remove the main sg hashmap for labels

scopegraphs-macros/src/label.rs

@@ -28,21 +28,41 @@ pub fn impl_label(input: DeriveInput) -> TokenStream {
     }
 
     let mut variant_names = Vec::new();
+    let mut variant_numbers = Vec::new();
 
-    for variant in variants {
+    for (num, variant) in variants.into_iter().enumerate() {
         if !variant.fields.is_empty() {
             return quote_spanned!(
                 variant.span() => compile_error!("cannot derive Label for an enum with fields on variants");
             )
             .into();
         }
 
+        if variant.discriminant.is_some() {
+            return quote_spanned!(
+                variant.span() => compile_error!("cannot derive Label for an enum with custom discriminated variants. Use `Label::to_usize()`");
+            )
+                .into();
+        }
+
         variant_names.push(variant.ident);
+        variant_numbers.push(num);
     }
+    let num_variants = variant_numbers.len();
 
     let name = input.ident;
     quote! {
-        impl scopegraphs::Label for #name {
+        unsafe impl scopegraphs::Label for #name {
+            type Array<T> = [T; #num_variants];
+
+            fn to_usize(&self) -> usize {
+                match *self {
+                    #(
+                        Self::#variant_names => #variant_numbers
+                    ),*
+                }
+            }
+
             fn iter() -> impl Iterator<Item = Self> {
                 [
                     #(

scopegraphs/src/completeness/critical_edge.rs

@@ -1,5 +1,5 @@
 use crate::completeness::Completeness;
-use crate::{Scope, ScopeGraph};
+use crate::{Label, Scope, ScopeGraph};
 use std::cell::RefCell;
 use std::{collections::HashSet, hash::Hash};
 
@@ -38,7 +38,7 @@ impl<LABEL: Hash + Eq> CriticalEdgeSet<LABEL> {
 /// Provides utility function to create scopes with particular open edges.
 ///
 /// Should not be called externally, but only from utility function on [`crate::ScopeGraph`].
-pub trait CriticalEdgeBasedCompleteness<LABEL, DATA>: Completeness<LABEL, DATA> {
+pub trait CriticalEdgeBasedCompleteness<LABEL: Label, DATA>: Completeness<LABEL, DATA> {
     /// Initializes a new scope with a certain set of edges that are still considered "open".
     fn init_scope_with(&self, open_edges: HashSet<LABEL>);
 }
@@ -68,7 +68,7 @@ pub struct Delay<LABEL> {
 /// Convenience alias for the type of `Result` returned from queries using [critical edge based completion](CriticalEdgeBasedCompleteness)
 pub type EdgesOrDelay<EDGES, LABEL> = Result<EDGES, Delay<LABEL>>;
 
-impl<'sg, LABEL: Hash + Eq, DATA, CMPL> ScopeGraph<'sg, LABEL, DATA, CMPL>
+impl<'sg, LABEL: Hash + Eq + Label, DATA, CMPL> ScopeGraph<'sg, LABEL, DATA, CMPL>
 where
     CMPL: CriticalEdgeBasedCompleteness<LABEL, DATA>,
 {
@@ -91,7 +91,7 @@ where
     }
 }
 
-impl<'sg, LABEL: Hash + Eq, DATA, CMPL> ScopeGraph<'sg, LABEL, DATA, CMPL>
+impl<'sg, LABEL: Hash + Eq + Label, DATA, CMPL> ScopeGraph<'sg, LABEL, DATA, CMPL>
 where
     DATA: Default,
     CMPL: CriticalEdgeBasedCompleteness<LABEL, DATA>,

scopegraphs/src/completeness/explicit.rs

@@ -19,19 +19,19 @@ use std::{collections::HashSet, hash::Hash};
 /// Returns [`Delay`] when edges are retrieved (e.g. during query resolution) for an edge that is
 /// not yet closed.
 #[derive(Debug)]
-pub struct ExplicitClose<LABEL> {
+pub struct ExplicitClose<LABEL: Label> {
     critical_edges: CriticalEdgeSet<LABEL>,
 }
 
