Declare which index levels a node reads and nullify the rest

node-graph/graph-craft/src/proto.rs

@@ -505,7 +505,13 @@ impl ProtoNetwork {
 
 		let (extract, inject, own_deps) = {
 			let dependencies = &self.nodes[node_index].1.context_features;
-			let own_deps = ContextModification::from_sources(dependencies.extract, dependencies.sources());
+			// Documents predating the level mask deserialize as all-levels, so a
+			// node that declares no index read must not contribute one.
+			let index_levels = match dependencies.extract.contains(core_types::context::ContextFeatures::INDEX) {
+				true => dependencies.index_levels,
+				false => core_types::context::IndexLevels::empty(),
+			};
+			let own_deps = ContextModification::from_sources(dependencies.extract, dependencies.sources()).with_index_levels(index_levels);
 			(dependencies.extract, dependencies.inject, own_deps)
 		};
 

node-graph/libraries/core-types/src/context.rs

@@ -34,7 +34,11 @@ pub trait ExtractPointerPosition {
 pub trait ExtractPosition {
 	fn try_position(&self) -> Option<impl Iterator<Item = DVec2>>;
 }
-pub trait ExtractIndex {
+/// The level sentinel for a reader whose level is not known at compile time,
+/// so every level of the index chain must survive nullification.
+pub const ALL_INDEX_LEVELS: u8 = u8::MAX;
+
+pub trait ExtractIndices {
 	fn try_index(&self) -> Option<impl Iterator<Item = usize>>;
 	fn innermost_index(&self) -> u64 {
 		self.try_index().and_then(|mut indices| indices.next()).unwrap_or(0) as u64
@@ -52,6 +56,18 @@ pub trait ExtractIndex {
 		}
 	}
 }
+
+/// `LEVEL` is the level of the index chain a node reads, counted outwards from
+/// the innermost. Declaring it narrows the cache key to that level, and reading
+/// through `index` keeps the declaration and the read from drifting apart.
+/// Repeat the bound to declare several, then spell the level at each read.
+pub trait ExtractIndex<const LEVEL: u8 = 0>: ExtractIndices {
+	fn index(&self) -> u64 {
+		self.try_index().and_then(|mut levels| levels.nth(LEVEL as usize)).unwrap_or(0) as u64
+	}
+}
+
+impl<T: ExtractIndices, const LEVEL: u8> ExtractIndex<LEVEL> for T {}
 pub trait ExtractVarArgs {
 	// TODO: Consider returning a slice or something like that
 
@@ -154,7 +170,8 @@ pub enum ContextFeature {
 	ExtractAnimationTime,
 	ExtractPointerPosition,
 	ExtractPosition,
-	ExtractIndex,
+	/// Carries the declared level, counted outwards from the innermost.
+	ExtractIndex(u8),
 	ExtractVarArgs,
 	InjectFootprint,
 	InjectRealTime,
@@ -187,6 +204,93 @@ impl graphene_hash::CacheHash for ContextFeatures {
 	}
 }
 
+/// Which levels of the index chain survive nullification, as a mask over levels
+/// counted outwards from the innermost. Levels past 31 collapse to "all".
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default, dyn_any::DynAny)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct IndexLevels(u32);
+
+impl IndexLevels {
+	pub const fn empty() -> Self {
+		Self(0)
+	}
+
+	pub const fn all() -> Self {
+		Self(u32::MAX)
+	}
+
+	/// The innermost level alone, which is what every reader but `read_index`
+	/// addresses, so documents predating the mask migrate to it.
+	pub const fn innermost() -> Self {
+		Self(1)
+	}
+
+	pub const fn is_empty(self) -> bool {
+		self.0 == 0
+	}
+
+	pub fn with_level(self, level: u8) -> Self {
+		match level {
+			ALL_INDEX_LEVELS => Self::all(),
+			level if (level as u32) < u32::BITS => Self(self.0 | 1 << level),
+			_ => Self::all(),
+		}
+	}
+
+	pub const fn contains(self, other: Self) -> bool {
+		self.0 & other.0 == other.0
+	}
+
+	pub const fn is_all(self) -> bool {
+		self.0 == u32::MAX
+	}
+
+	/// Levels at or past `u32::BITS` are only readable through the all-levels
+	/// sentinel, so they count as declared whenever the mask is saturated.
+	pub const fn contains_level(self, level: usize) -> bool {
+		match level < u32::BITS as usize {
+			true => self.0 & 1 << level != 0,
+			false => self.is_all(),
+		}
+	}
+}
+
+/// Zeroes every index level outside `levels`, preserving the chain's depth so
+/// outer levels keep their positions for readers that do address them. Returns
+/// `None` only when the arena is exhausted.
+pub fn nullify_index_levels<'s>(head: IndexLink<'s>, levels: IndexLevels, arena: &'s crate::arena::Arena) -> Option<IndexLink<'s>> {
+	if levels.is_all() {
+		return Some(head);
+	}
+	let indices: Vec<u64> = core::iter::successors(Some(&head), |link| link.outer).map(|link| link.index).collect();
+	let masked = |level: usize| match levels.contains_level(level) {
+		true => indices[level],
+		false => 0,
+	};
+	if (0..indices.len()).all(|level| levels.contains_level(level) || indices[level] == 0) {
+		return Some(head);
+	}
+	// Built outermost inwards so each link can reference the one already placed.
+	let mut outer: Option<&'s IndexLink<'s>> = None;
+	for level in (1..indices.len()).rev() {
+		let link = IndexLink { index: masked(level), outer };
+		outer = Some(arena.alloc(link)?.0);
+	}
+	Some(IndexLink { index: masked(0), outer })
+}
+
+impl core::ops::BitOrAssign for IndexLevels {
+	fn bitor_assign(&mut self, other: Self) {
+		self.0 |= other.0;
+	}
+}
+
+impl graphene_hash::CacheHash for IndexLevels {
+	fn cache_hash<H: core::hash::Hasher>(&self, state: &mut H) {
+		core::hash::Hash::hash(self, state);
+	}
+}
+
 impl ContextFeatures {
 	pub fn name(&self) -> &'static str {
 		match *self {
@@ -211,13 +315,31 @@ impl ContextFeatures {
 pub struct ContextDependencies {
 	pub extract: ContextFeatures,
 	pub inject: ContextFeatures,
+	/// Which index levels the node reads; empty means it reads none. Documents
+	/// written before the field existed default to the whole chain.
+	#[cfg_attr(feature = "serde", serde(default = "IndexLevels::innermost"))]
+	pub index_levels: IndexLevels,
 	#[cfg_attr(feature = "serde", serde(default, deserialize_with = "deserialize_sorted_sources"))]
 	sources: Vec<SourceId>,
 }
 
