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//------------------------------------------------------------------------------
// <copyright file="FieldNameLookup.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
// <owner current="false" primary="false">Microsoft</owner>
//------------------------------------------------------------------------------
namespace System.Data
{
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
using System.Globalization;
using System.Text;
internal sealed class FieldNameLookup { // V1.2.3300, MDAC 69015, 71470
// hashtable stores the index into the _fieldNames, match via case-sensitive
private Hashtable _fieldNameLookup;
// original names for linear searches when exact matches fail
private string[] _fieldNames;
// if _defaultLocaleID is -1 then _compareInfo is initialized with InvariantCulture CompareInfo
// otherwise it is specified by the server? for the correct compare info
private CompareInfo _compareInfo;
private int _defaultLocaleID;
public FieldNameLookup(System.Collections.ObjectModel.ReadOnlyCollection<string> columnNames, int defaultLocaleID) {
int length = columnNames.Count;
string[] fieldNames = new string[length];
for (int i = 0; i < length; ++i) {
fieldNames[i] = columnNames[i];
Debug.Assert(null != fieldNames[i], "MDAC 66681");
}
_fieldNames = fieldNames;
_defaultLocaleID = defaultLocaleID;
GenerateLookup();
}
public FieldNameLookup(IDataRecord reader, int defaultLocaleID) { // V1.2.3300
int length = reader.FieldCount;
string[] fieldNames = new string[length];
for (int i = 0; i < length; ++i) {
fieldNames[i] = reader.GetName(i);
Debug.Assert(null != fieldNames[i], "MDAC 66681");
}
_fieldNames = fieldNames;
_defaultLocaleID = defaultLocaleID;
}
public int GetOrdinal(string fieldName) { // V1.2.3300
if (null == fieldName) {
throw EntityUtil.ArgumentNull("fieldName");
}
int index = IndexOf(fieldName);
if (-1 == index) {
throw EntityUtil.IndexOutOfRange(fieldName);
}
return index;
}
public int IndexOf(string fieldName) { // V1.2.3300
if (null == _fieldNameLookup) {
GenerateLookup();
}
int index;
object value = _fieldNameLookup[fieldName];
if (null != value) {
// via case sensitive search, first match with lowest ordinal matches
index = (int) value;
}
else {
// via case insensitive search, first match with lowest ordinal matches
index = LinearIndexOf(fieldName, CompareOptions.IgnoreCase);
if (-1 == index) {
// do the slow search now (kana, width insensitive comparison)
index = LinearIndexOf(fieldName, EntityUtil.StringCompareOptions);
}
}
return index;
}
private int LinearIndexOf(string fieldName, CompareOptions compareOptions) {
CompareInfo compareInfo = _compareInfo;
if (null == compareInfo) {
if (-1 != _defaultLocaleID) {
compareInfo = CompareInfo.GetCompareInfo(_defaultLocaleID);
}
if (null == compareInfo) {
compareInfo = CultureInfo.InvariantCulture.CompareInfo;
}
_compareInfo = compareInfo;
}
int length = _fieldNames.Length;
for (int i = 0; i < length; ++i) {
if (0 == compareInfo.Compare(fieldName, _fieldNames[i], compareOptions)) {
_fieldNameLookup[fieldName] = i; // add an exact match for the future
return i;
}
}
return -1;
}
// RTM common code for generating Hashtable from array of column names
private void GenerateLookup() {
int length = _fieldNames.Length;
Hashtable hash = new Hashtable(length);
// via case sensitive search, first match with lowest ordinal matches
for (int i = length-1; 0 <= i; --i) {
string fieldName = _fieldNames[i];
hash[fieldName] = i;
}
_fieldNameLookup = hash;
}
}
}
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