Introspection

3 files changed, 46 insertions, 8 deletions

diff --git a/library/src/layout/mod.rs b/library/src/layout/mod.rs
index e3691732..047d78f9 100644
--- a/library/src/layout/mod.rs
+++ b/library/src/layout/mod.rs
@@ -59,9 +59,11 @@ impl LayoutRoot for Content {
         fn cached(
             node: &Content,
             world: comemo::Tracked<dyn World>,
+            provider: TrackedMut<StabilityProvider>,
+            introspector: Tracked<Introspector>,
             styles: StyleChain,
         ) -> SourceResult<Document> {
-            let mut vt = Vt { world };
+            let mut vt = Vt { world, provider, introspector };
             let scratch = Scratch::default();
             let (realized, styles) = realize_root(&mut vt, &scratch, node, styles)?;
             realized
@@ -70,7 +72,13 @@ impl LayoutRoot for Content {
                 .layout_root(&mut vt, styles)
         }
 
-        cached(self, vt.world, styles)
+        cached(
+            self,
+            vt.world,
+            TrackedMut::reborrow_mut(&mut vt.provider),
+            vt.introspector,
+            styles,
+        )
     }
 }
 
@@ -97,10 +105,12 @@ impl Layout for Content {
         fn cached(
             node: &Content,
             world: comemo::Tracked<dyn World>,
+            provider: TrackedMut<StabilityProvider>,
+            introspector: Tracked<Introspector>,
             styles: StyleChain,
             regions: &Regions,
         ) -> SourceResult<Fragment> {
-            let mut vt = Vt { world };
+            let mut vt = Vt { world, provider, introspector };
             let scratch = Scratch::default();
             let (realized, styles) = realize_block(&mut vt, &scratch, node, styles)?;
             let barrier = Style::Barrier(realized.id());
@@ -111,7 +121,14 @@ impl Layout for Content {
                 .layout(&mut vt, styles, regions)
         }
 
-        cached(self, vt.world, styles, regions)
+        cached(
+            self,
+            vt.world,
+            TrackedMut::reborrow_mut(&mut vt.provider),
+            vt.introspector,
+            styles,
+            regions,
+        )
     }
 }
 
@@ -290,6 +307,15 @@ impl<'a, 'v, 't> Builder<'a, 'v, 't> {
         content: &'a Content,
         styles: StyleChain<'a>,
     ) -> SourceResult<()> {
+        // Prepare only if this is the first application for this node.
+        if let Some(node) = content.with::<dyn Prepare>() {
+            if !content.is_prepared() {
+                let prepared = node.prepare(self.vt, content.clone().prepared(), styles);
+                let stored = self.scratch.content.alloc(prepared);
+                return self.accept(stored, styles);
+            }
+        }
+
         if let Some(styled) = content.to::<StyledNode>() {
             return self.styled(styled, styles);
         }
diff --git a/library/src/layout/page.rs b/library/src/layout/page.rs
index 08411ad1..dee77abd 100644
--- a/library/src/layout/page.rs
+++ b/library/src/layout/page.rs
@@ -5,7 +5,7 @@ use crate::prelude::*;
 use crate::text::TextNode;
 
 /// Layouts its child onto one or multiple pages.
-#[derive(PartialEq, Clone, Hash)]
+#[derive(Clone, Hash)]
 pub struct PageNode(pub Content);
 
 #[node]
@@ -157,7 +157,7 @@ impl PagebreakNode {
 }
 
 /// A header, footer, foreground or background definition.
-#[derive(Debug, Clone, PartialEq, Hash)]
+#[derive(Debug, Clone, Hash)]
 pub enum Marginal {
     /// Nothing,
     None,
diff --git a/library/src/layout/par.rs b/library/src/layout/par.rs
index e96845dd..78e9b2a3 100644
--- a/library/src/layout/par.rs
+++ b/library/src/layout/par.rs
@@ -57,13 +57,15 @@ impl ParNode {
         fn cached(
             par: &ParNode,
             world: Tracked<dyn World>,
+            provider: TrackedMut<StabilityProvider>,
+            introspector: Tracked<Introspector>,
             styles: StyleChain,
             consecutive: bool,
             width: Abs,
             base: Size,
             expand: bool,
         ) -> SourceResult<Fragment> {
-            let mut vt = Vt { world };
+            let mut vt = Vt { world, provider, introspector };
 
             // Collect all text into one string for BiDi analysis.
             let (text, segments) = collect(par, &styles, consecutive);
@@ -80,7 +82,17 @@ impl ParNode {
             finalize(&mut vt, &p, &lines, width, base, expand)
         }
 
-        cached(self, vt.world, styles, consecutive, width, base, expand)
+        cached(
+            self,
+            vt.world,
+            TrackedMut::reborrow_mut(&mut vt.provider),
+            vt.introspector,
+            styles,
+            consecutive,
+            width,
+            base,
+            expand,
+        )
     }
 }