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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 using Data.Sql;
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8
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9 class CountBuilder : MethodCallBuilder
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10 {
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11 public static string[] MethodNames = new[] { "Count", "LongCount" };
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12
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13 protected override bool CanBuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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14 {
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15 return methodCall.IsQueryable(MethodNames);
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16 }
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17
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18 protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
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19 {
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20 var returnType = methodCall.Method.ReturnType;
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21 var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
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22
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23 if (sequence.SqlQuery != buildInfo.SqlQuery)
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24 {
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25 if (sequence is JoinBuilder.GroupJoinSubQueryContext)
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26 {
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27 var ctx = new CountContext(buildInfo.Parent, sequence, returnType)
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28 {
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29 SqlQuery = ((JoinBuilder.GroupJoinSubQueryContext)sequence).GetCounter(methodCall)
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30 };
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31
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32 ctx.Sql = ctx.SqlQuery;
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33 ctx.FieldIndex = ctx.SqlQuery.Select.Add(SqlFunction.CreateCount(returnType, ctx.SqlQuery), "cnt");
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34
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35 return ctx;
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36 }
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37
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38 if (sequence is GroupByBuilder.GroupByContext)
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39 {
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40 return new CountContext(buildInfo.Parent, sequence, returnType)
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41 {
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42 Sql = SqlFunction.CreateCount(returnType, sequence.SqlQuery),
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43 FieldIndex = -1
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44 };
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45 }
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46 }
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47
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48 if (sequence.SqlQuery.Select.IsDistinct ||
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49 sequence.SqlQuery.Select.TakeValue != null ||
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50 sequence.SqlQuery.Select.SkipValue != null ||
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51 !sequence.SqlQuery.GroupBy.IsEmpty)
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52 {
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53 sequence.ConvertToIndex(null, 0, ConvertFlags.Key);
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54 sequence = new SubQueryContext(sequence);
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55 }
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56
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57 if (sequence.SqlQuery.OrderBy.Items.Count > 0)
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58 {
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59 if (sequence.SqlQuery.Select.TakeValue == null && sequence.SqlQuery.Select.SkipValue == null)
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60 sequence.SqlQuery.OrderBy.Items.Clear();
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61 else
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62 sequence = new SubQueryContext(sequence);
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63 }
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64
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65 var context = new CountContext(buildInfo.Parent, sequence, returnType);
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66
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67 context.Sql = context.SqlQuery;
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68 context.FieldIndex = context.SqlQuery.Select.Add(SqlFunction.CreateCount(returnType, context.SqlQuery), "cnt");
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69
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70 return context;
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71 }
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72
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73 protected override SequenceConvertInfo Convert(
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74 ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo, ParameterExpression param)
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75 {
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76 return null;
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77 }
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78
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79 internal class CountContext : SequenceContextBase
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80 {
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81 public CountContext(IBuildContext parent, IBuildContext sequence, Type returnType)
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82 : base(parent, sequence, null)
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83 {
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84 _returnType = returnType;
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85 }
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86
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87 readonly Type _returnType;
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88 private SqlInfo[] _index;
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89
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90 public int FieldIndex;
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91 public ISqlExpression Sql;
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92
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93 public override void BuildQuery<T>(Query<T> query, ParameterExpression queryParameter)
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94 {
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95 var expr = Builder.BuildSql(_returnType, FieldIndex);
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96 var mapper = Builder.BuildMapper<object>(expr);
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97
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98 query.SetElementQuery(mapper.Compile());
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99 }
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100
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101 public override Expression BuildExpression(Expression expression, int level)
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102 {
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103 return Builder.BuildSql(_returnType, ConvertToIndex(expression, level, ConvertFlags.Field)[0].Index);
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104 }
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105
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106 public override SqlInfo[] ConvertToSql(Expression expression, int level, ConvertFlags flags)
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107 {
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108 switch (flags)
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109 {
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110 case ConvertFlags.Field : return new[] { new SqlInfo { Query = Parent.SqlQuery, Sql = Sql } };
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111 }
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112
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113 throw new InvalidOperationException();
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114 }
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115
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116 public override SqlInfo[] ConvertToIndex(Expression expression, int level, ConvertFlags flags)
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117 {
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118 switch (flags)
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119 {
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120 case ConvertFlags.Field :
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121 return _index ?? (_index = new[]
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122 {
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123 new SqlInfo { Query = Parent.SqlQuery, Index = Parent.SqlQuery.Select.Add(Sql), Sql = Sql, }
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124 });
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125 }
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126
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127 throw new InvalidOperationException();
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128 }
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129
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130 public override IsExpressionResult IsExpression(Expression expression, int level, RequestFor requestFlag)
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131 {
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132 switch (requestFlag)
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133 {
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134 case RequestFor.Expression : return IsExpressionResult.True;
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135 }
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136
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137 return IsExpressionResult.False;
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138 }
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139
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140 public override IBuildContext GetContext(Expression expression, int level, BuildInfo buildInfo)
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141 {
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142 return Sequence.GetContext(expression, level, buildInfo);
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143 }
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144
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145 public override ISqlExpression GetSubQuery(IBuildContext context)
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146 {
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147 var query = context.SqlQuery;
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148
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149 if (query == SqlQuery)
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150 {
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151 var col = query.Select.Columns[query.Select.Columns.Count - 1];
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152
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153 query.Select.Columns.RemoveAt(query.Select.Columns.Count - 1);
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154
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155 return col.Expression;
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156 }
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157
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158 return null;
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159 }
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160 }
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161 }
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162 }
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