UpdateCompiler.cs source code in C# .NET

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Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Map / Update / Internal / UpdateCompiler.cs / 1305376 / UpdateCompiler.cs

                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System.Data.Metadata.Edm; 
// For the purposes of the update compiler, the member name fully describes the member
// within the table entity set.
// It's convenient to use 'string' to represent the member, because it allows us to
// painlessly associate members of the transient extent (the table in C-Space) with 
// the real extent (the table in S-Space).
using System.Data.Common; 
using System.Collections.Generic; 
using System.Text;
using System.Diagnostics; 
using System.Globalization;
using System.Data.Common.Utils;
using System.Data.SqlClient.SqlGen;
using System.Data.Common.CommandTrees; 
using System.Data.Entity;
using System.Data.Common.CommandTrees.ExpressionBuilder; 
namespace System.Data.Mapping.Update.Internal 
{
    ///  
    /// This class implements compilation of DML operation requests to some
    /// format (e.g. canonical query tree or T-SQL)
    /// 
    internal sealed class UpdateCompiler 
    {
        #region Constructors 
        ///  
        /// Initialize an update compiler.
        ///  
        /// Update context.
        internal UpdateCompiler(UpdateTranslator translator)
        {
            m_translator = translator; 
        }
        #endregion 
 
        #region Fields
        internal readonly UpdateTranslator m_translator; 
        private const string s_targetVarName = "target";
        #endregion

        ///  
        /// Builds a delete command.
        ///  
        /// Value of the row being deleted. 
        /// Context for the table containing row.
        /// Delete command. 
        internal UpdateCommand BuildDeleteCommand(PropagatorResult oldRow, TableChangeProcessor processor)
        {
            // If we're deleting a row, the row must always be touched
            bool rowMustBeTouched = true; 

            // Initialize DML command tree 
            DbExpressionBinding target = GetTarget(processor); 

            // Create delete predicate 
            DbExpression predicate = BuildPredicate(target, oldRow, null, processor, ref rowMustBeTouched);
            DbDeleteCommandTree commandTree = new DbDeleteCommandTree(m_translator.MetadataWorkspace, DataSpace.SSpace, target, predicate);

            // Set command 
            // Initialize delete command
            UpdateCommand command = new DynamicUpdateCommand(processor, m_translator, ModificationOperator.Delete, oldRow, null, commandTree, null); 
 
            return command;
        } 

        /// 
        /// Builds an update command.
        ///  
        /// Old value of the row being updated.
        /// New value for the row being updated. 
        /// Context for the table containing row. 
        /// Update command.
        internal UpdateCommand BuildUpdateCommand(PropagatorResult oldRow, 
            PropagatorResult newRow, TableChangeProcessor processor)
        {
            // If we're updating a row, the row may not need to be touched (e.g., no concurrency validation required)
            bool rowMustBeTouched = false; 

            DbExpressionBinding target = GetTarget(processor); 
 
            // Create set clauses and returning parameter
            Dictionary outputIdentifiers; 
            DbExpression returning;
            List setClauses = new List();
            foreach (DbModificationClause clause in BuildSetClauses(
                target, newRow, oldRow, processor, /* insertMode */ false, out outputIdentifiers, out returning, 
                ref rowMustBeTouched))
            { 
                setClauses.Add(clause); 
            }
 
            // Construct predicate identifying the row to modify
            DbExpression predicate = BuildPredicate(target, oldRow, newRow, processor, ref rowMustBeTouched);

            // Determine if there is nothing to do (i.e., no values to set, 
            // no computed columns, and no concurrency validation required)
            if (!rowMustBeTouched && 0 == setClauses.Count) 
            { 
                return null;
            } 

            // Initialize DML command tree
            DbUpdateCommandTree commandTree =
                new DbUpdateCommandTree(m_translator.MetadataWorkspace, DataSpace.SSpace, target, predicate, setClauses.AsReadOnly(), returning); 

            // Create command 
            UpdateCommand command = new DynamicUpdateCommand(processor, m_translator, ModificationOperator.Update, oldRow, newRow, commandTree, outputIdentifiers); 

            return command; 
        }

        /// 
        /// Builds insert command. 
        /// 
        /// Row to insert. 
        /// Context for the table we're inserting into. 
        /// Insert command.
        internal UpdateCommand BuildInsertCommand(PropagatorResult newRow, TableChangeProcessor processor) 
        {
            // Bind the insert target
            DbExpressionBinding target = GetTarget(processor);
 
