/// <summary>
/// Visit an <see cref="InputReferenceExpression"/>, producing a new InputReferenceExpression
/// based on the visited form of the <see cref="QueryableResourceExpression"/> that is referenced by
/// the InputReferenceExpression argument, <paramref name="ire"/>.
/// </summary>
/// <param name="ire">InputReferenceExpression expression to visit</param>
/// <returns>Visited InputReferenceExpression expression</returns>
internal virtual Expression VisitInputReferenceExpression(InputReferenceExpression ire)
{
Debug.Assert(ire != null, "ire != null -- otherwise caller never should have visited here");
ResourceExpression re = (ResourceExpression)this.Visit(ire.Target);
return(re.CreateReference());
}
/// <summary>
/// Creates an <see cref="InputReferenceExpression"/> that refers to this component of the resource path.
/// The returned expression is guaranteed to be reference-equal (object.ReferenceEquals)
/// to any other InputReferenceExpression that also refers to this resource path component.
/// </summary>
/// <returns>The InputReferenceExpression that refers to this resource path component</returns>
internal InputReferenceExpression CreateReference()
{
if (this.inputRef == null)
{
this.inputRef = new InputReferenceExpression(this);
}
return(this.inputRef);
}
/// <summary>
/// Instructs this resource set expression to use the input reference expression from <paramref name="newInput"/> as it's
/// own input reference, and to retarget the input reference from <paramref name="newInput"/> to this resource set expression.
/// </summary>
/// <param name="newInput">The resource set expression from which to take the input reference.</param>
/// <remarks>Used exclusively by ResourceBinder.RemoveTransparentScope.</remarks>
internal void OverrideInputReference(QueryableResourceExpression newInput)
{
Debug.Assert(newInput != null, "Original resource set cannot be null");
Debug.Assert(this.inputRef == null, "OverrideInputReference cannot be called if the target has already been referenced");
InputReferenceExpression inputRef = newInput.inputRef;
if (inputRef != null)
{
this.inputRef = inputRef;
inputRef.OverrideTarget(this);
}
}
/// <summary>
/// Input resource set references are intentionally omitted from the URL string for the top level
/// references to input parameter (i.e. outside of any/all methods).
/// For parameter references to input (range variable for Where) inside any/all methods we write "$it".
/// </summary>
/// <param name="ire">The input reference</param>
/// <returns>The same input reference expression</returns>
internal override Expression VisitInputReferenceExpression(InputReferenceExpression ire)
{
// This method intentionally does not write anything to the URI for implicit references to the input parameter ($it).
// This is how 'Where(<input>.Id == 5)' becomes '$filter=Id eq 5'.
Debug.Assert(ire != null, "ire != null");
if (this.parent == null || (!this.InSubScope && this.parent.NodeType != ExpressionType.MemberAccess && this.parent.NodeType != ExpressionType.TypeAs && this.parent.NodeType != ExpressionType.Call))
{
// Ideally we refer to the parent expression as the un-translatable one,
// because we cannot reference 'this' as a standalone expression; however
// if the parent is null for any reason, we fall back to the expression itself.
string expressionText = (this.parent != null) ? this.parent.ToString() : ire.ToString();
throw new NotSupportedException(Strings.ALinq_CantTranslateExpression(expressionText));
}
// Write "$it" for input parameter reference inside any/all methods
if (this.InSubScope || this.parent.NodeType == ExpressionType.Call)
{
this.builder.Append(XmlConstants.ImplicitFilterParameter);
}
return(ire);
}
/// <summary>
/// Input resource set references are intentionally omitted from the URL string for the top level
/// refences to input parameter (i.e. outside of any/all methods).
/// For parameter references to input (range variable for Where) inside any/all methods we write "$it".
/// </summary>
/// <param name="ire">The input reference</param>
/// <returns>The same input reference expression</returns>
internal override Expression VisitInputReferenceExpression(InputReferenceExpression ire)
{
// This method intentionally does not write anything to the URI for implicit references to the input parameter ($it).
// This is how 'Where(<input>.Id == 5)' becomes '$filter=Id eq 5'.
Debug.Assert(ire != null, "ire != null");
if (this.parent == null || (!this.InSubScope && this.parent.NodeType != ExpressionType.MemberAccess && this.parent.NodeType != ExpressionType.TypeAs && this.parent.NodeType != ExpressionType.Call))
{
// Ideally we refer to the parent expression as the un-translatable one,
// because we cannot reference 'this' as a standalone expression; however
// if the parent is null for any reasonn, we fall back to the expression itself.
string expressionText = (this.parent != null) ? this.parent.ToString() : ire.ToString();
throw new NotSupportedException(Strings.ALinq_CantTranslateExpression(expressionText));
}
// Write "$it" for input parameter reference inside any/all methods
if (this.InSubScope || this.parent.NodeType == ExpressionType.Call)
{
this.builder.Append(XmlConstants.ImplicitFilterParameter);
}
return ire;
}
/// <summary>
/// Resolves member accesses that represent transparent scope property accesses to the corresponding resource,
/// iff the input resource is enclosed in a transparent scope and the specified MemberExpression represents
/// such a property access.
