DodSequenceMerge.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / XmlUtils / System / Xml / Xsl / Runtime / DodSequenceMerge.cs / 1305376 / DodSequenceMerge.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
using System; 
using System.Collections.Generic; 
using System.Xml.XPath;
using System.Diagnostics; 
using System.Globalization;
using System.ComponentModel;

namespace System.Xml.Xsl.Runtime { 

    ///  
    /// Merges several doc-order-distinct sequences into a single doc-order-distinct sequence. 
    /// 
    [EditorBrowsable(EditorBrowsableState.Never)] 
    public struct DodSequenceMerge {
        private IList firstSequence;
        private List> sequencesToMerge;
        private int nodeCount; 
        private XmlQueryRuntime runtime;
 
        ///  
        /// Initialize this instance of DodSequenceMerge.
        ///  
        public void Create(XmlQueryRuntime runtime) {
            this.firstSequence = null;
            this.sequencesToMerge = null;
            this.nodeCount = 0; 
            this.runtime = runtime;
        } 
 
        /// 
        /// Add a new sequence to the list of sequences to merge. 
        /// 
        public void AddSequence(IList sequence) {
            // Ignore empty sequences
            if (sequence.Count == 0) 
                return;
 
            if (this.firstSequence == null) { 
                this.firstSequence = sequence;
            } 
            else {
                if (this.sequencesToMerge == null) {
                    this.sequencesToMerge = new List>();
                    MoveAndInsertSequence(this.firstSequence.GetEnumerator()); 
                    this.nodeCount = this.firstSequence.Count;
                } 
 
                MoveAndInsertSequence(sequence.GetEnumerator());
                this.nodeCount += sequence.Count; 
            }
        }

        ///  
        /// Return the fully merged sequence.
        ///  
        public IList MergeSequences() { 
            XmlQueryNodeSequence newSequence;
 
            // Zero sequences to merge
            if (this.firstSequence == null)
                return XmlQueryNodeSequence.Empty;
 
            // One sequence to merge
            if (this.sequencesToMerge == null || this.sequencesToMerge.Count <= 1) 
                return this.firstSequence; 

            // Two or more sequences to merge 
            newSequence = new XmlQueryNodeSequence(this.nodeCount);

            while (this.sequencesToMerge.Count != 1) {
                // Save last item in list in temp variable, and remove it from list 
                IEnumerator sequence = this.sequencesToMerge[this.sequencesToMerge.Count - 1];
                this.sequencesToMerge.RemoveAt(this.sequencesToMerge.Count - 1); 
 
                // Add current node to merged sequence
                newSequence.Add(sequence.Current); 

                // Now move to the next node, and re-insert it into the list in reverse document order
                MoveAndInsertSequence(sequence);
            } 

            // Add nodes in remaining sequence to end of list 
            Debug.Assert(this.sequencesToMerge.Count == 1, "While loop should terminate when count == 1"); 
            do {
                newSequence.Add(this.sequencesToMerge[0].Current); 
            }
            while (this.sequencesToMerge[0].MoveNext());

            return newSequence; 
        }
 
        ///  
        /// Move to the next item in the sequence.  If there is no next item, then do not
        /// insert the sequence.  Otherwise, call InsertSequence. 
        /// 
        private void MoveAndInsertSequence(IEnumerator sequence) {
            if (sequence.MoveNext())
                InsertSequence(sequence); 
        }
 
        ///  
        /// Insert the specified sequence into the list of sequences to be merged.
        /// Insert it in reverse document order with respect to the current nodes in other sequences. 
        /// 
        private void InsertSequence(IEnumerator sequence) {
            for (int i = this.sequencesToMerge.Count - 1; i >= 0; i--) {
                int cmp = this.runtime.ComparePosition(sequence.Current, this.sequencesToMerge[i].Current); 

                if (cmp == -1) { 
                    // Insert after current item 
                    this.sequencesToMerge.Insert(i + 1, sequence);
                    return; 
                }
                else if (cmp == 0) {
                    // Found duplicate, so skip the duplicate
                    if (!sequence.MoveNext()) { 
                        // No more nodes, so don't insert anything
                        return; 
                    } 

                    // Next node must be after current node in document order, so don't need to reset loop 
                }
            }

            // Insert at beginning of list 
            this.sequencesToMerge.Insert(0, sequence);
        } 
    } 
}
 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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DodSequenceMerge.cs source code in C# .NET

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