Counters

9 files changed, 171 insertions, 85 deletions

diff --git a/library/src/layout/container.rs b/library/src/layout/container.rs
index a48933a7..0b7f7eb1 100644
--- a/library/src/layout/container.rs
+++ b/library/src/layout/container.rs
@@ -145,7 +145,7 @@ impl Layout for BoxNode {
         }
 
         // Apply metadata.
-        frame.meta(styles);
+        frame.meta(styles, false);
 
         Ok(Fragment::frame(frame))
     }
@@ -336,7 +336,7 @@ impl Layout for BlockNode {
             // Measure to ensure frames for all regions have the same width.
             if sizing.x == Smart::Auto {
                 let pod = Regions::one(size, Axes::splat(false));
-                let frame = body.layout(vt, styles, pod)?.into_frame();
+                let frame = body.measure(vt, styles, pod)?.into_frame();
                 size.x = frame.width();
                 expand.x = true;
             }
@@ -389,7 +389,7 @@ impl Layout for BlockNode {
 
         // Apply metadata.
         for frame in &mut frames {
-            frame.meta(styles);
+            frame.meta(styles, false);
         }
 
         Ok(Fragment::frames(frames))
diff --git a/library/src/layout/enum.rs b/library/src/layout/enum.rs
index 33b297e7..1c08cd5f 100644
--- a/library/src/layout/enum.rs
+++ b/library/src/layout/enum.rs
@@ -100,7 +100,7 @@ pub struct EnumNode {
     ///   [Ahead],
     /// )
     /// ```
-    #[default(NonZeroUsize::new(1).unwrap())]
+    #[default(NonZeroUsize::ONE)]
     pub start: NonZeroUsize,
 
     /// Whether to display the full numbering, including the numbers of
@@ -180,7 +180,7 @@ impl Layout for EnumNode {
 
             let resolved = if full {
                 parents.push(number);
-                let content = numbering.apply(vt.world(), &parents)?.display();
+                let content = numbering.apply(vt.world, &parents)?.display();
                 parents.pop();
                 content
             } else {
@@ -188,7 +188,7 @@ impl Layout for EnumNode {
                     Numbering::Pattern(pattern) => {
                         TextNode::packed(pattern.apply_kth(parents.len(), number))
                     }
-                    other => other.apply(vt.world(), &[number])?.display(),
+                    other => other.apply(vt.world, &[number])?.display(),
                 }
             };
 
diff --git a/library/src/layout/flow.rs b/library/src/layout/flow.rs
index 2671b983..096c575e 100644
--- a/library/src/layout/flow.rs
+++ b/library/src/layout/flow.rs
@@ -47,7 +47,16 @@ impl Layout for FlowNode {
                 || child.is::<CircleNode>()
                 || child.is::<ImageNode>()
             {
-                layouter.layout_single(vt, &child, styles)?;
+                let layoutable = child.with::<dyn Layout>().unwrap();
+                layouter.layout_single(vt, layoutable, styles)?;
+            } else if child.is::<MetaNode>() {
+                let mut frame = Frame::new(Size::zero());
+                frame.meta(styles, true);
+                layouter.items.push(FlowItem::Frame(
+                    frame,
+                    Axes::new(Align::Top, Align::Left),
+                    true,
+                ));
             } else if child.can::<dyn Layout>() {
                 layouter.layout_multiple(vt, &child, styles)?;
             } else if child.is::<ColbreakNode>() {
@@ -173,14 +182,13 @@ impl<'a> FlowLayouter<'a> {
     fn layout_single(
         &mut self,
         vt: &mut Vt,
-        content: &Content,
+        content: &dyn Layout,
         styles: StyleChain,
     ) -> SourceResult<()> {
         let aligns = AlignNode::alignment_in(styles).resolve(styles);
         let sticky = BlockNode::sticky_in(styles);
         let pod = Regions::one(self.regions.base(), Axes::splat(false));
-        let layoutable = content.with::<dyn Layout>().unwrap();
-        let frame = layoutable.layout(vt, styles, pod)?.into_frame();
+        let frame = content.layout(vt, styles, pod)?.into_frame();
         self.layout_item(FlowItem::Frame(frame, aligns, sticky));
         self.last_was_par = false;
         Ok(())
diff --git a/library/src/layout/grid.rs b/library/src/layout/grid.rs
index b6e86afd..47d3ab86 100644
--- a/library/src/layout/grid.rs
+++ b/library/src/layout/grid.rs
@@ -386,7 +386,7 @@ impl<'a, 'v> GridLayouter<'a, 'v> {
 
