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

   1 //------------------------------------------------------------------------------
   2 // <copyright file="ByteStorage.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 ByteStorage : DataStorage {
  17
  18         private const Byte defaultValue = 0;
  19
  20         private Byte[] values;
  21
  22         internal ByteStorage(DataColumn column)
  23         : base(column, typeof(Byte), defaultValue, StorageType.Byte) {
  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                         UInt64 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                         Int64 meanSum = (Int64)defaultValue;
  45                         int meanCount = 0;
  46                         foreach (int record in records) {
  47                             if (IsNull(record))
  48                                 continue;
  49                             checked { meanSum += (Int64)values[record];}
  50                             meanCount++;
  51                             hasData = true;
  52                         }
  53                         if (hasData) {
  54                             Byte mean;
  55                             checked {mean = (Byte)(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                         Byte min = Byte.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                         Byte max = Byte.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(Byte));
 137             }
 138             throw ExceptionBuilder.AggregateException(kind, DataType);
 139         }
 140
 141          override public int Compare(int recordNo1, int recordNo2) {
 142             Byte valueNo1 = values[recordNo1];
 143             Byte 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);
 151             //return(valueNo1 - valueNo2); // copied from Byte.CompareTo(Byte)
 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             Byte valueNo1 = values[recordNo];
 166             if ((defaultValue == valueNo1) && IsNull(recordNo)) {
 167                 return -1;
 168             }
 169             return valueNo1.CompareTo((Byte)value);
 170             //return(valueNo1 - valueNo2); // copied from Byte.CompareTo(Byte)
 171         }
 172
 173         public override object ConvertValue(object value) {
 174             if (NullValue != value) {
 175                 if (null != value) {
 176                     value = ((IConvertible)value).ToByte(FormatProvider);
 177                 }
 178                 else {
 179                     value = NullValue;
 180                 }
 181             }
 182             return value;
 183         }
 184
 185         override public void Copy(int recordNo1, int recordNo2) {
 186             CopyBits(recordNo1, recordNo2);
 187             values[recordNo2] = values[recordNo1];
 188         }
 189
 190          override public Object Get(int record) {
 191             Byte value = values[record];
 192             if (value != defaultValue) {
 193                 return value;
 194             }
 195             return GetBits(record);
 196         }
 197
 198          override public void Set(int record, Object value) {
 199             System.Diagnostics.Debug.Assert(null != value, "null value");
 200             if (NullValue == value) {
 201                 values[record] = defaultValue;
 202                 SetNullBit(record, true);
 203             }
 204             else {
 205                 values[record] = ((IConvertible)value).ToByte(FormatProvider);
 206                 SetNullBit(record, false);
 207             }
 208         }
 209
 210          override public void SetCapacity(int capacity) {
 211             Byte[] newValues = new Byte[capacity];
 212             if (null != values) {
 213                 Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length));
 214             }
 215             values = newValues;
 216             base.SetCapacity(capacity);
 217         }
 218
 219          override public object ConvertXmlToObject(string s) {
 220             return XmlConvert.ToByte(s);
 221         }
 222
 223         override public string ConvertObjectToXml(object value) {
 224             return XmlConvert.ToString((Byte) value);
 225         }
 226
 227         override protected object GetEmptyStorage(int recordCount) {
 228             return new Byte[recordCount];
 229         }
 230
 231         override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
 232             Byte[] typedStore = (Byte[]) store;
 233             typedStore[storeIndex] = values[record];
 234             nullbits.Set(storeIndex, IsNull(record));
 235         }
 236
 237         override protected void SetStorage(object store, BitArray nullbits) {
 238             values = (Byte[]) store;
 239             SetNullStorage(nullbits);
 240         }
 241     }
 242 }