Helpers.cs source code in C# .NET

                        Code:
                         / Dotnetfx_Vista_SP2 / Dotnetfx_Vista_SP2 / 8.0.50727.4016 / DEVDIV / depot / DevDiv / releases / Orcas / QFE / ndp / fx / src / DataEntity / System / Data / Common / Utils / Helpers.cs / 2 / Helpers.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text; 
using System.Globalization;
using System.Diagnostics; 
 
namespace System.Data.Common.Utils {
 
    // Miscellaneous helper routines
    internal static class Helpers {

        #region Trace methods 
        // effects: Trace args according to the CLR format string with a new line
        internal static void FormatTraceLine(string format, params object[] args) { 
            Trace.WriteLine(String.Format(CultureInfo.InvariantCulture, format, args)); 
        }
 
        // effects: Trace the string with a new line
        internal static void StringTrace(string arg) {
            Trace.Write(arg);
        } 

        // effects: Trace the string without adding a new line 
        internal static void StringTraceLine(string arg) { 
            Trace.WriteLine(arg);
        } 
        #endregion

        #region Misc Helpers
        // effects: compares two sets using the given comparer - removes 
        // duplicates if they exist
        internal static bool IsSetEqual(IEnumerable list1, IEnumerable list2, IEqualityComparer comparer) 
        { 
            Set set1 = new Set(list1, comparer);
            Set set2 = new Set(list2, comparer); 

            return set1.SetEquals(set2);
        }
 
        // effects: Given a stream of values of type "SubType", returns a
        // stream of values of type "SuperType" where SuperType is a 
        // superclass/supertype of SubType 
        internal static IEnumerable AsSuperTypeList(IEnumerable values)
            where SubType : SuperType { 
            foreach (SubType value in values) {
                yield return value;
            }
        } 

        ///  
        /// Builds a balanced binary tree with the specified nodes as leaves. 
        /// Note that the current elements of  MAY be overwritten
        /// as the leaves are combined to produce the tree. 
        /// 
        /// The type of each node in the tree
        /// The leaf nodes to combine into an balanced binary tree
        /// A function that produces a new node that is the combination of the two specified argument nodes 
        /// The single node that is the root of the balanced binary tree
        internal static TNode BuildBalancedTreeInPlace(IList nodes, Func combinator) 
        { 
            EntityUtil.CheckArgumentNull(nodes, "nodes");
            EntityUtil.CheckArgumentNull(combinator, "combinator"); 

            Debug.Assert(nodes.Count > 0, "At least one node is required");

            // If only one node is present, return the single node. 
            if (nodes.Count == 1)
            { 
                return nodes[0]; 
            }
 
            // For the two-node case, simply combine the two nodes and return the result.
            if (nodes.Count == 2)
            {
                return combinator(nodes[0], nodes[1]); 
            }
 
            // 
            // Build the balanced tree in a bottom-up fashion.
            // On each iteration, an even number of nodes are paired off using the 
            // combinator function, reducing the total number of available leaf nodes
            // by half each time. If the number of nodes in an iteration is not even,
            // the 'last' node in the set is omitted, then combined with the last pair
            // that is produced. 
            // Nodes are collected from left to right with newly combined nodes overwriting
            // nodes from the previous iteration that have already been consumed (as can 
            // be seen by 'writePos' lagging 'readPos' in the main statement of the loop below). 
            // When a single available leaf node remains, this node is the root of the
            // balanced binary tree and can be returned to the caller. 
            //
            int nodesToPair = nodes.Count;
            while (nodesToPair != 1)
            { 
                bool combineModulo = ((nodesToPair & 0x1) == 1);
                if (combineModulo) 
                { 
                    nodesToPair--;
                } 

                int writePos = 0;
                for (int readPos = 0; readPos < nodesToPair; readPos += 2)
                { 
                    nodes[writePos++] = combinator(nodes[readPos], nodes[readPos + 1]);
                } 
 
                if (combineModulo)
                { 
                    int updatePos = writePos - 1;
                    nodes[updatePos] = combinator(nodes[updatePos], nodes[nodesToPair]);
                }
 
