|
//------------------------------------------------------------------------------
// <copyright file="ContentIterators.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
using System;
using System.Xml;
using System.Xml.XPath;
using System.Xml.Schema;
using System.Diagnostics;
using System.Collections;
using System.ComponentModel;
namespace System.Xml.Xsl.Runtime {
/// <summary>
/// Iterate over all child content nodes (this is different from the QIL Content operator, which iterates over content + attributes).
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct ContentIterator {
private XPathNavigator navCurrent;
private bool needFirst;
/// <summary>
/// Initialize the ContentIterator.
/// </summary>
public void Create(XPathNavigator context) {
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, context);
this.needFirst = true;
}
/// <summary>
/// Position the iterator on the next child content node. Return true if such a child exists and
/// set Current property. Otherwise, return false (Current property is undefined).
/// </summary>
public bool MoveNext() {
if (this.needFirst) {
this.needFirst = !this.navCurrent.MoveToFirstChild();
return !this.needFirst;
}
return this.navCurrent.MoveToNext();
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned true.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
}
/// <summary>
/// Iterate over all child elements with a matching name.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct ElementContentIterator {
private string localName, ns;
private XPathNavigator navCurrent;
private bool needFirst;
/// <summary>
/// Initialize the ElementContentIterator.
/// </summary>
public void Create(XPathNavigator context, string localName, string ns) {
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, context);
this.localName = localName;
this.ns = ns;
this.needFirst = true;
}
/// <summary>
/// Position the iterator on the next child element with a matching name. Return true if such a child exists and
/// set Current property. Otherwise, return false (Current property is undefined).
/// </summary>
public bool MoveNext() {
if (this.needFirst) {
this.needFirst = !this.navCurrent.MoveToChild(this.localName, this.ns);
return !this.needFirst;
}
return this.navCurrent.MoveToNext(this.localName, this.ns);
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned true.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
}
/// <summary>
/// Iterate over all child content nodes with a matching node kind.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct NodeKindContentIterator {
private XPathNodeType nodeType;
private XPathNavigator navCurrent;
private bool needFirst;
/// <summary>
/// Initialize the NodeKindContentIterator.
/// </summary>
public void Create(XPathNavigator context, XPathNodeType nodeType) {
Debug.Assert(nodeType != XPathNodeType.Attribute && nodeType != XPathNodeType.Namespace);
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, context);
this.nodeType = nodeType;
this.needFirst = true;
}
/// <summary>
/// Position the iterator on the next child content node with a matching node kind. Return true if such a child
/// exists and set Current property. Otherwise, return false (Current property is undefined).
/// </summary>
public bool MoveNext() {
if (this.needFirst) {
this.needFirst = !this.navCurrent.MoveToChild(this.nodeType);
return !this.needFirst;
}
return this.navCurrent.MoveToNext(this.nodeType);
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned true.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
}
/// <summary>
/// Iterate over all attributes.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct AttributeIterator {
private XPathNavigator navCurrent;
private bool needFirst;
/// <summary>
/// Initialize the AttributeIterator.
/// </summary>
public void Create(XPathNavigator context) {
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, context);
this.needFirst = true;
}
/// <summary>
/// Position the iterator on the attribute. Return true if such a child exists and set Current
/// property. Otherwise, return false (Current property is undefined).
/// </summary>
public bool MoveNext() {
if (this.needFirst) {
this.needFirst = !this.navCurrent.MoveToFirstAttribute();
return !this.needFirst;
}
return this.navCurrent.MoveToNextAttribute();
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned true.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
}
/// <summary>
/// Iterate over all namespace nodes.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct NamespaceIterator {
private XPathNavigator navCurrent;
private XmlNavigatorStack navStack;
/// <summary>
/// Initialize the NamespaceIterator.
/// </summary>
public void Create(XPathNavigator context) {
// Push all of context's in-scope namespaces onto a stack in order to return them in document order
// (MoveToXXXNamespace methods return namespaces in reverse document order)
this.navStack.Reset();
if (context.MoveToFirstNamespace(XPathNamespaceScope.All)) {
do {
// Don't return the default namespace undeclaration
if (context.LocalName.Length != 0 || context.Value.Length != 0)
this.navStack.Push(context.Clone());
}
while (context.MoveToNextNamespace(XPathNamespaceScope.All));
context.MoveToParent();
}
}
/// <summary>
/// Pop the top namespace from the stack and save it as navCurrent. If there are no more namespaces, return false.
