49 lines
1.7 KiB
C#
49 lines
1.7 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Linq.Expressions;
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namespace System.Data.Linq.SqlClient {
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using System.Data.Linq;
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/// <summary>
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/// Turn CROSS APPLY into CROSS JOIN when the right side
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/// of the apply doesn't reference anything on the left side.
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///
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/// Any query which has a CROSS APPLY which cannot be converted to
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/// a CROSS JOIN is annotated so that we can give a meaningful
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/// error message later for SQL2K.
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/// </summary>
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internal class SqlCrossApplyToCrossJoin {
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internal static SqlNode Reduce(SqlNode node, SqlNodeAnnotations annotations) {
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Reducer r = new Reducer();
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r.Annotations = annotations;
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return r.Visit(node);
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}
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class Reducer : SqlVisitor {
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internal SqlNodeAnnotations Annotations;
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internal override SqlSource VisitJoin(SqlJoin join) {
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if (join.JoinType == SqlJoinType.CrossApply) {
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// Look down the left side to see what table aliases are produced.
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HashSet<SqlAlias> p = SqlGatherProducedAliases.Gather(join.Left);
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// Look down the right side to see what table aliases are consumed.
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HashSet<SqlAlias> c = SqlGatherConsumedAliases.Gather(join.Right);
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// Look at each consumed alias and see if they are mentioned in produced.
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if (p.Overlaps(c)) {
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Annotations.Add(join, new SqlServerCompatibilityAnnotation(Strings.SourceExpressionAnnotation(join.SourceExpression), SqlProvider.ProviderMode.Sql2000));
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// Can't reduce because this consumed alias is produced on the left.
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return base.VisitJoin(join);
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}
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// Can turn this into a CROSS JOIN
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join.JoinType = SqlJoinType.Cross;
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return VisitJoin(join);
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}
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return base.VisitJoin(join);
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}
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}
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}
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}
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