                     let size = Size::new(available, height);
                     let pod = Regions::one(size, Axes::splat(false));
-                    let frame = cell.layout(self.vt, self.styles, pod)?.into_frame();
+                    let frame = cell.measure(self.vt, self.styles, pod)?.into_frame();
                     resolved.set_max(frame.width());
                 }
             }
@@ -457,7 +457,7 @@ impl<'a, 'v> GridLayouter<'a, 'v> {
                 let mut pod = self.regions;
                 pod.size.x = rcol;
 
-                let frames = cell.layout(self.vt, self.styles, pod)?.into_frames();
+                let frames = cell.measure(self.vt, self.styles, pod)?.into_frames();
                 if let [first, rest @ ..] = frames.as_slice() {
                     skip |=
                         first.is_empty() && rest.iter().any(|frame| !frame.is_empty());
diff --git a/library/src/layout/list.rs b/library/src/layout/list.rs
index 6d605868..c954ab67 100644
--- a/library/src/layout/list.rs
+++ b/library/src/layout/list.rs
@@ -128,7 +128,7 @@ impl Layout for ListNode {
         };
 
         let depth = self.depth(styles);
-        let marker = self.marker(styles).resolve(vt.world(), depth)?;
+        let marker = self.marker(styles).resolve(vt.world, depth)?;
 
         let mut cells = vec![];
         for item in self.children() {
diff --git a/library/src/layout/mod.rs b/library/src/layout/mod.rs
index eb440b7f..fc0279eb 100644
--- a/library/src/layout/mod.rs
+++ b/library/src/layout/mod.rs
@@ -47,10 +47,7 @@ use std::mem;
 
 use typed_arena::Arena;
 use typst::diag::SourceResult;
-use typst::model::{
-    applicable, realize, Content, Node, SequenceNode, StyleChain, StyleVecBuilder,
-    StyledNode,
-};
+use typst::model::{applicable, realize, SequenceNode, StyleVecBuilder, StyledNode};
 
 use crate::math::{FormulaNode, LayoutMath};
 use crate::meta::DocumentNode;
@@ -103,6 +100,22 @@ pub trait Layout {
         styles: StyleChain,
         regions: Regions,
     ) -> SourceResult<Fragment>;
+
+    /// Layout without side effects.
+    ///
+    /// This node must be layouted again in the same order for the results to be
+    /// valid.
+    fn measure(
+        &self,
+        vt: &mut Vt,
+        styles: StyleChain,
+        regions: Regions,
+    ) -> SourceResult<Fragment> {
+        vt.provider.save();
+        let result = self.layout(vt, styles, regions);
+        vt.provider.restore();
+        result
+    }
 }
 
 impl Layout for Content {
@@ -417,7 +430,10 @@ impl<'a> FlowBuilder<'a> {
         let last_was_parbreak = self.1;
         self.1 = false;
 
-        if content.is::<VNode>() || content.is::<ColbreakNode>() {
+        if content.is::<VNode>()
+            || content.is::<ColbreakNode>()
+            || content.is::<MetaNode>()
+        {
             self.0.push(content.clone(), styles);
             return true;
         }
@@ -457,7 +473,12 @@ struct ParBuilder<'a>(BehavedBuilder<'a>);
 
 impl<'a> ParBuilder<'a> {
     fn accept(&mut self, content: &'a Content, styles: StyleChain<'a>) -> bool {
-        if content.is::<SpaceNode>()
+        if content.is::<MetaNode>() {
+            if !self.0.is_basically_empty() {
+                self.0.push(content.clone(), styles);
+                return true;
+            }
+        } else if content.is::<SpaceNode>()
             || content.is::<TextNode>()
             || content.is::<HNode>()
             || content.is::<LinebreakNode>()
diff --git a/library/src/layout/page.rs b/library/src/layout/page.rs
index e469bf10..8ad76387 100644
--- a/library/src/layout/page.rs
+++ b/library/src/layout/page.rs
@@ -1,6 +1,8 @@
+use std::ptr;
 use std::str::FromStr;
 
