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1 using System;
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2 using System.Linq.Expressions;
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3
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4 namespace BLToolkit.Data.Linq.Builder
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5 {
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6 using BLToolkit.Linq;
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7
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8 class DistinctBuilder : MethodCallBuilder
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9 {
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10 protected override bool CanBuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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11 {
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12 return methodCall.IsQueryable("Distinct");
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13 }
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14
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15 protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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16 {
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17 var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
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18 var sql = sequence.SqlQuery;
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19
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20 if (sql.Select.TakeValue != null || sql.Select.SkipValue != null)
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21 sequence = new SubQueryContext(sequence);
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22
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23 sequence.SqlQuery.Select.IsDistinct = true;
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24 sequence.ConvertToIndex(null, 0, ConvertFlags.All);
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25
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26 return sequence;
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27 }
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28
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29 protected override SequenceConvertInfo Convert(
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30 ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo, ParameterExpression param)
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31 {
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32 return null;
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33 }
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34 }
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35 }
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