mcs/class/referencesource/System.Data/System/Data/Common/SingleStorage.cs

   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
  22         public SingleStorage(DataColumn column)
  23         : base(column, typeof(Single), defaultValue, StorageType.Single) {
  24         }
  25
  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
 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
 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
 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
 184         override public void Copy(int recordNo1, int recordNo2) {
 185             CopyBits(recordNo1, recordNo2);
 186             values[recordNo2] = values[recordNo1];
 187         }
 188
 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
 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
 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
 218         override public object ConvertXmlToObject(string s) {
 219             return XmlConvert.ToSingle(s);
 220         }
 221
 222         override public string ConvertObjectToXml(object value) {
 223             return XmlConvert.ToString((Single)value);
 224         }
 225
 226         override protected object GetEmptyStorage(int recordCount) {
 227             return new Single[recordCount];
 228         }
 229
 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
 236         override protected void SetStorage(object store, BitArray nullbits) {
 237             values = (Single[]) store;
 238             SetNullStorage(nullbits);
 239         }
 240     }
 241 }