/// </summary>
/// <param name="m">MemberExpression expression to visit</param>
/// <returns>
/// An InputReferenceExpression if the member access represents a transparent scope property
/// access that can be resolved to a resource in the path that produces the input resource;
/// otherwise the same MemberExpression is returned.
/// </returns>
internal override Expression VisitMemberAccess(MemberExpression m)
{
// If the current input resource is not enclosed in a transparent scope, then this
// MemberExpression cannot represent a valid transparent scope access based on the input parameter.
if (this.inputResource == null ||
!this.inputResource.HasTransparentScope)
{
return(base.VisitMemberAccess(m));
}
ParameterExpression innerParamRef = null;
Stack <PropertyInfo> nestedAccesses = new Stack <PropertyInfo>();
MemberExpression memberRef = m;
while (memberRef != null &&
PlatformHelper.IsProperty(memberRef.Member) &&
memberRef.Expression != null)
{
nestedAccesses.Push((PropertyInfo)memberRef.Member);
if (memberRef.Expression.NodeType == ExpressionType.Parameter)
{
innerParamRef = (ParameterExpression)memberRef.Expression;
}
memberRef = memberRef.Expression as MemberExpression;
}
// Only continue if the inner non-MemberExpression is the input reference ParameterExpression and
// at least one property reference is present - otherwise this cannot be a transparent scope access.
if (innerParamRef != this.inputParameter || nestedAccesses.Count == 0)
{
return(m);
}
ResourceExpression target = this.input;
QueryableResourceExpression targetResource = this.inputResource;
bool transparentScopeTraversed = false;
// Process all the traversals through transparent scopes.
while (nestedAccesses.Count > 0)
{
if (targetResource == null || !targetResource.HasTransparentScope)
{
break;
}
// Peek the property; pop it once it's consumed
// (it could be a non-transparent-identifier access).
PropertyInfo currentProp = nestedAccesses.Peek();
// If this is the accessor for the target, then the member
// refers to the target itself.
if (currentProp.Name.Equals(targetResource.TransparentScope.Accessor, StringComparison.Ordinal))
{
target = targetResource;
nestedAccesses.Pop();
transparentScopeTraversed = true;
continue;
}
// This member could also be one of the in-scope sources of the target.
Expression source;
if (!targetResource.TransparentScope.SourceAccessors.TryGetValue(currentProp.Name, out source))
{
break;
}
transparentScopeTraversed = true;
nestedAccesses.Pop();
Debug.Assert(source != null, "source != null -- otherwise ResourceBinder created an accessor to nowhere");
InputReferenceExpression sourceReference = source as InputReferenceExpression;
if (sourceReference == null)
{
targetResource = source as QueryableResourceExpression;
if (targetResource == null || !targetResource.HasTransparentScope)
{
target = (ResourceExpression)source;
}
}
else
{
targetResource = sourceReference.Target as QueryableResourceExpression;
target = targetResource;
}
}
// If no traversals were made, the original expression is OK.
if (!transparentScopeTraversed)
{
return(m);
}
// Process traversals after the transparent scope.
Expression result = this.CreateReference(target);
while (nestedAccesses.Count > 0)
{
result = Expression.Property(result, nestedAccesses.Pop());
}
return(result);
}
/// <summary>
/// Visit an <see cref="InputReferenceExpression"/>, producing a new InputReferenceExpression
/// based on the visited form of the <see cref="QueryableResourceExpression"/> that is referenced by
/// the InputReferenceExpression argument, <paramref name="ire"/>.
/// </summary>
/// <param name="ire">InputReferenceExpression expression to visit</param>
/// <returns>Visited InputReferenceExpression expression</returns>
internal virtual Expression VisitInputReferenceExpression(InputReferenceExpression ire)
{
Debug.Assert(ire != null, "ire != null -- otherwise caller never should have visited here");
ResourceExpression re = (ResourceExpression)this.Visit(ire.Target);
return re.CreateReference();
}
/// <summary>
/// Creates an <see cref="InputReferenceExpression"/> that refers to this component of the resource path.
/// The returned expression is guaranteed to be reference-equal (object.ReferenceEquals)
/// to any other InputReferenceExpression that also refers to this resource path component.
/// </summary>
/// <returns>The InputReferenceExpression that refers to this resource path component</returns>
internal InputReferenceExpression CreateReference()
{
if (this.inputRef == null)
{
this.inputRef = new InputReferenceExpression(this);
}
return this.inputRef;
}