-impl<LABEL> Default for ExplicitClose<LABEL> {
+impl<LABEL: Label> Default for ExplicitClose<LABEL> {
     fn default() -> Self {
         ExplicitClose {
             critical_edges: CriticalEdgeSet::default(),
         }
     }
 }
 
-impl<LABEL> Sealed for ExplicitClose<LABEL> {}
+impl<LABEL: Label> Sealed for ExplicitClose<LABEL> {}
 
 impl<LABEL: Hash + Eq + Label, DATA> Completeness<LABEL, DATA> for ExplicitClose<LABEL> {
     fn cmpl_new_scope(&self, _: &InnerScopeGraph<LABEL, DATA>, _: Scope) {
@@ -101,15 +101,15 @@ impl<LABEL: Hash + Eq + Label, DATA> CriticalEdgeBasedCompleteness<LABEL, DATA>
     }
 }
 
-impl<LABEL: Hash + Eq> ExplicitClose<LABEL> {
+impl<LABEL: Label + Hash> ExplicitClose<LABEL> {
     /// Close a scope for a certain label
     /// // TODO: link to "closing" in concepts
     pub fn close(&self, scope: Scope, label: &LABEL) {
         self.critical_edges.close(scope, label);
     }
 }
 
-impl<'sg, LABEL: Hash + Eq, DATA> ScopeGraph<'sg, LABEL, DATA, ExplicitClose<LABEL>> {
+impl<'sg, LABEL: Label + Hash, DATA> ScopeGraph<'sg, LABEL, DATA, ExplicitClose<LABEL>> {
     // TODO: fix this sentence
     /// Closes an edge, (i.e., prohibit future new
     ///
@@ -120,7 +120,7 @@ impl<'sg, LABEL: Hash + Eq, DATA> ScopeGraph<'sg, LABEL, DATA, ExplicitClose<LAB
     /// # use scopegraphs::Storage;
     /// # use scopegraphs::ScopeGraph;
     ///
-    /// # #[derive(Eq, Hash, PartialEq, Label)] enum Lbl { Def }
+    /// # #[derive(Eq, Hash, PartialEq, Label, Copy, Clone)] enum Lbl { Def }
     /// # use Lbl::*;
     /// let storage = Storage::new();
     /// let mut sg = ScopeGraph::<Lbl, usize, _>::new(&storage, ExplicitClose::default());
@@ -199,7 +199,7 @@ impl<'sg, LABEL: Hash + Eq, DATA> ScopeGraph<'sg, LABEL, DATA, ExplicitClose<LAB
     }
 }
 
-impl<'sg, LABEL: Hash + Eq + Copy, DATA> ScopeGraph<'sg, LABEL, DATA, FutureCompleteness<LABEL>> {
+impl<'sg, LABEL: Label + Hash, DATA> ScopeGraph<'sg, LABEL, DATA, FutureCompleteness<LABEL>> {
     // TODO: update this example to use futures
     // TODO: fix this sentence
     /// Closes an edge, (i.e., prohibit future new
@@ -210,7 +210,7 @@ impl<'sg, LABEL: Hash + Eq + Copy, DATA> ScopeGraph<'sg, LABEL, DATA, FutureComp
     /// # use scopegraphs::ScopeGraph;
     /// # use scopegraphs_macros::Label;
     /// # use scopegraphs::Storage;
-    /// # #[derive(Eq, Hash, PartialEq, Label)] enum Lbl { Def }
+    /// # #[derive(Eq, Hash, PartialEq, Label, Copy, Clone)] enum Lbl { Def }
     /// # use Lbl::*;
     /// let storage = Storage::new();
     /// let mut sg = ScopeGraph::<Lbl, usize, _>::new(&storage, ExplicitClose::default());

scopegraphs/src/completeness/future.rs

@@ -20,12 +20,12 @@ use std::task::{Poll, Waker};
 ///
 /// Extends, and contains an instance of, [`ExplicitClose`].
 #[derive(Debug)]
-pub struct FutureCompleteness<LABEL> {
+pub struct FutureCompleteness<LABEL: Label> {
     explicit_close: ExplicitClose<LABEL>,
     wakers: RefCell<HashMap<Delay<LABEL>, Vec<Waker>>>,
 }
 
