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1 using System;
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2 using System.Data;
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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 CastBuilder : 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 return methodCall.IsQueryable("Cast");
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14 }
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15
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16 protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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17 {
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18 var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
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19
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20 return new CastContext(sequence, methodCall);
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21 }
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22
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23 protected override SequenceConvertInfo Convert(
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24 ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo, ParameterExpression param)
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25 {
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26 return null;
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27 }
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28
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29 class CastContext : PassThroughContext
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30 {
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31 public CastContext(IBuildContext context, MethodCallExpression methodCall)
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32 : base(context)
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33 {
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34 _methodCall = methodCall;
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35 }
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36
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37 private readonly MethodCallExpression _methodCall;
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38
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39 public override void BuildQuery<T>(Query<T> query, ParameterExpression queryParameter)
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40 {
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41 var expr = BuildExpression(null, 0);
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42 var mapper = Builder.BuildMapper<T>(expr);
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43
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44 query.SetQuery(mapper.Compile());
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45 }
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46
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47 public override Expression BuildExpression(Expression expression, int level)
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48 {
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49 var expr = base.BuildExpression(expression, level);
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50 var type = _methodCall.Method.GetGenericArguments()[0];
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51
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52 if (expr.Type != type)
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53 expr = Expression.Convert(expr, type);
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54
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55 return expr;
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56 }
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57 }
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58 }
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59 }
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