1 //------------------------------------------------------------------------------
2 // <copyright file="SingleStorage.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 SingleStorage : DataStorage {
17 
18         private const Single defaultValue = 0.0f;
19 
20         private Single[] values;
21 
SingleStorage(DataColumn column)22         public SingleStorage(DataColumn column)
23         : base(column, typeof(Single), defaultValue, StorageType.Single) {
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                         Single 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                             Single mean;
55                             checked {mean = (Single)(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 
97                     case AggregateType.Min:
98                         Single min = Single.MaxValue;
99                         for (int i = 0; i < records.Length; i++) {
100                             int record = records[i];
101                             if (IsNull(record))
102                                 continue;
103                             min=Math.Min(values[record], min);
104                             hasData = true;
105                         }
106                         if (hasData) {
107                             return min;
108                         }
109                         return NullValue;
110 
111                     case AggregateType.Max:
112                         Single max = Single.MinValue;
113                         for (int i = 0; i < records.Length; i++) {
114                             int record = records[i];
115                             if (IsNull(record))
116                                 continue;
117                             max=Math.Max(values[record], max);
118                             hasData = true;
119                         }
120                         if (hasData) {
121                             return max;
122                         }
123                         return NullValue;
124 
125                     case AggregateType.First:
126                         if (records.Length > 0) {
127                             return values[records[0]];
128                         }
129                         return null;
130 
131                     case AggregateType.Count:
132                         return base.Aggregate(records, kind);
133 
134                 }
135             }
136             catch (OverflowException) {
137                 throw ExprException.Overflow(typeof(Single));
138             }
139             throw ExceptionBuilder.AggregateException(kind, DataType);
140         }
141 
Compare(int recordNo1, int recordNo2)142         override public int Compare(int recordNo1, int recordNo2) {
143             Single valueNo1 = values[recordNo1];
144             Single valueNo2 = values[recordNo2];
145 
146             if (valueNo1 == defaultValue || valueNo2 == defaultValue) {
147                 int bitCheck = CompareBits(recordNo1, recordNo2);
148                 if (0 != bitCheck)
149                     return bitCheck;
150             }
151             return valueNo1.CompareTo(valueNo2); // not simple, checks Nan
152         }
153 
CompareValueTo(int recordNo, object value)154         public override int CompareValueTo(int recordNo, object value) {
155             System.Diagnostics.Debug.Assert(0 <= recordNo, "Invalid record");
156             System.Diagnostics.Debug.Assert(null != value, "null value");
157 
158             if (NullValue == value) {
159                 if (IsNull(recordNo)) {
160                     return 0;
161                 }
162                 return 1;
163             }
164 
165             Single valueNo1 = values[recordNo];
166             if ((defaultValue == valueNo1) && IsNull(recordNo)) {
167                 return -1;
168             }
169             return valueNo1.CompareTo((Single)value);
170         }
171 
ConvertValue(object value)172         public override object ConvertValue(object value) {
173             if (NullValue != value) {
174                 if (null != value) {
175                     value = ((IConvertible)value).ToSingle(FormatProvider);
176                 }
177                 else {
178                     value = NullValue;
179                 }
180             }
181             return value;
182         }
183 
Copy(int recordNo1, int recordNo2)184         override public void Copy(int recordNo1, int recordNo2) {
185             CopyBits(recordNo1, recordNo2);
186             values[recordNo2] = values[recordNo1];
187         }
188 
Get(int record)189         override public Object Get(int record) {
190             Single value = values[record];
191             if (value != defaultValue) {
192                 return value;
193             }
194             return GetBits(record);
195         }
196 
Set(int record, Object value)197         override public void Set(int record, Object value) {
198             System.Diagnostics.Debug.Assert(null != value, "null value");
199             if (NullValue == value) {
200                 values[record] = defaultValue;
201                 SetNullBit(record, true);
202             }
203             else {
204                 values[record] = ((IConvertible)value).ToSingle(FormatProvider);
205                 SetNullBit(record, false);
206             }
207         }
208 
SetCapacity(int capacity)209         override public void SetCapacity(int capacity) {
210             Single[] newValues = new Single[capacity];
211             if (null != values) {
212                 Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length));
213             }
214             values = newValues;
215             base.SetCapacity(capacity);
216         }
217 
ConvertXmlToObject(string s)218         override public object ConvertXmlToObject(string s) {
219             return XmlConvert.ToSingle(s);
220         }
221 
ConvertObjectToXml(object value)222         override public string ConvertObjectToXml(object value) {
223             return XmlConvert.ToString((Single)value);
224         }
225 
GetEmptyStorage(int recordCount)226         override protected object GetEmptyStorage(int recordCount) {
227             return new Single[recordCount];
228         }
229 
CopyValue(int record, object store, BitArray nullbits, int storeIndex)230         override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
231             Single[] typedStore = (Single[]) store;
232             typedStore[storeIndex] = values[record];
233             nullbits.Set(storeIndex, IsNull(record));
234         }
235 
SetStorage(object store, BitArray nullbits)236         override protected void SetStorage(object store, BitArray nullbits) {
237             values = (Single[]) store;
238             SetNullStorage(nullbits);
239         }
240     }
241 }
242