-impl<LABEL> Default for FutureCompleteness<LABEL> {
+impl<LABEL: Label> Default for FutureCompleteness<LABEL> {
     fn default() -> Self {
         Self {
             explicit_close: ExplicitClose::<LABEL>::default(),
@@ -34,7 +34,7 @@ impl<LABEL> Default for FutureCompleteness<LABEL> {
     }
 }
 
-impl<LABEL> Sealed for FutureCompleteness<LABEL> {}
+impl<LABEL: Label> Sealed for FutureCompleteness<LABEL> {}
 
 impl<LABEL: Hash + Eq + Label + Copy, DATA> Completeness<LABEL, DATA>
     for FutureCompleteness<LABEL>
@@ -94,7 +94,7 @@ impl<LABEL: Hash + Eq + Label + Copy, DATA> Completeness<LABEL, DATA>
     }
 }
 
-impl<LABEL: Hash + Eq + Copy> FutureCompleteness<LABEL> {
+impl<LABEL: Label + Hash> FutureCompleteness<LABEL> {
     pub(crate) fn close(&self, scope: Scope, label: &LABEL) {
         self.explicit_close.close(scope, label);
         for waker in self

scopegraphs/src/completeness/mod.rs

@@ -34,6 +34,7 @@ mod private {
 }
 
 use crate::scopegraph::{InnerScopeGraph, Scope};
+use crate::Label;
 use private::Sealed;
 
 /*** Completeness trait ***/
@@ -61,7 +62,7 @@ use private::Sealed;
 /// You cannot define your own completeness strategies to ensure that only verified implementations are available.
 // TODO: @Aron could you document this?
 #[allow(missing_docs)]
-pub trait Completeness<LABEL, DATA>: Sealed {
+pub trait Completeness<LABEL: Label, DATA>: Sealed {
     fn cmpl_new_scope(&self, inner_scope_graph: &InnerScopeGraph<LABEL, DATA>, scope: Scope);
 
     /// Should initialize a scope without possibility to extend it with edges

scopegraphs/src/completeness/unchecked.rs

@@ -1,7 +1,7 @@
 use crate::completeness::private::Sealed;
 use crate::completeness::Completeness;
 use crate::scopegraph::{InnerScopeGraph, Scope};
-use std::hash::Hash;
+use crate::Label;
 
 /// No-Op implementation of [`Completeness`].
 #[derive(Debug)]
@@ -23,7 +23,7 @@ impl UncheckedCompleteness {
     }
 }
 
-impl<LABEL: Hash + Eq, DATA> Completeness<LABEL, DATA> for UncheckedCompleteness {
+impl<LABEL: Label, DATA> Completeness<LABEL, DATA> for UncheckedCompleteness {
     fn cmpl_new_scope(&self, _: &InnerScopeGraph<LABEL, DATA>, _: Scope) {}
 