-use super::ColumnsNode;
+use super::{AlignNode, ColumnsNode};
+use crate::meta::{Counter, CounterAction, CounterNode, Numbering};
 use crate::prelude::*;
 
 /// Layouts its child onto one or multiple pages.
@@ -130,7 +132,7 @@ pub struct PageNode {
     /// emissions and mitigate the impacts
     /// of a rapidly changing climate.
     /// ```
-    #[default(NonZeroUsize::new(1).unwrap())]
+    #[default(NonZeroUsize::ONE)]
     pub columns: NonZeroUsize,
 
     /// The page's background color.
@@ -147,49 +149,84 @@ pub struct PageNode {
     /// ```
     pub fill: Option<Paint>,
 
-    /// The page's header.
+    /// How to [number]($func/numbering) the pages.
     ///
-    /// The header is placed in the top margin of each page.
+    /// If an explicit `footer` is given, the numbering is ignored.
     ///
-    /// - Content: The content will be placed in the header.
-    /// - A function: The function will be called with the page number (starting
-    ///   at one) as its only argument. The content it returns will be placed in
-    ///   the header.
-    /// - `{none}`: The header will be empty.
+    /// ```example
+    /// #set page(
+    ///   height: 100pt,
+    ///   margin: (top: 16pt, bottom: 24pt),
+    ///   numbering: "1 / 1",
+    /// )
+    ///
+    /// #lorem(48)
+    /// ```
+    pub numbering: Option<Numbering>,
+
+    /// The alignment of the page numbering.
     ///
     /// ```example
-    /// #set par(justify: true)
     /// #set page(
-    ///   margin: (x: 24pt, y: 32pt),
-    ///   header: align(horizon + right, text(8pt)[_Exercise Sheet 3_]),
+    ///   margin: (top: 16pt, bottom: 24pt),
+    ///   numbering: "1",
+    ///   number-align: right,
     /// )
     ///
-    /// #lorem(18)
+    /// #lorem(30)
     /// ```
-    pub header: Option<Marginal>,
+    #[default(Align::Center.into())]
+    pub number_align: Axes<Option<GenAlign>>,
 
-    /// The page's footer.
+    /// The page's header. Fills the top margin of each page.
     ///
-    /// The footer is placed in the bottom margin of each page.
+    /// ```example
+    /// #set par(justify: true)
+    /// #set page(
+    ///   margin: (top: 32pt, bottom: 20pt),
+    ///   header: [
+    ///     #set text(8pt)
+    ///     #smallcaps[Typst Academcy]
+    ///     #h(1fr) _Exercise Sheet 3_
+    ///   ],
+    /// )
     ///
-    /// - Content: The content will be placed in the footer.
-    /// - A function: The function will be called with the page number (starting
-    ///   at one) as its only argument. The content it returns will be placed in
-    ///   the footer.
-    /// - `{none}`: The footer will be empty.
+    /// #lorem(19)
+    /// ```
+    pub header: Option<Content>,
+
+    /// The amount the header is raised into the top margin.
+    #[resolve]
+    #[default(Ratio::new(0.3).into())]
+    pub header_ascent: Rel<Length>,
+
+    /// The page's footer. Fills the bottom margin of each page.
+    ///
+    /// For just a page number, the `numbering` property, typically suffices. If
+    /// you want to create a custom footer, but still display the page number,
+    /// you can directly access the [page counter]($func/counter).
     ///
     /// ```example
     /// #set par(justify: true)
     /// #set page(
-    ///   margin: (x: 24pt, y: 32pt),
-    ///   footer: i => align(horizon + right,
-    ///     text(8pt, numbering("I", i))
-    ///   )
+    ///   height: 100pt,
+    ///   margin: 20pt,
+    ///   footer: [
+    ///     #set align(right)
+    ///     #set text(8pt)
+    ///     #counter(page).get("1") of
+    ///     #counter(page).final("I")
+    ///   ]
     /// )
     ///
-    /// #lorem(18)
+    /// #lorem(48)
     /// ```
-    pub footer: Option<Marginal>,
+    pub footer: Option<Content>,
+
+    /// The amount the footer is lowered into the bottom margin.
+    #[resolve]
+    #[default(Ratio::new(0.3).into())]
+    pub footer_descent: Rel<Length>,
 
