Refactor|FS|libcore: Registering new File interpreters

FileSystem is now allows registering any number of File interpreters.

Added interpreters in LibraryFile and ZipArchive.

doomsday/sdk/libcore/include/de/data/ziparchive.h

@@ -14,14 +14,15 @@
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
  * General Public License for more details. You should have received a copy of
  * the GNU Lesser General Public License along with this program; if not, see:
- * http://www.gnu.org/licenses</small> 
+ * http://www.gnu.org/licenses</small>
  */
 
 #ifndef LIBDENG2_ZIPARCHIVE_H
 #define LIBDENG2_ZIPARCHIVE_H
 
 #include "../Archive"
 #include "../NativePath"
+#include "../filesys/IInterpreter"
 
 namespace de {
 
@@ -98,6 +99,10 @@ class DENG2_PUBLIC ZipArchive : public Archive
      */
     static bool recognize(NativePath const &path);
 
+    struct DENG2_PUBLIC Interpreter : public filesys::IInterpreter {
+        File *interpretFile(File *sourceData) const override;
+    };
+
 protected:
     void readFromSource(Entry const &entry, Path const &path, IBlock &uncompressedData) const;
 

doomsday/sdk/libcore/include/de/filesys/IInterpreter

@@ -0,0 +1 @@
+#include "iinterpreter.h"

doomsday/sdk/libcore/include/de/filesys/filesystem.h

@@ -24,6 +24,7 @@
 #include "../Folder"
 #include "../FileIndex"
 #include "../System"
+#include "IInterpreter"
 
 #include <QFlags>
 #include <functional>
@@ -116,6 +117,20 @@ class DENG2_PUBLIC FileSystem : public System
      */
     FileSystem();
 
+    /**
+     * Registers a new file content interpreter.
+     *
+     * A file interpreter takes a "raw" file (e.g., byte array) and provides
+     * access to the file contents in a high-level manner (e.g., an Image).
+     * Registered interpreters get used automatically when feeds populate
+     * folders with files.
+     *
+     * All registered interpreters are consulted in last-to-first order.
+     *
+     * @param interpreter  Interpreter object. Ownership not taken.
+     */
+    void addInterpreter(filesys::IInterpreter const &interpreter);
+
     void printIndex();
 
     Folder &root();

doomsday/sdk/libcore/include/de/filesys/iinterpreter.h

@@ -0,0 +1,54 @@
+/** @file iinterpreter.h  File interpreter.
+ *
+ * @authors Copyright (c) 2015 Jaakko Keränen <jaakko.keranen@iki.fi>
+ *
+ * @par License
+ * LGPL: http://www.gnu.org/licenses/lgpl.html
+ *
+ * <small>This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 3 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 Lesser
+ * General Public License for more details. You should have received a copy of
+ * the GNU Lesser General Public License along with this program; if not, see:
+ * http://www.gnu.org/licenses</small>
+ */
+
+#ifndef LIBDENG2_FILESYS_IINTERPRETER_H
+#define LIBDENG2_FILESYS_IINTERPRETER_H
+
+namespace de {
+
+class File;
+
+namespace filesys {
+
+/**
+ * File interpreter interface.
+ */
+class IInterpreter
+{
+public:
+    virtual ~IInterpreter() {}
+
+    /**
+     * Attempts to interpret a file.
+     *
+     * @param file  File whose contents are being interpreted. If
+     *              interpretation is possible, ownership of @a file is
+     *              given to the interpreter.
+     *
+     * @return  Interpreter for the file (ownership given to caller), or
+     * NULL if no possible interpretation was recognized (in which case
+     * ownership of @a file is retained by the caller).
+     */
+    virtual File *interpretFile(File *file) const = 0;
+};
+
+} // namespace filesys
+} // namespace de
+
+#endif // LIBDENG2_FILESYS_IINTERPRETER_H
+

doomsday/sdk/libcore/include/de/filesys/libraryfile.h

@@ -14,18 +14,19 @@
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
  * General Public License for more details. You should have received a copy of
  * the GNU Lesser General Public License along with this program; if not, see:
- * http://www.gnu.org/licenses</small> 
+ * http://www.gnu.org/licenses</small>
  */
 
