Replace VST3 category string with enum slice

I've been putting this off for a while, but now is finally the day. We
already did this for CLAP a while back. This is both simpler and less
error prone.

BREAKING_CHANGES.md

@@ -6,6 +6,14 @@ new and what's changed, this document lists all breaking changes in reverse
 chronological order. If a new feature did not require any changes to existing
 code then it will not be listed here.
 
+## [2023-02-01]
+
+- The `Vst3Plugin::VST3_CATEGORIES` string constant has been replaced by a
+  `Vst3Plugin::VST3_SUBCATEGORIES` constant of type `&[Vst3SubCategory]`.
+  `Vst3SubCategory` is an enum containing all of VST3's predefined categories,
+  and it behaves similarly to the `ClapFeature` enum used for CLAP plugins. This
+  makes defining subcategories for VST3 plugins easier and less error prone.
+
 ## [2023-01-31]
 
 - NIH-plug has gained support MIDI SysEx in a simple, type-safe, and

plugins/buffr_glitch/src/lib.rs

@@ -431,6 +431,7 @@ impl ClapPlugin for BuffrGlitch {
     const CLAP_SUPPORT_URL: Option<&'static str> = None;
     const CLAP_FEATURES: &'static [ClapFeature] = &[
         ClapFeature::AudioEffect,
+        ClapFeature::Synthesizer,
         ClapFeature::Stereo,
         ClapFeature::Glitch,
     ];
@@ -438,7 +439,11 @@ impl ClapPlugin for BuffrGlitch {
 
 impl Vst3Plugin for BuffrGlitch {
     const VST3_CLASS_ID: [u8; 16] = *b"BuffrGlitch.RvdH";
-    const VST3_CATEGORIES: &'static str = "Fx";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] = &[
+        Vst3SubCategory::Fx,
+        Vst3SubCategory::Synth,
+        Vst3SubCategory::Custom("Glitch"),
+    ];
 }
 
 nih_export_clap!(BuffrGlitch);

plugins/crisp/src/lib.rs

@@ -507,7 +507,11 @@ impl ClapPlugin for Crisp {
 
 impl Vst3Plugin for Crisp {
     const VST3_CLASS_ID: [u8; 16] = *b"CrispPluginRvdH.";
-    const VST3_CATEGORIES: &'static str = "Fx|Filter|Distortion";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] = &[
+        Vst3SubCategory::Fx,
+        Vst3SubCategory::Filter,
+        Vst3SubCategory::Distortion,
+    ];
 }
 
 nih_export_clap!(Crisp);

plugins/crossover/src/lib.rs

@@ -401,7 +401,8 @@ impl ClapPlugin for Crossover {
 
 impl Vst3Plugin for Crossover {
     const VST3_CLASS_ID: [u8; 16] = *b"CrossoverRvdH...";
-    const VST3_CATEGORIES: &'static str = "Fx|Tools";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(Crossover);

plugins/diopser/src/lib.rs

@@ -355,7 +355,8 @@ impl ClapPlugin for Diopser {
 
 impl Vst3Plugin for Diopser {
     const VST3_CLASS_ID: [u8; 16] = *b"DiopserPlugRvdH.";
-    const VST3_CATEGORIES: &'static str = "Fx|Filter";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Filter];
 }
 
 nih_export_clap!(Diopser);

plugins/examples/gain/src/lib.rs

@@ -195,7 +195,8 @@ impl ClapPlugin for Gain {
 
 impl Vst3Plugin for Gain {
     const VST3_CLASS_ID: [u8; 16] = *b"GainMoistestPlug";
-    const VST3_CATEGORIES: &'static str = "Fx|Dynamics";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(Gain);

plugins/examples/gain_gui_egui/src/lib.rs

@@ -225,7 +225,8 @@ impl ClapPlugin for Gain {
 
 impl Vst3Plugin for Gain {
     const VST3_CLASS_ID: [u8; 16] = *b"GainGuiYeahBoyyy";
-    const VST3_CATEGORIES: &'static str = "Fx|Dynamics";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(Gain);

plugins/examples/gain_gui_iced/src/lib.rs

@@ -167,7 +167,8 @@ impl ClapPlugin for Gain {
 
 impl Vst3Plugin for Gain {
     const VST3_CLASS_ID: [u8; 16] = *b"GainGuiIcedAaAAa";
-    const VST3_CATEGORIES: &'static str = "Fx|Dynamics";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(Gain);

plugins/examples/gain_gui_vizia/src/lib.rs

@@ -166,7 +166,8 @@ impl ClapPlugin for Gain {
 
 impl Vst3Plugin for Gain {
     const VST3_CLASS_ID: [u8; 16] = *b"GainGuiVIIIZIAAA";
-    const VST3_CATEGORIES: &'static str = "Fx|Dynamics";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(Gain);

plugins/examples/midi_inverter/src/lib.rs

@@ -227,7 +227,8 @@ impl ClapPlugin for MidiInverter {
 
 impl Vst3Plugin for MidiInverter {
     const VST3_CLASS_ID: [u8; 16] = *b"M1d1Inv3r70rzAaA";
-    const VST3_CATEGORIES: &'static str = "Instrument|Tools";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Instrument, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(MidiInverter);