     /// Content in the page's background.
     ///
@@ -197,35 +234,30 @@ pub struct PageNode {
     /// used to place a background image or a watermark.
     ///
     /// ```example
-    /// #set page(background: align(
-    ///   center + horizon,
-    ///   rotate(24deg,
-    ///     text(18pt, fill: rgb("FFCBC4"))[*CONFIDENTIAL*]
-    ///   ),
+    /// #set page(background: rotate(24deg,
+    ///   text(18pt, fill: rgb("FFCBC4"))[
+    ///     *CONFIDENTIAL*
+    ///   ]
     /// ))
     ///
     /// = Typst's secret plans
-    ///
-    /// In the year 2023, we plan to take over the world
-    /// (of typesetting).
+    /// In the year 2023, we plan to take
+    /// over the world (of typesetting).
     /// ```
-    pub background: Option<Marginal>,
+    pub background: Option<Content>,
 
     /// Content in the page's foreground.
     ///
     /// This content will overlay the page's body.
     ///
     /// ```example
-    /// #set page(foreground: align(
-    ///   center + horizon,
-    ///   text(24pt)[🥸],
-    /// ))
+    /// #set page(foreground: text(24pt)[🥸])
     ///
     /// Reviewer 2 has marked our paper
     /// "Weak Reject" because they did
     /// not understand our approach...
     /// ```
-    pub foreground: Option<Marginal>,
+    pub foreground: Option<Content>,
 
     /// The contents of the page(s).
     ///
@@ -238,12 +270,7 @@ pub struct PageNode {
 
 impl PageNode {
     /// Layout the page run into a sequence of frames, one per page.
-    pub fn layout(
-        &self,
-        vt: &mut Vt,
-        mut page: usize,
-        styles: StyleChain,
-    ) -> SourceResult<Fragment> {
+    pub fn layout(&self, vt: &mut Vt, styles: StyleChain) -> SourceResult<Fragment> {
         // When one of the lengths is infinite the page fits its content along
         // that axis.
         let width = self.width(styles).unwrap_or(Abs::inf());
@@ -278,10 +305,18 @@ impl PageNode {
         let mut fragment = child.layout(vt, styles, regions)?;
 
         let fill = self.fill(styles);
-        let header = self.header(styles);
-        let footer = self.footer(styles);
         let foreground = self.foreground(styles);
         let background = self.background(styles);
+        let header = self.header(styles);
+        let header_ascent = self.header_ascent(styles);
+        let footer = self.footer(styles).or_else(|| {
+            self.numbering(styles).map(|numbering| {
+                CounterNode::new(Counter::Page, CounterAction::Both(numbering))
+                    .pack()
+                    .aligned(self.number_align(styles))
+            })
+        });
+        let footer_descent = self.footer_descent(styles);
 