 #ifndef LIBDENG2_LIBRARYFILE_H
 #define LIBDENG2_LIBRARYFILE_H
 
 #include "../File"
+#include "IInterpreter"
 
 namespace de {
 
 class Library;
-    
+
 /**
  * Provides a way to load and unload a shared library. The Library will be
  * loaded automatically when someone attempts to use it. Unloading the
@@ -108,6 +109,10 @@ class DENG2_PUBLIC LibraryFile : public File
      */
     static bool recognize(File const &file);
 
+    struct DENG2_PUBLIC Interpreter : public filesys::IInterpreter {
+        File *interpretFile(File *sourceData) const override;
+    };
+
 private:
     Library *_library;
 };

doomsday/sdk/libcore/src/core/app.cpp

@@ -20,19 +20,20 @@
 #include "de/Animation"
 #include "de/App"
 #include "de/ArchiveFeed"
+#include "de/ArchiveFolder"
 #include "de/ArrayValue"
 #include "de/Block"
 #include "de/DictionaryValue"
 #include "de/DirectoryFeed"
 #include "de/FileLogSink"
-#include "de/PackageFeed"
+#include "de/LibraryFile"
 #include "de/Log"
 #include "de/LogBuffer"
 #include "de/LogFilter"
 #include "de/Module"
 #include "de/NativeFile"
 #include "de/NumberValue"
-#include "de/ArchiveFolder"
+#include "de/PackageFeed"
 #include "de/Record"
 #include "de/ScriptSystem"
 #include "de/Version"
@@ -143,6 +144,12 @@ DENG2_PIMPL(App)
         // Built-in systems.
         systems << &fs << &scriptSys;
 
+        // Built-in file interpreters.
+        static LibraryFile::Interpreter intrpLibraryFile;
+        static ZipArchive::Interpreter  intrpZipArchive;
+        fs.addInterpreter(intrpLibraryFile);
+        fs.addInterpreter(intrpZipArchive);
+
         // Native App module.
         appModule.addArray("audienceForGameChange"); // game change observers
         scriptSys.addNativeModule("App", appModule);

doomsday/sdk/libcore/src/data/ziparchive.cpp

@@ -14,7 +14,7 @@
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
  * General Public License for more details. You should have received a copy of
  * the GNU Lesser General Public License along with this program; if not, see:
- * http://www.gnu.org/licenses</small> 
+ * http://www.gnu.org/licenses</small>
  */
 
 #include "de/ZipArchive"
@@ -30,6 +30,10 @@
 #include "de/Date"
 #include "de/Zeroed"
 
+// Interpretations:
+#include "de/game/SavedSession"
+#include "de/ArchiveFolder"
+
 #include <cstring>
 #include <zlib.h>
 
@@ -632,4 +636,48 @@ void ZipArchive::ZipEntry::update()
     }
 }
 
+File *ZipArchive::Interpreter::interpretFile(File *sourceData) const
+{
+    if(recognize(*sourceData))
+    {
+        try
+        {
+            // It is a ZIP archive: we will represent it as a folder.
+            std::unique_ptr<ArchiveFolder> package;
+
+            if(sourceData->name().fileNameExtension() == ".save")
+            {
+                /// @todo fixme: Don't assume this is a save package.
+                LOG_RES_VERBOSE("Interpreted %s as a SavedSession") << sourceData->description();
+                package.reset(new game::SavedSession(*sourceData, sourceData->name()));
+            }
+            else
+            {
+                LOG_RES_VERBOSE("Interpreted %s as a ZIP format archive") << sourceData->description();
+                package.reset(new ArchiveFolder(*sourceData, sourceData->name()));
+            }
+
+            // Archive opened successfully, give ownership of the source to the folder.
+            package->setSource(sourceData);
+            return package.release();
+        }
+        catch(Archive::FormatError const &)
+        {
+            // Even though it was recognized as an archive, the file
+            // contents may still prove to be corrupted.
+            LOG_RES_WARNING("Archive in %s is invalid") << sourceData->description();
+        }
+        catch(IByteArray::OffsetError const &)
+        {
+            LOG_RES_WARNING("Archive in %s is truncated") << sourceData->description();
+        }
+        catch(IIStream::InputError const &er)
+        {
+            LOG_RES_WARNING("Failed to read %s") << sourceData->description();
+            LOGDEV_RES_WARNING("%s") << er.asText();
+        }
+    }
+    return nullptr;
+}
+
 } // namespace de