plugins/examples/poly_mod_synth/src/lib.rs

@@ -612,7 +612,8 @@ impl ClapPlugin for PolyModSynth {
 // modulation
 impl Vst3Plugin for PolyModSynth {
     const VST3_CLASS_ID: [u8; 16] = *b"PolyM0dSynth1337";
-    const VST3_CATEGORIES: &'static str = "Instrument|Synth";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Instrument, Vst3SubCategory::Synth];
 }
 
 nih_export_clap!(PolyModSynth);

plugins/examples/sine/src/lib.rs

@@ -213,7 +213,11 @@ impl ClapPlugin for Sine {
 
 impl Vst3Plugin for Sine {
     const VST3_CLASS_ID: [u8; 16] = *b"SineMoistestPlug";
-    const VST3_CATEGORIES: &'static str = "Instrument|Synth|Tools";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] = &[
+        Vst3SubCategory::Instrument,
+        Vst3SubCategory::Synth,
+        Vst3SubCategory::Tools,
+    ];
 }
 
 nih_export_clap!(Sine);

plugins/examples/stft/src/lib.rs

@@ -179,7 +179,8 @@ impl ClapPlugin for Stft {
 
 impl Vst3Plugin for Stft {
     const VST3_CLASS_ID: [u8; 16] = *b"StftMoistestPlug";
-    const VST3_CATEGORIES: &'static str = "Fx|Tools";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(Stft);

plugins/examples/sysex/src/lib.rs

@@ -102,7 +102,11 @@ impl ClapPlugin for SysEx {
 
 impl Vst3Plugin for SysEx {
     const VST3_CLASS_ID: [u8; 16] = *b"SysExCoolPluginn";
-    const VST3_CATEGORIES: &'static str = "Fx|Instrument|Tools";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] = &[
+        Vst3SubCategory::Fx,
+        Vst3SubCategory::Instrument,
+        Vst3SubCategory::Tools,
+    ];
 }
 
 nih_export_clap!(SysEx);

plugins/loudness_war_winner/src/lib.rs

@@ -261,7 +261,12 @@ impl ClapPlugin for LoudnessWarWinner {
 
 impl Vst3Plugin for LoudnessWarWinner {
     const VST3_CLASS_ID: [u8; 16] = *b"LoudnessWar.RvdH";
-    const VST3_CATEGORIES: &'static str = "Fx|Dynamics|Distortion";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] = &[
+        Vst3SubCategory::Fx,
+        Vst3SubCategory::Dynamics,
+        Vst3SubCategory::Distortion,
+        Vst3SubCategory::Custom("Pain"),
+    ];
 }
 
 nih_export_clap!(LoudnessWarWinner);

plugins/puberty_simulator/src/lib.rs

@@ -431,7 +431,8 @@ impl ClapPlugin for PubertySimulator {
 
 impl Vst3Plugin for PubertySimulator {
     const VST3_CLASS_ID: [u8; 16] = *b"PubertySim..RvdH";
-    const VST3_CATEGORIES: &'static str = "Fx|Pitch Shift";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::PitchShift];
 }
 
 nih_export_clap!(PubertySimulator);

plugins/safety_limiter/src/lib.rs

@@ -340,7 +340,8 @@ impl ClapPlugin for SafetyLimiter {
 
 impl Vst3Plugin for SafetyLimiter {
     const VST3_CLASS_ID: [u8; 16] = *b"SafetyLimtrRvdH.";
-    const VST3_CATEGORIES: &'static str = "Fx|Tools";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
+        &[Vst3SubCategory::Fx, Vst3SubCategory::Tools];
 }
 
 nih_export_clap!(SafetyLimiter);

plugins/spectral_compressor/src/lib.rs

@@ -581,7 +581,11 @@ impl ClapPlugin for SpectralCompressor {
 
 impl Vst3Plugin for SpectralCompressor {
     const VST3_CLASS_ID: [u8; 16] = *b"SpectrlComprRvdH";
-    const VST3_CATEGORIES: &'static str = "Fx|Dynamics|Spectral";
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] = &[
+        Vst3SubCategory::Fx,
+        Vst3SubCategory::Dynamics,
+        Vst3SubCategory::Custom("Spectral"),
+    ];
 }
 
 nih_export_clap!(SpectralCompressor);

src/plugin.rs

@@ -12,6 +12,7 @@ use crate::midi::MidiConfig;
 use crate::params::Params;
 use crate::wrapper::clap::features::ClapFeature;
 use crate::wrapper::state::PluginState;
+pub use crate::wrapper::vst3::subcategories::Vst3SubCategory;
 