     fn cmpl_new_complete_scope(

scopegraphs/src/label.rs

@@ -1,7 +1,54 @@
+use std::array;
+
+pub(crate) trait ArrayInit<T> {
+    fn init_from_fn(init: impl FnMut() -> T) -> Self;
+}
+
+impl<T, const N: usize> ArrayInit<T> for [T; N] {
+    fn init_from_fn(mut init: impl FnMut() -> T) -> Self {
+        array::from_fn(|_| init())
+    }
+}
+
+unsafe impl Label for () {
+    type Array<T> = [T; 1];
+
+    fn to_usize(&self) -> usize {
+        0
+    }
+
+    fn iter() -> impl Iterator<Item = Self>
+    where
+        Self: Sized,
+    {
+        [()].into_iter()
+    }
+
+    fn iter_ref() -> impl Iterator<Item = &'static Self>
+    where
+        Self: Sized + 'static,
+    {
+        [&()].into_iter()
+    }
+}
+
 /// Represents types that can be used as labels on [`scopegraph edges`](crate::concepts::edges).
 ///
-/// Can be derived.
-pub trait Label {
+/// Can, and should, be derived using the [`Label`](scopegraphs_macros::Label) derive macro.
+///
+/// # Safety
+///
+/// This trait is unsafe to implement by yourself, as code in this library depends on the fact
+/// that [`to_usize`](Label::to_usize) returns a list of consecutive indices from 0 to [`NUM_LABELS`](Label::NUM_LABELS) - 1
+pub unsafe trait Label: Eq + Copy {
+    /// The type of an array of these labels, with one slot for each label type.
+    /// NOTE: using an associated const doesn't work without full const generics
+    #[allow(private_bounds)]
+    type Array<T>: AsRef<[T]> + AsMut<[T]> + ArrayInit<T>;
+
+    /// Convert any label to a unique usize, which m
+    fn to_usize(&self) -> usize;
+
     /// Iterate over all possible labels that this label type could be.
     fn iter() -> impl Iterator<Item = Self>
     where

scopegraphs/src/lib.rs

@@ -46,7 +46,7 @@ pub use storage::Storage;
 /// use scopegraphs::*;
 /// use scopegraphs::Label;
 ///
-/// #[derive(Label, Debug, PartialEq, Eq)]
+/// #[derive(Label, Debug, PartialEq, Eq, Copy, Clone)]
 /// pub enum Alphabet {
 ///     A,
 ///     B,

scopegraphs/src/render/mod.rs

@@ -3,7 +3,7 @@
 //! Generally, use `sg.render_to(filename, Settings::default()` for the most basic rendering.
 
 use crate::completeness::Completeness;
-use crate::{Scope, ScopeGraph};
+use crate::{Label, Scope, ScopeGraph};
 use std::fs::File;
 use std::io;
 use std::io::Write;
@@ -75,7 +75,7 @@ pub struct EdgeTo {
 }
 
 /// Modifies how an edge label is rendered.
-pub trait RenderScopeLabel {
+pub trait RenderScopeLabel: Label {
     /// Render a single label
     fn render(&self) -> String;
 }
@@ -128,7 +128,7 @@ fn escape_text_mermaid(inp: &str) -> String {
 }
 
 impl<
-        LABEL: Clone + RenderScopeLabel,
+        LABEL: Clone + RenderScopeLabel + Label,
         DATA: RenderScopeData + Clone,
         CMPL: Completeness<LABEL, DATA>,
     > ScopeGraph<'_, LABEL, DATA, CMPL>

scopegraphs/src/render/traverse.rs

@@ -14,8 +14,10 @@ pub fn traverse<'sg, LABEL: RenderScopeLabel, DATA, CMPL: Completeness<LABEL, DA
         .flat_map(|(scope, edges)| {
             (*edges)
                 .borrow()
+                .as_ref()
                 .iter()
-                .flat_map(|(lbl, edges_with_lbl)| {
+                .zip(LABEL::iter())
+                .flat_map(|(edges_with_lbl, lbl)| {
                     edges_with_lbl
                         .iter()
                         .map(|edge| Edge {

