1 files changed, 189 insertions, 0 deletions
diff --git a/tools/Sandcastle/Source/BuildAssembler/BuildComponents/IndexedFileCache.cs b/tools/Sandcastle/Source/BuildAssembler/BuildComponents/IndexedFileCache.cs
new file mode 100644
index 0000000..62425d8
--- /dev/null
+++ b/tools/Sandcastle/Source/BuildAssembler/BuildComponents/IndexedFileCache.cs
@@ -0,0 +1,189 @@
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Xml;
+using System.Xml.XPath;
+
+namespace Microsoft.Ddue.Tools
+{
+	// the storage system
+
+	internal class IndexedFileCache
+	{
+
+		public IndexedFileCache(string keyXPath, string valueXPath, int cacheSize)
+		{
+			valueExpression = XPathExpression.Compile(valueXPath);
+
+			keyExpression = XPathExpression.Compile(keyXPath);
+
+			_cacheSize = cacheSize;
+
+			cache = new Dictionary<string, IndexedFile>(_cacheSize);
+
+			lruLinkedList = new LinkedList<string>();
+		}
+
+		// search pattern for value nodes to be mapped
+		private XPathExpression valueExpression;
+
+		// search pattern for the key identifier (relative to the value node)
+		private XPathExpression keyExpression;
+
+		// an index mapping topic IDs to files
+		private Dictionary<string, string> idToFileMap = new Dictionary<string, string>();
+
+		public int ParseDocuments(string wildcardPath)
+		{
+			string directoryPart = Path.GetDirectoryName(wildcardPath);
+			if (String.IsNullOrEmpty(directoryPart)) directoryPart = Environment.CurrentDirectory;
+			directoryPart = Path.GetFullPath(directoryPart);
+			string filePart = Path.GetFileName(wildcardPath);
+			string[] files = Directory.GetFiles(directoryPart, filePart);
+			// WriteMessage(MessageLevel.Info, String.Format("Found {0} files.", files.Length) );
+			foreach (string file in files)
+			{
+				ParseDocument(file);
+			}
+			return (files.Length);
+		}
+
+		private void ParseDocument(string file)
+		{
+			try
+			{
+				XPathDocument document = new XPathDocument(file);
+				XPathNodeIterator valueNodes = document.CreateNavigator().Select(valueExpression);
+				foreach (XPathNavigator valueNode in valueNodes)
+				{
+					XPathNavigator keyNode = valueNode.SelectSingleNode(keyExpression);
+					if (keyNode == null) continue;
+					string key = keyNode.Value;
+
+					// log multiple occurences of a single id
+					if (idToFileMap.ContainsKey(key))
+					{
+						// WriteMessage(MessageLevel.Warn, String.Format("Entries for the key '{0}' occur in both '{1}' and '{2}'. The first entry will be used.", key, idToFileMap[key], file));
+					}
+					else
+					{
+						idToFileMap[key] = file;
+					}
+				}
+			}
+			catch (XmlException)
+			{
+				// WriteMessage(MessageLevel.Error, e.Message);
+			}
+		}
+
+		// a simple document caching mechanism
+
+		private int _cacheSize = 10;
+
+		private LinkedList<String> lruLinkedList;
+
+		private Dictionary<string, IndexedFile> cache;
+
+
+		private IndexedFile GetCachedDocument(string identifier)
+		{
+			string file;
+			if (idToFileMap.TryGetValue(identifier, out file))
+			{
+				IndexedFile document;
+				if (cache.TryGetValue(file, out document))
+				{
+					// move the file from its current position to the head of the lru linked list
+					lruLinkedList.Remove(document.ListNode);
+					lruLinkedList.AddFirst(document.ListNode);
+				}
+				else
+				{
+					// not in the cache, so load and index a new source file
+					document = new IndexedFile(file, valueExpression, keyExpression);
+					if (cache.Count >= _cacheSize)
+					{
+						// the cache is full
+						// the last node in the linked list has the path of the next file to remove from the cache
+						if (lruLinkedList.Last != null)
+						{
+							cache.Remove(lruLinkedList.Last.Value);
+							lruLinkedList.RemoveLast();
+						}
+					}
+					// add the new file to the cache and to the head of the lru linked list
+					cache.Add(file, document);
+					document.ListNode = lruLinkedList.AddFirst(file);
+				}
+				return (document);
+			}
+			else
+			{
+				return (null);
+			}
+		}
+
+		public XPathNavigator GetContent(string identifier)
+		{
+
+			// get the document containing the identifier
+			IndexedFile document = GetCachedDocument(identifier);
+			if (document == null) return (null);
+
+			// select the comment part of the document
+			return document.GetContent(identifier);
+		}
+
+		public int Count
+		{
+			get
+			{
+				return (idToFileMap.Count);
+			}
+		}
+
+	}
+
+	internal class IndexedFile
+	{
+		Dictionary<string, XPathNavigator> valueIndex = new Dictionary<string, XPathNavigator>();
+
+		public IndexedFile(string filepath, XPathExpression valueExpression, XPathExpression keyExpression)
+		{
+			XPathDocument xpDoc = new XPathDocument(filepath);
+			XPathNodeIterator valueNodes = xpDoc.CreateNavigator().Select(valueExpression);
+			foreach (XPathNavigator valueNode in valueNodes)
+			{
+				XPathNavigator keyNode = valueNode.SelectSingleNode(keyExpression);
+				if (keyNode == null)
+					continue;
+				string key = keyNode.Value;
+				if (!valueIndex.ContainsKey(key))
+					valueIndex.Add(key, valueNode);
+			}
+		}
+
+		public XPathNavigator GetContent(string key)
+		{
+			return valueIndex[key];
+		}
+
+		private LinkedListNode<string> listNode;
+		public LinkedListNode<string> ListNode
+		{
+			get
+			{
+				return (listNode);
+			}
+			set
+			{
+				listNode = value;
+			}
+		}
+
+	}
+
+}