            // Create set clauses and returning parameter
            Dictionary outputIdentifiers; 
            DbExpression returning; 
            bool rowMustBeTouched = true; // for inserts, the row must always be touched
            List setClauses = new List(); 
            foreach (DbModificationClause clause in BuildSetClauses(target, newRow, null, processor, /* insertMode */ true, out outputIdentifiers,
                out returning, ref rowMustBeTouched))
            {
                setClauses.Add(clause); 
            }
 
            // Initialize DML command tree 
            DbInsertCommandTree commandTree =
                new DbInsertCommandTree(m_translator.MetadataWorkspace, DataSpace.SSpace, target, setClauses.AsReadOnly(), returning); 

            // Create command
            UpdateCommand command = new DynamicUpdateCommand(processor, m_translator, ModificationOperator.Insert, null, newRow, commandTree, outputIdentifiers);
 
            return command;
        } 
 
        /// 
        /// Determines column/value used to set values for a row. 
        /// 
        /// 
        /// The following columns are not included in the result:
        ///  
        /// Keys (if we're inserting the entity, not updating it)
        /// Values flagged 'preserve' (these are values the propagator claims are 
        /// untouched) 
        /// Server generated values.
        ///  
        /// 
        /// Expression binding representing the table.
        /// Row containing values to set.
        /// Context for table. 
        /// Determines whether key columns and 'preserve' columns are
        /// omitted from the list. 
        /// Dictionary listing server generated identifiers. 
        /// DbExpression describing result projection for server generated values.
        /// Indicates whether the row must be touched 
        /// because it produces a value (e.g. computed)
        /// Column value pairs.
        private IEnumerable BuildSetClauses(DbExpressionBinding target, PropagatorResult row,
            PropagatorResult originalRow, TableChangeProcessor processor, bool insertMode, out Dictionary outputIdentifiers, out DbExpression returning, 
            ref bool rowMustBeTouched)
        { 
            Dictionary setClauses = new Dictionary(); 
            List> returningArguments = new List>();
            outputIdentifiers = new Dictionary(); 

            // Determine which flags indicate a property should be omitted from the set list.
            PropagatorFlags omitMask = insertMode ? PropagatorFlags.NoFlags :
                PropagatorFlags.Preserve | PropagatorFlags.Unknown; 

            for (int propertyOrdinal = 0; propertyOrdinal < processor.Table.ElementType.Properties.Count; propertyOrdinal++) 
            { 
                EdmProperty property = processor.Table.ElementType.Properties[propertyOrdinal];
 
                // Type members and result values are ordinally aligned
                PropagatorResult propertyResult = row.GetMemberValue(propertyOrdinal);

                if (PropagatorResult.NullIdentifier != propertyResult.Identifier) 
                {
                    // retrieve principal value 
                    propertyResult = propertyResult.ReplicateResultWithNewValue( 
                        m_translator.KeyManager.GetPrincipalValue(propertyResult));
                } 

                bool omitFromSetList = false;

                Debug.Assert(propertyResult.IsSimple); 

                // Determine if this is a key value 
                bool isKey = false; 
                for (int i = 0; i < processor.KeyOrdinals.Length; i++)
                { 
                    if (processor.KeyOrdinals[i] == propertyOrdinal)
                    {
                        isKey = true;
                        break; 
                    }
                } 
 
                // check if this value should be omitted
                PropagatorFlags flags = PropagatorFlags.NoFlags; 
                if (!insertMode && isKey)
                {
                    // Keys are only set for inserts
                    omitFromSetList = true; 
                }
                else 
                { 
                    // See if this value has been marked up with some context. If so, add the flag information
                    // from the markup. Markup includes information about whether the property is a concurrency value, 
                    // whether it is known (it may be a property that is preserved across an update for instance)
                    flags |= propertyResult.PropagatorFlags;
                }
 
                // Determine if this value is server-generated
                StoreGeneratedPattern genPattern = MetadataHelper.GetStoreGeneratedPattern(property); 
                bool isServerGen = genPattern == StoreGeneratedPattern.Computed || 
                    (insertMode && genPattern == StoreGeneratedPattern.Identity);
                if (isServerGen) 
                {
                    DbPropertyExpression propertyExpression = target.Variable.Property(property);
                    returningArguments.Add(new KeyValuePair(property.Name, propertyExpression));
 