 impl ContextDependencies {
 	pub fn new(extract: ContextFeatures, inject: ContextFeatures) -> Self {
-		Self { extract, inject, sources: Vec::new() }
+		let index_levels = match extract.contains(ContextFeatures::INDEX) {
+			true => IndexLevels::innermost(),
+			false => IndexLevels::empty(),
+		};
+		Self {
+			extract,
+			inject,
+			index_levels,
+			sources: Vec::new(),
+		}
+	}
+
+	pub fn with_index_levels(mut self, index_levels: IndexLevels) -> Self {
+		self.index_levels = index_levels;
+		self
 	}
 
 	pub fn sources(&self) -> &[SourceId] {
@@ -239,6 +361,9 @@ impl ContextDependencies {
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct ContextModification {
 	pub features: ContextFeatures,
+	/// Which index levels survive; consulted only when `features` keeps `INDEX`.
+	#[cfg_attr(feature = "serde", serde(default = "IndexLevels::innermost"))]
+	pub index_levels: IndexLevels,
 	#[cfg_attr(feature = "serde", serde(deserialize_with = "deserialize_sorted_sources"))]
 	sources: Vec<SourceId>,
 }
@@ -253,10 +378,23 @@ impl ContextModification {
 	}
 
 	pub fn from_sources(features: ContextFeatures, sources: &[SourceId]) -> Self {
-		let mut modification = Self { features, sources: Vec::new() };
+		let index_levels = match features.contains(ContextFeatures::INDEX) {
+			true => IndexLevels::all(),
+			false => IndexLevels::empty(),
+		};
+		let mut modification = Self {
+			features,
+			index_levels,
+			sources: Vec::new(),
+		};
 		modification.add_sources(sources);
 		modification
 	}
+
+	pub fn with_index_levels(mut self, index_levels: IndexLevels) -> Self {
+		self.index_levels = index_levels;
+		self
+	}
 }
 
 /// Restores the sorted-and-deduplicated invariant that `contains` and `difference`
@@ -273,6 +411,7 @@ fn deserialize_sorted_sources<'de, D: serde::Deserializer<'de>>(deserializer: D)
 impl core::ops::BitOrAssign<&ContextModification> for ContextModification {
 	fn bitor_assign(&mut self, other: &Self) {
 		self.features |= other.features;
+		self.index_levels |= other.index_levels;
 		merge_sorted_sources(&mut self.sources, &other.sources);
 	}
 }
@@ -298,13 +437,14 @@ impl core::ops::BitAndAssign<ContextFeatures> for ContextModification {
 impl ContextModification {
 	pub fn contains(&self, other: &Self) -> bool {
 		debug_assert!(self.sources.is_sorted() && other.sources.is_sorted());
-		self.features.contains(other.features) && other.sources.iter().all(|id| self.sources.binary_search(id).is_ok())
+		self.features.contains(other.features) && self.index_levels.contains(other.index_levels) && other.sources.iter().all(|id| self.sources.binary_search(id).is_ok())
 	}
 
