Simplify node construction

12 files changed, 78 insertions, 128 deletions

diff --git a/src/eval/template.rs b/src/eval/template.rs
index b1559b8f..42c93b56 100644
--- a/src/eval/template.rs
+++ b/src/eval/template.rs
@@ -1,5 +1,6 @@
 use std::convert::TryFrom;
 use std::fmt::{self, Debug, Formatter};
+use std::hash::Hash;
 use std::mem;
 use std::ops::{Add, AddAssign};
 use std::rc::Rc;
@@ -8,8 +9,8 @@ use super::Str;
 use crate::diag::StrResult;
 use crate::geom::{Align, Dir, GenAxis, Length, Linear, Sides, Size};
 use crate::layout::{
-    BlockNode, Decoration, InlineNode, PadNode, PageNode, ParChild, ParNode, Spacing,
-    StackChild, StackNode,
+    BlockLevel, BlockNode, Decoration, InlineLevel, InlineNode, PadNode, PageNode,
+    ParChild, ParNode, Spacing, StackChild, StackNode,
 };
 use crate::style::Style;
 use crate::util::EcoString;
@@ -57,9 +58,9 @@ impl Template {
     pub fn from_inline<F, T>(f: F) -> Self
     where
         F: Fn(&Style) -> T + 'static,
-        T: Into<InlineNode>,
+        T: InlineLevel + Hash + 'static,
     {
-        let node = TemplateNode::Inline(Rc::new(move |s| f(s).into()));
+        let node = TemplateNode::Inline(Rc::new(move |s| f(s).pack()));
         Self(Rc::new(vec![node]))
     }
 
@@ -67,9 +68,9 @@ impl Template {
     pub fn from_block<F, T>(f: F) -> Self
     where
         F: Fn(&Style) -> T + 'static,
-        T: Into<BlockNode>,
+        T: BlockLevel + Hash + 'static,
     {
-        let node = TemplateNode::Block(Rc::new(move |s| f(s).into()));
+        let node = TemplateNode::Block(Rc::new(move |s| f(s).pack()));
         Self(Rc::new(vec![node]))
     }
 
@@ -396,7 +397,7 @@ impl PageBuilder {
         let Self { size, padding, hard } = self;
         (!child.children.is_empty() || (keep && hard)).then(|| PageNode {
             size,
-            child: PadNode { padding, child: child.into() }.into(),
+            child: PadNode { padding, child: child.pack() }.pack(),
         })
     }
 }
@@ -502,7 +503,7 @@ impl ParBuilder {
     fn build(self) -> Option<StackChild> {
         let Self { align, dir, leading, children, .. } = self;
         (!children.is_empty())
-            .then(|| StackChild::Node(ParNode { dir, leading, children }.into(), align))
+            .then(|| StackChild::Node(ParNode { dir, leading, children }.pack(), align))
     }
 }
 
diff --git a/src/eval/walk.rs b/src/eval/walk.rs
index 9dd7cd2e..cd9809a2 100644
--- a/src/eval/walk.rs
+++ b/src/eval/walk.rs
@@ -3,7 +3,7 @@ use std::rc::Rc;
 use super::{Eval, EvalContext, Str, Template, Value};
 use crate::diag::TypResult;
 use crate::geom::Align;
-use crate::layout::{ParChild, ParNode, Spacing, StackChild, StackNode};
+use crate::layout::{BlockLevel, ParChild, ParNode, Spacing, StackChild, StackNode};
 use crate::syntax::*;
 use crate::util::BoolExt;
 
@@ -118,9 +118,9 @@ fn walk_item(ctx: &mut EvalContext, label: Str, body: Template) {
         StackNode {
             dir: style.dir,
             children: vec![
-                StackChild::Node(label.into(), Align::Start),
+                StackChild::Node(label.pack(), Align::Start),
                 StackChild::Spacing(Spacing::Linear((style.text.size / 2.0).into())),
-                StackChild::Node(body.to_stack(&style).into(), Align::Start),
+                StackChild::Node(body.to_stack(&style).pack(), Align::Start),
             ],
         }
     });
diff --git a/src/layout/grid.rs b/src/layout/grid.rs
index 7220d7c2..57986b48 100644
--- a/src/layout/grid.rs
+++ b/src/layout/grid.rs
@@ -1,8 +1,7 @@
 use super::*;
 
