Import dotnetDBF for error handling.
This commit is contained in:
Patrick Fic
487
dotnetdbf/DBFReader.cs
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487
dotnetdbf/DBFReader.cs
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@@ -0,0 +1,487 @@
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/*
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DBFReader
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Class for reading the records assuming that the given
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InputStream contains DBF data.
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This file is part of DotNetDBF package.
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original author (javadbf): anil@linuxense.com 2004/03/31
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License: LGPL (http://www.gnu.org/copyleft/lesser.html)
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ported to C# (DotNetDBF): Jay Tuley <jay+dotnetdbf@tuley.name> 6/28/2007
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*/
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using System;
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using System.Collections.Generic;
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using System.Globalization;
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using System.IO;
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using System.Text;
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using System.Linq;
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namespace DotNetDBF
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{
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public class DBFReader : DBFBase, IDisposable
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{
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private BinaryReader _dataInputStream;
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private DBFHeader _header;
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private Stream _dataMemo;
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private string _dataMemoLoc;
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private int[] _selectFields = new int[] {};
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private int[] _orderedSelectFields = new int[] {};
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/* Class specific variables */
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private bool _isClosed = true;
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/**
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Initializes a DBFReader object.
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When this constructor returns the object
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will have completed reading the header (meta date) and
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header information can be queried there on. And it will
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be ready to return the first row.
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@param InputStream where the data is read from.
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*/
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public void SetSelectFields(params string[] aParams)
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{
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_selectFields =
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aParams.Select(
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it =>
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Array.FindIndex(_header.FieldArray,
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jt => jt.Name.Equals(it, StringComparison.OrdinalIgnoreCase))).ToArray();
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_orderedSelectFields = _selectFields.OrderBy(it => it).ToArray();
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}
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public DBFField[] GetSelectFields()
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{
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return _selectFields.Any()
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? _selectFields.Select(it => _header.FieldArray[it]).ToArray()
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: _header.FieldArray;
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}
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public DBFReader(string anIn)
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{
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try
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{
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_dataInputStream = new BinaryReader(
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File.Open(anIn,
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FileMode.Open,
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FileAccess.Read,
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FileShare.Read)
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);
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var dbtPath = Path.ChangeExtension(anIn, "dbt");
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if (File.Exists(dbtPath))
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{
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_dataMemoLoc = dbtPath;
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}
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_isClosed = false;
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_header = new DBFHeader();
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_header.Read(_dataInputStream);
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/* it might be required to leap to the start of records at times */
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var t_dataStartIndex = _header.HeaderLength
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- (32 + (32 * _header.FieldArray.Length))
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- 1;
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if (t_dataStartIndex > 0)
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{
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_dataInputStream.ReadBytes((t_dataStartIndex));
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}
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}
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catch (IOException ex)
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{
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throw new DBFException("Failed To Read DBF", ex);
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}
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}
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public DBFReader(Stream anIn)
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{
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try
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{
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_dataInputStream = new BinaryReader(anIn);
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_isClosed = false;
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_header = new DBFHeader();
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_header.Read(_dataInputStream);
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/* it might be required to leap to the start of records at times */
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var t_dataStartIndex = _header.HeaderLength
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- (32 + (32 * _header.FieldArray.Length))
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- 1;
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if (t_dataStartIndex > 0)
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{
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_dataInputStream.ReadBytes((t_dataStartIndex));
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}
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}
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catch (IOException e)
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{
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throw new DBFException("Failed To Read DBF", e);
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}
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}
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/**
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Returns the number of records in the DBF.
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*/
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public int RecordCount => _header.NumberOfRecords;
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/**
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Returns the asked Field. In case of an invalid index,
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it returns a ArrayIndexOutOfBoundsException.
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@param index. Index of the field. Index of the first field is zero.
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*/
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public DBFField[] Fields => _header.FieldArray;
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#region IDisposable Members
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/// <summary>Performs application-defined tasks associated with freeing, releasing,
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/// or resetting unmanaged resources.</summary>
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/// <filterpriority>2</filterpriority>
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public void Dispose()
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{
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Close();
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}
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#endregion
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public string DataMemoLoc
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{
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get => _dataMemoLoc;
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set => _dataMemoLoc = value;
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}
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public delegate Stream LazyStream();
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private Stream _loadedStream;
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private LazyStream GetLazyStreamFromLocation()
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{
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if (_dataMemo == null && !string.IsNullOrEmpty(_dataMemoLoc))
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{
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return () => _loadedStream ??
