1 //------------------------------------------------------------------------------
2 // <copyright file="DoubleStorage.cs" company="Microsoft">
3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
4 // </copyright>
5 // <owner current="true" primary="true">Microsoft</owner>
6 // <owner current="true" primary="false">Microsoft</owner>
7 // <owner current="false" primary="false">Microsoft</owner>
8 //------------------------------------------------------------------------------
9 
10 namespace System.Data.Common {
11     using System;
12     using System.Xml;
13     using System.Data.SqlTypes;
14     using System.Collections;
15 
16     internal sealed class DoubleStorage : DataStorage {
17 
18         private const Double defaultValue = 0.0d;
19 
20         private Double[] values;
21 
DoubleStorage(DataColumn column)22         internal DoubleStorage(DataColumn column)
23         : base(column, typeof(Double), defaultValue, StorageType.Double) {
24         }
25 
Aggregate(int[] records, AggregateType kind)26         override public Object Aggregate(int[] records, AggregateType kind) {
27             bool hasData = false;
28             try {
29                 switch (kind) {
30                     case AggregateType.Sum:
31                         Double sum = defaultValue;
32                         foreach (int record in records) {
33                             if (IsNull(record))
34                                 continue;
35                             checked { sum += values[record];}
36                             hasData = true;
37                         }
38                         if (hasData) {
39                             return sum;
40                         }
41                         return NullValue;
42 
43                     case AggregateType.Mean:
44                         Double meanSum = (Double)defaultValue;
45                         int meanCount = 0;
46                         foreach (int record in records) {
47                             if (IsNull(record))
48                                 continue;
49                             checked { meanSum += (Double)values[record];}
50                             meanCount++;
51                             hasData = true;
52                         }
53                         if (hasData) {
54                             Double mean;
55                             checked {mean = (Double)(meanSum / meanCount);}
56                             return mean;
57                         }
58                         return NullValue;
59 
60                     case AggregateType.Var:
61                     case AggregateType.StDev:
62                         int count = 0;
63                         double var = (double)defaultValue;
64                         double prec = (double)defaultValue;
65                         double dsum = (double)defaultValue;
66                         double sqrsum = (double)defaultValue;
67 
68                         foreach (int record in records) {
69                             if (IsNull(record))
70                                 continue;
71                             dsum += (double)values[record];
72                             sqrsum += (double)values[record]*(double)values[record];
73                             count++;
74                         }
75 
76                         if (count > 1) {
77                             var = ((double)count * sqrsum - (dsum * dsum));
78                             prec = var / (dsum * dsum);
79 
80                             // we are dealing with the risk of a cancellation error
81                             // double is guaranteed only for 15 digits so a difference
82                             // with a result less than 1e-15 should be considered as zero
83 
84                             if ((prec < 1e-15) || (var <0))
85                                 var = 0;
86                             else
87                                 var = var / (count * (count -1));
88 
89                             if (kind == AggregateType.StDev) {
90                                 return Math.Sqrt(var);
91                             }
92                             return var;
93                         }
94                         return NullValue;
95 
96                     case AggregateType.Min:
97                         Double min = Double.MaxValue;
98                         for (int i = 0; i < records.Length; i++) {
99                             int record = records[i];
100                             if (IsNull(record))
101                                 continue;
102                             min=Math.Min(values[record], min);
103                             hasData = true;
104                         }
105                         if (hasData) {
106                             return min;
107                         }
108                         return NullValue;
109 
110                     case AggregateType.Max:
111                         Double max = Double.MinValue;
112                         for (int i = 0; i < records.Length; i++) {
113                             int record = records[i];
114                             if (IsNull(record))
