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1 using System;
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2 using System.Linq;
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3 using System.Linq.Expressions;
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4
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5 namespace BLToolkit.Data.Linq.Builder
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6 {
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7 using BLToolkit.Linq;
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8
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9 class OrderByBuilder : MethodCallBuilder
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10 {
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11 protected override bool CanBuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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12 {
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13 if (!methodCall.IsQueryable("OrderBy", "OrderByDescending", "ThenBy", "ThenByDescending"))
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14 return false;
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15
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16 var body = ((LambdaExpression)methodCall.Arguments[1].Unwrap()).Body.Unwrap();
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17
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18 if (body.NodeType == ExpressionType.MemberInit)
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19 {
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20 var mi = (MemberInitExpression)body;
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21 bool throwExpr;
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22
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23 if (mi.NewExpression.Arguments.Count > 0 || mi.Bindings.Count == 0)
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24 throwExpr = true;
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25 else
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26 throwExpr = mi.Bindings.Any(b => b.BindingType != MemberBindingType.Assignment);
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27
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28 if (throwExpr)
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29 throw new NotSupportedException(string.Format("Explicit construction of entity type '{0}' in order by is not allowed.", body.Type));
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30 }
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31
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32 return true;
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33 }
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34
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35 protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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36 {
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37 var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
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38
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39 if (sequence.SqlQuery.Select.TakeValue != null || sequence.SqlQuery.Select.SkipValue != null)
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40 sequence = new SubQueryContext(sequence);
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41
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42 var lambda = (LambdaExpression)methodCall.Arguments[1].Unwrap();
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43 var sparent = sequence.Parent;
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44 var order = new ExpressionContext(buildInfo.Parent, sequence, lambda);
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45 var body = lambda.Body.Unwrap();
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46 var sql = builder.ConvertExpressions(order, body, ConvertFlags.Key);
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47
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48 builder.ReplaceParent(order, sparent);
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49
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50 if (!methodCall.Method.Name.StartsWith("Then"))
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51 sequence.SqlQuery.OrderBy.Items.Clear();
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52
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53 foreach (var expr in sql)
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54 {
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55 var e = builder.ConvertSearchCondition(sequence, expr.Sql);
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56 sequence.SqlQuery.OrderBy.Expr(e, methodCall.Method.Name.EndsWith("Descending"));
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57 }
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58
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59 return sequence;
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60 }
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61
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62 protected override SequenceConvertInfo Convert(
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63 ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo, ParameterExpression param)
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64 {
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65 return null;
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66 }
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67 }
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68 }
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