FragmentQuery.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Map / ViewGeneration / QueryRewriting / FragmentQuery.cs / 1305376 / FragmentQuery.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Diagnostics;
using System.Collections.Generic;
using System.Text;
using System.Data.Common.Utils; 
using System.Data.Common.Utils.Boolean;
using System.Data.Mapping.ViewGeneration.Structures; 
using System.Data.Metadata.Edm; 
using System.Linq;
using System.Globalization; 

namespace System.Data.Mapping.ViewGeneration.QueryRewriting
{
    internal class FragmentQuery : ITileQuery 
    {
        private BoolExpression m_fromVariable; // optional 
        private string m_label; // optional 

        private HashSet m_attributes; 
        private BoolExpression m_condition;

        public HashSet Attributes
        { 
            get { return m_attributes; }
        } 
 
        public BoolExpression Condition
        { 
            get { return m_condition; }
        }

        public static FragmentQuery Create(BoolExpression fromVariable, CellQuery cellQuery) 
        {
            BoolExpression whereClause = cellQuery.WhereClause; 
            whereClause = whereClause.MakeCopy(); 
            whereClause.ExpensiveSimplify();
            return new FragmentQuery(null /*label*/, fromVariable, new HashSet(cellQuery.GetProjectedMembers()), whereClause); 
        }

        public static FragmentQuery Create(string label, RoleBoolean roleBoolean, CellQuery cellQuery)
        { 
            BoolExpression whereClause = cellQuery.WhereClause.Create(roleBoolean);
            whereClause = BoolExpression.CreateAnd(whereClause, cellQuery.WhereClause); 
            //return new FragmentQuery(label, null /* fromVariable */, new HashSet(cellQuery.GetProjectedMembers()), whereClause); 
            // don't need any attributes
            whereClause = whereClause.MakeCopy(); 
            whereClause.ExpensiveSimplify();
            return new FragmentQuery(label, null /* fromVariable */, new HashSet(), whereClause);
        }
 
        public static FragmentQuery Create(IEnumerable attrs, BoolExpression whereClause)
        { 
            return new FragmentQuery(null /* no name */, null /* no fromVariable*/, attrs, whereClause); 
        }
 
        public static FragmentQuery Create(BoolExpression whereClause)
        {
            return new FragmentQuery(null /* no name */, null /* no fromVariable*/, new MemberPath[] { }, whereClause);
        } 

        internal FragmentQuery(string label, BoolExpression fromVariable, IEnumerable attrs, BoolExpression condition) 
        { 
            m_label = label;
            m_fromVariable = fromVariable; 
            m_condition = condition;
            m_attributes = new HashSet(attrs);
        }
 
        public BoolExpression FromVariable
        { 
            get { return m_fromVariable; } 
        }
 
        public string Description
        {
            get
            { 
                string label = m_label;
                if (label == null && m_fromVariable != null) 
                { 
                    label = m_fromVariable.ToString();
                } 
                return label;
            }
        }
 
        public override string ToString()
        { 
            // attributes 
            StringBuilder b = new StringBuilder();
            foreach (MemberPath value in this.Attributes) 
            {
                if (b.Length > 0) { b.Append(','); }
                b.Append(value.ToString());
            } 

            if (Description != null && Description != b.ToString()) 
            { 
                return String.Format(CultureInfo.InvariantCulture, "{0}: [{1} where {2}]", Description, b, this.Condition);
            } 
            else
            {
                return String.Format(CultureInfo.InvariantCulture, "[{0} where {1}]", b, this.Condition);
            } 
        }
 
        #region Static methods 

        // creates a condition member=value 
        internal static BoolExpression CreateMemberCondition(MemberPath path, Constant domainValue, MemberDomainMap domainMap)
        {
            if (domainValue is TypeConstant)
            { 
                return BoolExpression.CreateLiteral(new TypeRestriction(new MemberProjectedSlot(path),
                                                    new Domain(domainValue, domainMap.GetDomain(path))), domainMap); 
            } 
            else
            { 
                return BoolExpression.CreateLiteral(new ScalarRestriction(new MemberProjectedSlot(path),
                                                    new Domain(domainValue, domainMap.GetDomain(path))), domainMap);
            }
        } 

        internal static IEqualityComparer GetEqualityComparer(FragmentQueryProcessor qp) 
        { 
            return new FragmentQueryEqualityComparer(qp);
        } 

        #endregion

        #region Equality Comparer 
        // Two queries are "equal" if they project the same set of attributes
        // and their WHERE clauses are equivalent 
        private class FragmentQueryEqualityComparer : IEqualityComparer 
        {
            FragmentQueryProcessor _qp; 

            internal FragmentQueryEqualityComparer(FragmentQueryProcessor qp)
            {
                _qp = qp; 
            }
 
            #region IEqualityComparer Members 

            public bool Equals(FragmentQuery x, FragmentQuery y) 
            {
                if (!x.Attributes.SetEquals(y.Attributes))
                {
                    return false; 
                }
                return _qp.IsEquivalentTo(x, y); 
            } 

            // Hashing a bit naive: it exploits syntactic properties, 
            // i.e., some semantically equivalent queries may produce different hash codes
            // But that's fine for usage scenarios in QueryRewriter.cs
            public int GetHashCode(FragmentQuery q)
            { 
                int attrHashCode = 0;
                foreach (MemberPath member in q.Attributes) 
                { 
                    attrHashCode ^= MemberPath.EqualityComparer.GetHashCode(member);
                } 
                int varHashCode = 0;
                int constHashCode = 0;
                foreach (MemberRestriction oneOf in q.Condition.MemberRestrictions)
                { 
                    varHashCode ^= MemberPath.EqualityComparer.GetHashCode(oneOf.RestrictedMemberSlot.MemberPath);
                    foreach (Constant constant in oneOf.Domain.Values) 
                    { 
                        constHashCode ^= Constant.EqualityComparer.GetHashCode(constant);
                    } 
                }
                return attrHashCode * 13 + varHashCode * 7 + constHashCode;
            }
 
            #endregion
        } 
        #endregion 

    } 

}

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

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