115                                 continue;
116                             max=Math.Max(values[record], max);
117                             hasData = true;
118                         }
119                         if (hasData) {
120                             return max;
121                         }
122                         return NullValue;
123 
124                     case AggregateType.First:
125                         if (records.Length > 0) {
126                             return values[records[0]];
127                         }
128                         return null;
129 
130                     case AggregateType.Count:
131                         return base.Aggregate(records, kind);
132 
133                 }
134             }
135             catch (OverflowException) {
136                 throw ExprException.Overflow(typeof(Double));
137             }
138             throw ExceptionBuilder.AggregateException(kind, DataType);
139         }
140 
Compare(int recordNo1, int recordNo2)141         override public int Compare(int recordNo1, int recordNo2) {
142             Double valueNo1 = values[recordNo1];
143             Double valueNo2 = values[recordNo2];
144 
145             if (valueNo1 == defaultValue || valueNo2 == defaultValue) {
146                 int bitCheck = CompareBits(recordNo1, recordNo2);
147                 if (0 != bitCheck)
148                     return bitCheck;
149             }
150             return valueNo1.CompareTo(valueNo2); // not simple, checks Nan
151         }
152 
CompareValueTo(int recordNo, object value)153         public override int CompareValueTo(int recordNo, object value) {
154             System.Diagnostics.Debug.Assert(0 <= recordNo, "Invalid record");
155             System.Diagnostics.Debug.Assert(null != value, "null value");
156 
157             if (NullValue == value) {
158                 if (IsNull(recordNo)) {
159                     return 0;
160                 }
161                 return 1;
162             }
163 
164             Double valueNo1 = values[recordNo];
165             if ((defaultValue == valueNo1) && IsNull(recordNo)) {
166                 return -1;
167             }
168             return valueNo1.CompareTo((Double)value);
169         }
170 
ConvertValue(object value)171         public override object ConvertValue(object value) {
172             if (NullValue != value) {
173                 if (null != value) {
174                     value = ((IConvertible)value).ToDouble(FormatProvider);
175                 }
176                 else {
177                     value = NullValue;
178                 }
179             }
180             return value;
181         }
182 
Copy(int recordNo1, int recordNo2)183         override public void Copy(int recordNo1, int recordNo2) {
184             CopyBits(recordNo1, recordNo2);
185             values[recordNo2] = values[recordNo1];
186         }
187 
Get(int record)188         override public Object Get(int record) {
189             Double value = values[record];
190             if (value != defaultValue) {
191                 return value;
192             }
193             return GetBits(record);
194         }
195 
Set(int record, Object value)196         override public void Set(int record, Object value) {
197             System.Diagnostics.Debug.Assert(null != value, "null value");
198             if (NullValue == value) {
199                 values[record] = defaultValue;
200                 SetNullBit(record, true);
201             }
202             else {
203                 values[record] = ((IConvertible)value).ToDouble(FormatProvider);
204                 SetNullBit(record, false);
205             }
206         }
207 
SetCapacity(int capacity)208         override public void SetCapacity(int capacity) {
209             Double[] newValues = new Double[capacity];
210             if (null != values) {
211                 Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length));
212             }
213             values = newValues;
214             base.SetCapacity(capacity);
215         }
216 
ConvertXmlToObject(string s)217         override public object ConvertXmlToObject(string s) {
218             return XmlConvert.ToDouble(s);
219         }
220 
ConvertObjectToXml(object value)221         override public string ConvertObjectToXml(object value) {
222             return XmlConvert.ToString((Double) value);
223         }
224 
GetEmptyStorage(int recordCount)225         override protected object GetEmptyStorage(int recordCount) {
226             return new Double[recordCount];
227         }
228 
CopyValue(int record, object store, BitArray nullbits, int storeIndex)229         override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
230             Double[] typedStore = (Double[]) store;
231             typedStore[storeIndex] = values[record];
232             nullbits.Set(storeIndex, IsNull(record));
233         }
234 
SetStorage(object store, BitArray nullbits)235         override protected void SetStorage(object store, BitArray nullbits) {
236             values = (Double[]) store;
237             SetNullStorage(nullbits);
238         }
239     }
240 }
241