                nodesToPair /= 2;
            } 
 
            return nodes[0];
        } 

        #endregion
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text; 
using System.Globalization;
using System.Diagnostics; 
 
namespace System.Data.Common.Utils {
 
    // Miscellaneous helper routines
    internal static class Helpers {

        #region Trace methods 
        // effects: Trace args according to the CLR format string with a new line
        internal static void FormatTraceLine(string format, params object[] args) { 
            Trace.WriteLine(String.Format(CultureInfo.InvariantCulture, format, args)); 
        }
 
        // effects: Trace the string with a new line
        internal static void StringTrace(string arg) {
            Trace.Write(arg);
        } 

        // effects: Trace the string without adding a new line 
        internal static void StringTraceLine(string arg) { 
            Trace.WriteLine(arg);
        } 
        #endregion

        #region Misc Helpers
        // effects: compares two sets using the given comparer - removes 
        // duplicates if they exist
        internal static bool IsSetEqual(IEnumerable list1, IEnumerable list2, IEqualityComparer comparer) 
        { 
            Set set1 = new Set(list1, comparer);
            Set set2 = new Set(list2, comparer); 

            return set1.SetEquals(set2);
        }
 
        // effects: Given a stream of values of type "SubType", returns a
        // stream of values of type "SuperType" where SuperType is a 
        // superclass/supertype of SubType 
        internal static IEnumerable AsSuperTypeList(IEnumerable values)
            where SubType : SuperType { 
            foreach (SubType value in values) {
                yield return value;
            }
        } 

        ///  
        /// Builds a balanced binary tree with the specified nodes as leaves. 
        /// Note that the current elements of  MAY be overwritten
        /// as the leaves are combined to produce the tree. 
        /// 
        /// The type of each node in the tree
        /// The leaf nodes to combine into an balanced binary tree
        /// A function that produces a new node that is the combination of the two specified argument nodes 
        /// The single node that is the root of the balanced binary tree
        internal static TNode BuildBalancedTreeInPlace(IList nodes, Func combinator) 
        { 
            EntityUtil.CheckArgumentNull(nodes, "nodes");
            EntityUtil.CheckArgumentNull(combinator, "combinator"); 

            Debug.Assert(nodes.Count > 0, "At least one node is required");

            // If only one node is present, return the single node. 
            if (nodes.Count == 1)
            { 
                return nodes[0]; 
            }
 
            // For the two-node case, simply combine the two nodes and return the result.
            if (nodes.Count == 2)
            {
                return combinator(nodes[0], nodes[1]); 
            }
 
            // 
            // Build the balanced tree in a bottom-up fashion.
            // On each iteration, an even number of nodes are paired off using the 
            // combinator function, reducing the total number of available leaf nodes
            // by half each time. If the number of nodes in an iteration is not even,
            // the 'last' node in the set is omitted, then combined with the last pair
            // that is produced. 
            // Nodes are collected from left to right with newly combined nodes overwriting
            // nodes from the previous iteration that have already been consumed (as can 
            // be seen by 'writePos' lagging 'readPos' in the main statement of the loop below). 
            // When a single available leaf node remains, this node is the root of the
            // balanced binary tree and can be returned to the caller. 
            //
            int nodesToPair = nodes.Count;
            while (nodesToPair != 1)
            { 
                bool combineModulo = ((nodesToPair & 0x1) == 1);
                if (combineModulo) 
                { 
                    nodesToPair--;
                } 

                int writePos = 0;
                for (int readPos = 0; readPos < nodesToPair; readPos += 2)
                { 
                    nodes[writePos++] = combinator(nodes[readPos], nodes[readPos + 1]);
                } 
 
                if (combineModulo)
                { 
                    int updatePos = writePos - 1;
                    nodes[updatePos] = combinator(nodes[updatePos], nodes[nodesToPair]);
                }
 
                nodesToPair /= 2;
            } 
 
            return nodes[0];
        } 

        #endregion
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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