/// </summary>
public bool MoveNext() {
if (this.navStack.IsEmpty)
return false;
this.navCurrent = this.navStack.Pop();
return true;
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned true.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
}
/// <summary>
/// Iterate over all attribute and child content nodes.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct AttributeContentIterator {
private XPathNavigator navCurrent;
private bool needFirst;
/// <summary>
/// Initialize the AttributeContentIterator.
/// </summary>
public void Create(XPathNavigator context) {
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, context);
this.needFirst = true;
}
/// <summary>
/// Position the iterator on the next child content node with a matching node kind. Return true if such a child
/// exists and set Current property. Otherwise, return false (Current property is undefined).
/// </summary>
public bool MoveNext() {
if (this.needFirst) {
this.needFirst = !XmlNavNeverFilter.MoveToFirstAttributeContent(this.navCurrent);
return !this.needFirst;
}
return XmlNavNeverFilter.MoveToNextAttributeContent(this.navCurrent);
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned true.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
}
/// <summary>
/// Iterate over child content nodes or following-sibling nodes. Maintain document order by using a stack. Input
/// nodes are assumed to be in document order, but can contain one another (ContentIterator doesn't allow this).
/// </summary>
/// <remarks>
/// 1. Assume that the list I of input nodes is in document order, with no duplicates. There are N nodes in list I.
/// 2. For each node in list I, derive a list of nodes consisting of matching children or following-sibling nodes.
/// Call these lists S(1)...S(N).
/// 3. Let F be the first node in any list S(X), where X >= 1 and X < N
/// 4. There exists exactly one contiguous sequence of lists S(Y)...S(Z), where Y > X and Z <= N, such that the lists
/// S(X+1)...S(N) can be partitioned into these three groups:
/// a. 1st group (S(X+1)...S(Y-1)) -- All nodes in these lists precede F in document order
/// b. 2nd group (S(Y)...S(Z)) -- All nodes in these lists are duplicates of nodes in list S(X)
/// c. 3rd group (> S(Z)) -- All nodes in these lists succeed F in document order
/// 5. Given #4, node F can be returned once all nodes in the 1st group have been returned. Lists S(Y)...S(Z) can be
/// discarded. And only a single node in the 3rd group need be generated in order to guarantee that all nodes in
/// the 1st and 2nd groups have already been generated.
/// </remarks>
[EditorBrowsable(EditorBrowsableState.Never)]
public struct ContentMergeIterator {
private XmlNavigatorFilter filter;
private XPathNavigator navCurrent, navNext;
private XmlNavigatorStack navStack;
private IteratorState state;
private enum IteratorState {
NeedCurrent = 0,
HaveCurrentNeedNext,
HaveCurrentNoNext,
HaveCurrentHaveNext,
};
/// <summary>
/// Initialize the ContentMergeIterator (merge multiple sets of content nodes in document order and remove duplicates).
/// </summary>
public void Create(XmlNavigatorFilter filter) {
this.filter = filter;
this.navStack.Reset();
this.state = IteratorState.NeedCurrent;
}
/// <summary>
/// Position this iterator to the next content or sibling node. Return IteratorResult.NoMoreNodes if there are
/// no more content or sibling nodes. Return IteratorResult.NeedInputNode if the next input node needs to be
/// fetched first. Return IteratorResult.HaveCurrent if the Current property is set to the next node in the
/// iteration.
/// </summary>
public IteratorResult MoveNext(XPathNavigator input) {
return MoveNext(input, true);
}
/// <summary>
/// Position this iterator to the next content or sibling node. Return IteratorResult.NoMoreNodes if there are
/// no more content or sibling nodes. Return IteratorResult.NeedInputNode if the next input node needs to be
/// fetched first. Return IteratorResult.HaveCurrent if the Current property is set to the next node in the
/// iteration.