 	pub fn difference(&self, other: &Self) -> Self {
 		debug_assert!(other.sources.is_sorted());
 		Self {
 			features: self.features.difference(other.features),
+			index_levels: self.index_levels,
 			sources: self.sources.iter().copied().filter(|id| other.sources.binary_search(id).is_err()).collect(),
 		}
 	}
@@ -326,14 +466,18 @@ impl From<&[ContextFeature]> for ContextDependencies {
 	fn from(features: &[ContextFeature]) -> Self {
 		let mut extract = ContextFeatures::empty();
 		let mut inject = ContextFeatures::empty();
+		let mut index_levels = IndexLevels::empty();
 		for feature in features {
+			if let ContextFeature::ExtractIndex(level) = feature {
+				index_levels = index_levels.with_level(*level);
+			}
 			extract |= match feature {
 				ContextFeature::ExtractFootprint => ContextFeatures::FOOTPRINT,
 				ContextFeature::ExtractRealTime => ContextFeatures::REAL_TIME,
 				ContextFeature::ExtractAnimationTime => ContextFeatures::ANIMATION_TIME,
 				ContextFeature::ExtractPointerPosition => ContextFeatures::POINTER_POSITION,
 				ContextFeature::ExtractPosition => ContextFeatures::POSITION,
-				ContextFeature::ExtractIndex => ContextFeatures::INDEX,
+				ContextFeature::ExtractIndex(_) => ContextFeatures::INDEX,
 				ContextFeature::ExtractVarArgs => ContextFeatures::VARARGS,
 				_ => ContextFeatures::empty(),
 			};
@@ -348,7 +492,12 @@ impl From<&[ContextFeature]> for ContextDependencies {
 				_ => ContextFeatures::empty(),
 			};
 		}
-		Self { extract, inject, sources: Vec::new() }
+		Self {
+			extract,
+			inject,
+			index_levels,
+			sources: Vec::new(),
+		}
 	}
 }
 
@@ -388,7 +537,7 @@ impl<T: ExtractPosition + Sync> ExtractPosition for Option<T> {
 		self.as_ref().and_then(|x| x.try_position())
 	}
 }
-impl<T: ExtractIndex> ExtractIndex for Option<T> {
+impl<T: ExtractIndices> ExtractIndices for Option<T> {
 	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
 		self.as_ref().and_then(|x| x.try_index())
 	}
@@ -446,7 +595,7 @@ impl<T: ExtractPosition + Sync> ExtractPosition for Arc<T> {
 		(**self).try_position()
 	}
 }
-impl<T: ExtractIndex> ExtractIndex for Arc<T> {
+impl<T: ExtractIndices> ExtractIndices for Arc<T> {
 	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
 		(**self).try_index()
 	}
@@ -739,7 +888,7 @@ pub trait DeriveCtx {
 	fn with_varargs<'s>(&'s self, varargs: &'s VarArgLink<'s>) -> Derived<'s, Self>;
 	fn with_position<'s>(&'s self, position: &'s PositionLink<'s>) -> Derived<'s, Self>;
 	fn with_scope<'s>(&'s self, scope: &'s EvalScope<'s>) -> Derived<'s, Self>;
-	fn nullified<'s>(&'s self, keep: ContextFeatures, scope: &'s EvalScope<'s>) -> Derived<'s, Self>;
+	fn nullified<'s>(&'s self, keep: ContextFeatures, index: IndexLink<'s>, scope: &'s EvalScope<'s>) -> Derived<'s, Self>;
 
 	fn modify_footprint(&self, modify: impl FnOnce(&mut Footprint)) -> ModifiedFootprint<'_, Self>
 	where
@@ -850,7 +999,7 @@ impl ExtractPointerPosition for CtxSnapshot {
 	}
 }
 
-impl ExtractIndex for CtxSnapshot {
+impl ExtractIndices for CtxSnapshot {
 	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
 		self.index.as_ref().map(|levels| levels.iter().copied())
 	}
@@ -975,15 +1124,12 @@ impl<'a> ContextImpl<'a> {
 		ContextImpl { position: Some(position), ..*self }
 	}
 
-	pub fn nullified<'s>(&self, keep: ContextFeatures, scope: &'s EvalScope<'s>) -> ContextImpl<'s>
+	pub fn nullified<'s>(&self, keep: ContextFeatures, index: IndexLink<'s>, scope: &'s EvalScope<'s>) -> ContextImpl<'s>
 	where
 		'a: 's,
 	{
 		ContextImpl {
-			index: match keep.contains(ContextFeatures::INDEX) {
-				true => self.index,
-				false => IndexLink { index: 0, outer: None },
-			},
+			index,
 			position: self.position.filter(|_| keep.contains(ContextFeatures::POSITION)),
 			varargs: self.varargs.filter(|_| keep.contains(ContextFeatures::VARARGS)),
 			footprint: self.footprint.filter(|_| keep.contains(ContextFeatures::FOOTPRINT)),
@@ -1060,7 +1206,7 @@ impl ExtractPointerPosition for ContextImpl<'_> {
 		self.scope.pointer_position
 	}
 }
-impl ExtractIndex for ContextImpl<'_> {
+impl ExtractIndices for ContextImpl<'_> {
 	fn try_index(&self) -> Option<impl Iterator<Item = usize>> {
 		Some(std::iter::successors(Some(&self.index), |link| link.outer).map(|link| link.index as usize))
 	}
@@ -1161,8 +1307,8 @@ impl<'a> DeriveCtx for ContextImpl<'a> {
 		ContextImpl::with_scope(self, scope)
 	}
 