scopegraphs/src/resolve/lookup.rs

@@ -89,7 +89,7 @@ where
     }
 }
 
-struct ResolutionContext<'storage, 'sg: 'rslv, 'rslv, LABEL, DATA, CMPL, DWF, LO, DEq> {
+struct ResolutionContext<'storage, 'sg: 'rslv, 'rslv, LABEL: Label, DATA, CMPL, DWF, LO, DEq> {
     all_edges: Vec<EdgeOrData<LABEL>>,
     sg: &'sg ScopeGraph<'storage, LABEL, DATA, CMPL>,
     data_wellformedness: &'rslv DWF,
@@ -106,7 +106,7 @@ type EnvCache<LABEL, ENVC> = RefCell<HashMap<EdgeOrData<LABEL>, Rc<ENVC>>>;
 impl<'storage, 'sg: 'rslv, 'rslv, LABEL, DATA, CMPL, DWF, LO, DEq>
     ResolutionContext<'storage, 'sg, 'rslv, LABEL, DATA, CMPL, DWF, LO, DEq>
 where
-    LABEL: Copy + Debug + Hash + Eq,
+    LABEL: Label + Debug + Hash,
     DATA: Debug,
     ResolvedPath<'sg, LABEL, DATA>: Hash + Eq,
     CMPL: Completeness<LABEL, DATA>,

scopegraphs/src/resolve/mod.rs

@@ -8,7 +8,7 @@ use std::marker::PhantomData;
 use std::rc::Rc;
 
 mod params;
-use crate::{Scope, ScopeGraph};
+use crate::{Label, Scope, ScopeGraph};
 pub use params::*;
 use scopegraphs_regular_expressions::RegexMatcher;
 
@@ -412,7 +412,7 @@ pub trait Resolve<'sg, 'rslv> {
 }
 
 /// A query over a scope graph. Read more [here](crate::concepts)
-pub struct Query<'storage, 'sg, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq> {
+pub struct Query<'storage, 'sg, 'rslv, LABEL: Label, DATA, CMPL, PWF, DWF, LO, DEq> {
     _phantom: PhantomData<&'rslv ()>,
     scope_graph: &'sg ScopeGraph<'storage, LABEL, DATA, CMPL>,
     path_wellformedness: PWF,
@@ -421,7 +421,7 @@ pub struct Query<'storage, 'sg, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq> {
     data_equivalence: DEq,
 }
 
-impl<'sg, 'storage, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq>
+impl<'sg, 'storage, 'rslv, LABEL: Label, DATA, CMPL, PWF, DWF, LO, DEq>
     Query<'sg, 'storage, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq>
 {
     /// Add a [path well-formedness](crate::concepts::path_wellformedness) to this query.
@@ -436,7 +436,7 @@ impl<'sg, 'storage, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq>
     /// # let storage = Storage::new();
     /// # let scopegraph = ScopeGraph::<Lbl, (), _>::new(&storage, unsafe{UncheckedCompleteness::new()});
     ///
-    /// #[derive(Label)]
+    /// #[derive(Label, Eq, PartialEq, Copy, Clone)]
     /// pub enum Lbl {
     ///     Lexical,
     ///     Definition
@@ -547,7 +547,7 @@ impl<'sg, 'storage, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq>
     /// # let scopegraph = ScopeGraph::<Lbl, (), _>::new(&storage, unsafe{UncheckedCompleteness::new()});
     /// use scopegraphs_macros::label_order;
     ///
-    /// #[derive(Label, Copy, Clone)]
+    /// #[derive(Label, Copy, Clone, PartialEq, Eq)]
     /// pub enum Lbl {
     ///     Lexical,
     ///     Definition
@@ -596,7 +596,7 @@ impl<'sg, 'storage, 'rslv, LABEL, DATA, CMPL, PWF, DWF, LO, DEq>
     }
 }
 
-impl<'storage, LABEL, DATA, CMPL> ScopeGraph<'storage, LABEL, DATA, CMPL> {
+impl<'storage, LABEL: Label, DATA, CMPL> ScopeGraph<'storage, LABEL, DATA, CMPL> {
     /// Build a query over the scope graph.
     pub fn query<'sg>(
         &'sg self,