XPathMultyIterator.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / XPath / Internal / XPathMultyIterator.cs / 1 / XPathMultyIterator.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
 
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; 
        }
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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XPathMultyIterator.cs source code in C# .NET

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