private QueryOperator UpdateSelect(SelectOperator op, MonadMember src, QueryTree selector)
{
if (src != op.Source || selector != op.Selector)
{
return(MakeSelect(op, src, selector));
}
return(op);
}
/// <summary>
/// Visits a <see cref="SelectOperator" /> and coalesces it with any possible child operators.
/// </summary>
/// <param name="op">The operator to visit.</param>
/// <returns>The coalesced operator.</returns>
protected internal override QueryOperator VisitSelect(SelectOperator op)
{
var source = VisitAndConvert <MonadMember>(op.Source);
var selector = Visit(op.Selector);
var srcOperator = source.QueryNodeType == QueryNodeType.Operator ? (QueryOperator)source : null;
var srcSelect = srcOperator != null && srcOperator.NodeType == OperatorType.Select ? (SelectOperator)srcOperator : null;
if (srcSelect != null && op.InputElementType == srcSelect.ElementType)
{
var p = Expression.Parameter(srcSelect.InputElementType);
// Optimization when both lambda abstractions don't abstract over anything
if (TryExtractNullaryLambdaBody(srcSelect.Selector, out Expression selector1) && TryExtractNullaryLambdaBody(selector, out Expression selector2))
{
var reduced = BetaReducer.Reduce(Expression.Invoke(selector2, Expression.Invoke(selector1, p)));
return(op.QueryExpressionFactory.Select(
op.ElementType,
srcSelect.InputElementType,
srcSelect.Source,
DefaultQueryExpressionFactory.Instance.LambdaAbstraction(
Expression.Lambda(
Expression.Lambda(
reduced,
p
)
),
Array.Empty <QueryTree>()
)
));
}
var p1 = Expression.Parameter(typeof(Func <,>).MakeGenericType(srcSelect.InputElementType, srcSelect.ElementType));
var p2 = Expression.Parameter(typeof(Func <,>).MakeGenericType(op.InputElementType, op.ElementType));
return(op.QueryExpressionFactory.Select(
op.ElementType,
srcSelect.InputElementType,
srcSelect.Source,
DefaultQueryExpressionFactory.Instance.LambdaAbstraction(
Expression.Lambda(
Expression.Lambda(
Expression.Invoke(p2, Expression.Invoke(p1, p)),
p
),
p1,
p2
),
new[] { srcSelect.Selector, selector }
)
));
}
return(op.Update(source, selector));
}
/// <summary>
/// Visits a <see cref="SelectOperator" /> node.
/// </summary>
/// <param name="op">Node to visit.</param>
/// <returns>Result of visiting the node.</returns>
protected internal override QueryOperator VisitSelect(SelectOperator op)
{
var src = VisitAndConvert <MonadMember>(op.Source);
var selector = Visit(op.Selector);
if (src != op.Source || selector != op.Selector)
{
return(MakeSelect(op, src, selector));
}
return(op);
}
/// <summary>
/// Visits a <see cref="SelectOperator" /> node.
/// </summary>
/// <param name="op">Node to visit.</param>
/// <returns>Result of visiting the node.</returns>
protected internal override QueryOperator VisitSelect(SelectOperator op)
{
var elementType = VisitType(op.ElementType);
var inputElementType = VisitType(op.InputElementType);
var src = VisitAndConvert <MonadMember>(op.Source);
var selector = Visit(op.Selector);
if (src != op.Source || selector != op.Selector || elementType != op.ElementType || inputElementType != op.InputElementType)
{
return(MakeSelect(op, elementType, inputElementType, src, selector));
}
return(op);
}
/// <summary>
/// Makes a <see cref="SelectOperator" /> with the given children.
/// </summary>
/// <param name="node">Original query expression.</param>
/// <param name="source">Source query expression.</param>
/// <param name="selector">Selector query expression.</param>
/// <returns>Representation of the original query expression.</returns>
protected sealed override QueryOperator MakeSelect(SelectOperator node, MonadMember source, QueryTree selector)
{
return(node.QueryExpressionFactory.Select(node.ElementType, node.InputElementType, source, selector));
}
/// <summary>
/// Creates a textual representation of the SelectOperator with the given children.