 /// A node that arranges its children in a grid.
-#[derive(Debug)]
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Debug, Hash)]
 pub struct GridNode {
     /// Defines sizing for content rows and columns.
     pub tracks: Spec<Vec<TrackSizing>>,
@@ -40,12 +39,6 @@ impl BlockLevel for GridNode {
     }
 }
 
-impl From<GridNode> for BlockNode {
-    fn from(node: GridNode) -> Self {
-        Self::new(node)
-    }
-}
-
 /// Performs grid layout.
 struct GridLayouter<'a> {
     /// The original expand state of the target region.
diff --git a/src/layout/image.rs b/src/layout/image.rs
index 59b4c6ef..b410895b 100644
--- a/src/layout/image.rs
+++ b/src/layout/image.rs
@@ -2,8 +2,7 @@ use super::*;
 use crate::image::ImageId;
 
 /// An image node.
-#[derive(Debug)]
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Debug, Hash)]
 pub struct ImageNode {
     /// The id of the image file.
     pub id: ImageId,
@@ -43,9 +42,3 @@ impl InlineLevel for ImageNode {
         frame
     }
 }
-
-impl From<ImageNode> for InlineNode {
-    fn from(node: ImageNode) -> Self {
-        Self::new(node)
-    }
-}
diff --git a/src/layout/mod.rs b/src/layout/mod.rs
index 651daa21..ffbf2668 100644
--- a/src/layout/mod.rs
+++ b/src/layout/mod.rs
@@ -29,6 +29,7 @@ pub use stack::*;
 pub use text::*;
 
 use std::fmt::{self, Debug, Formatter};
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 use crate::font::FontStore;
@@ -37,13 +38,6 @@ use crate::image::ImageStore;
 use crate::util::OptionExt;
 use crate::Context;
 
-#[cfg(feature = "layout-cache")]
-use {
-    fxhash::FxHasher64,
-    std::any::Any,
-    std::hash::{Hash, Hasher},
-};
-
 /// Layout a page-level node into a collection of frames.
 pub fn layout<T>(ctx: &mut Context, node: &T) -> Vec<Rc<Frame>>
 where
@@ -129,9 +123,21 @@ pub trait BlockLevel: Debug {
         ctx: &mut LayoutContext,
         regions: &Regions,
     ) -> Vec<Constrained<Rc<Frame>>>;
+
+    /// Convert to a packed block-level node.
+    fn pack(self) -> BlockNode
+    where
+        Self: Sized + Hash + 'static,
+    {
+        BlockNode {
+            #[cfg(feature = "layout-cache")]
+            hash: hash_node(&self),
+            node: Rc::new(self),
+        }
+    }
 }
 
-/// A dynamic [block-level](BlockLevel) layouting node.
+/// A packed [block-level](BlockLevel) layouting node with precomputed hash.
 #[derive(Clone)]
 pub struct BlockNode {
     node: Rc<dyn BlockLevel>,
@@ -139,29 +145,6 @@ pub struct BlockNode {
     hash: u64,
 }
 
-impl BlockNode {
-    /// Create a new dynamic node from any block-level node.
-    #[cfg(not(feature = "layout-cache"))]
-    pub fn new<T>(node: T) -> Self
-    where
-        T: BlockLevel + 'static,
-    {
-        Self { node: Rc::new(node) }
-    }
-
-    /// Create a new dynamic node from any block-level node.
-    #[cfg(feature = "layout-cache")]
-    pub fn new<T>(node: T) -> Self
-    where
-        T: BlockLevel + Hash + 'static,
-    {
-        Self {
-            hash: hash_node(&node),
-            node: Rc::new(node),
-        }
-    }
-}
-
 impl BlockLevel for BlockNode {
     fn layout(
         &self,
@@ -194,12 +177,21 @@ impl BlockLevel for BlockNode {
             frames
         })
     }
+
+    fn pack(self) -> BlockNode
+    where
+        Self: Sized + Hash + 'static,
+    {
+        self
+    }
 }
 
-#[cfg(feature = "layout-cache")]
 impl Hash for BlockNode {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        state.write_u64(self.hash);
+    fn hash<H: Hasher>(&self, _state: &mut H) {
+        #[cfg(feature = "layout-cache")]
+        _state.write_u64(self.hash);
+        #[cfg(not(feature = "layout-cache"))]
+        unimplemented!()
     }
 }
 
