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// Copyright (c) Dr. Dirk Lellinger. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace SlobViewer.Slob
{
/// <summary>
/// Represents a dictionary retrieved from a SLOB file.
/// </summary>
public class SlobDictionaryFileBased : IWordDictionary
{
public string FileName { get; set; }
Stream _stream;
/// <summary>
/// The encoding of the keys and the content.
/// </summary>
System.Text.Encoding _encoding;
/// <summary>
/// The compression method of the content.
/// </summary>
string _compression;
/// <summary>
/// The dictionary of tags of this SLOB file. The tags represent metadata for the SLOB file.
/// </summary>
Dictionary<string, string> _tags;
/// <summary>
/// The types of content. The <see cref="StoreItemInMemory"/>s contain a table which stores for each content item an index into this list of content types,
/// so that each content item has a designated content type.
/// </summary>
string[] _contentTypes;
/// <summary>
/// The list of keys of this dictionary.
/// </summary>
Reference[] _references;
/// <summary>
/// The store items, i.e. the list of values. Each store item contains multiple values, in order to have a better compression factor of the content.
/// </summary>
StoreItemFileBased[] _storeItems;
byte[] _buffer = new byte[1024 * 1024];
/// <summary>
/// Initializes a new instance of the <see cref="SlobDictionaryFileBased"/> class.
/// </summary>
/// <param name="encoding">The encoding of the content.</param>
/// <param name="compression">The compression type of the content.</param>
/// <param name="tags">The tags (metadata of this dictionary).</param>
/// <param name="contentTypes">The content types.</param>
/// <param name="references">The references (keys of the dictionary).</param>
/// <param name="storeItems">The store items (each store item contains multiple content items).</param>
public SlobDictionaryFileBased(
Stream stream,
Encoding encoding,
string compression,
Dictionary<string, string> tags,
string[] contentTypes,
Reference[] references,
StoreItemFileBased[] storeItems)
{
_stream = stream;
_encoding = encoding;
_compression = compression;
_tags = tags;
_contentTypes = contentTypes;
_references = references;
_storeItems = storeItems;
}
/// <summary>Gets all keys of this dictionary.</summary>
/// <returns></returns>
public string[] GetKeys()
{
return _references.Select(x => x.Key).ToArray();
}
/// <summary>
/// Gets a number of <paramref name="count"/> keys including the key given in <paramref name="key"/> (if found).
/// </summary>
/// <param name="key">The key to search for.</param>
/// <param name="count">The number of keys following the given key.</param>
/// <returns>A array of keys, including the key given (if it is found in the dictionary). The size of the array is equal to or less than <paramref name="count"/>.</returns>
public string[] GetKeys(string key, int count)
{
int i;
for (i = 0; i < _references.Length; ++i)
{
if (0 >= string.Compare(key, _references[i].Key))
break;
}
if (i == _references.Length)
return null;
var len = Math.Min(count, _references.Length - i);
var result = new string[len];
for (int k = 0; k < len; ++k)
result[k] = _references[i + k].Key;
return result;
}
/// <summary>
/// Try to get the content for the specified <paramref name="key"/>.
/// </summary>
/// <param name="key">The key for which the content should be retrieved..</param>
/// <param name="value">If successfull, contains the retrieved content and the content identification.</param>
/// <returns>True if the content with the specified key was found; otherwise, false.</returns>
public bool TryGetValue(string key, out (string Content, string ContentId) value)
{
int i;
for (i = 0; i < _references.Length; ++i)
{
if (0 == string.Compare(key, _references[i].Key))
break;
}
if (i == _references.Length)
{
value = (null, null);
return false;
}
var blobIndex = _references[i].BinIndex;
var itemIndex = _references[i].ItemIndex;
var storeItem = _storeItems[blobIndex];
System.Diagnostics.Debug.WriteLine($"GetAt, key: {key}, blb={blobIndex}, iti={itemIndex}");
var item = storeItem.GetAt(itemIndex, _stream, _encoding, _compression, _buffer);
value = (item.Content, _contentTypes[item.ContentId]);
return true;
}
/// <summary>
/// Gets the <see cref="System.ValueTuple{System.String, System.String}"/> with the specified key.
/// </summary>
/// <value>
/// The value <see cref="System.ValueTuple{System.String, System.String}"/> for the specified key.
/// </value>
/// <param name="key">The key.</param>
/// <returns>The value <see cref="System.ValueTuple{System.String, System.String}"/> for the specified key.</returns>
public (string Content, string ContentId) this[string key]
{
get
{
TryGetValue(key, out var value);
return value;
}
}
}
}
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