Refactor execution context 🏗

- The execution context is a lot more structured: Instead of a magic stack of arbitrary objects there are static objects for pages, stacks and paragraphs
- Page softness/keeping mechanic is now a lot simpler than before

5 files changed, 9 insertions, 17 deletions

diff --git a/src/library/align.rs b/src/library/align.rs
index 07566f2d..98feb3ef 100644
--- a/src/library/align.rs
+++ b/src/library/align.rs
@@ -89,15 +89,14 @@ pub fn align(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
             }
         }
 
-        // If `had_center` wasn't flushed by now, it's the only argument and then we
-        // default to applying it to the cross axis.
+        // If `had_center` wasn't flushed by now, it's the only argument and
+        // then we default to applying it to the cross axis.
         if had_center {
             ctx.state.aligns.cross = Align::Center;
         }
 
         if ctx.state.aligns.main != snapshot.aligns.main {
-            ctx.end_par_group();
-            ctx.start_par_group();
+            ctx.push_linebreak();
         }
 
         if let Some(body) = &body {
diff --git a/src/library/pad.rs b/src/library/pad.rs
index 0bf93093..ba28bf8e 100644
--- a/src/library/pad.rs
+++ b/src/library/pad.rs
@@ -29,7 +29,7 @@ pub fn pad(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
     Value::template("pad", move |ctx| {
         let snapshot = ctx.state.clone();
 
-        let child = ctx.exec(&body);
+        let child = ctx.exec(&body).into();
         ctx.push(NodePad { padding, child });
 
         ctx.state = snapshot;
diff --git a/src/library/page.rs b/src/library/page.rs
index 4ab92b31..963ab913 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -83,25 +83,20 @@ pub fn page(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
         }
 
         ctx.set_dirs(Gen::new(main, cross));
+        ctx.finish_page(false, Softness::Hard);
 
-        let mut softness = ctx.end_page_group(|_| false);
         if let Some(body) = &body {
             // TODO: Restrict body to a single page?
-            ctx.start_page_group(Softness::Hard);
             body.exec(ctx);
-            ctx.end_page_group(|s| s == Softness::Hard);
-            softness = Softness::Soft;
             ctx.state = snapshot;
+            ctx.finish_page(true, Softness::Soft);
         }
-
-        ctx.start_page_group(softness);
     })
 }
 
 /// `pagebreak`: Start a new page.
 pub fn pagebreak(_: &mut EvalContext, _: &mut ValueArgs) -> Value {
     Value::template("pagebreak", move |ctx| {
-        ctx.end_page_group(|_| true);
-        ctx.start_page_group(Softness::Hard);
+        ctx.finish_page(true, Softness::Hard);
     })
 }
diff --git a/src/library/shapes.rs b/src/library/shapes.rs
index 9c466318..254a2285 100644
--- a/src/library/shapes.rs
+++ b/src/library/shapes.rs
@@ -31,7 +31,7 @@ pub fn box_(ctx: &mut EvalContext, args: &mut ValueArgs) -> Value {
 
         ctx.set_dirs(Gen::new(main, cross));
 
-        let child = ctx.exec(&body);
+        let child = ctx.exec(&body).into();
         let fixed = NodeFixed { width, height, child };
         if let Some(color) = color {
             ctx.push(NodeBackground {
diff --git a/src/library/spacing.rs b/src/library/spacing.rs
index 624890e9..3cc718b2 100644
--- a/src/library/spacing.rs
+++ b/src/library/spacing.rs
@@ -25,9 +25,7 @@ fn spacing(ctx: &mut EvalContext, args: &mut ValueArgs, axis: SpecAxis) -> Value
             let amount = linear.resolve(ctx.state.font.font_size());
             let spacing = NodeSpacing { amount, softness: Softness::Hard };
             if axis == ctx.state.dirs.main.axis() {
-                ctx.end_par_group();
-                ctx.push(spacing);
-                ctx.start_par_group();
+                ctx.push_into_stack(spacing);
             } else {
                 ctx.push(spacing);
             }