-	fn nullified<'s>(&'s self, keep: ContextFeatures, scope: &'s EvalScope<'s>) -> ContextImpl<'s> {
-		ContextImpl::nullified(self, keep, scope)
+	fn nullified<'s>(&'s self, keep: ContextFeatures, index: IndexLink<'s>, scope: &'s EvalScope<'s>) -> ContextImpl<'s> {
+		ContextImpl::nullified(self, keep, index, scope)
 	}
 }
 

node-graph/node-macro/src/parsing.rs

@@ -345,7 +345,7 @@ pub(crate) struct Input {
 	pub(crate) pat_ident: PatIdent,
 	pub(crate) ty: Type,
 	pub(crate) implementations: Punctuated<Type, Comma>,
-	pub(crate) context_features: Vec<Ident>,
+	pub(crate) context_features: Vec<ContextFeatureDecl>,
 }
 
 impl Parse for Implementation {
@@ -868,8 +868,46 @@ fn parse_read_tuple(pat_tuple: &syn::PatTuple, ty: &Type, attrs: &[Attribute], i
 	Ok(field)
 }
 
+/// A declared context feature; `ExtractIndex` carries the index level it reads.
+#[derive(Debug, Clone, PartialEq)]
+pub(crate) struct ContextFeatureDecl {
+	pub(crate) ident: Ident,
+	pub(crate) level: Option<u8>,
+}
+
+impl ContextFeatureDecl {
+	pub(crate) fn new(ident: Ident) -> Self {
+		Self { ident, level: None }
+	}
+}
+
+impl quote::ToTokens for ContextFeatureDecl {
+	fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
+		let ident = &self.ident;
+		match self.level {
+			Some(level) => tokens.extend(quote::quote!(#ident(#level))),
+			None => ident.to_tokens(tokens),
+		}
+	}
+}
+
+/// The level of an `ExtractIndex<N>` bound, defaulting to the innermost.
+fn parse_index_level(segment: &syn::PathSegment) -> u8 {
+	let syn::PathArguments::AngleBracketed(arguments) = &segment.arguments else {
+		return 0;
+	};
+	for argument in &arguments.args {
+		if let syn::GenericArgument::Const(syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(int), .. })) = argument
+			&& let Ok(level) = int.base10_parse::<u8>()
+		{
+			return level;
+		}
+	}
+	0
+}
+
 /// Parse context feature identifiers from the trait bounds of a context parameter.
-fn parse_context_feature_idents(ty: &Type) -> Vec<Ident> {
+fn parse_context_feature_idents(ty: &Type) -> Vec<ContextFeatureDecl> {
 	let mut features = Vec::new();
 
 	// Check if this is an impl trait (impl Ctx + ...)
@@ -879,12 +917,20 @@ fn parse_context_feature_idents(ty: &Type) -> Vec<Ident> {
 				// Extract the last segment of the trait path
 				if let Some(segment) = path.segments.last() {
 					match segment.ident.to_string().as_str() {
+						"ExtractIndex" => features.push(ContextFeatureDecl {
+							ident: segment.ident.clone(),
+							level: Some(parse_index_level(segment)),
+						}),
+						// Reading the chain without a statically known level keeps every level.
+						"ExtractIndices" => features.push(ContextFeatureDecl {
+							ident: format_ident!("ExtractIndex"),
+							level: Some(u8::MAX),
+						}),
 						"ExtractFootprint"
 						| "ExtractRealTime"
 						| "ExtractAnimationTime"
 						| "ExtractPointerPosition"
 						| "ExtractPosition"
-						| "ExtractIndex"
 						| "ExtractVarArgs"
 						| "InjectFootprint"
 						| "InjectRealTime"
@@ -892,7 +938,7 @@ fn parse_context_feature_idents(ty: &Type) -> Vec<Ident> {
 						| "InjectPointerPosition"
 						| "InjectPosition"
 						| "InjectVarArgs" => {
-							features.push(segment.ident.clone());
+							features.push(ContextFeatureDecl::new(segment.ident.clone()));
 						}
 						// InjectIndex stays undeclared: a record node's injection
 						// re-addresses lanes derived from the incoming index, so it
@@ -1605,7 +1651,7 @@ mod tests {
 				pat_ident: pat_ident("_"),
 				ty: parse_quote!(impl Ctx + ExtractFootprint),
 				implementations: Punctuated::new(),
-				context_features: vec![format_ident!("ExtractFootprint")],
+				context_features: vec![ContextFeatureDecl::new(format_ident!("ExtractFootprint"))],
 			},
 			output_type: parse_quote!(Vector),
 			output_depth: 0,

node-graph/nodes/gcore/src/context.rs

@@ -1,7 +1,7 @@
 use core_types::gpoll::{Extent, GPoll, GraphError, Interrupt};
 use core_types::list::List;
 use core_types::{Color, ExtractVarArgs};
-use core_types::{Ctx, ExtractIndex, ExtractPosition};
+use core_types::{Ctx, ExtractIndex, ExtractIndices, ExtractPosition};
 use glam::DVec2;
 use graphic_types::vector_types::GradientStops;
 use graphic_types::{Graphic, Vector};
@@ -64,7 +64,7 @@ fn vararg_lanes<T: 'static>(ctx: &impl ExtractVarArgs, level: u8) -> GPoll<Exten
 
