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//------------------------------------------------------------------------------
// <copyright file="XPathMultyIterator.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
namespace MS.Internal.Xml.XPath {
using System;
using System.Xml;
using System.Xml.XPath;
using System.Diagnostics;
using System.Globalization;
using System.Collections;
internal class XPathMultyIterator: ResetableIterator {
protected ResetableIterator[] arr;
protected int firstNotEmpty;
protected int position;
public XPathMultyIterator(ArrayList inputArray) {
// NOTE: We do not clone the passed inputArray supposing that it is not changed outside of this class
this.arr = new ResetableIterator[inputArray.Count];
for (int i = 0; i < this.arr.Length; i ++) {
this.arr[i] = new XPathArrayIterator((ArrayList) inputArray[i]);
}
Init();
}
private void Init() {
for (int i = 0; i < arr.Length; i ++) {
Advance(i);
}
for (int i = arr.Length - 2; firstNotEmpty <= i; ) {
if (SiftItem(i)) {
i --;
}
}
}
// returns false is iterator at pos reached it's end & as a result head of the array may be moved
bool Advance(int pos) {
if (! arr[pos].MoveNext()) {
if (firstNotEmpty != pos) {
ResetableIterator empty = arr[pos];
Array.Copy(arr, firstNotEmpty, arr, firstNotEmpty + 1, pos - firstNotEmpty);
arr[firstNotEmpty] = empty;
}
firstNotEmpty ++;
return false;
}
return true;
}
#if false
string dump { get { return Dump(); } }
string Dump(ResetableIterator it) {
it = (ResetableIterator) it.Clone();
System.Text.StringBuilder sb = new System.Text.StringBuilder();
sb.Append("(");
do {
XPathNavigator nav = it.Current.Clone();
nav.MoveToAttribute("id1", "");
sb.Append(nav.Value);
sb.Append(", ");
} while (it.MoveNext());
sb.Length = sb.Length - 2;
sb.Append(")");
return sb.ToString();
}
string Dump() {
System.Text.StringBuilder sb = new System.Text.StringBuilder();
for (int i = 0; i < arr.Length; i ++) {
sb.Append(i);
sb.Append(": ");
if (i < firstNotEmpty) {
sb.Append("()");
} else {
sb.Append(Dump(arr[i]));
}
sb.Append("; ");
}
return sb.ToString();
}
#endif
// Invariant: a[i] < a[i+1] for i > item
// returns flase is head of the list was moved & as a result consistancy of list depends on head consistancy.
bool SiftItem(int item) {
Debug.Assert(firstNotEmpty <= item && item < arr.Length);
ResetableIterator it = arr[item];
while (item + 1 < arr.Length) {
XmlNodeOrder order = Query.CompareNodes(it.Current, arr[item + 1].Current);
if (order == XmlNodeOrder.Before) {
break;
}
if (order == XmlNodeOrder.After) {
arr[item] = arr[item + 1];
//arr[item + 1] = it;
item ++;
} else { // Same
arr[item] = it;
if (! Advance(item)) {
return false;
}
it = arr[item];
}
}
arr[item] = it;
return true;
}
public override void Reset() {
firstNotEmpty = 0;
position = 0;
for (int i = 0; i < arr.Length; i ++) {
arr[i].Reset();
}
Init();
}
public XPathMultyIterator(XPathMultyIterator it) {
this.arr = (ResetableIterator[]) it.arr.Clone();
this.firstNotEmpty = it.firstNotEmpty;
this.position = it.position;
}
public override XPathNodeIterator Clone() {
return new XPathMultyIterator(this);
}
public override XPathNavigator Current {
get {
Debug.Assert(position != 0, "MoveNext() wasn't called");
Debug.Assert(firstNotEmpty < arr.Length, "MoveNext() returned false");
return arr[firstNotEmpty].Current;
}
}
public override int CurrentPosition { get { return position; } }
public override bool MoveNext() {
// NOTE: MoveNext() may be called even if the previous call to MoveNext() returned false, SQLBUDT 330810
if (firstNotEmpty >= arr.Length) {
return false;
}
if (position != 0) {
if (Advance(firstNotEmpty)) {
SiftItem(firstNotEmpty);
}
if (firstNotEmpty >= arr.Length) {
return false;
}
}
position ++;
return true;
}
}
}
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