doomsday/sdk/libcore/src/filesys/filesystem.cpp

@@ -14,7 +14,7 @@
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
  * General Public License for more details. You should have received a copy of
  * the GNU Lesser General Public License along with this program; if not, see:
- * http://www.gnu.org/licenses</small> 
+ * http://www.gnu.org/licenses</small>
  */
 
 #include "de/FS"
@@ -35,6 +35,8 @@ static FileIndex const emptyIndex; // never contains any files
 
 DENG2_PIMPL_NOREF(FileSystem)
 {
+    QList<filesys::IInterpreter const *> interpreters;
+
     /// The main index to all files in the file system.
     FileIndex index;
 
@@ -58,6 +60,11 @@ DENG2_PIMPL_NOREF(FileSystem)
 FileSystem::FileSystem() : d(new Instance)
 {}
 
+void FileSystem::addInterpreter(filesys::IInterpreter const &interpreter)
+{
+    d->interpreters.prepend(&interpreter);
+}
+
 void FileSystem::refresh()
 {
     LOG_AS("FS::refresh");
@@ -136,62 +143,23 @@ Folder &FileSystem::makeFolderWithFeed(String const &path, Feed *feed,
 
 File *FileSystem::interpret(File *sourceData)
 {
-    LOG_AS("FS::interpret");
-
-    /// @todo  One should be able to define new interpreters dynamically.
+    DENG2_ASSERT(sourceData != nullptr);
 
+    LOG_AS("FS::interpret");
     try
     {
-        if(LibraryFile::recognize(*sourceData))
-        {
-            LOG_RES_VERBOSE("Interpreted ") << sourceData->description() << " as a shared library";
-
-            // It is a shared library intended for Doomsday.
-            return new LibraryFile(sourceData);
-        }
-        if(ZipArchive::recognize(*sourceData))
+        for(filesys::IInterpreter const *i : d->interpreters)
         {
-            try
-            {
-                // It is a ZIP archive: we will represent it as a folder.
-                std::auto_ptr<ArchiveFolder> package;
-
-                if(sourceData->name().fileNameExtension() == ".save")
-                {
-                    /// @todo fixme: Don't assume this is a save package.
-                    LOG_RES_VERBOSE("Interpreted %s as a SavedSession") << sourceData->description();
-                    package.reset(new game::SavedSession(*sourceData, sourceData->name()));
-                }
-                else
-                {
-                    LOG_RES_VERBOSE("Interpreted %s as a ZIP format archive") << sourceData->description();
-                    package.reset(new ArchiveFolder(*sourceData, sourceData->name()));
-                }
-
-                // Archive opened successfully, give ownership of the source to the folder.
-                package->setSource(sourceData);
-                return package.release();
-            }
-            catch(Archive::FormatError const &)
-            {
-                // Even though it was recognized as an archive, the file
-                // contents may still prove to be corrupted.
-                LOG_RES_WARNING("Archive in %s is invalid") << sourceData->description();
-            }
-            catch(IByteArray::OffsetError const &)
-            {
-                LOG_RES_WARNING("Archive in %s is truncated") << sourceData->description();
-            }
-            catch(IIStream::InputError const &er)
+            if(auto *file = i->interpretFile(sourceData))
             {
-                LOG_RES_WARNING("Failed to read %s") << sourceData->description();
-                LOGDEV_RES_WARNING("%s") << er.asText();
+                return file;
             }
         }
     }
-    catch(Error const &err)
+    catch(Error const &er)
     {
-        LOG_RES_ERROR("") << err.asText();
+        LOG_RES_ERROR("Failed to interpret contents of %s: %s")
+                << sourceData->description() << er.asText();
 
         // The error is one we don't know how to handle. We were given
         // responsibility of the source file, so it has to be deleted.