 fn vararg_element<T: Clone + 'static>(ctx: &(impl ExtractVarArgs + ExtractIndex)) -> Result<T, Interrupt> {
 	vararg_list::<T>(ctx)
-		.and_then(|list| list.element(ctx.innermost_index() as usize))
+		.and_then(|list| list.element(ctx.index() as usize))
 		.cloned()
 		.ok_or_else(|| GraphError::new("vararg row addressed past its items").into())
 }
@@ -138,7 +138,9 @@ fn read_position(
 /// Nested loops can enable 2D or higher-dimensional iteration by using the *Loop Level* parameter to read the index from outer levels of loops.
 #[node_macro::node(category("Context"), path(core_types::vector))]
 fn read_index(
-	ctx: impl Ctx + ExtractIndex,
+	// `loop_level` is a runtime input, so no level is statically known and the
+	// whole chain has to survive nullification.
+	ctx: impl Ctx + ExtractIndices,
 	_primary: (),
 	/// The number of nested loops to traverse outwards (from the innermost loop) to get the index from. The most upstream loop is level 0, and downstream loops add levels.
 	///

node-graph/nodes/gcore/src/context_modification.rs

@@ -1,5 +1,5 @@
-use core_types::context::{ContextModification, Ctx, DeriveCtx};
-use core_types::gpoll::Interrupt;
+use core_types::context::{ContextFeatures, ContextModification, Ctx, DeriveCtx, IndexLink, nullify_index_levels};
+use core_types::gpoll::{ErrorKind, GraphError, Interrupt};
 
 /// Filters out what should be unused components of the context based on the specified requirements.
 /// This node is inserted by the compiler to "zero out" unused context components.
@@ -12,5 +12,15 @@ fn context_modification<T>(
 	modification: ContextModification,
 ) -> Result<T, Interrupt> {
 	let scope = ctx.scope().nullified(modification.features, Some(modification.sources()));
-	value.eval(&ctx.nullified(modification.features, &scope))
+	let exhausted = || {
+		Interrupt::from(GraphError {
+			kind: ErrorKind::ArenaExhausted,
+			trace: Vec::new(),
+		})
+	};
+	let index = match modification.features.contains(ContextFeatures::INDEX) {
+		true => nullify_index_levels(ctx.index_head(), modification.index_levels, scope.arena()).ok_or_else(exhausted)?,
+		false => IndexLink { index: 0, outer: None },
+	};
+	value.eval(&ctx.nullified(modification.features, index, &scope))
 }

node-graph/nodes/gcore/src/memo.rs

@@ -41,7 +41,7 @@ fn memoize<'e>(
 	// keys with the lane normalized away.
 	let leveled = content.layout().depth > 0;
 	let lane = match leveled {
-		true => ctx.innermost_index() as usize,
+		true => ctx.index() as usize,
 		false => 0,
 	};
 	let key = match leveled {
@@ -203,7 +203,7 @@ fn monitor<'e>(
 	// computes lane by lane. Serving THIS lane out of that batch rather than
 	// evaluating the content separately is what keeps the cost linear: the extra
 	// eval would double the work under every enclosing monitor.
-	if content.layout().depth > 0 && ctx.innermost_index() == 0 {
+	if content.layout().depth > 0 && ctx.index() == 0 {
 		return match content.materialize_level(ctx, ctx.arena()) {
 			LevelStatus::Batch(batch, finality) => {
 				// SAFETY: the batch came from this edge, so it carries the edge's layout.
@@ -235,7 +235,7 @@ fn monitor<'e>(
 		};
 	}
 	let result = content.eval(&ctx);
-	if ctx.innermost_index() == 0
+	if ctx.index() == 0
 		&& let GPoll::Final(value) | GPoll::Partial(value) = &result
 	{
 		// SAFETY: the value came from this edge, so it carries the edge's layout.

node-graph/nodes/gcore/src/record.rs

@@ -7,7 +7,7 @@
 
 use core_types::attribute::{Attr, EditorLayerPath, Opacity, RemoveAttr, Transform};
 use glam::DAffine2;
-use core_types::context::{DeriveCtx, ExtractIndex, IndexLink, InjectIndex};
+use core_types::context::{DeriveCtx, ExtractIndex, ExtractIndices, IndexLink, InjectIndex};
 use core_types::extent::{ExtentIn, LevelIn, ListIn, ValueIn};
 use core_types::gpoll::{ErrorKind, Extent, GPoll, GraphError, Interrupt, Level};
 use core_types::node::Lane;
@@ -58,8 +58,8 @@ fn fade<T>(_: impl Ctx, (element, opacity): (T, Attr<Opacity>), factor: f64) ->
 /// writes a per-copy opacity indexed by the copy's own index.
 #[node_macro::node(category("Test"), extent(repeat_opacity_extent))]
 fn repeat_opacity(ctx: impl Ctx + ExtractIndex, element: f64, count: u32) -> IList<(f64, Attr<Opacity>)> {
-	debug_assert!(ctx.innermost_index() < count as u64, "repeat addressed past its copy count");
-	emit(element, Attr(ctx.innermost_index() as f64))
+	debug_assert!(ctx.index() < count as u64, "repeat addressed past its copy count");
+	emit(element, Attr(ctx.index() as f64))
 }
 
