Define an enum for VST3 subcategories

Because looking these up and inputting them by hand every time is both
cumbersome and error prone.

src/wrapper/vst3.rs

@@ -6,6 +6,7 @@ mod factory;
 mod inner;
 mod note_expressions;
 mod param_units;
+pub mod subcategories;
 mod view;
 mod wrapper;
 

src/wrapper/vst3/subcategories.rs

@@ -0,0 +1,88 @@
+//! Subcategories for VST3 plugins. This is essentially the same thing as tags, keyword, or
+//! categories. Hosts may use these to organize plugins.
+
+/// A subcategory for a VST3 plugin. See
+/// <https://github.com/steinbergmedia/vst3_pluginterfaces/blob/bc5ff0f87aaa3cd28c114810f4f03c384421ad2c/vst/ivstaudioprocessor.h#L49-L90>
+/// for a list of all predefined subcategories. Multiple subcategories are concatenated to a string
+/// separated by pipe characters, and the total length of this string may not exceed 127 characters.
+pub enum Vst3SubCategory {
+    // These are the main categories, every plugin should have at least one of these, I think
+    Fx,
+    Instrument,
+    Spatial,
+    // These are optional
+    Analyzer,
+    Delay,
+    Distortion,
+    Drum,
+    Dynamics,
+    Eq,
+    External,
+    Filter,
+    Generator,
+    Mastering,
+    Modulation,
+    Network,
+    Piano,
+    PitchShift,
+    Restoration,
+    Reverb,
+    Sampler,
+    Synth,
+    Tools,
+    UpDownmix,
+    // These are used for plugins that _only_ support this channel configuration, they're also
+    // optional
+    Mono,
+    Stereo,
+    Surround,
+    Ambisonics,
+    // There are also a couple special 'Only*' subcategories that convey special information about
+    // the plugin. The framework is responsible for adding these, and they shouldn't be added
+    // manually.
+    /// A non-predefined subcategory. Hosts may display this among its plugin categories.
+    Custom(&'static str),
+}
+
+impl Vst3SubCategory {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Vst3SubCategory::Fx => "Fx",
+            Vst3SubCategory::Instrument => "Instrument",
+            Vst3SubCategory::Spatial => "Spatial",
+            Vst3SubCategory::Analyzer => "Analyzer",
+            Vst3SubCategory::Delay => "Delay",
+            Vst3SubCategory::Distortion => "Distortion",
+            Vst3SubCategory::Drum => "Drum",
+            Vst3SubCategory::Dynamics => "Dynamics",
+            Vst3SubCategory::Eq => "EQ",
+            Vst3SubCategory::External => "External",
+            Vst3SubCategory::Filter => "Filter",
+            Vst3SubCategory::Generator => "Generator",
+            Vst3SubCategory::Mastering => "Mastering",
+            Vst3SubCategory::Modulation => "Modulation",
+            Vst3SubCategory::Network => "Network",
+            Vst3SubCategory::Piano => "Piano",
+            Vst3SubCategory::PitchShift => "Pitch Shift",
+            Vst3SubCategory::Restoration => "Restoration",
+            Vst3SubCategory::Reverb => "Reverb",
+            Vst3SubCategory::Sampler => "Sampler",
+            Vst3SubCategory::Synth => "Synth",
+            Vst3SubCategory::Tools => "Tools",
+            Vst3SubCategory::UpDownmix => "Up-Downmix",
+            Vst3SubCategory::Mono => "Mono",
+            Vst3SubCategory::Stereo => "Stereo",
+            Vst3SubCategory::Surround => "Surround",
+            Vst3SubCategory::Ambisonics => "Ambisonics",
+            Vst3SubCategory::Custom(s) => {
+                nih_debug_assert!(
+                    !s.contains('|'),
+                    "'{}' contains a pipe character ('|'), which is not allowed",
+                    s
+                );
+
+                s
+            }
+        }
+    }
+}