mcs/class/referencesource/System.Data/System/Data/Common/SQLTypes/SQLByteStorage.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="SQLByteStorage.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.Diagnostics;
  15     using System.Globalization;
  16     using System.IO;
  17     using System.Xml.Serialization;
  18     using System.Collections;
  19
  20     internal sealed class SqlByteStorage : DataStorage {
  21
  22         private SqlByte[] values;
  23
  24         public SqlByteStorage(DataColumn column)
  25         : base(column, typeof(SqlByte), SqlByte.Null, SqlByte.Null, StorageType.SqlByte) {
  26         }
  27
  28         override public Object Aggregate(int[] records, AggregateType kind) {
  29             bool hasData = false;
  30             try {
  31                 switch (kind) {
  32                     case AggregateType.Sum:
  33                         SqlInt64 sum =  0;
  34                         foreach (int record in records) {
  35                             if (IsNull(record))
  36                                 continue;
  37                             checked { sum += values[record];}
  38                             hasData = true;
  39                         }
  40                         if (hasData) {
  41                             return sum;
  42                         }
  43                         return NullValue;
  44
  45                     case AggregateType.Mean:
  46                         SqlInt64 meanSum = 0;
  47                         int meanCount = 0;
  48                         foreach (int record in records) {
  49                             if (IsNull(record))
  50                                 continue;
  51                             checked { meanSum += values[record].ToSqlInt64();}
  52                             meanCount++;
  53                             hasData = true;
  54                         }
  55                         if (hasData) {
  56                             SqlByte mean = 0;
  57                             checked {mean = (meanSum / (SqlInt64)meanCount).ToSqlByte();}
  58                             return mean;
  59                         }
  60                         return NullValue;
  61
  62                     case AggregateType.Var:
  63                     case AggregateType.StDev:
  64                         int count = 0;
  65                         SqlDouble var = (SqlDouble)0;
  66                         SqlDouble prec = (SqlDouble)0;
  67                         SqlDouble dsum = (SqlDouble)0;
  68                         SqlDouble sqrsum = (SqlDouble)0;
  69
  70                         foreach (int record in records) {
  71                             if (IsNull(record))
  72                                 continue;
  73                             dsum += values[record].ToSqlDouble();
  74                             sqrsum += values[record].ToSqlDouble() * values[record].ToSqlDouble();
  75                             count++;
  76                         }
  77
  78                         if (count > 1) {
  79                             var = ((SqlDouble)count * sqrsum - (dsum * dsum));
  80                             prec = var / (dsum * dsum);
  81
  82                             // we are dealing with the risk of a cancellation error
  83                             // double is guaranteed only for 15 digits so a difference
  84                             // with a result less than 1e-15 should be considered as zero
  85
  86                             if ((prec < 1e-15) || (var <0))
  87                                 var = 0;
  88                             else
  89                                 var = var / (count * (count -1));
  90
  91                             if (kind == AggregateType.StDev) {
  92                                return  Math.Sqrt(var.Value);
  93                             }
  94                             return var;
  95                         }
  96                         return NullValue;
  97
  98                     case AggregateType.Min:
  99                         SqlByte min = SqlByte.MaxValue;
 100                         for (int i = 0; i < records.Length; i++) {
 101                             int record = records[i];
 102                             if (IsNull(record))
 103                                 continue;
 104                             if ((SqlByte.LessThan(values[record], min)).IsTrue)
 105                                 min = values[record];
 106                             hasData = true;
 107                         }
 108                         if (hasData) {
 109                             return min;
 110                         }
 111                         return NullValue;
 112
 113                     case AggregateType.Max:
 114                         SqlByte max = SqlByte.MinValue;
 115                         for (int i = 0; i < records.Length; i++) {
 116                             int record = records[i];
 117                             if (IsNull(record))
 118                                 continue;
 119                             if ((SqlByte.GreaterThan(values[record], max)).IsTrue)
 120                                 max = values[record];
 121                             hasData = true;
 122                         }
 123                         if (hasData) {
 124                             return max;
 125                         }
 126                         return NullValue;
 127
 128                     case AggregateType.First:
 129                         if (records.Length > 0) {
 130                             return values[records[0]];
 131                         }
 132                         return null;// no data => null
 133
 134                     case AggregateType.Count:
 135                         count = 0;
 136                         for (int i = 0; i < records.Length; i++) {
 137                             if (!IsNull(records[i]))
 138                                 count++;
 139                         }
 140                         return count;
 141                 }
 142             }
 143             catch (OverflowException) {
 144                 throw ExprException.Overflow(typeof(SqlByte));
 145             }
 146             throw ExceptionBuilder.AggregateException(kind, DataType);
 147         }
 148
 149         override public int Compare(int recordNo1, int recordNo2) {
 150             return values[recordNo1].CompareTo(values[recordNo2]);
 151         }
 152
 153         override public int CompareValueTo(int recordNo, Object value) {
 154             return values[recordNo].CompareTo((SqlByte)value);
 155         }
 156
 157         override public object ConvertValue(object value) {
 158             if (null != value) {
 159                 return SqlConvert.ConvertToSqlByte(value);
 160             }
 161             return NullValue;
 162         }
 163
 164
 165         override public void Copy(int recordNo1, int recordNo2) {
 166             values[recordNo2] = values[recordNo1];
 167         }
 168
 169         override public Object Get(int record) {
 170             return values[record];
 171         }
 172
 173         override public bool IsNull(int record) {
 174             return (values[record].IsNull);
 175         }
 176
 177         override public void Set(int record, Object value) {
 178             values[record] =  SqlConvert.ConvertToSqlByte(value);
 179         }
 180
 181         override public void SetCapacity(int capacity) {
 182             SqlByte[] newValues = new SqlByte[capacity];
 183             if (null != values) {
 184                 Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length));
 185             }
 186             values = newValues;
 187         }
 188
 189         override public object ConvertXmlToObject(string s) {
 190             SqlByte newValue = new SqlByte();
 191             string tempStr =string.Concat("<col>", s, "</col>"); // this is done since you can give fragmet to reader,
 192             StringReader strReader = new  StringReader(tempStr);
 193
 194             IXmlSerializable tmp = newValue;
 195
 196             using (XmlTextReader xmlTextReader = new XmlTextReader(strReader)) {
 197                 tmp.ReadXml(xmlTextReader);
 198             }
 199             return ((SqlByte)tmp);
 200         }
 201
 202         override public string ConvertObjectToXml(object value) {
 203             Debug.Assert(!DataStorage.IsObjectNull(value), "we shouldn't have null here");
 204             Debug.Assert((value.GetType() == typeof(SqlByte)), "wrong input type");
 205
 206             StringWriter strwriter = new StringWriter(FormatProvider);
 207
 208             using (XmlTextWriter xmlTextWriter = new XmlTextWriter (strwriter)) {
 209                 ((IXmlSerializable)value).WriteXml(xmlTextWriter);
 210             }
 211             return (strwriter.ToString ());
 212         }
 213
 214         override protected object GetEmptyStorage(int recordCount) {
 215             return new SqlByte[recordCount];
 216         }
 217
 218         override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
 219             SqlByte[] typedStore = (SqlByte[]) store;
 220             typedStore[storeIndex] = values[record];
 221             nullbits.Set(record, IsNull(record));
 222         }
 223
 224         override protected void SetStorage(object store, BitArray nullbits) {
 225             values = (SqlByte[]) store;
 226             //SetNullStorage(nullbits);
 227         }
 228     }
 229 }