 #[node_macro::node(category("Test"))]
@@ -155,7 +155,7 @@ fn extend<T>(
 		GPoll::Pending => return Err(Interrupt::Pending),
 		_ => return Err(GraphError::new("extend over a non-exact base extent").into()),
 	};
-	let lane = ctx.innermost_index();
+	let lane = ctx.index();
 	match lane < split {
 		true => base.eval(ctx),
 		false => {
@@ -210,7 +210,7 @@ fn omit_element<T>(ctx: impl Ctx + ExtractIndex + InjectIndex + Copy, content: i
 		GPoll::Pending => return Err(Interrupt::Pending),
 		_ => return Err(GraphError::new("omit over a non-exact extent").into()),
 	};
-	let lane = ctx.innermost_index();
+	let lane = ctx.index();
 	let source = match resolve_index(index, total) {
 		Some(omitted) if lane >= omitted => lane + 1,
 		_ => lane,
@@ -270,7 +270,7 @@ fn extract_element(_: impl Ctx + InjectIndex + Copy, list: IList<f64>, index: f6
 #[node_macro::node(category("Test"), extent(mirror_extent))]
 fn mirror(ctx: impl Ctx + ExtractIndex + InjectIndex + Copy, content: IList<f64>, keep_original: bool) -> Result<IList<(f64, Attr<Transform>)>, Interrupt> {
 	let total = content.len() as u64;
-	let lane = ctx.innermost_index();
+	let lane = ctx.index();
 	let (source, mirrored) = match (keep_original, lane < total) {
 		(true, true) => (lane, false),
 		(true, false) => (lane - total, true),

node-graph/nodes/graphic/src/graphic.rs

@@ -71,7 +71,7 @@ pub fn omit_element<T>(
 		GPoll::Pending => return Err(Interrupt::Pending),
 		_ => return Err(GraphError::new("omit over a non-exact extent").into()),
 	};
-	let lane = ctx.innermost_index();
+	let lane = ctx.index();
 	let source = match resolve_index(index, total) {
 		Some(omitted) if lane >= omitted => lane + 1,
 		_ => lane,
@@ -115,7 +115,7 @@ fn map<Row: Clone + Send + Sync + CacheHash + 'static, T>(
 	#[implementations(Graphic, Vector, Raster<CPU>, Color, GradientStops, String)] content: IList<Row>,
 	mapped: impl Node<Context<'_>, Output = IList<T>>,
 ) -> Result<IList<T>, Interrupt> {
-	let mut remaining = ctx.innermost_index();
+	let mut remaining = ctx.index();
 	for row in 0..content.len() {
 		let item = crate::record::vararg_row(content, row);
 		let scoped = ctx.push_vararg(&item);
@@ -276,7 +276,7 @@ fn mirror<'e>(
 	mirror_lane(
 		ctx.arena(),
 		legacy_render_list_of(content),
-		ctx.innermost_index() as usize,
+		ctx.index() as usize,
 		relative_to_bounds,
 		offset,
 		angle,
@@ -334,7 +334,7 @@ fn mirror_vector<'e>(
 	mirror_lane(
 		ctx.arena(),
 		legacy_render_list_of(content),
-		ctx.innermost_index() as usize,
+		ctx.index() as usize,
 		relative_to_bounds,
 		offset,
 		angle,
@@ -403,7 +403,7 @@ pub fn extend<T>(
 		GPoll::Pending => return Err(Interrupt::Pending),
 		_ => return Err(GraphError::new("extend over a non-exact base extent").into()),
 	};
-	let lane = ctx.innermost_index();
+	let lane = ctx.index();
 	match lane < split {
 		true => base.eval(ctx),
 		false => {
@@ -586,7 +586,7 @@ pub use _to_graphic_unit_mod::to_graphic_unit_entries;
 /// Removes a level of nesting from a `Graphic[]`, or all nesting if "Fully Flatten" is enabled.
 #[node_macro::node(category("General"), extent(flatten_graphic_extent))]
 pub fn flatten_graphic(ctx: impl Ctx + ExtractIndex + InjectIndex + Copy, content: IList<Graphic>, fully_flatten: bool) -> Result<IList<(Graphic, Attr<TransformAttr>)>, Interrupt> {
-	let mut remaining = ctx.innermost_index() as usize;
+	let mut remaining = ctx.index() as usize;
 	for row in 0..content.len() {
 		let graphic = content.element_ref(row);
 		let count = crate::record::leaf_count(graphic, fully_flatten, 0);

