Move the configuration object to src/common/

src/common/configuration.h

@@ -0,0 +1,89 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020  Robbert van der Helm
+//
+// 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 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#ifdef __WINE__
+#include "../wine-host/boost-fix.h"
+#endif
+#include <boost/filesystem.hpp>
+
+#include <optional>
+
+/**
+ * An object that's used to provide plugin-specific configuration. Right now
+ * this is only used to declare plugin groups. A plugin group is a set of
+ * plugins that will be hosted in the same process rather than individually so
+ * they can share resources. Configuration file loading works as follows:
+ *
+ * 1. `load_config_for(path)` from `src/plugin/utils.h` gets called with a path
+ *    to the copy of or symlink to `libyabridge.so` that the plugin host has
+ *    tried to load.
+ * 2. We start looking for a file named `yabridge.toml` in the same directory as
+ *    that `.so` file, iteratively continuing to search one directory higher
+ *    until we either find the file or we reach the filesystem root.
+ * 3. If the file is found, then parse it as a TOML file and look for the first
+ *    table whose key is a glob pattern that (partially) matches the relative
+ *    path between the found `yabridge.toml` and the `.so` file. As a rule of
+ *    thumb, if the `find <pattern> -type f` command executed in Bash would list
+ *    the `.so` file, then the following table in `yabridge.tmol` would also
+ *    match the same `.so` file:
+ *
+ *    ```toml
+ *    ["<patern>"]
+ *    group = "..."
+ *    ```
+ * 4. If one of these glob patterns could be matched with the relative path of
+ *    the `.so` file then we'll use the settings specified in that section.
+ *    Otherwise the default settings will be used.
+ */
+class Configuration {
+   public:
+    /**
+     * Create an empty configuration object with default settings.
+     */
+    Configuration();
+
+    /**
+     * Load the configuration for an instance of yabridge from a configuration
+     * file by matching the plugin's relative path to the glob patterns in that
+     * configuration file. Will leave the object empty if the plugin cannot be
+     * matched to any of the patterns. Not meant to be used directly.
+     *
+     * @throw toml::parsing_error If the file could not be parsed.
+     *
+     * @see ../plugin/utils.h:load_config_for
+     */
+    Configuration(const boost::filesystem::path& config_path,
+                  const boost::filesystem::path& yabridge_path);
+
+    /**
+     * The name of the plugin group that should be used for the plugin this
+     * configuration object was created for. If not set, then the plugin should
+     * be hosted individually instead.
+     */
+    std::optional<std::string> group;
+
+    /**
+     * The path to the configuration file that was parsed.
+     */
+    std::optional<boost::filesystem::path> matched_file;
+
+    /**
+     * The matched glob pattern in the above configuration file.
+     */
+    std::optional<std::string> matched_pattern;
+};