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

   1 //------------------------------------------------------------------------------
   2 // <copyright file="SQLSingleStorage.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">[....]</owner>
   6 // <owner current="true" primary="false">[....]</owner>
   7 // <owner current="false" primary="false">[....]</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 SqlSingleStorage : DataStorage {
  21
  22         private SqlSingle[] values;
  23
  24         public SqlSingleStorage(DataColumn column)
  25         : base(column, typeof(SqlSingle), SqlSingle.Null, SqlSingle.Null, StorageType.SqlSingle) {
  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                         SqlSingle sum =  0.0f;
  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                         SqlDouble meanSum = (SqlDouble) 0.0f;
  47                         int meanCount = 0;
  48                         foreach (int record in records) {
  49                             if (IsNull(record))
  50                                 continue;
  51
  52                             checked { meanSum += values[record].ToSqlDouble();}
  53                             meanCount++;
  54                             hasData = true;
  55                         }
  56                         if (hasData) {
  57                             SqlSingle mean = 0;
  58                             checked {mean = (meanSum /(SqlDouble) meanCount).ToSqlSingle();}
  59                             return mean;
  60                         }
  61                         return NullValue;
  62
  63                     case AggregateType.Var:
  64                     case AggregateType.StDev:
  65                         int count = 0;
  66                         SqlDouble var = (SqlDouble)0;
  67                         SqlDouble prec = (SqlDouble)0;
  68                         SqlDouble dsum = (SqlDouble)0;
  69                         SqlDouble sqrsum = (SqlDouble)0;
  70
  71                         foreach (int record in records) {
  72                             if (IsNull(record))
  73                                 continue;
  74                             dsum += values[record].ToSqlDouble();
  75                             sqrsum += (values[record]).ToSqlDouble() * (values[record]).ToSqlDouble();
  76                             count++;
  77                         }
  78
  79                         if (count > 1) {
  80                             var = ((SqlDouble)count * sqrsum - (dsum * dsum));
  81                             prec = var / (dsum * dsum);
  82
  83                             // we are dealing with the risk of a cancellation error
  84                             // double is guaranteed only for 15 digits so a difference
  85                             // with a result less than 1e-15 should be considered as zero
  86
  87                             if ((prec < 1e-15) || (var <0))
  88                                 var = 0;
  89                             else
  90                                 var = var / (count * (count -1));
  91
  92                             if (kind == AggregateType.StDev) {
  93                                return  Math.Sqrt(var.Value);
  94                             }
  95                             return var;
  96                         }
  97                         return NullValue;
  98
  99                     case AggregateType.Min:
 100                         SqlSingle min = SqlSingle.MaxValue;
 101                         for (int i = 0; i < records.Length; i++) {
 102                             int record = records[i];
 103                             if (IsNull(record))
 104                                 continue;
 105
 106                             if ((SqlSingle.LessThan(values[record], min)).IsTrue)
 107                                 min = values[record];
 108                             hasData = true;
 109                         }
 110                         if (hasData)
 111                             return min;
 112                         return NullValue;
 113
 114                     case AggregateType.Max:
 115                         SqlSingle max = SqlSingle.MinValue;
 116                         for (int i = 0; i < records.Length; i++) {
 117                             int record = records[i];
 118                             if (IsNull(record))
 119                                 continue;
 120
 121                             if ((SqlSingle.GreaterThan(values[record], max)).IsTrue)
 122                                 max = values[record];
 123                             hasData = true;
 124                         }
 125                         if (hasData)
 126                             return max;
 127                         return NullValue;
 128
 129                     case AggregateType.First:
 130                         if (records.Length > 0) {
 131                             return values[records[0]];
 132                         }
 133                         return null;
 134
 135                     case AggregateType.Count:
 136                         count = 0;
 137                         for (int i = 0; i < records.Length; i++) {
 138                             if (!IsNull(records[i]))
 139                                 count++;
 140                         }
 141                         return count;
 142                 }
 143             }
 144             catch (OverflowException) {
 145                 throw ExprException.Overflow(typeof(SqlSingle));
 146             }
 147             throw ExceptionBuilder.AggregateException(kind, DataType);
 148         }
 149
 150         override public int Compare(int recordNo1, int recordNo2) {
 151             return values[recordNo1].CompareTo(values[recordNo2]);
 152         }
 153
 154         override public int CompareValueTo(int recordNo, Object value) {
 155             return values[recordNo].CompareTo((SqlSingle)value);
 156         }
 157
 158         override public object ConvertValue(object value) {
 159             if (null != value) {
 160                 return SqlConvert.ConvertToSqlSingle(value);
 161             }
 162             return NullValue;
 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.ConvertToSqlSingle(value);
 179         }
 180
 181         override public void SetCapacity(int capacity) {
 182             SqlSingle[] newValues = new SqlSingle[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             SqlSingle newValue = new SqlSingle();
 191             string tempStr =string.Concat("<col>", s, "</col>"); // this is done since you can give fragmet to reader, bug 98767
 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 ((SqlSingle)tmp);
 200         }
 201
 202         override public string ConvertObjectToXml(object value) {
 203             Debug.Assert(!DataStorage.IsObjectNull(value), "we should have null here");
 204             Debug.Assert((value.GetType() == typeof(SqlSingle)), "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 SqlSingle[recordCount];
 216         }
 217
 218         override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
 219             SqlSingle[] typedStore = (SqlSingle[]) store;
 220             typedStore[storeIndex] = values[record];
 221             nullbits.Set(storeIndex, IsNull(record));
 222         }
 223
 224         override protected void SetStorage(object store, BitArray nullbits) {
 225             values = (SqlSingle[]) store;
 226             //SetNullStorage(nullbits);
 227         }
 228     }
 229 }