node-graph/nodes/graphic/src/record.rs

@@ -85,7 +85,7 @@ pub(crate) fn locate(graphic: &Graphic, transform: DAffine2, fully_flatten: bool
 /// rides as a leaf with its embedded transforms untouched.
 #[node_macro::node(category("Test"), extent(flatten_extent))]
 fn flatten(ctx: impl Ctx + ExtractIndex + InjectIndex + Copy, content: IList<Graphic>, fully_flatten: bool) -> Result<IList<(Graphic, Attr<Transform>)>, Interrupt> {
-	let mut remaining = ctx.innermost_index() as usize;
+	let mut remaining = ctx.index() as usize;
 	for row in 0..content.len() {
 		let graphic = content.element_ref(row);
 		let count = leaf_count(graphic, fully_flatten, 0);
@@ -157,7 +157,7 @@ fn map<Row: Clone + Send + Sync + core_types::CacheHash + 'static, T>(
 	#[implementations(Graphic, Vector, Raster<CPU>, Color, GradientStops, String)] content: IList<Row>,
 	mapped: impl Node<Context<'_>, Output = IList<T>>,
 ) -> Result<IList<IList<T>>, Interrupt> {
-	let mut remaining = ctx.innermost_index();
+	let mut remaining = ctx.index();
 	for row in 0..content.len() {
 		let item = vararg_row(content, row);
 		let scoped = ctx.push_vararg(&item);
@@ -181,7 +181,7 @@ fn flat_map<Row: Clone + Send + Sync + core_types::CacheHash + 'static, T>(
 	#[implementations(Graphic, Vector, Raster<CPU>, Color, GradientStops, String)] content: IList<Row>,
 	mapped: impl Node<Context<'_>, Output = IList<T>>,
 ) -> Result<IList<T>, Interrupt> {
-	let mut remaining = ctx.innermost_index();
+	let mut remaining = ctx.index();
 	for row in 0..content.len() {
 		let item = vararg_row(content, row);
 		let scoped = ctx.push_vararg(&item);
@@ -201,7 +201,7 @@ fn flat_map<Row: Clone + Send + Sync + core_types::CacheHash + 'static, T>(
 #[node_macro::node(category("Test"), extent(flatten_levels_extent))]
 fn flatten_levels<T>(ctx: impl Ctx + DeriveCtx + ExtractIndex, content: impl Node<Context<'_>, Output = IList<IList<T>>>) -> Result<IList<T>, Interrupt> {
 	let head = ctx.index_head();
-	content.eval(&ctx.promoted(&head, ctx.innermost_index()))
+	content.eval(&ctx.promoted(&head, ctx.index()))
 }
 
 /// The collapsed level's extent is the sum of the inner extents across the
@@ -237,7 +237,7 @@ mod tests {
 	use core_types::SourceId;
 	use core_types::arena::Arena;
 	use core_types::attribute::Attribute as AttributeMarker;
-	use core_types::context::{ContextImpl, EvalScope, ExtractArena};
+	use core_types::context::{ContextImpl, EvalScope, ExtractArena, ExtractIndices};
 	use core_types::list::{Item, List};
 	use core_types::node::Node;
 	use core_types::record::{self, Layout, Rec, RecordSource, RecordValue, stack};

node-graph/nodes/math/src/lib.rs

@@ -811,7 +811,7 @@ fn hsla_to_color(_: impl Ctx, _primary: (), hue: Fraction, #[default(1.)] satura
 #[node_macro::node(category("Color"), name("Hex to Color"))]
 fn hex_to_color(ctx: impl Ctx + ExtractIndex + InjectIndex + Copy, hex_code: String) -> Result<IList<Color>, Interrupt> {
 	// An invalid input serves an empty level: no color
-	match (core_types::misc::parse_css_color(&hex_code), ctx.innermost_index()) {
+	match (core_types::misc::parse_css_color(&hex_code), ctx.index()) {
 		(Some(color), 0) => Ok(color),
 		_ => Err(GraphError::past_end().into()),
 	}
@@ -839,7 +839,7 @@ fn spread_method(_: impl Ctx, gradient: GradientStops, spread_method: vector_typ
 #[node_macro::node(category("Color"))]
 fn sample_gradient(ctx: impl Ctx + ExtractIndex + InjectIndex + Copy, _primary: (), gradient: IList<GradientStops>, position: Fraction) -> Result<IList<Color>, Interrupt> {
 	// An unwired gradient serves an empty level: no color
-	if gradient.is_empty() || ctx.innermost_index() != 0 {
+	if gradient.is_empty() || ctx.index() != 0 {
 		return Err(GraphError::past_end().into());
 	}
 
@@ -1035,7 +1035,7 @@ mod graphene_test {
 		type Output = f64;
 
 		fn eval(&self, input: &Input) -> GPoll<f64> {
-			GPoll::Final(input.innermost_index() as f64)
+			GPoll::Final(input.index() as f64)
 		}
 	}
 

node-graph/nodes/raster/src/image_color_palette.rs

@@ -59,7 +59,7 @@ fn image_color_palette(
 		})
 		.collect();
 
-	palette.get(ctx.innermost_index() as usize).copied().ok_or_else(|| GraphError::past_end().into())
+	palette.get(ctx.index() as usize).copied().ok_or_else(|| GraphError::past_end().into())
 }
 
