn);
}
// TODO : compute column type, do not return first..
return(columns.First());
}
case ScalarSubquery scalarSubquery:
{
var column = scalarSubquery
.QueryExpression
.GetFields(logger, file)
.First()
.Copy(columnName);
return(column);
}
case CoalesceExpression coalesceExpression:
{
var columns = coalesceExpression
.Expressions
.Select(x => x.GetField(columnName, logger, file))
.Where(x => x.Type != FieldType.NotSpecified)
.ToList();
// TODO : compute column type, do not return first..
// https://docs.microsoft.com/en-us/sql/t-sql/language-elements/coalesce-transact-sql?view=sql-server-2017
// Returns the data type of expression with the highest data type precedence. If all expressions are nonnullable, the result is typed as nonnullable.
return(columns
.FirstOrDefault()
?.Copy(columnName) ?? new UnknownField()
{
Name = columnName,
});
}
case NullIfExpression nullIfExpression:
{
// Returns the same type as the first expression
return(nullIfExpression
.FirstExpression
.GetField(columnName, logger, file)
.Copy(columnName));
}
case AtTimeZoneCall atTimeZoneCall:
{
return(atTimeZoneCall
.DateValue
.GetField(columnName, logger, file));
}
case IIfCall iifCall:
{
var firstField = iifCall.ThenExpression.GetField(columnName, logger, file);
var secondField = iifCall.ElseExpression.GetField(columnName, logger, file);
// TODO : Returns the data type with the highest precedence from the types in true_value and false_value. For more information
return(firstField);
}
case ParameterlessCall parameterlessCall:
return(parameterlessCall.GetField(columnName, logger, file));
default:
{
logger.Log(LogLevel.Warning,
LogType.NotSupportedYet,
file.Path,
$"Unable to determine column type from scalar expression. Fragment: \"{scalarExpression.GetTokenText()}\"");
return(new UnknownField()
{
Name = columnName,
});
}
}
}
public static Field GetField(
this ScalarExpression scalarExpression,
ColumnDefinition column,
IEnumerable <ColumnDefinition> columns,
ILogger logger,
SchemaFile file
)
{
switch (scalarExpression)
{
case ValueExpression valueExpression:
return(valueExpression.GetField(column.ColumnIdentifier.Value, logger, file));
case ParenthesisExpression parenthesisExpression:
return(parenthesisExpression.Expression.GetField(column, columns, logger, file));
case ColumnReferenceExpression columnReferenceExpression:
return(columnReferenceExpression.GetField(logger, file, columns));
case BinaryExpression binaryExpression:
{
// TODO : what if you're working with different types, which one should be reported? (..compute the value)
var first = binaryExpression.FirstExpression.GetField(column, columns, logger, file);
var second = binaryExpression.SecondExpression.GetField(column, columns, logger, file);
var result = first.Type != FieldType.NotSpecified ? first : second;
return(result.Copy(column.ColumnIdentifier.Value));
}
case ConvertCall convertCall:
{
var name = column.ColumnIdentifier.Value;
var isNullable = column.IsNullable();
return(convertCall.DataType.GetField(name, isNullable, logger, file));
}
case FunctionCall functionCall:
{
// TODO : do not return first.. compute the value
var first = functionCall
.Parameters
.Select(x => x.GetField(column, columns, logger, file))
.FirstOrDefault(x => x.Type != FieldType.NotSpecified);
if (first != null)
{
return(first);
}
break;
}
}
logger.Log(LogLevel.Error, $"Unable to determine column type from scalar expression. Fragment: \"{scalarExpression.GetTokenText()}\"");
return(new UnknownField()
{
Name = column.ColumnIdentifier.Value,
});
}