                    // check if this is a server generated identifier
                    int identifier = propertyResult.Identifier; 
                    if (PropagatorResult.NullIdentifier != identifier) 
                    {
                        if (m_translator.KeyManager.HasPrincipals(identifier)) 
                        {
                            throw EntityUtil.InvalidOperation(System.Data.Entity.Strings.Update_GeneratedDependent(property.Name));
                        }
                        outputIdentifiers.Add(identifier, property.Name); 

                        // If this property maps an identifier (in the update pipeline) it may 
                        // also be a store key. If so, the pattern had better be "Identity" 
                        // since otherwise we're dealing with a mutable key.
                        if (genPattern != StoreGeneratedPattern.Identity && 
                            processor.IsKeyProperty(propertyOrdinal))
                        {
                            throw EntityUtil.NotSupported(System.Data.Entity.Strings.Update_NotSupportedComputedKeyColumn(
                                EdmProviderManifest.StoreGeneratedPatternFacetName, 
                                XmlConstants.Computed,
                                XmlConstants.Identity, 
                                property.Name, 
                                property.DeclaringType.FullName));
                        } 
                    }
                }

                if (PropagatorFlags.NoFlags != (flags & (omitMask))) 
                {
                    // column value matches "omit" pattern, therefore should not be set 
                    omitFromSetList = true; 
                }
                else if (isServerGen) 
                {
                    // column value does not match "omit" pattern, but it is server generated
                    // so it cannot be set
                    omitFromSetList = true; 

                    // if the row has a modified value overridden by server gen, 
                    // it must still be touched in order to retrieve the value 
                    rowMustBeTouched = true;
                } 

                // make the user is not updating an identity value
                if (!omitFromSetList && !insertMode && genPattern == StoreGeneratedPattern.Identity)
                { 
                    //throw the error only if the value actually changed
                    Debug.Assert(originalRow != null, "Updated records should have a original row"); 
                    PropagatorResult originalPropertyResult = originalRow.GetMemberValue(propertyOrdinal); 
                    Debug.Assert(originalPropertyResult.IsSimple, "Server Gen property that is not primitive?");
                    Debug.Assert(propertyResult.IsSimple, "Server Gen property that is not primitive?"); 
                    if (!originalPropertyResult.GetSimpleValue().Equals(propertyResult.GetSimpleValue()))
                    {
                        throw EntityUtil.InvalidOperation(System.Data.Entity.Strings.Update_ModifyingIdentityColumn(
                            XmlConstants.Identity, 
                            property.Name,
                            property.DeclaringType.FullName)); 
                    } 
                    else
                    { 
                        omitFromSetList = true;
                    }
                }
 
                if (!omitFromSetList) { setClauses.Add(property, propertyResult); }
            } 
 
            // Construct returning projection
            if (0 < returningArguments.Count) 
            {
                returning = DbExpressionBuilder.NewRow(returningArguments);
            }
            else 
            {
                returning = null; 
            } 

            // Construct clauses corresponding to the set clauses 
            List result = new List(setClauses.Count);
            foreach (KeyValuePair setClause in setClauses)
            {
                EdmProperty property = setClause.Key; 

                result.Add(new DbSetClause( 
                    GeneratePropertyExpression(target, setClause.Key), 
                    GenerateValueExpression(setClause.Key, setClause.Value)));
            } 

            return result;
        }
 
        /// 
        /// Determines predicate used to identify a row in a table. 
        ///  
        /// 
        /// Columns are included in the list when: 
        /// 
        /// They are keys for the table
        /// They are concurrency values
        ///  
        /// 
        /// Expression binding representing the table containing the row 
        /// Values for the row being located. 
        /// Values being updated (may be null).
        /// Context for the table containing the row. 
        /// Output parameter indicating whether a row must be touched
        /// (whether it's being modified or not) because it contains a concurrency value
        /// Column/value pairs.
        private DbExpression BuildPredicate(DbExpressionBinding target, PropagatorResult referenceRow, PropagatorResult current, 
            TableChangeProcessor processor, ref bool rowMustBeTouched)
        { 
            Dictionary whereClauses = new Dictionary(); 

