internals: virtualized the doc fetcher interface

2012-06-05 07:16:11 +02:00
parent 42378d05e3
commit 643f4d56bb
12 changed files with 389 additions and 112 deletions
@@ -0,0 +1,71 @@
+/* Copyright (C) 2012 J.F.Dockes
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the
+ *   Free Software Foundation, Inc.,
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+#ifndef _FETCHER_H_INCLUDED_
+#define _FETCHER_H_INCLUDED_
+
+#include <sys/stat.h>
+#include <string>
+
+#include "rcldoc.h"
+
+class RclConfig;
+
+/** 
+ * Definition for a generic method to retrieve the data
+ * for a document designated by its index data (udi/ipath/url).
+ * This is used to retrieve the data for previewing. The
+ * actual implementation is specific to the kind of backend (file
+ * system, beagle cache, others in the future ?), and of course may
+ * share code with the indexing-time functions from the specific backend.
+ */
+class DocFetcher {
+public:
+    /** A RawDoc is the data for a source document either as a memory
+       block, or pointed to by a file name */
+    struct RawDoc {
+	enum RawDocKind {RDK_FILENAME, RDK_DATA};
+	RawDocKind kind;
+	std::string data; // Doc data or file name
+	struct stat st; // Only used if RDK_FILENAME
+    };
+
+    /** 
+     * Return the data for the requested document, either as a
+     * file-system file or as a memory object (maybe stream too in the
+     * future?) 
+     * @param cnf the global config
+     * @param idoc the data gathered from the index for this doc (udi/ipath)
+     * @param out we may return either a file name or the document data. 
+     */
+    virtual bool fetch(RclConfig* cnf, const Rcl::Doc& idoc, RawDoc& out) = 0;
+    
+    /** 
+     * Return the signature for the requested document. This is used for
+     * up-to-date tests performed out of indexing (e.g.: verifying that a 
+     * document is not stale before previewing it).
+     * @param cnf the global config
+     * @param idoc the data gathered from the index for this doc (udi/ipath)
+     * @param sig output. 
+     */
+    virtual bool makesig(RclConfig* cnf, const Rcl::Doc& idoc, string& sig) = 0;
+    virtual ~DocFetcher() {}
+};
+
+/** Returns an appropriate fetcher object given the backend string identifier */
+DocFetcher *docFetcherMake(const Rcl::Doc& idoc);
+
+#endif /* _FETCHER_H_INCLUDED_ */