SQLByteStorage.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Data / System / Data / Common / SQLTypes / SQLByteStorage.cs / 1305376 / SQLByteStorage.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 SqlByteStorage : DataStorage {

        private SqlByte[] values;
 
        public SqlByteStorage(DataColumn column)
        : base(column, typeof(SqlByte), SqlByte.Null, SqlByte.Null) { 
        } 

        override public Object Aggregate(int[] records, AggregateType kind) { 
            bool hasData = false;
            try {
                switch (kind) {
                    case AggregateType.Sum: 
                        SqlInt64 sum =  0;
                        foreach (int record in records) { 
                            if (IsNull(record)) 
                                continue;
                            checked { sum += values[record];} 
                            hasData = true;
                        }
                        if (hasData) {
                            return sum; 
                        }
                        return NullValue; 
 
                    case AggregateType.Mean:
                        SqlInt64 meanSum = 0; 
                        int meanCount = 0;
                        foreach (int record in records) {
                            if (IsNull(record))
                                continue; 
                            checked { meanSum += values[record].ToSqlInt64();}
                            meanCount++; 
                            hasData = true; 
                        }
                        if (hasData) { 
                            SqlByte mean = 0;
                            checked {mean = (meanSum / (SqlInt64)meanCount).ToSqlByte();}
                            return mean;
                        } 
                        return NullValue;
 
                    case AggregateType.Var: 
                    case AggregateType.StDev:
                        int count = 0; 
                        SqlDouble var = (SqlDouble)0;
                        SqlDouble prec = (SqlDouble)0;
                        SqlDouble dsum = (SqlDouble)0;
                        SqlDouble sqrsum = (SqlDouble)0; 

                        foreach (int record in records) { 
                            if (IsNull(record)) 
                                continue;
                            dsum += values[record].ToSqlDouble(); 
                            sqrsum += values[record].ToSqlDouble() * values[record].ToSqlDouble();
                            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: 
                        SqlByte min = SqlByte.MaxValue;
                        for (int i = 0; i < records.Length; i++) { 
                            int record = records[i];
                            if (IsNull(record))
                                continue;
                            if ((SqlByte.LessThan(values[record], min)).IsTrue) 
                                min = values[record];
                            hasData = true; 
                        } 
                        if (hasData) {
                            return min; 
                        }
                        return NullValue;

                    case AggregateType.Max: 
                        SqlByte max = SqlByte.MinValue;
                        for (int i = 0; i < records.Length; i++) { 
                            int record = records[i]; 
                            if (IsNull(record))
                                continue; 
                            if ((SqlByte.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(SqlByte));
            } 
            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((SqlByte)value); 
        }

        override public object ConvertValue(object value) {
            if (null != value) { 
                return SqlConvert.ConvertToSqlByte(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.ConvertToSqlByte(value); 
        } 

        override public void SetCapacity(int capacity) { 
            SqlByte[] newValues = new SqlByte[capacity];
            if (null != values) {
                Array.Copy(values, 0, newValues, 0, Math.Min(capacity, values.Length));
            } 
            values = newValues;
        } 
 
        override public object ConvertXmlToObject(string s) {
            SqlByte newValue = new SqlByte(); 
            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 ((SqlByte)tmp); 
        }

        override public string ConvertObjectToXml(object value) {
            Debug.Assert(!DataStorage.IsObjectNull(value), "we shouldn't have null here"); 
            Debug.Assert((value.GetType() == typeof(SqlByte)), "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 SqlByte[recordCount]; 
        }
 
        override protected void CopyValue(int record, object store, BitArray nullbits, int storeIndex) {
            SqlByte[] typedStore = (SqlByte[]) store;
            typedStore[storeIndex] = values[record];
            nullbits.Set(record, IsNull(record)); 
        }
 
        override protected void SetStorage(object store, BitArray nullbits) { 
            values = (SqlByte[]) store;
            //SetNullStorage(nullbits); 
        }
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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