PathBox.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataWeb / Client / System / Data / Services / Client / ALinq / PathBox.cs / 1305376 / PathBox.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
//--------------------------------------------------------------------- 
namespace System.Data.Services.Client 
{
    #region Namespaces. 

    using System;
    using System.Text;
    using System.Collections.Generic; 
    using System.Diagnostics;
    using System.Reflection; 
    using System.Linq; 
    using System.Linq.Expressions;
 
    #endregion Namespaces.

    /// 
    /// Holds state (Path, lambda parameter stack, etc) for projection analysis. 
    /// 
    internal class PathBox 
    { 
        #region Private fields.
 
        /// This class is used as a marker for an entity projected in its entirety.
        private const char EntireEntityMarker = UriHelper.ASTERISK;

        private readonly List projectionPaths = new List(); 

        private readonly List expandPaths = new List(); 
 
        private readonly Stack parameterExpressions = new Stack();
 
        private readonly Dictionary basePaths = new Dictionary(ReferenceEqualityComparer.Instance);

        #endregion Private fields.
 
        /// Initializes a new  instance.
        internal PathBox() 
        { 
            // add a default empty path.
            projectionPaths.Add(new StringBuilder()); 
        }

        internal IEnumerable ProjectionPaths
        { 
            get
            { 
                return projectionPaths.Where(s => s.Length > 0).Select(s => s.ToString()).Distinct(); 
            }
        } 

        internal IEnumerable ExpandPaths
        {
            get 
            {
                return expandPaths.Where(s => s.Length > 0).Select(s => s.ToString()).Distinct(); 
            } 
        }
 
        internal void PushParamExpression(ParameterExpression pe)
        {
            StringBuilder basePath = projectionPaths.Last();
            basePaths.Add(pe, basePath.ToString()); 
            projectionPaths.Remove(basePath);
            parameterExpressions.Push(pe); 
        } 

        internal void PopParamExpression() 
        {
            parameterExpressions.Pop();
        }
 
        internal ParameterExpression ParamExpressionInScope
        { 
            get 
            {
                Debug.Assert(parameterExpressions.Count > 0); 
                return parameterExpressions.Peek();
            }
        }
 
        /// Starts a new path.
        internal void StartNewPath() 
        { 
            Debug.Assert(this.ParamExpressionInScope != null, "this.ParamExpressionInScope != null -- should not be starting new path with no lambda parameter in scope.");
 
            StringBuilder sb = new StringBuilder(basePaths[this.ParamExpressionInScope]);
            RemoveEntireEntityMarkerIfPresent(sb);
            expandPaths.Add(new StringBuilder(sb.ToString()));
            AddEntireEntityMarker(sb); 
            projectionPaths.Add(sb);
        } 
 
        internal void AppendToPath(PropertyInfo pi)
        { 
            Debug.Assert(pi != null, "pi != null");

            StringBuilder sb;
            Type t = TypeSystem.GetElementType(pi.PropertyType); 

            if (ClientType.CheckElementTypeIsEntity(t)) 
            { 
                // an entity, so need to append to expand path also
                sb = expandPaths.Last(); 
                Debug.Assert(sb != null);  // there should always be an expand path because must call StartNewPath first.
                if (sb.Length > 0)
                {
                    sb.Append(UriHelper.FORWARDSLASH); 
                }
 
                sb.Append(pi.Name); 
            }
 
            sb = projectionPaths.Last();
            Debug.Assert(sb != null, "sb != null -- we are always building paths in the context of a parameter");

            RemoveEntireEntityMarkerIfPresent(sb); 

            if (sb.Length > 0) 
            { 
                sb.Append(UriHelper.FORWARDSLASH);
            } 

            sb.Append(pi.Name);

            if (ClientType.CheckElementTypeIsEntity(t)) 
            {
                AddEntireEntityMarker(sb); 
            } 
        }
 
        private static void RemoveEntireEntityMarkerIfPresent(StringBuilder sb)
        {
            if (sb.Length > 0 && sb[sb.Length - 1] == EntireEntityMarker)
            { 
                sb.Remove(sb.Length - 1, 1);
            } 
 
            if (sb.Length > 0 && sb[sb.Length - 1] == UriHelper.FORWARDSLASH)
            { 
                sb.Remove(sb.Length - 1, 1);
            }
        }
 
        private static void AddEntireEntityMarker(StringBuilder sb)
        { 
            if (sb.Length > 0) 
            {
                sb.Append(UriHelper.FORWARDSLASH); 
            }

            sb.Append(EntireEntityMarker);
        } 
    }
} 

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

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