 #[cfg(test)]

node-graph/nodes/raster/src/std_nodes.rs

@@ -107,7 +107,7 @@ pub fn combine_channels<'e>(
 	)>,
 	Interrupt,
 > {
-	let lane = ctx.innermost_index() as usize;
+	let lane = ctx.index() as usize;
 	let max_len = red.len().max(green.len()).max(blue.len()).max(alpha.len());
 	if lane >= max_len {
 		return Err(GraphError::past_end().into());

node-graph/nodes/repeat/src/repeat_nodes.rs

@@ -231,7 +231,7 @@ mod test {
 		type Output = RecordValue<'e>;
 
 		fn eval(&self, input: &ContextImpl<'e>) -> GPoll<RecordValue<'e>> {
-			use core_types::context::{ExtractArena, ExtractIndex};
+			use core_types::context::{ExtractArena, ExtractIndices};
 			let (vector, transform) = &self.rows[input.innermost_index() as usize % self.rows.len()];
 			let dst = stack::push(self.layout.frame_bytes());
 			// SAFETY: dst is the claimed frame of this layout; offsets are the layout's own.

node-graph/nodes/vector/src/vector_modification_nodes.rs

@@ -18,7 +18,7 @@ fn path_modify<'e>(
 	node_path: Vec<NodeId>,
 ) -> Result<(Vector, Attr<'e, EditorLayerPath>, RemoveAttr<EditorClickTarget>), Interrupt> {
 	let mut element = element;
-	if ctx.innermost_index() == 0 {
+	if ctx.index() == 0 {
 		modification.apply(&mut element);
 	}
 

node-graph/nodes/vector/src/vector_nodes.rs

@@ -101,7 +101,7 @@ fn assign_colors<'e>(
 	#[widget(ParsedWidgetOverride::Custom = "assign_colors_repeat_every")]
 	repeat_every: u32,
 ) -> Result<IList<(Vector, Attr<'e, TransformAttr>, Attr<'e, Fill>, Attr<'e, StrokeAttr>, Attr<'e, EditorLayerPath>)>, Interrupt> {
-	let lane = ctx.innermost_index() as usize;
+	let lane = ctx.index() as usize;
 	if lane >= content.len() {
 		return Err(GraphError::past_end().into());
 	}
@@ -173,7 +173,7 @@ fn assign_colors_graphic<'e>(
 	seed: SeedValue,
 	repeat_every: u32,
 ) -> Result<IList<(Graphic, Attr<'e, TransformAttr>, Attr<'e, EditorLayerPath>)>, Interrupt> {
-	let lane = ctx.innermost_index() as usize;
+	let lane = ctx.index() as usize;
 	if lane >= content.len() {
 		return Err(GraphError::past_end().into());
 	}
@@ -1549,7 +1549,7 @@ fn solidify_stroke<'e>(
 	)>,
 	Interrupt,
 > {
-	solidify_lane(ctx.arena(), legacy_graphic_list_of(content), ctx.innermost_index() as usize)
+	solidify_lane(ctx.arena(), legacy_graphic_list_of(content), ctx.index() as usize)
 }
 
 /// A fill-bearing row splits into a fill lane and a solidified stroke lane,
@@ -1588,7 +1588,7 @@ fn solidify_stroke_vector<'e>(
 	)>,
 	Interrupt,
 > {
-	solidify_lane(ctx.arena(), legacy_graphic_list_of(content), ctx.innermost_index() as usize)
+	solidify_lane(ctx.arena(), legacy_graphic_list_of(content), ctx.index() as usize)
 }
 
 fn solidify_stroke_vector_extent(content: ListIn<'_, Vector>, level: LevelIn) -> GPoll<Extent> {
@@ -1655,7 +1655,7 @@ fn separate_subpaths<'e>(
 	Interrupt,
 > {
 	let output = separate_subpaths_core(legacy_vector_list_of(content));
-	emit_legacy_lane(ctx.arena(), output, ctx.innermost_index() as usize)
+	emit_legacy_lane(ctx.arena(), output, ctx.index() as usize)
 }
 
 /// A row splits into one lane per subpath, so the count depends on the
@@ -1726,7 +1726,7 @@ fn map_points<'e>(
 		}
 	}
 
-	emit_legacy_lane(ctx.arena(), content, ctx.innermost_index() as usize)
+	emit_legacy_lane(ctx.arena(), content, ctx.index() as usize)
 }
 
 fn map_points_extent(content: ListIn<'_, Vector>, _mapped: ExtentIn<'_>, level: LevelIn) -> GPoll<Extent> {
@@ -2176,7 +2176,7 @@ fn cut_path<'e>(
 	Interrupt,
 > {
 	let output = cut_path_core(legacy_vector_list_of(content), progression, reverse, parameterized_distance);
-	emit_legacy_lane(ctx.arena(), output, ctx.innermost_index() as usize)
+	emit_legacy_lane(ctx.arena(), output, ctx.index() as usize)
 }
 
 fn cut_path_extent(content: ListIn<'_, Vector>, _progression: ValueIn<'_, f64>, _reverse: ValueIn<'_, bool>, _parameterized_distance: ValueIn<'_, bool>, level: LevelIn) -> GPoll<Extent> {