/// </summary>
internal IteratorResult MoveNext(XPathNavigator input, bool isContent) {
switch (this.state) {
case IteratorState.NeedCurrent:
// If there are no more input nodes, then iteration is complete
if (input == null)
return IteratorResult.NoMoreNodes;
// Save the input node as the current node
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, input);
// If matching child or sibling is found, then we have a current node
if (isContent ? this.filter.MoveToContent(this.navCurrent) :
this.filter.MoveToFollowingSibling(this.navCurrent))
this.state = IteratorState.HaveCurrentNeedNext;
return IteratorResult.NeedInputNode;
case IteratorState.HaveCurrentNeedNext:
if (input == null) {
// There are no more input nodes, so enter HaveCurrentNoNext state and return Current
this.state = IteratorState.HaveCurrentNoNext;
return IteratorResult.HaveCurrentNode;
}
// Save the input node as the next node
this.navNext = XmlQueryRuntime.SyncToNavigator(this.navNext, input);
// If matching child or sibling is found,
if (isContent ? this.filter.MoveToContent(this.navNext) :
this.filter.MoveToFollowingSibling(this.navNext)) {
// Then compare position of current and next nodes
this.state = IteratorState.HaveCurrentHaveNext;
return DocOrderMerge();
}
// Input node does not result in matching child or sibling, so get next input node
return IteratorResult.NeedInputNode;
case IteratorState.HaveCurrentNoNext:
case IteratorState.HaveCurrentHaveNext:
// If the current node has no more matching siblings,
if (isContent ? !this.filter.MoveToNextContent(this.navCurrent) :
!this.filter.MoveToFollowingSibling(this.navCurrent)) {
if (this.navStack.IsEmpty) {
if (this.state == IteratorState.HaveCurrentNoNext) {
// No more input nodes, so iteration is complete
return IteratorResult.NoMoreNodes;
}
// Make navNext the new current node and fetch a new navNext
this.navCurrent = XmlQueryRuntime.SyncToNavigator(this.navCurrent, this.navNext);
this.state = IteratorState.HaveCurrentNeedNext;
return IteratorResult.NeedInputNode;
}
// Pop new current node from the stack
this.navCurrent = this.navStack.Pop();
}
// If there is no next node, then no need to call DocOrderMerge; just return the current node
if (this.state == IteratorState.HaveCurrentNoNext)
return IteratorResult.HaveCurrentNode;
// Compare positions of current and next nodes
return DocOrderMerge();
}
Debug.Assert(false, "Invalid IteratorState " + this.state);
return IteratorResult.NoMoreNodes;
}
/// <summary>
/// Return the current result navigator. This is only defined after MoveNext() has returned IteratorResult.HaveCurrentNode.
/// </summary>
public XPathNavigator Current {
get { return this.navCurrent; }
}
/// <summary>
/// If the context node-set returns a node that is contained in the subtree of the previous node,
/// then returning children of each node in "natural" order may not correspond to document order.
/// Therefore, in order to guarantee document order, keep a stack in order to push the sibling of
/// ancestor nodes. These siblings will not be returned until all of the descendants' children are
/// returned first.
/// </summary>
private IteratorResult DocOrderMerge() {
XmlNodeOrder cmp;
Debug.Assert(this.state == IteratorState.HaveCurrentHaveNext);
// Compare location of navCurrent with navNext
cmp = this.navCurrent.ComparePosition(this.navNext);
// If navCurrent is before navNext in document order,
// If cmp = XmlNodeOrder.Unknown, then navCurrent is before navNext (since input is is doc order)
if (cmp == XmlNodeOrder.Before || cmp == XmlNodeOrder.Unknown) {
// Then navCurrent can be returned (it is guaranteed to be first in document order)
return IteratorResult.HaveCurrentNode;
}
// If navCurrent is after navNext in document order, then delay returning navCurrent
// Otherwise, discard navNext since it is positioned to the same node as navCurrent
if (cmp == XmlNodeOrder.After) {
this.navStack.Push(this.navCurrent);
this.navCurrent = this.navNext;
this.navNext = null;
}
// Need next input node
this.state = IteratorState.HaveCurrentNeedNext;
return IteratorResult.NeedInputNode;
}
}
}
|