Add import utilities for foreign instruments

plugins/CMakeLists.txt

@@ -1,10 +1,15 @@
 add_library(plugins-common STATIC EXCLUDE_FROM_ALL
     "common/plugin/MessageUtils.h"
-    "common/plugin/MessageUtils.cpp")
+    "common/plugin/MessageUtils.cpp"
+    "common/plugin/ForeignInstrument.h"
+    "common/plugin/ForeignInstrument.cpp"
+    "common/plugin/foreign_instruments/AudioFile.h"
+    "common/plugin/foreign_instruments/AudioFile.cpp")
 target_include_directories(plugins-common PUBLIC "common")
 target_link_libraries(plugins-common
     PUBLIC sfizz::spin_mutex
-    PUBLIC absl::strings)
+    PUBLIC sfizz::filesystem absl::strings
+    PRIVATE sfizz::pugixml absl::memory)
 add_library(sfizz::plugins-common ALIAS plugins-common)
 
 if((SFIZZ_LV2 AND SFIZZ_LV2_UI) OR SFIZZ_VST)

plugins/common/plugin/ForeignInstrument.cpp

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#include "ForeignInstrument.h"
+#include "foreign_instruments/AudioFile.h"
+
+namespace sfz {
+
+InstrumentFormatRegistry::InstrumentFormatRegistry()
+    : formats_ {
+            &AudioFileInstrumentFormat::getInstance(),
+      }
+{
+}
+
+InstrumentFormatRegistry& InstrumentFormatRegistry::getInstance()
+{
+    static InstrumentFormatRegistry registry;
+    return registry;
+}
+
+const InstrumentFormat* InstrumentFormatRegistry::getMatchingFormat(const fs::path& path) const
+{
+    const InstrumentFormat* resultFormat = nullptr;
+
+    for (const InstrumentFormat* currentFormat : formats_) {
+        if (currentFormat->matchesFilePath(path)) {
+            resultFormat = currentFormat;
+            break;
+        }
+    }
+
+    return resultFormat;
+}
+
+} // namespace sfz

plugins/common/plugin/ForeignInstrument.h

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#pragma once
+#include <ghc/fs_std.hpp>
+#include <string>
+#include <vector>
+#include <memory>
+
+namespace sfz {
+
+class InstrumentFormat;
+class InstrumentImporter;
+
+/**
+ * Registry of known non-SFZ instrument formats
+ */
+class InstrumentFormatRegistry {
+private:
+    InstrumentFormatRegistry();
+
+public:
+    /**
+     * @brief Get the single instance of the registry
+     */
+    static InstrumentFormatRegistry& getInstance();
+
+    /**
+     * @brief Get a format which is able to handle a file which goes by the
+     * given path name, or null otherwise.
+     */
+    const InstrumentFormat* getMatchingFormat(const fs::path& path) const;
+
+private:
+    std::vector<const InstrumentFormat*> formats_;
+};
+
+/**
+ * Description of a non-SFZ instrument format
+ */
+class InstrumentFormat {
+public:
+    virtual ~InstrumentFormat() {}
+
+    /**
+     * @brief Get the name of the instrument format
+     */
+    virtual const char* name() const noexcept = 0;
+
+    /**
+     * @brief Checks whether this importer matches files of the given path
+     *
+     * This should check for a pattern like such as a file extension, but not
+     * examine the contents of the file itself.
+     */
+    virtual bool matchesFilePath(const fs::path& path) const = 0;
+
+    /**
+     * @brief Create a new importer for instrument files of this format
+     */
+    virtual std::unique_ptr<InstrumentImporter> createImporter() const = 0;
+};
+
+/**
+ * Importer of non-SFZ instruments
+ */
+class InstrumentImporter {
+public:
+    /**
+     * @brief Get the format that this importer converts from
+     */
+    virtual const InstrumentFormat* getFormat() const noexcept = 0;
+
+    /**
+     * @brief Process the file and convert to an equivalent SFZ string
+     */
+    virtual std::string convertToSfz(const fs::path& path) const = 0;
+};
+
+} // namespace sfz

plugins/common/plugin/foreign_instruments/AudioFile.cpp

@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#include "AudioFile.h"
+#include <absl/strings/match.h>
+#include <absl/strings/string_view.h>
+#include <absl/memory/memory.h>
+#include <locale>
+#include <sstream>
+
+namespace sfz {
+
+static const char* kRecognizedAudioExtensions[] = {
+    ".wav", ".flac", ".ogg", ".mp3", ".aif", ".aiff", ".aifc",
+};
+
+///
+AudioFileInstrumentFormat& AudioFileInstrumentFormat::getInstance()
+{
+    static AudioFileInstrumentFormat format;
+    return format;
+}
+
+const char* AudioFileInstrumentFormat::name() const noexcept
+{
+    return "Audio file";
+}
+
+bool AudioFileInstrumentFormat::matchesFilePath(const fs::path& path) const
+{
+    const std::string ext = path.extension().u8string();
+
+    for (absl::string_view knownExt : kRecognizedAudioExtensions) {
+        if (absl::EqualsIgnoreCase(ext, knownExt))
+            return true;
+    }
+
+    return false;
+}
+
+std::unique_ptr<InstrumentImporter> AudioFileInstrumentFormat::createImporter() const
+{
+    return absl::make_unique<AudioFileInstrumentImporter>();
+}
+
+///
+std::string AudioFileInstrumentImporter::convertToSfz(const fs::path& path) const
+{
+    std::ostringstream os;
+    os.imbue(std::locale::classic());
+    os << "<region>sample=" << path.filename().u8string();
+    return os.str();
+}
+
+const InstrumentFormat* AudioFileInstrumentImporter::getFormat() const noexcept
+{
+    return &AudioFileInstrumentFormat::getInstance();
+}
+
+} // namespace sfz

plugins/common/plugin/foreign_instruments/AudioFile.h

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#pragma once
+#include "../ForeignInstrument.h"
+
+namespace sfz {
+
+class AudioFileInstrumentFormat : public InstrumentFormat {
+private:
+    AudioFileInstrumentFormat() noexcept = default;
+
+public:
+    static AudioFileInstrumentFormat& getInstance();
+    const char* name() const noexcept override;
+    bool matchesFilePath(const fs::path& path) const override;
+    std::unique_ptr<InstrumentImporter> createImporter() const override;
+};
+
+///
+class AudioFileInstrumentImporter : public InstrumentImporter {
+public:
+    std::string convertToSfz(const fs::path& path) const override;
+    const InstrumentFormat* getFormat() const noexcept override;
+};
+
+} // namespace sfz