            // add all concurrency tokens (note that keys are always concurrency tokens as well) 
            int propertyOrdinal = 0;
            foreach (EdmProperty member in processor.Table.ElementType.Properties)
            {
                // members and result values are ordinally aligned 
                PropagatorResult expectedValue = referenceRow.GetMemberValue(propertyOrdinal);
                PropagatorResult newValue = null == current ? null : current.GetMemberValue(propertyOrdinal); 
 
                // check if the rowMustBeTouched value should be set to true (if it isn't already
                // true and we've come across a concurrency value) 
                if (!rowMustBeTouched &&
                    (HasFlag(expectedValue, PropagatorFlags.ConcurrencyValue) ||
                     HasFlag(newValue, PropagatorFlags.ConcurrencyValue)))
                { 
                    rowMustBeTouched = true;
                } 
 
                // determine if this is a concurrency value
                if (!whereClauses.ContainsKey(member) && // don't add to the set clause twice 
                    (HasFlag(expectedValue, PropagatorFlags.ConcurrencyValue | PropagatorFlags.Key) ||
                     HasFlag(newValue, PropagatorFlags.ConcurrencyValue | PropagatorFlags.Key))) // tagged as concurrency value
                {
                    whereClauses.Add(member, expectedValue); 
                }
                propertyOrdinal++; 
            } 

            // Build a binary AND expression tree from the clauses 
            DbExpression predicate = null;
            foreach (KeyValuePair clause in whereClauses)
            {
                DbExpression clauseExpression = GenerateEqualityExpression(target, clause.Key, clause.Value); 
                if (null == predicate) { predicate = clauseExpression; }
                else { predicate = predicate.And(clauseExpression); } 
            } 

            Debug.Assert(null != predicate, "some predicate term must exist"); 

            return predicate;
        }
 
        // Effects: given a "clause" in the form of a property/value pair, produces an equality expression. If the
        // value is null, creates an IsNull expression 
        // Requires: all arguments are set 
        private DbExpression GenerateEqualityExpression(DbExpressionBinding target, EdmProperty property, PropagatorResult value)
        { 
            Debug.Assert(null != target && null != property && null != value);

            DbExpression propertyExpression = GeneratePropertyExpression(target, property);
            DbExpression valueExpression = GenerateValueExpression(property, value); 
            if (valueExpression.ExpressionKind == DbExpressionKind.Null)
            { 
                return propertyExpression.IsNull(); 
            }
            return propertyExpression.Equal(valueExpression); 
        }

        // Effects: given a property, produces a property expression
        // Requires: all arguments are set 
        private static DbExpression GeneratePropertyExpression(DbExpressionBinding target, EdmProperty property)
        { 
            Debug.Assert(null != target && null != property); 

            return target.Variable.Property(property); 
        }

        // Effects: given a propagator result, produces a constant expression describing that value.
        // Requires: all arguments are set, and the value must be simple (scalar) 
        private DbExpression GenerateValueExpression(EdmProperty property, PropagatorResult value)
        { 
            Debug.Assert(null != value && value.IsSimple && null != property); 

            if (value.IsNull) 
            {
                return DbExpressionBuilder.Null(Helper.GetModelTypeUsage(property));
            }
            object principalValue = m_translator.KeyManager.GetPrincipalValue(value); 

            if (Convert.IsDBNull(principalValue)) 
            { 
                // although the result may be marked non-null (because it is an identifier) it is possible
                // there is no corresponding real value for the property yet 
                return DbExpressionBuilder.Null(Helper.GetModelTypeUsage(property));
            }
            else
            { 
                return DbExpressionBuilder.Constant(Helper.GetModelTypeUsage(property), principalValue);
            } 
        } 

        // Effects: returns true iff. the input propagator result has some flag defined in "flags" 
        // Requires: input is set
        private static bool HasFlag(PropagatorResult input, PropagatorFlags flags)
        {
            if (null == input) { return false; } 
            return (PropagatorFlags.NoFlags != (flags & input.PropagatorFlags));
        } 
 
        // Effects: initializes the target (table being modified) for the given DML command tree according
        // to the table managed by the processor. 
        // Requires: all arguments set
        private static DbExpressionBinding GetTarget(TableChangeProcessor processor)
        {
            Debug.Assert(null != processor); 

            // use a fixed var name since the command trees all have exactly one binding 
            return processor.Table.Scan().BindAs(s_targetVarName); 
        }
    } 
}

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

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