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(_loadedStream = File.Open(_dataMemoLoc, FileMode.Open, FileAccess.Read,
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FileShare.Read));
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}
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if (_dataMemo != null)
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{
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return () => _dataMemo;
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}
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return null;
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}
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public Stream DataMemo
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{
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get => _dataMemo;
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set => _dataMemo = value;
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}
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public override string ToString()
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{
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var sb =
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new StringBuilder(_header.Year + "/" + _header.Month + "/"
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+ _header.Day + "\n"
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+ "Total records: " + _header.NumberOfRecords +
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"\nHeader length: " + _header.HeaderLength +
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"");
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for (var i = 0; i < _header.FieldArray.Length; i++)
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{
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sb.Append(_header.FieldArray[i].Name);
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sb.Append("\n");
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}
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return sb.ToString();
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}
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public void Close()
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{
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_loadedStream?.Close();
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_dataMemo?.Close();
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_dataInputStream.Close();
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_dataMemo?.Dispose();
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_isClosed = true;
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}
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/**
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Reads the returns the next row in the DBF stream.
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@returns The next row as an Object array. Types of the elements
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these arrays follow the convention mentioned in the class description.
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*/
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public object[] NextRecord(bool throwOnParsingError = true)
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{
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return NextRecord(_selectFields, _orderedSelectFields, throwOnParsingError);
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}
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internal object[] NextRecord(IEnumerable<int> selectIndexes, IList<int> sortedIndexes, bool throwOnParsingError = true)
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{
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if (_isClosed)
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{
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throw new DBFException("Source is not open");
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}
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var tOrderdSelectIndexes = sortedIndexes;
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var recordObjects = new object[_header.FieldArray.Length];
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try
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{
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var isDeleted = false;
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do
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{
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if (isDeleted)
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{
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_dataInputStream.ReadBytes(_header.RecordLength - 1);
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}
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int t_byte = _dataInputStream.ReadByte();
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if (t_byte == DBFFieldType.EndOfData)
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{
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return null;
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}
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isDeleted = (t_byte == '*');
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} while (isDeleted);
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var j = 0;
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var k = -1;
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for (var i = 0; i < _header.FieldArray.Length; i++)
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{
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if (tOrderdSelectIndexes.Count == j && j != 0
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||
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(tOrderdSelectIndexes.Count > j && tOrderdSelectIndexes[j] > i && tOrderdSelectIndexes[j] != k))
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{
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_dataInputStream.BaseStream.Seek(_header.FieldArray[i].FieldLength, SeekOrigin.Current);
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continue;
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}
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if (tOrderdSelectIndexes.Count > j)
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k = tOrderdSelectIndexes[j];
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j++;
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switch (_header.FieldArray[i].DataType)
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{
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case NativeDbType.Char:
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var b_array = new byte[
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_header.FieldArray[i].FieldLength
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];
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_dataInputStream.Read(b_array, 0, b_array.Length);
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recordObjects[i] = CharEncoding.GetString(b_array).TrimEnd();
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break;
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case NativeDbType.Date:
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var t_byte_year = new byte[4];
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_dataInputStream.Read(t_byte_year,
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0,
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t_byte_year.Length);
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var t_byte_month = new byte[2];
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_dataInputStream.Read(t_byte_month,
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0,
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t_byte_month.Length);
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var t_byte_day = new byte[2];
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_dataInputStream.Read(t_byte_day,
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0,
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t_byte_day.Length);
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try
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{
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var tYear = CharEncoding.GetString(t_byte_year);
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var tMonth = CharEncoding.GetString(t_byte_month);
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var tDay = CharEncoding.GetString(t_byte_day);
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if (int.TryParse(tYear, out var tIntYear) &&
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int.TryParse(tMonth, out var tIntMonth) &&
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int.TryParse(tDay, out var tIntDay))
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{
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recordObjects[i] = new DateTime(
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tIntYear,
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tIntMonth,
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tIntDay);
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}
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else
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{
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recordObjects[i] = null;
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}
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}
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catch (ArgumentOutOfRangeException)
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{
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/* this field may be empty or may have improper value set */
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recordObjects[i] = null;
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}
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break;
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case NativeDbType.Float:
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try
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{
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var t_float = new byte[
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_header.FieldArray[i].FieldLength
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];
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_dataInputStream.Read(t_float, 0, t_float.Length);
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var tParsed = CharEncoding.GetString(t_float);
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var tLast = tParsed.Substring(tParsed.Length - 1);
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if (tParsed.Length > 0
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&& tLast != " "
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&& tLast != NullSymbol)
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{
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//
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// A Float in FoxPro has 20 significant digits, since it is
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// stored as a string with possible E-postfix notation.
