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comparison Source/Data/Linq/Builder/AggregationBuilder.cs @ 0:f990fcb411a9

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Копия текущей версии из github
author cin
date Thu, 27 Mar 2014 21:46:09 +0400
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-1:000000000000 0:f990fcb411a9
1 using System;
2 using System.Linq;
3 using System.Linq.Expressions;
4
5 namespace BLToolkit.Data.Linq.Builder
6 {
7 using BLToolkit.Linq;
8 using Data.Sql;
9 using Reflection;
10
11 class AggregationBuilder : MethodCallBuilder
12 {
13 public static string[] MethodNames = new[] { "Average", "Min", "Max", "Sum" };
14
15 protected override bool CanBuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
16 {
17 return methodCall.IsQueryable(MethodNames);
18 }
19
20 protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
21 {
22 var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
23
24 if (sequence.SqlQuery.Select.IsDistinct ||
25 sequence.SqlQuery.Select.TakeValue != null ||
26 sequence.SqlQuery.Select.SkipValue != null ||
27 !sequence.SqlQuery.GroupBy.IsEmpty)
28 {
29 sequence = new SubQueryContext(sequence);
30 }
31
32 if (!sequence.SqlQuery.OrderBy.IsEmpty)
33 {
34 if (sequence.SqlQuery.Select.TakeValue == null && sequence.SqlQuery.Select.SkipValue == null)
35 sequence.SqlQuery.OrderBy.Items.Clear();
36 else
37 sequence = new SubQueryContext(sequence);
38 }
39
40 var context = new AggregationContext(buildInfo.Parent, sequence, methodCall);
41 var sql = sequence.ConvertToSql(null, 0, ConvertFlags.Field).Select(_ => _.Sql).ToArray();
42
43 if (sql.Length == 1 && sql[0] is SqlQuery)
44 {
45 var query = (SqlQuery)sql[0];
46
47 if (query.Select.Columns.Count == 1)
48 {
49 var join = SqlQuery.OuterApply(query);
50 context.SqlQuery.From.Tables[0].Joins.Add(join.JoinedTable);
51 sql[0] = query.Select.Columns[0];
52 }
53 }
54
55 context.Sql = context.SqlQuery;
56 context.FieldIndex = context.SqlQuery.Select.Add(
57 new SqlFunction(methodCall.Type, methodCall.Method.Name, sql));
58
59 return context;
60 }
61
62 protected override SequenceConvertInfo Convert(
63 ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo, ParameterExpression param)
64 {
65 return null;
66 }
67
68 class AggregationContext : SequenceContextBase
69 {
70 public AggregationContext(IBuildContext parent, IBuildContext sequence, MethodCallExpression methodCall)
71 : base(parent, sequence, null)
72 {
73 _returnType = methodCall.Method.ReturnType;
74 _methodName = methodCall.Method.Name;
75 }
76
77 readonly string _methodName;
78 readonly Type _returnType;
79 private SqlInfo[] _index;
80
81 public int FieldIndex;
82 public ISqlExpression Sql;
83
84 static object CheckNullValue(object value, object context)
85 {
86 if (value == null || value is DBNull)
87 throw new InvalidOperationException(string.Format("Function {0} returns non-nullable value, but result is NULL. Use nullable version of the function instead.", context));
88
89 return value;
90 }
91
92 public override void BuildQuery<T>(Query<T> query, ParameterExpression queryParameter)
93 {
94 var expr = BuildExpression(FieldIndex);
95 var mapper = Builder.BuildMapper<object>(expr);
96
97 query.SetElementQuery(mapper.Compile());
98 }
99
100 public override Expression BuildExpression(Expression expression, int level)
101 {
102 return BuildExpression(ConvertToIndex(expression, level, ConvertFlags.Field)[0].Index);
103 }
104
105 Expression BuildExpression(int fieldIndex)
106 {
107 Expression expr;
108
109 if (_returnType.IsClass || _methodName == "Sum" || TypeHelper.IsNullableType(_returnType))
110 {
111 expr = Builder.BuildSql(_returnType, fieldIndex);
112 }
113 else
114 {
115 expr = Builder.BuildSql(
116 _returnType,
117 fieldIndex,
118 ReflectionHelper.Expressor<object>.MethodExpressor(o => CheckNullValue(o, o)),
119 Expression.Constant(_methodName));
120 }
121
122 return expr;
123 }
124
125 public override SqlInfo[] ConvertToSql(Expression expression, int level, ConvertFlags flags)
126 {
127 switch (flags)
128 {
129 case ConvertFlags.All :
130 case ConvertFlags.Key :
131 case ConvertFlags.Field : return Sequence.ConvertToSql(expression, level + 1, flags);
132 }
133
134 throw new InvalidOperationException();
135 }
136
137 public override SqlInfo[] ConvertToIndex(Expression expression, int level, ConvertFlags flags)
138 {
139 switch (flags)
140 {
141 case ConvertFlags.Field :
142 return _index ?? (_index = new[]
143 {
144 new SqlInfo { Query = Parent.SqlQuery, Index = Parent.SqlQuery.Select.Add(Sql), Sql = Sql, }
145 });
146 }
147
148 throw new InvalidOperationException();
149 }
150
151 public override IsExpressionResult IsExpression(Expression expression, int level, RequestFor requestFlag)
152 {
153 switch (requestFlag)
154 {
155 case RequestFor.Root : return new IsExpressionResult(Lambda != null && expression == Lambda.Parameters[0]);
156 case RequestFor.Expression : return IsExpressionResult.True;
157 }
158
159 return IsExpressionResult.False;
160 }
161
162 public override IBuildContext GetContext(Expression expression, int level, BuildInfo buildInfo)
163 {
164 throw new InvalidOperationException();
165 }
166 }
167 }
168 }