Better space coalescing logic 🌧

This creates a smaller state machine helper type for softness coalescing, which does not own the resulting nodes. While this creates a bit more duplication in stack and par builder, it makes it a lot easier to integrate additional logic into the paragraph builder.

Furthermore:
- Line breaks are now "hard", that is, not coalesced with each other.
- Text nodes with equal style are now merged allowing for example `f{}i` to form a ligature.

9 files changed, 18 insertions, 18 deletions

diff --git a/src/library/align.rs b/src/library/align.rs
index d5811bf4..ccb25b34 100644
--- a/src/library/align.rs
+++ b/src/library/align.rs
@@ -52,7 +52,7 @@ pub fn align(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
         if let Some(vertical) = vertical {
             ctx.state.aligns.main = vertical.to_align(Dir::TTB);
             if ctx.state.aligns.main != snapshot.aligns.main {
-                ctx.push_linebreak();
+                ctx.parbreak();
             }
         }
 
diff --git a/src/library/image.rs b/src/library/image.rs
index 020f7d50..ed7b2268 100644
--- a/src/library/image.rs
+++ b/src/library/image.rs
@@ -23,7 +23,7 @@ pub fn image(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
             let loaded = ctx.env.resources.load(&path.v, ImageResource::parse);
             if let Some((res, img)) = loaded {
                 let dimensions = img.buf.dimensions();
-                ctx.push_into_par(ImageNode { res, dimensions, width, height });
+                ctx.push(ImageNode { res, dimensions, width, height });
             } else {
                 ctx.diag(error!(path.span, "failed to load image"));
             }
diff --git a/src/library/lang.rs b/src/library/lang.rs
index 79015c7d..1248b707 100644
--- a/src/library/lang.rs
+++ b/src/library/lang.rs
@@ -32,7 +32,7 @@ pub fn lang(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
             }
         }
 
-        ctx.push_parbreak();
+        ctx.parbreak();
     })
 }
 
diff --git a/src/library/markup.rs b/src/library/markup.rs
index d7d750ea..ac2356a9 100644
--- a/src/library/markup.rs
+++ b/src/library/markup.rs
@@ -14,7 +14,7 @@ use crate::syntax::{HeadingNode, RawNode};
 /// A template that inserts a line break.
 pub fn linebreak(_: &mut EvalContext, _: &mut FuncArgs) -> Value {
     Value::template(Node::LINEBREAK, move |ctx| {
-        ctx.push_linebreak();
+        ctx.linebreak();
     })
 }
 
@@ -24,7 +24,7 @@ pub fn linebreak(_: &mut EvalContext, _: &mut FuncArgs) -> Value {
 /// A template that inserts a paragraph break.
 pub fn parbreak(_: &mut EvalContext, _: &mut FuncArgs) -> Value {
     Value::template(Node::PARBREAK, move |ctx| {
-        ctx.push_parbreak();
+        ctx.parbreak();
     })
 }
 
@@ -118,7 +118,7 @@ pub fn heading(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
         body.exec(ctx);
         ctx.state = snapshot;
 
-        ctx.push_parbreak();
+        ctx.parbreak();
     })
 }
 
@@ -155,7 +155,7 @@ pub fn raw(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
 
     Value::template(Node::RAW, move |ctx| {
         if block {
-            ctx.push_parbreak();
+            ctx.parbreak();
         }
 
         let snapshot = ctx.state.clone();
@@ -164,7 +164,7 @@ pub fn raw(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
         ctx.state = snapshot;
 
         if block {
-            ctx.push_parbreak();
+            ctx.parbreak();
         }
     })
 }
diff --git a/src/library/pad.rs b/src/library/pad.rs
index d6b69007..7c422239 100644
--- a/src/library/pad.rs
+++ b/src/library/pad.rs
@@ -32,6 +32,6 @@ pub fn pad(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
 
     Value::template("pad", move |ctx| {
         let child = ctx.exec_group(&body).into();
-        ctx.push_into_par(PadNode { padding, child });
+        ctx.push(PadNode { padding, child });
     })
 }
diff --git a/src/library/page.rs b/src/library/page.rs
index fb3542ed..7b8557be 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -83,13 +83,13 @@ pub fn page(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
             std::mem::swap(&mut page.size.width, &mut page.size.height);
         }
 
-        ctx.finish_page(false, true, span);
+        ctx.pagebreak(false, true, span);
 
         if let Some(body) = &body {
             // TODO: Restrict body to a single page?
             body.exec(ctx);
             ctx.state = snapshot;
-            ctx.finish_page(true, false, span);
+            ctx.pagebreak(true, false, span);
         }
     })
 }
@@ -101,6 +101,6 @@ pub fn page(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
 pub fn pagebreak(_: &mut EvalContext, args: &mut FuncArgs) -> Value {
     let span = args.span;
     Value::template("pagebreak", move |ctx| {
-        ctx.finish_page(true, true, span);
+        ctx.pagebreak(true, true, span);
     })
 }
diff --git a/src/library/par.rs b/src/library/par.rs
index cf2549bf..92fc20e8 100644
--- a/src/library/par.rs
+++ b/src/library/par.rs
@@ -27,6 +27,6 @@ pub fn par(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
             ctx.state.par.word_spacing = word_spacing;
         }
 
-        ctx.push_parbreak();
+        ctx.parbreak();
     })
 }
diff --git a/src/library/shapes.rs b/src/library/shapes.rs
index 6f9e6677..6c6a2f0b 100644
--- a/src/library/shapes.rs
+++ b/src/library/shapes.rs
@@ -63,13 +63,13 @@ fn rect_impl(
         let node = FixedNode { width, height, aspect, child };
 
         if let Some(color) = fill {
-            ctx.push_into_par(BackgroundNode {
+            ctx.push(BackgroundNode {
                 shape: BackgroundShape::Rect,
                 fill: Fill::Color(color),
                 child: node.into(),
             });
         } else {
-            ctx.push_into_par(node);
+            ctx.push(node);
         }
     })
 }
@@ -146,13 +146,13 @@ fn ellipse_impl(
         };
 
         if let Some(color) = fill {
-            ctx.push_into_par(BackgroundNode {
+            ctx.push(BackgroundNode {
                 shape: BackgroundShape::Ellipse,
                 fill: Fill::Color(color),
                 child: node.into(),
             });
         } else {
-            ctx.push_into_par(node);
+            ctx.push(node);
         }
     })
 }
diff --git a/src/library/spacing.rs b/src/library/spacing.rs
index 6a67a653..36cd88fb 100644
--- a/src/library/spacing.rs
+++ b/src/library/spacing.rs
@@ -32,7 +32,7 @@ fn spacing_impl(
     Value::template(name, move |ctx| {
         if let Some(linear) = spacing {
             let amount = linear.resolve(ctx.state.font.resolve_size());
-            ctx.push_spacing(axis, amount, 0);
+            ctx.push_spacing(axis, amount);
         }
     })
 }