Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / Common / SQLTypes / SQLDoubleStorage.cs / 1 / SQLDoubleStorage.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //[....] //----------------------------------------------------------------------------- namespace System.Data.Common { using System; using System.Xml; using System.Data.SqlTypes; using System.Diagnostics; using System.Globalization; using System.IO; using System.Xml.Serialization; using System.Collections; internal sealed class SqlDoubleStorage : DataStorage { private SqlDouble[] values; public SqlDoubleStorage(DataColumn column) : base(column, typeof(SqlDouble), SqlDouble.Null, SqlDouble.Null) { } override public Object Aggregate(int[] records, AggregateType kind) { bool hasData = false; try { switch (kind) { case AggregateType.Sum: SqlDouble sum = 0.0d; foreach (int record in records) { if (IsNull(record)) continue; checked { sum += values[record];} hasData = true; } if (hasData) { return sum; } return NullValue; case AggregateType.Mean: SqlDouble meanSum = 0.0d; int meanCount = 0; foreach (int record in records) { if (IsNull(record)) continue; checked { meanSum += values[record];} meanCount++; hasData = true; } if (hasData) { SqlDouble mean = 0.0d; checked {mean = (meanSum / (SqlDouble) meanCount);} return mean; } return NullValue; case AggregateType.Var: case AggregateType.StDev: int count = 0; SqlDouble var = (SqlDouble)0.0d; SqlDouble prec = (SqlDouble)0.0d; SqlDouble dsum = (SqlDouble)0.0d; SqlDouble sqrsum = (SqlDouble)0.0d; foreach (int record in records) { if (IsNull(record)) continue; dsum += values[record]; sqrsum += values[record]*values[record]; count++; } if (count > 1) { var = ((SqlDouble)count * sqrsum - (dsum * dsum)); prec = var / (dsum * dsum); // we are dealing with the risk of a cancellation error // double is guaranteed only for 15 digits so a difference // with a result less than 1e-15 should be considered as zero if ((prec < 1e-15) || (var <0)) var = 0; else var = var / (count * (count -1)); if (kind == AggregateType.StDev) { return Math.Sqrt(var.Value); } return var; } return NullValue; case AggregateType.Min: SqlDouble min = SqlDouble.MaxValue; for (int i = 0; i < records.Length; i++) { int record = records[i]; if (IsNull(record)) continue; if ((SqlDouble.LessThan(values[record], min)).IsTrue) min = values[record]; hasData = true; } if (hasData) { return min; } return NullValue; case AggregateType.Max: SqlDouble max = SqlDouble.MinValue; for (int i = 0; i < records.Length; i++) { int record = records[i]; if (IsNull(record)) continue; if ((SqlDouble.GreaterThan(values[record], max)).IsTrue) max = values[record]; hasData = true; } if (hasData) { return max; } return NullValue; case AggregateType.First: if (records.Length > 0) { return values[records[0]]; } return null;// no data => null case AggregateType.Count: count = 0; for (int i = 0; i < records.Length; i++) { if (!IsNull(records[i])) count++; } return count; } } catch (OverflowException) { throw ExprException.Overflow(typeof(SqlDouble)); } throw ExceptionBuilder.AggregateException(kind, DataType); } override public int Compare(int recordNo1, int recordNo2) { return values[recordNo1].CompareTo(values[recordNo2]); } override public int CompareValueTo(int recordNo, Object value) { return values[recordNo].CompareTo((SqlDouble)value); } override public object ConvertValue(object value) { if (null != value) { return SqlConvert.ConvertToSqlDouble(value); } return NullValue; } override public void Copy(int recordNo1, int recordNo2) { values[recordNo2] = values[recordNo1]; } override public Object Get(int record) { return values[record]; } override public bool IsNull(int record) { return(values[record].IsNull); } override public void Set(int record, Object value) { values[record] = SqlConvert.ConvertToSqlDouble( value); } override public void SetCapacity(int capacity) { SqlDouble[] newValues = new SqlDouble[capacity]; if (null != values) { Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length)); } values = newValues; } override public object ConvertXmlToObject(string s) { SqlDouble newValue = new SqlDouble(); string tempStr =string.Concat("", s, ""); // this is done since you can give fragmet to reader, bug 98767 StringReader strReader = new StringReader(tempStr); IXmlSerializable tmp = newValue; using (XmlTextReader xmlTextReader = new XmlTextReader(strReader)) { tmp.ReadXml(xmlTextReader); } return ((SqlDouble)tmp); } override public string ConvertObjectToXml(object value) { Debug.Assert(!DataStorage.IsObjectNull(value), "we shouldn't have null here"); Debug.Assert((value.GetType() == typeof(SqlDouble)), "wrong input type"); StringWriter strwriter = new StringWriter(FormatProvider); using (XmlTextWriter xmlTextWriter = new XmlTextWriter (strwriter)) { ((IXmlSerializable)value).WriteXml(xmlTextWriter); } return (strwriter.ToString ()); } override protected object GetEmptyStorage(int recordCount) { return new SqlDouble[recordCount]; } override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) { SqlDouble[] typedStore = (SqlDouble[]) store; typedStore[storeIndex] = values[record]; nullbits.Set(storeIndex, IsNull(record)); } override protected void SetStorage(object store, BitArray nullbits) { values = (SqlDouble[]) store; //SetNullStorage(nullbits); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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