private static void Comparer_VerifyWhere <T>(XArray left, XArray right, CompareOperator cOp) where T : IComparable <T>
{
ComparerExtensions.Comparer comparer = TypeProviderFactory.Get(typeof(T).Name).TryGetComparer(cOp);
BitVector vector = new BitVector(left.Count);
// Verify 'Set' on an empty set works as expected (normal matches)
comparer(left, right, vector);
Comparer_VerifySetMatches <T>(vector, left, right, cOp);
}
public TermExpression(IXTable source, IXColumn left, CompareOperator op, IXColumn right)
{
_evaluate = EvaluateNormal;
// Save arguments as-is for ToString()
_left = left;
_cOp = op;
_right = right;
// Disallow constant <op> constant [likely error not wrapping column name]
if (_left is ConstantColumn && _right is ConstantColumn)
{
throw new ArgumentException($"({left} {op.ToQueryForm()} {right}) is comparing two constants. Wrap [ColumnNames] in braces.");
}
// If the left side is a constant and the operator can be swapped, move it to the right side.
// Comparers can check if the right side is constant and run a faster loop when that's the case.
if (_left.IsConstantColumn() && !(_right.IsConstantColumn()))
{
if (op.TryInvertCompareOperator(out op))
{
_left = right;
_right = left;
}
}
// Disallow unquoted constants used as strings
if (_right.IsConstantColumn() && _left.ColumnDetails.Type == typeof(String8) && _right.ColumnDetails.Type == typeof(String8))
{
ConstantColumn cRight = _right as ConstantColumn;
if (cRight != null && !cRight.IsNull && cRight.WasUnwrappedLiteral)
{
throw new ArgumentException($"{right} is compared to a string, but is unquoted. Strings must be quoted.");
}
}
// Convert the right side to the left side type if required
// This means constants will always be casted to the other side type.
if (_left.ColumnDetails.Type != _right.ColumnDetails.Type)
{
_right = CastedColumn.Build(source, _right, _left.ColumnDetails.Type, ValueKinds.Invalid);
}
// Get the left and right getters
_leftGetter = _left.CurrentGetter();
_rightGetter = _right.CurrentGetter();
// Null comparison is generic
if (_right.IsNullConstant())
{
if (op == CompareOperator.Equal)
{
_comparer = WhereIsNull;
}
else if (op == CompareOperator.NotEqual)
{
_comparer = WhereIsNotNull;
}
else
{
throw new ArgumentException($"Only equals and not equals operators are supported against null.");
}
}
else if (_left.IsNullConstant())
{
_left = _right;
if (op == CompareOperator.Equal)
{
_comparer = WhereIsNull;
}
else if (op == CompareOperator.NotEqual)
{
_comparer = WhereIsNotNull;
}
else
{
throw new ArgumentException($"Only equals and not equals operators are supported against null.");
}
}
else
{
// Get a comparer which can compare the values
_comparer = TypeProviderFactory.Get(left.ColumnDetails.Type).TryGetComparer(op);
if (_comparer == null)
{
throw new ArgumentException($"No comparer found for type {left.ColumnDetails.Type.Name}.");
}
}
// Optimize Enum to Constant comparisons to use the underlying indices
if (_left.IsEnumColumn() && _right.IsConstantColumn())
{
// Get an optimized comparer against the indices rather than values
IXColumn replacedRight = _right;
_comparer = SetComparer.ConvertToEnumIndexComparer(_left, _comparer, ref replacedRight, source);
// Get the indices on the left side
_leftGetter = _left.IndicesCurrentGetter();
// Use the updated value for the right side
_rightGetter = replacedRight.CurrentGetter();
}
// Allow String8 to constant Contains queries to compare on the raw byte[] and int[]
if (op == CompareOperator.Contains && _right.IsConstantColumn() && _left.ColumnDetails.Type == typeof(String8) && !_left.IsEnumColumn())
{
Func <object> rawGetter = _left.ComponentGetter(ColumnComponent.String8Raw);
if (rawGetter != null)
{
String8 rightValue = (String8)_right.ValuesGetter()().Array.GetValue(0);
String8Comparer string8Comparer = new String8Comparer();
_evaluate = (vector) =>
{
String8Raw raw = (String8Raw)rawGetter();
string8Comparer.WhereContains(raw, rightValue, vector);
};
}
}
}
/// <summary>
/// ConvertToEnumIndexComparer takes a comparer on the values of the enum and translates it to a comparer
/// which can operate on the byte[] indices instead.
/// </summary>
/// <param name="leftColumn">EnumColumn being compared</param>
/// <param name="currentComparer">Current Comparison function requested by TermExpression</param>
/// <param name="rightColumn">Constant being compared against</param>
/// <param name="source">IXTable containing comparison</param>
/// <returns>Comparer to compare the (updated) right Constant to the EnumColumn.Indices (rather than Values)</returns>
public static ComparerExtensions.Comparer ConvertToEnumIndexComparer(IXColumn leftColumn, ComparerExtensions.Comparer currentComparer, ref IXColumn rightColumn, IXTable source)
{
Func <XArray> valuesGetter = leftColumn.ValuesGetter();
if (valuesGetter == null)
{
throw new ArgumentException("ConvertToEnumIndexComparer is only valid for columns implementing Values.");
}
// Get all distinct values from the left side and find matches
XArray left = leftColumn.ValuesGetter()();
XArray right = rightColumn.ValuesGetter()();
BitVector set = new BitVector(left.Count);
currentComparer(left, right, set);
// NOTE: When EnumColumn values are sorted, can convert comparisons to non-equality native accelerated compare.
if (set.Count == 0)
{
// If there were no matches, always return none
return(None);
}
else if (set.Count == left.Count)
{
// If everything matched, always return everything
return(All);
}
else if (set.Count == 1)
{
// Convert the constant to the one matching index and make the comparison for index equals that
rightColumn = new ConstantColumn(source, (byte)set.GetSingle(), typeof(byte));
return(TypeProviderFactory.Get(typeof(byte)).TryGetComparer(CompareOperator.Equal));
}
else if (set.Count == left.Count - 1)
{
set.Not(set.Count);
// Convert the constant to the one non-matching index and make the comparison for index doesn't equal that
rightColumn = new ConstantColumn(source, (byte)set.GetSingle(), typeof(byte));
return(TypeProviderFactory.Get(typeof(byte)).TryGetComparer(CompareOperator.NotEqual));
}
else
{
// Otherwise, build a matcher for values in the set
return(new SetComparer(set).Evaluate);
}
}