         // Realize overlays.
         for frame in &mut fragment {
@@ -292,26 +327,38 @@ impl PageNode {
             let size = frame.size();
             let pad = padding.resolve(styles).relative_to(size);
             let pw = size.x - pad.left - pad.right;
-            let py = size.y - pad.bottom;
-            for (marginal, pos, area) in [
-                (&header, Point::with_x(pad.left), Size::new(pw, pad.top)),
-                (&footer, Point::new(pad.left, py), Size::new(pw, pad.bottom)),
-                (&foreground, Point::zero(), size),
-                (&background, Point::zero(), size),
-            ] {
-                let in_background = std::ptr::eq(marginal, &background);
-                let Some(marginal) = marginal else { continue };
-                let content = marginal.resolve(vt, page)?;
+            for marginal in [&header, &footer, &background, &foreground] {
+                let Some(content) = marginal else { continue };
+
+                let (pos, area, align);
+                if ptr::eq(marginal, &header) {
+                    let ascent = header_ascent.relative_to(pad.top);
+                    pos = Point::with_x(pad.left);
+                    area = Size::new(pw, pad.top - ascent);
+                    align = Align::Bottom.into();
+                } else if ptr::eq(marginal, &footer) {
+                    let descent = footer_descent.relative_to(pad.bottom);
+                    pos = Point::new(pad.left, size.y - pad.bottom + descent);
+                    area = Size::new(pw, pad.bottom - descent);
+                    align = Align::Top.into();
+                } else {
+                    pos = Point::zero();
+                    area = size;
+                    align = Align::CENTER_HORIZON.into();
+                };
+
                 let pod = Regions::one(area, Axes::splat(true));
-                let sub = content.layout(vt, styles, pod)?.into_frame();
-                if in_background {
+                let sub = content
+                    .clone()
+                    .styled(AlignNode::set_alignment(align))
+                    .layout(vt, styles, pod)?
+                    .into_frame();
+                if ptr::eq(marginal, &header) || ptr::eq(marginal, &background) {
                     frame.prepend_frame(pos, sub);
                 } else {
                     frame.push_frame(pos, sub);
                 }
             }
-
-            page += 1;
         }
 
         Ok(fragment)
@@ -358,7 +405,7 @@ impl Marginal {
             Self::Content(content) => content.clone(),
             Self::Func(func) => {
                 let args = Args::new(func.span(), [Value::Int(page as i64)]);
-                func.call_detached(vt.world(), args)?.display()
+                func.call_detached(vt.world, args)?.display()
             }
         })
     }
diff --git a/library/src/layout/par.rs b/library/src/layout/par.rs
index 244a61a9..1906dd7c 100644
--- a/library/src/layout/par.rs
+++ b/library/src/layout/par.rs
@@ -325,6 +325,8 @@ enum Segment<'a> {
     Formula(&'a FormulaNode),
     /// A box with arbitrary content.
     Box(&'a BoxNode, bool),
+    /// Metadata.
+    Meta,
 }
 
 impl Segment<'_> {
@@ -334,7 +336,7 @@ impl Segment<'_> {
             Self::Text(len) => len,
             Self::Spacing(_) => SPACING_REPLACE.len_utf8(),
             Self::Box(_, true) => SPACING_REPLACE.len_utf8(),
-            Self::Formula(_) | Self::Box(_, _) => NODE_REPLACE.len_utf8(),
+            Self::Formula(_) | Self::Box(_, _) | Self::Meta => NODE_REPLACE.len_utf8(),
         }
     }
 }
@@ -599,6 +601,9 @@ fn collect<'a>(
             let frac = node.width(styles).is_fractional();
             full.push(if frac { SPACING_REPLACE } else { NODE_REPLACE });
             Segment::Box(node, frac)
+        } else if child.is::<MetaNode>() {
+            full.push(NODE_REPLACE);
+            Segment::Meta
         } else {
             bail!(child.span(), "unexpected paragraph child");
         };
@@ -679,6 +684,11 @@ fn prepare<'a>(
                     items.push(Item::Frame(frame));
                 }
             }
+            Segment::Meta => {
+                let mut frame = Frame::new(Size::zero());
+                frame.meta(styles, true);
+                items.push(Item::Frame(frame));
+            }
         }
 
         cursor = end;
diff --git a/library/src/layout/table.rs b/library/src/layout/table.rs
index 6daafdbb..024bb0d6 100644
--- a/library/src/layout/table.rs
+++ b/library/src/layout/table.rs
@@ -233,7 +233,7 @@ impl<T: Cast + Clone> Celled<T> {
             Self::Func(func) => {
                 let args =
                     Args::new(func.span(), [Value::Int(x as i64), Value::Int(y as i64)]);
-                func.call_detached(vt.world(), args)?.cast().at(func.span())?
+                func.call_detached(vt.world, args)?.cast().at(func.span())?
             }
         })
     }