Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / Common / DoubleStorage.cs / 1 / DoubleStorage.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //[....] //----------------------------------------------------------------------------- namespace System.Data.Common { using System; using System.Xml; using System.Data.SqlTypes; using System.Collections; internal sealed class DoubleStorage : DataStorage { private const Double defaultValue = 0.0d; private Double[] values; internal DoubleStorage(DataColumn column) : base(column, typeof(Double), defaultValue) { } override public Object Aggregate(int[] records, AggregateType kind) { bool hasData = false; try { switch (kind) { case AggregateType.Sum: Double sum = defaultValue; foreach (int record in records) { if (IsNull(record)) continue; checked { sum += values[record];} hasData = true; } if (hasData) { return sum; } return NullValue; case AggregateType.Mean: Double meanSum = (Double)defaultValue; int meanCount = 0; foreach (int record in records) { if (IsNull(record)) continue; checked { meanSum += (Double)values[record];} meanCount++; hasData = true; } if (hasData) { Double mean; checked {mean = (Double)(meanSum / meanCount);} return mean; } return NullValue; case AggregateType.Var: case AggregateType.StDev: int count = 0; double var = (double)defaultValue; double prec = (double)defaultValue; double dsum = (double)defaultValue; double sqrsum = (double)defaultValue; foreach (int record in records) { if (IsNull(record)) continue; dsum += (double)values[record]; sqrsum += (double)values[record]*(double)values[record]; count++; } if (count > 1) { var = ((double)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); } return var; } return NullValue; case AggregateType.Min: Double min = Double.MaxValue; for (int i = 0; i < records.Length; i++) { int record = records[i]; if (IsNull(record)) continue; min=Math.Min(values[record], min); hasData = true; } if (hasData) { return min; } return NullValue; case AggregateType.Max: Double max = Double.MinValue; for (int i = 0; i < records.Length; i++) { int record = records[i]; if (IsNull(record)) continue; max=Math.Max(values[record], max); hasData = true; } if (hasData) { return max; } return NullValue; case AggregateType.First: if (records.Length > 0) { return values[records[0]]; } return null; case AggregateType.Count: return base.Aggregate(records, kind); } } catch (OverflowException) { throw ExprException.Overflow(typeof(Double)); } throw ExceptionBuilder.AggregateException(kind, DataType); } override public int Compare(int recordNo1, int recordNo2) { Double valueNo1 = values[recordNo1]; Double valueNo2 = values[recordNo2]; if (valueNo1 == defaultValue || valueNo2 == defaultValue) { int bitCheck = CompareBits(recordNo1, recordNo2); if (0 != bitCheck) return bitCheck; } return valueNo1.CompareTo(valueNo2); // not simple, checks Nan } public override int CompareValueTo(int recordNo, object value) { System.Diagnostics.Debug.Assert(0 <= recordNo, "Invalid record"); System.Diagnostics.Debug.Assert(null != value, "null value"); if (NullValue == value) { if (IsNull(recordNo)) { return 0; } return 1; } Double valueNo1 = values[recordNo]; if ((defaultValue == valueNo1) && IsNull(recordNo)) { return -1; } return valueNo1.CompareTo((Double)value); } public override object ConvertValue(object value) { if (NullValue != value) { if (null != value) { value = ((IConvertible)value).ToDouble(FormatProvider); } else { value = NullValue; } } return value; } override public void Copy(int recordNo1, int recordNo2) { CopyBits(recordNo1, recordNo2); values[recordNo2] = values[recordNo1]; } override public Object Get(int record) { Double value = values[record]; if (value != defaultValue) { return value; } return GetBits(record); } override public void Set(int record, Object value) { System.Diagnostics.Debug.Assert(null != value, "null value"); if (NullValue == value) { values[record] = defaultValue; SetNullBit(record, true); } else { values[record] = ((IConvertible)value).ToDouble(FormatProvider); SetNullBit(record, false); } } override public void SetCapacity(int capacity) { Double[] newValues = new Double[capacity]; if (null != values) { Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length)); } values = newValues; base.SetCapacity(capacity); } override public object ConvertXmlToObject(string s) { return XmlConvert.ToDouble(s); } override public string ConvertObjectToXml(object value) { return XmlConvert.ToString((Double) value); } override protected object GetEmptyStorage(int recordCount) { return new Double[recordCount]; } override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) { Double[] typedStore = (Double[]) store; typedStore[storeIndex] = values[record]; nullbits.Set(storeIndex, IsNull(record)); } override protected void SetStorage(object store, BitArray nullbits) { values = (Double[]) 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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