@@ -216,9 +208,21 @@ impl Debug for BlockNode {
 pub trait InlineLevel: Debug {
     /// Layout the node into a frame.
     fn layout(&self, ctx: &mut LayoutContext, space: Length, base: Size) -> Frame;
+
+    /// Convert to a packed inline-level node.
+    fn pack(self) -> InlineNode
+    where
+        Self: Sized + Hash + 'static,
+    {
+        InlineNode {
+            #[cfg(feature = "layout-cache")]
+            hash: hash_node(&self),
+            node: Rc::new(self),
+        }
+    }
 }
 
-/// A dynamic [inline-level](InlineLevel) layouting node.
+/// A packed [inline-level](InlineLevel) layouting node with precomputed hash.
 #[derive(Clone)]
 pub struct InlineNode {
     node: Rc<dyn InlineLevel>,
@@ -226,39 +230,25 @@ pub struct InlineNode {
     hash: u64,
 }
 
-impl InlineNode {
-    /// Create a new dynamic node from any inline-level node.
-    #[cfg(not(feature = "layout-cache"))]
-    pub fn new<T>(node: T) -> Self
-    where
-        T: InlineLevel + 'static,
-    {
-        Self { node: Rc::new(node) }
+impl InlineLevel for InlineNode {
+    fn layout(&self, ctx: &mut LayoutContext, space: Length, base: Size) -> Frame {
+        self.node.layout(ctx, space, base)
     }
 
-    /// Create a new dynamic node from any inline-level node.
-    #[cfg(feature = "layout-cache")]
-    pub fn new<T>(node: T) -> Self
+    fn pack(self) -> InlineNode
     where
-        T: InlineLevel + Hash + 'static,
+        Self: Sized + Hash + 'static,
     {
-        Self {
-            hash: hash_node(&node),
-            node: Rc::new(node),
-        }
-    }
-}
-
-impl InlineLevel for InlineNode {
-    fn layout(&self, ctx: &mut LayoutContext, space: Length, base: Size) -> Frame {
-        self.node.layout(ctx, space, base)
+        self
     }
 }
 
-#[cfg(feature = "layout-cache")]
 impl Hash for InlineNode {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        state.write_u64(self.hash);
+    fn hash<H: Hasher>(&self, _state: &mut H) {
+        #[cfg(feature = "layout-cache")]
+        _state.write_u64(self.hash);
+        #[cfg(not(feature = "layout-cache"))]
+        unimplemented!()
     }
 }
 
@@ -271,7 +261,8 @@ impl Debug for InlineNode {
 /// Hash a node alongside its type id.
 #[cfg(feature = "layout-cache")]
 fn hash_node(node: &(impl Hash + 'static)) -> u64 {
-    let mut state = FxHasher64::default();
+    use std::any::Any;
+    let mut state = fxhash::FxHasher64::default();
     node.type_id().hash(&mut state);
     node.hash(&mut state);
     state.finish()
diff --git a/src/layout/pad.rs b/src/layout/pad.rs
index 20fcc161..55c11e45 100644
--- a/src/layout/pad.rs
+++ b/src/layout/pad.rs
@@ -1,8 +1,7 @@
 use super::*;
 
 /// A node that adds padding to its child.
-#[derive(Debug)]
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Debug, Hash)]
 pub struct PadNode {
     /// The amount of padding.
     pub padding: Sides<Linear>,
@@ -74,9 +73,3 @@ impl BlockLevel for PadNode {
         frames
     }
 }
-
-impl From<PadNode> for BlockNode {
-    fn from(node: PadNode) -> Self {
-        Self::new(node)
-    }
-}
diff --git a/src/layout/par.rs b/src/layout/par.rs
index 64265b63..a645eb07 100644
--- a/src/layout/par.rs
+++ b/src/layout/par.rs
@@ -12,8 +12,7 @@ use crate::util::{EcoString, RangeExt, SliceExt};
 type Range = std::ops::Range<usize>;
 
 /// A node that arranges its children into a paragraph.
-#[derive(Debug)]
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Debug, Hash)]
 pub struct ParNode {
     /// The inline direction of this paragraph.
     pub dir: Dir,
@@ -24,7 +23,7 @@ pub struct ParNode {
 }
 
 /// A child of a paragraph node.
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Hash)]
 pub enum ParChild {
     /// Spacing between other nodes.
     Spacing(Spacing),
@@ -93,12 +92,6 @@ impl ParNode {
     }
 }
 
