///// <summary>
///// Gets a value indicating whether this instance can be reduced to a tree of standard expressions.
///// </summary>
///// <value>
///// <see langword="true"/> if this instance can be reduced; otherwise, <see langword="false"/>.
///// </value>
///// <remarks>
///// <para>
///// If this method returns <see langword="true"/>, the <see cref="Reduce"/> method can be called in order to produce a new
///// <see cref="Expression"/> that has the same semantics as this <see cref="ExtensionExpression"/> but consists of
///// expressions of standard node types.
///// </para>
///// <para>
///// Subclasses overriding the <see cref="CanReduce"/> property to return <see langword="true" /> must also override the <see cref="Reduce"/>
///// method and cannot call its base implementation.
///// </para>
///// </remarks>
//public virtual bool CanReduce
//{
// get { return false; }
//}
///// <summary>
///// Reduces this instance to a tree of standard expressions. If this instance cannot be reduced, the same <see cref="ExtensionExpression"/>
///// is returned.
///// </summary>
///// <returns>If <see cref="CanReduce"/> is <see langword="true" />, a reduced version of this <see cref="ExtensionExpression"/>; otherwise,
///// this <see cref="ExtensionExpression"/>.</returns>
///// <remarks>
///// <para>
///// This method can be called in order to produce a new <see cref="Expression"/> that has the same semantics as this
///// <see cref="ExtensionExpression"/> but consists of expressions of standard node types. The reduction need not be complete, nodes can be
///// returned that themselves must be reduced.
///// </para>
///// <para>
///// Subclasses overriding the <see cref="CanReduce"/> property to return <see langword="true" /> must also override this method and cannot
///// call the base implementation.
///// </para>
///// </remarks>
//public virtual Expression Reduce ()
//{
// if (CanReduce)
// throw new InvalidOperationException ("Reducible nodes must override the Reduce method.");
// return this;
//}
///// <summary>
///// Calls the <see cref="Reduce"/> method and checks certain invariants before returning the result. This method can only be called when
///// <see cref="CanReduce"/> returns <see langword="true" />.
///// </summary>
///// <returns>A reduced version of this <see cref="ExtensionExpression"/>.</returns>
///// <exception cref="InvalidOperationException">This <see cref="ExtensionExpression"/> is not reducible - or - the <see cref="Reduce"/> method
///// violated one of the invariants (see Remarks).</exception>
///// <remarks>
///// This method checks the following invariants:
///// <list type="bullet">
///// <item><see cref="Reduce"/> must not return <see langword="null" />.</item>
///// <item><see cref="Reduce"/> must not return the original <see cref="ExtensionExpression"/>.</item>
///// <item>
///// The new expression returned by <see cref="Reduce"/> must be assignment-compatible with the type of the original
///// <see cref="ExtensionExpression"/>.
///// </item>
///// </list>
///// </remarks>
//public Expression ReduceAndCheck ()
//{
// if (!CanReduce)
// throw new InvalidOperationException ("Reduce and check can only be called on reducible nodes.");
// var result = Reduce();
// if (result == null)
// throw new InvalidOperationException ("Reduce cannot return null.");
// if (result == this)
// throw new InvalidOperationException ("Reduce cannot return the original expression.");
// if (!Type.IsAssignableFrom (result.Type))
// throw new InvalidOperationException ("Reduce must produce an expression of a compatible type.");
// return result;
//}
/// <summary>
/// Accepts the specified visitor, by default dispatching to <see cref="ExpressionTreeVisitor.VisitExtensionExpression"/>.
/// Inheritors of the <see cref="ExtensionExpression"/> class can override this method in order to dispatch to a specific Visit method.
/// </summary>
/// <param name="visitor">The visitor whose Visit method should be invoked.</param>
/// <returns>The <see cref="Expression"/> returned by the visitor.</returns>
/// <remarks>
/// Overriders can test the <paramref name="visitor"/> for a specific interface. If the visitor supports the interface, the extension expression
/// can dispatch to the respective strongly-typed Visit method declared in the interface. If it does not, the extension expression should call
/// the base implementation of <see cref="Accept"/>, which will dispatch to <see cref="ExpressionTreeVisitor.VisitExtensionExpression"/>.
/// </remarks>
public virtual Expression Accept(ExpressionTreeVisitor visitor)
{
return(visitor.VisitExtensionExpression(this));
}
/// <summary>
/// Accepts the specified visitor, by default dispatching to <see cref="ExpressionTreeVisitor.VisitExtensionExpression"/>.
/// Inheritors of the <see cref="ExtensionExpression"/> class can override this method in order to dispatch to a specific Visit method.
/// </summary>
/// <param name="visitor">The visitor whose Visit method should be invoked.</param>
/// <returns>The <see cref="Expression"/> returned by the visitor.</returns>
/// <remarks>
/// Overriders can test the <paramref name="visitor"/> for a specific interface. If the visitor supports the interface, the extension expression
/// can dispatch to the respective strongly-typed Visit method declared in the interface. If it does not, the extension expression should call
/// the base implementation of <see cref="Accept"/>, which will dispatch to <see cref="ExpressionTreeVisitor.VisitExtensionExpression"/>.
/// </remarks>
public virtual Expression Accept(ExpressionTreeVisitor visitor)
{
ArgumentUtility.CheckNotNull("visitor", visitor);
return(visitor.VisitExtensionExpression(this));
}