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// An IEEE 754 float or double can not handle this number of digits
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// correctly. Therefor the only correct implementation is to use a decimal.
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//
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recordObjects[i] = decimal.Parse(tParsed,
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NumberStyles.Float | NumberStyles.AllowLeadingWhite,
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NumberFormatInfo.InvariantInfo);
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}
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else
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{
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recordObjects[i] = null;
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}
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}
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catch (FormatException e)
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{
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if (throwOnParsingError)
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throw new DBFException("Failed to parse Float", e);
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recordObjects[i] = default(decimal);
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}
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break;
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case NativeDbType.Numeric:
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try
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{
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var t_numeric = new byte[
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_header.FieldArray[i].FieldLength
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];
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_dataInputStream.Read(t_numeric,
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0,
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t_numeric.Length);
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var tParsed =
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CharEncoding.GetString(t_numeric);
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var tLast = tParsed.Substring(tParsed.Length - 1);
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if (tParsed.Length > 0
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&& tLast != " "
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&& tLast != NullSymbol)
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{
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recordObjects[i] = decimal.Parse(tParsed,
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NumberStyles.Float | NumberStyles.AllowLeadingWhite,
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NumberFormatInfo.InvariantInfo);
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}
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else
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{
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recordObjects[i] = null;
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}
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}
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catch (FormatException e)
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{
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if (throwOnParsingError)
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throw new DBFException(
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"Failed to parse Number", e);
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recordObjects[i] = default(decimal);
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}
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break;
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case NativeDbType.Logical:
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var t_logical = _dataInputStream.ReadByte();
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//todo find out whats really valid
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if (t_logical == 'Y' || t_logical == 't'
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|| t_logical == 'T'
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|| t_logical == 't')
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{
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recordObjects[i] = true;
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}
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else if (t_logical == DBFFieldType.UnknownByte)
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{
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recordObjects[i] = DBNull.Value;
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}
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else
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{
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recordObjects[i] = false;
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}
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break;
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case NativeDbType.Memo:
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if (
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string.IsNullOrEmpty(_dataMemoLoc) &&
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_dataMemo is null)
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{
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throw new Exception("Memo Location Not Set");
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}
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var rawMemoPointer = _dataInputStream.ReadBytes(_header.FieldArray[i].FieldLength);
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var memoPointer = CharEncoding.GetString(rawMemoPointer);
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if (string.IsNullOrEmpty(memoPointer))
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{
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recordObjects[i] = DBNull.Value;
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break;
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}
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if (!long.TryParse(memoPointer, out var tBlock))
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{
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//Because Memo files can vary and are often the least important data,
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//we will return null when it doesn't match our format.
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recordObjects[i] = DBNull.Value;
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break;
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}
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recordObjects[i] = new MemoValue(tBlock, this,
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_dataMemoLoc,
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GetLazyStreamFromLocation());
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break;
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default:
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{
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byte[] data = _dataInputStream.ReadBytes(_header.FieldArray[i].FieldLength);
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recordObjects[i] = data != null ? (object)data : DBNull.Value;
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break;
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}
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}
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}
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}
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catch (EndOfStreamException)
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{
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return null;
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}
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catch (IOException e)
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{
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throw new DBFException("Problem Reading File", e);
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}
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return selectIndexes.Any() ? selectIndexes.Select(it => recordObjects[it]).ToArray() : recordObjects;
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}
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}
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}
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Reference in New Issue
Block a user