 /// A function that can execute a plugin's [`BackgroundTask`][Plugin::BackgroundTask]s. A plugin can
 /// dispatch these tasks from the `initialize()` function, the `process()` function, or the GUI, so
@@ -249,12 +250,11 @@ pub trait Vst3Plugin: Plugin {
     ///
     /// This will be shuffled into a different byte order on Windows for project-compatibility.
     const VST3_CLASS_ID: [u8; 16];
-    /// One or more categories, separated by pipe characters (`|`), up to 127 characters. Anything
-    /// longer than that will be truncated. See the VST3 SDK for examples of common categories:
-    /// <https://github.com/steinbergmedia/vst3_pluginterfaces/blob/2ad397ade5b51007860bedb3b01b8afd2c5f6fba/vst/ivstaudioprocessor.h#L49-L90>
-    //
-    // TODO: Create a category enum similar to ClapFeature
-    const VST3_CATEGORIES: &'static str;
+    /// One or more subcategories. The host may use these to categorize the plugin. Internally this
+    /// slice will be converted to a string where each character is separated by a pipe character
+    /// (`|`). This string has a limit of 127 characters, and anything longer than that will be
+    /// truncated.
+    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory];
 
     /// [`VST3_CLASS_ID`][Self::VST3_CLASS_ID`] in the correct order for the current platform so
     /// projects and presets can be shared between platforms. This should not be overridden.

src/prelude.rs

@@ -30,3 +30,4 @@ pub use crate::plugin::{
 };
 pub use crate::wrapper::clap::features::ClapFeature;
 pub use crate::wrapper::state::PluginState;
+pub use crate::wrapper::vst3::subcategories::Vst3SubCategory;

src/wrapper/clap/features.rs

@@ -4,6 +4,7 @@
 /// A keyword for a CLAP plugin. See
 /// <https://github.com/free-audio/clap/blob/main/include/clap/plugin-features.h> for more
 /// information.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum ClapFeature {
     // These are the main categories, every plugin should have at least one of these
     Instrument,

src/wrapper/vst3/factory.rs

@@ -8,6 +8,7 @@ use vst3_sys::VST3;
 // Alias needed for the VST3 attribute macro
 use vst3_sys as vst3_com;
 
+use super::subcategories::Vst3SubCategory;
 use super::util::u16strlcpy;
 use super::wrapper::Wrapper;
 use crate::plugin::Vst3Plugin;
@@ -102,20 +103,7 @@ impl<P: Vst3Plugin> IPluginFactory2 for Factory<P> {
         strlcpy(&mut info.category, "Audio Module Class");
         strlcpy(&mut info.name, P::NAME);
         info.class_flags = 1 << 1; // kSimpleModeSupported
-
-        // No idea if any hosts do something with this, but it's part of VST3's example categories
-        // list
-        if P::HARD_REALTIME_ONLY {
-            nih_debug_assert!(!P::VST3_CATEGORIES.ends_with('|'));
-            nih_debug_assert!(!P::VST3_CATEGORIES.contains("OnlyRT"));
-            strlcpy(
-                &mut info.subcategories,
-                &format!("{}|OnlyRT", P::VST3_CATEGORIES),
-            );
-        } else {
-            strlcpy(&mut info.subcategories, P::VST3_CATEGORIES);
-        };
-
+        strlcpy(&mut info.subcategories, &make_subcategories_string::<P>());
         strlcpy(&mut info.vendor, P::VENDOR);
         strlcpy(&mut info.version, P::VERSION);
         strlcpy(&mut info.sdk_version, VST3_SDK_VERSION);
@@ -142,7 +130,7 @@ impl<P: Vst3Plugin> IPluginFactory3 for Factory<P> {
         strlcpy(&mut info.category, "Audio Module Class");
         u16strlcpy(&mut info.name, P::NAME);
         info.class_flags = 1 << 1; // kSimpleModeSupported
-        strlcpy(&mut info.subcategories, P::VST3_CATEGORIES);
+        strlcpy(&mut info.subcategories, &make_subcategories_string::<P>());
         u16strlcpy(&mut info.vendor, P::VENDOR);
         u16strlcpy(&mut info.version, P::VERSION);
         u16strlcpy(&mut info.sdk_version, VST3_SDK_VERSION);
@@ -155,3 +143,20 @@ impl<P: Vst3Plugin> IPluginFactory3 for Factory<P> {
         kResultOk
     }
 }
+
+fn make_subcategories_string<P: Vst3Plugin>() -> String {
+    // No idea if any hosts do something with OnlyRT, but it's part of VST3's example categories
+    // list. Plugins should not be adding this feature manually
+    nih_debug_assert!(!P::VST3_SUBCATEGORIES.contains(&Vst3SubCategory::Custom("OnlyRT")));
+    let category_string = P::VST3_SUBCATEGORIES
+        .iter()
+        .map(Vst3SubCategory::as_str)
+        .collect::<Vec<&str>>()
+        .join("|");
+
+    if P::HARD_REALTIME_ONLY {
+        format!("{category_string}|OnlyRT")
+    } else {
+        category_string
+    }
+}

src/wrapper/vst3/subcategories.rs

@@ -5,6 +5,7 @@
 /// <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.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Vst3SubCategory {
     // These are the main categories, every plugin should have at least one of these, I think
     Fx,