-impl From<ParNode> for BlockNode {
-    fn from(node: ParNode) -> Self {
-        Self::new(node)
-    }
-}
-
 impl Debug for ParChild {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match self {
diff --git a/src/layout/shape.rs b/src/layout/shape.rs
index 2e66a0dd..ed70dd95 100644
--- a/src/layout/shape.rs
+++ b/src/layout/shape.rs
@@ -4,8 +4,7 @@ use super::*;
 use crate::util::RcExt;
 
 /// Places its child into a sizable and fillable shape.
-#[derive(Debug)]
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Debug, Hash)]
 pub struct ShapeNode {
     /// Which shape to place the child into.
     pub shape: ShapeKind,
@@ -105,9 +104,3 @@ impl InlineLevel for ShapeNode {
         frame
     }
 }
-
-impl From<ShapeNode> for InlineNode {
-    fn from(node: ShapeNode) -> Self {
-        Self::new(node)
-    }
-}
diff --git a/src/layout/stack.rs b/src/layout/stack.rs
index dbd9ddb0..0fb3e3eb 100644
--- a/src/layout/stack.rs
+++ b/src/layout/stack.rs
@@ -3,8 +3,7 @@ use std::fmt::{self, Debug, Formatter};
 use super::*;
 
 /// A node that stacks its children.
-#[derive(Debug)]
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Debug, Hash)]
 pub struct StackNode {
     /// The stacking direction.
     pub dir: Dir,
@@ -13,7 +12,7 @@ pub struct StackNode {
 }
 
 /// A child of a stack node.
-#[cfg_attr(feature = "layout-cache", derive(Hash))]
+#[derive(Hash)]
 pub enum StackChild {
     /// Spacing between other nodes.
     Spacing(Spacing),
@@ -31,12 +30,6 @@ impl BlockLevel for StackNode {
     }
 }
 
-impl From<StackNode> for BlockNode {
-    fn from(node: StackNode) -> Self {
-        Self::new(node)
-    }
-}
-
 impl Debug for StackChild {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match self {
diff --git a/src/library/elements.rs b/src/library/elements.rs
index cd8a6f88..01efb405 100644
--- a/src/library/elements.rs
+++ b/src/library/elements.rs
@@ -99,6 +99,6 @@ fn shape_impl(
         fill: Some(Paint::Color(
             fill.unwrap_or(Color::Rgba(RgbaColor::new(175, 175, 175, 255))),
         )),
-        child: body.as_ref().map(|template| template.to_stack(style).into()),
+        child: body.as_ref().map(|template| template.to_stack(style).pack()),
     }))
 }
diff --git a/src/library/layout.rs b/src/library/layout.rs
index 4ef0926f..f7fb2882 100644
--- a/src/library/layout.rs
+++ b/src/library/layout.rs
@@ -154,7 +154,7 @@ pub fn boxed(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
             width,
             height,
             fill: fill.map(Paint::Color),
-            child: Some(body.to_stack(style).into()),
+            child: Some(body.to_stack(style).pack()),
         }
     })))
 }
@@ -186,7 +186,7 @@ pub fn pad(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     Ok(Value::Template(Template::from_block(move |style| {
         PadNode {
             padding,
-            child: body.to_stack(&style).into(),
+            child: body.to_stack(&style).pack(),
         }
     })))
 }
@@ -227,7 +227,7 @@ pub fn stack(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
                         children.push(StackChild::Spacing(v));
                     }
 
-                    let node = template.to_stack(style).into();
+                    let node = template.to_stack(style).pack();
                     children.push(StackChild::Node(node, style.aligns.block));
                     delayed = spacing;
                 }
@@ -283,7 +283,7 @@ pub fn grid(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
             gutter: gutter.clone(),
             children: children
                 .iter()
-                .map(|child| child.to_stack(&style).into())
+                .map(|child| child.to_stack(&style).pack())
                 .collect(),
         }
     })))
diff --git a/src/library/mod.rs b/src/library/mod.rs
index 6f8881c3..ac2085eb 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -20,7 +20,7 @@ use crate::diag::{At, TypResult};
 use crate::eval::{Args, Array, EvalContext, Scope, Str, Template, Value};
 use crate::font::{FontFamily, FontStretch, FontStyle, FontWeight, VerticalFontMetric};
 use crate::geom::*;
-use crate::layout::Spacing;
+use crate::layout::{BlockLevel, Spacing};
 use crate::style::Style;
 use crate::syntax::{Span, Spanned};