//-----------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation.
//
//-----------------------------------------------------------------------
namespace Microsoft.Isam.Esent.Interop
{
using System.Diagnostics;
using System.Globalization;
using System.Text;
using Microsoft.Isam.Esent.Interop.Windows8;
///
/// Base class for enumerators that return IndexInfo objects. Subclasses differ
/// by how they open the table.
///
internal abstract class IndexInfoEnumerator : TableEnumerator
{
///
/// Initializes a new instance of the class.
///
///
/// The session to use.
///
protected IndexInfoEnumerator(JET_SESID sesid) : base(sesid)
{
}
///
/// Gets or sets the indexlist used to retrieve data.
///
protected JET_INDEXLIST Indexlist { get; set; }
///
/// Gets the entry the cursor is currently positioned on.
///
/// The entry the cursor is currently positioned on.
protected override IndexInfo GetCurrent()
{
return this.GetIndexInfoFromIndexlist(this.Sesid, this.Indexlist);
}
///
/// Retrieves information about indexes on a table.
///
/// The session to use.
/// The name of the index.
/// Filled in with information about indexes on the table.
/// The type of information to retrieve.
protected abstract void GetIndexInfo(
JET_SESID sesid,
string indexname,
out string result,
JET_IdxInfo infoLevel);
///
/// Create an array of IndexSegment objects from the data in the current JET_INDEXLIST entry.
///
/// The session to use.
/// The indexlist to take the data from.
/// An array of IndexSegment objects containing the information for the current index.
private static IndexSegment[] GetIndexSegmentsFromIndexlist(JET_SESID sesid, JET_INDEXLIST indexlist)
{
var numSegments = (int)Api.RetrieveColumnAsInt32(sesid, indexlist.tableid, indexlist.columnidcColumn);
Debug.Assert(numSegments > 0, "Index has zero index segments");
// If we use the wide API (Vista+), then the temp table will be in UTF-16.
Encoding encodingOfTextColumns = EsentVersion.SupportsVistaFeatures ? Encoding.Unicode : LibraryHelpers.EncodingASCII;
var segments = new IndexSegment[numSegments];
for (int i = 0; i < numSegments; ++i)
{
string columnName = Api.RetrieveColumnAsString(
sesid,
indexlist.tableid,
indexlist.columnidcolumnname,
encodingOfTextColumns,
RetrieveColumnGrbit.None);
columnName = StringCache.TryToIntern(columnName);
var coltyp = (JET_coltyp)Api.RetrieveColumnAsInt32(sesid, indexlist.tableid, indexlist.columnidcoltyp);
var grbit =
(IndexKeyGrbit)Api.RetrieveColumnAsInt32(sesid, indexlist.tableid, indexlist.columnidgrbitColumn);
bool isAscending = IndexKeyGrbit.Ascending == grbit;
var cp = (JET_CP)Api.RetrieveColumnAsInt16(sesid, indexlist.tableid, indexlist.columnidCp);
bool isASCII = JET_CP.ASCII == cp;
segments[i] = new IndexSegment(columnName, coltyp, isAscending, isASCII);
if (i < numSegments - 1)
{
Api.JetMove(sesid, indexlist.tableid, JET_Move.Next, MoveGrbit.None);
}
}
return segments;
}
///
/// Create an IndexInfo object from the data in the current JET_INDEXLIST entry.
///
/// The session to use.
/// The indexlist to take the data from.
/// An IndexInfo object containing the information from that record.
private IndexInfo GetIndexInfoFromIndexlist(JET_SESID sesid, JET_INDEXLIST indexlist)
{
// If we use the wide API (Vista+), then the temp table will be in UTF-16.
Encoding encodingOfTextColumns = EsentVersion.SupportsVistaFeatures ? Encoding.Unicode : LibraryHelpers.EncodingASCII;
string name = Api.RetrieveColumnAsString(
sesid, indexlist.tableid, indexlist.columnidindexname, encodingOfTextColumns, RetrieveColumnGrbit.None);
name = StringCache.TryToIntern(name);
CultureInfo cultureInfo = null;
if (EsentVersion.SupportsWindows8Features)
{
string localeName;
this.GetIndexInfo(sesid, name, out localeName, Windows8IdxInfo.LocaleName);
cultureInfo = new CultureInfo(localeName);
}
else
{
#if !MANAGEDESENT_ON_CORECLR
// This probably won't work on platforms that don't support LCIDs. Newer environments have dropped
// LCIDs in favour of locale names. But currently JET_INDEXLIST doesn't expose columnidLocale.
int lcid = (int)Api.RetrieveColumnAsInt16(sesid, indexlist.tableid, indexlist.columnidLangid);
cultureInfo = LibraryHelpers.CreateCultureInfoByLcid(lcid);
#endif // !MANAGEDESENT_ON_CORECLR
}
uint lcmapFlags = (uint)Api.RetrieveColumnAsUInt32(sesid, indexlist.tableid, indexlist.columnidLCMapFlags);
CompareOptions compareOptions = Conversions.CompareOptionsFromLCMapFlags(lcmapFlags);
uint grbit = (uint)Api.RetrieveColumnAsUInt32(sesid, indexlist.tableid, indexlist.columnidgrbitIndex);
int keys = (int)Api.RetrieveColumnAsInt32(sesid, indexlist.tableid, indexlist.columnidcKey);
int entries = (int)Api.RetrieveColumnAsInt32(sesid, indexlist.tableid, indexlist.columnidcEntry);
int pages = (int)Api.RetrieveColumnAsInt32(sesid, indexlist.tableid, indexlist.columnidcPage);
IndexSegment[] segments = GetIndexSegmentsFromIndexlist(sesid, indexlist);
return new IndexInfo(
name,
cultureInfo,
compareOptions,
segments,
(CreateIndexGrbit)grbit,
keys,
entries,
pages);
}
}
}