/// </summary>
/// <param name="node">Original query expression.</param>
/// <param name="source">Source query expression.</param>
/// <param name="selector">Selector query expression.</param>
/// <returns>Representation of the original query expression.</returns>
protected override string MakeSelect(SelectOperator node, string source, string selector)
{
return(string.Format(CultureInfo.InvariantCulture, "@Select({0}, {1})", source, selector));
}
protected internal override QueryOperator VisitSelect(SelectOperator op)
{
var src = VisitAndConvert <MonadMember>(op.Source);
var selector = Visit(op.Selector);
if (TryCast <SelectOperator>(src, OperatorType.Select, out SelectOperator select1) &&
TryExtractNullaryLambdaBody <LambdaExpression>(select1.Selector, ExpressionType.Lambda, out LambdaExpression selector1) &&
TryGetNewAnonymousType(selector1.Body, out NewExpression anonCtor1) &&
TryExtractNullaryLambdaBody <LambdaExpression>(selector, ExpressionType.Lambda, out LambdaExpression selector2))
{
if (TryGetNewAnonymousType(selector2.Body, out NewExpression anonCtor2))
{
if (anonCtor2.Members.Count > 0 && anonCtor2.Arguments[0] == selector2.Parameters[0])
{
var newArgs = new Expression[anonCtor2.Members.Count];
newArgs[0] = anonCtor1;
for (var i = 1; i < newArgs.Length; i++)
{
var visitor = new ValidateMemberAccessesAndInlineVisitor(anonCtor1, selector1.Parameters[0], selector2.Parameters[0]);
newArgs[i] = visitor.Visit(anonCtor2.Arguments[i]);
if (!visitor.Valid)
{
return(UpdateSelect(op, src, selector));
}
}
var updated = anonCtor2.Update(newArgs);
var newBody =
DefaultQueryExpressionFactory.Instance.LambdaAbstraction(
Expression.Lambda(Expression.Lambda(updated, selector1.Parameters[0])),
Array.Empty <QueryTree>()
);
return
(op.QueryExpressionFactory.Select(
op.ElementType,
select1.InputElementType,
select1.Source,
newBody
));
}
}
else
{
var flatteningValidationVisitor = new ValidateMemberAccessVisitor(anonCtor1, selector2.Parameters[0]);
flatteningValidationVisitor.Visit(selector2.Body);
if (flatteningValidationVisitor.Valid)
{
var flattener = new AnonymousTypeFlattener(anonCtor1);
if (flattener.TryConstruct(out NewExpression c))
{
var t = c.Type;
var newParam = Expression.Parameter(t);
var flatteningVisitor = new InlineFlattenedTypeVisitor(anonCtor1, newParam, selector2.Parameters[0], flattener);
var f = flatteningVisitor.Visit(selector2.Body);
var child =
select1.QueryExpressionFactory.Select(
t,
select1.InputElementType,
select1.Source,
DefaultQueryExpressionFactory.Instance.LambdaAbstraction(
Expression.Lambda(Expression.Lambda(c, selector1.Parameters[0])),
Array.Empty <QueryTree>()
)
);
return
(op.QueryExpressionFactory.Select(
op.ElementType,
t,
child,
DefaultQueryExpressionFactory.Instance.LambdaAbstraction(
Expression.Lambda(Expression.Lambda(f, newParam)),
Array.Empty <QueryTree>()
)
));
}
}
}
}
return(UpdateSelect(op, src, selector));
}
/// <summary>
/// Makes a <see cref="SelectOperator" /> with the given children.
/// </summary>
/// <param name="node">Original query expression.</param>
/// <param name="source">Source query expression.</param>
/// <param name="elementType">Element type for the resulting operator.</param>
/// <param name="inputElementType">Input element type for the resulting operator.</param>
/// <param name="selector">Selector query expression.</param>
/// <returns>Representation of the original query expression.</returns>
protected virtual QueryOperator MakeSelect(SelectOperator node, Type elementType, Type inputElementType, MonadMember source, QueryTree selector)
{
return(node.QueryExpressionFactory.Select(elementType, inputElementType, source, selector));
}
