Split up some files

1 files changed, 484 insertions, 0 deletions

diff --git a/src/model/realize.rs b/src/model/realize.rs
new file mode 100644
index 00000000..895c4f33
--- /dev/null
+++ b/src/model/realize.rs
@@ -0,0 +1,484 @@
+use std::mem;
+
+use comemo::Tracked;
+use typed_arena::Arena;
+
+use super::{
+    Barrier, CollapsingBuilder, Content, Interruption, Layout, ShowNode, StyleChain,
+    StyleEntry, StyleMap, StyleVecBuilder, Target,
+};
+use crate::diag::SourceResult;
+use crate::geom::Numeric;
+use crate::library::layout::{FlowChild, FlowNode, PageNode, PlaceNode};
+use crate::library::structure::{DocNode, ListItem, ListNode, DESC, ENUM, LIST};
+use crate::library::text::{ParChild, ParNode};
+use crate::World;
+
+/// Builds a document or a flow node from content.
+pub(super) struct Builder<'a> {
+    /// The core context.
+    world: Tracked<'a, dyn World>,
+    /// Scratch arenas for building.
+    scratch: &'a Scratch<'a>,
+    /// The current document building state.
+    doc: Option<DocBuilder<'a>>,
+    /// The current flow building state.
+    flow: FlowBuilder<'a>,
+    /// The current paragraph building state.
+    par: ParBuilder<'a>,
+    /// The current list building state.
+    list: ListBuilder<'a>,
+}
+
+/// Temporary storage arenas for building.
+#[derive(Default)]
+pub(super) struct Scratch<'a> {
+    /// An arena where intermediate style chains are stored.
+    styles: Arena<StyleChain<'a>>,
+    /// An arena where intermediate content resulting from show rules is stored.
+    templates: Arena<Content>,
+}
+
+impl<'a> Builder<'a> {
+    pub fn new(
+        world: Tracked<'a, dyn World>,
+        scratch: &'a Scratch<'a>,
+        top: bool,
+    ) -> Self {
+        Self {
+            world,
+            scratch,
+            doc: top.then(|| DocBuilder::default()),
+            flow: FlowBuilder::default(),
+            par: ParBuilder::default(),
+            list: ListBuilder::default(),
+        }
+    }
+
+    pub fn into_doc(
+        mut self,
+        styles: StyleChain<'a>,
+    ) -> SourceResult<(DocNode, StyleChain<'a>)> {
+        self.interrupt(Interruption::Page, styles, true)?;
+        let (pages, shared) = self.doc.unwrap().pages.finish();
+        Ok((DocNode(pages), shared))
+    }
+
+    pub fn into_flow(
+        mut self,
+        styles: StyleChain<'a>,
+    ) -> SourceResult<(FlowNode, StyleChain<'a>)> {
+        self.interrupt(Interruption::Par, styles, false)?;
+        let (children, shared) = self.flow.0.finish();
+        Ok((FlowNode(children), shared))
+    }
+
+    pub fn accept(
+        &mut self,
+        content: &'a Content,
+        styles: StyleChain<'a>,
+    ) -> SourceResult<()> {
+        match content {
+            Content::Empty => return Ok(()),
+            Content::Text(text) => {
+                if let Some(realized) = styles.apply(self.world, Target::Text(text))? {
+                    let stored = self.scratch.templates.alloc(realized);
+                    return self.accept(stored, styles);
+                }
+            }
+
+            Content::Show(node, _) => return self.show(node, styles),
+            Content::Styled(styled) => return self.styled(styled, styles),
+            Content::Sequence(seq) => return self.sequence(seq, styles),
+
+            _ => {}
+        }
+
+        if self.list.accept(content, styles) {
+            return Ok(());
+        }
+
+        self.interrupt(Interruption::List, styles, false)?;
+
+        if let Content::Item(_) = content {
+            self.list.accept(content, styles);
+            return Ok(());
+        }
+
+        if self.par.accept(content, styles) {
+            return Ok(());
+        }
+
+        self.interrupt(Interruption::Par, styles, false)?;
+
+        if self.flow.accept(content, styles) {
+            return Ok(());
+        }
+
+        let keep = matches!(content, Content::Pagebreak { weak: false });
+        self.interrupt(Interruption::Page, styles, keep)?;
+
+        if let Some(doc) = &mut self.doc {
+            doc.accept(content, styles);
+        }
+
+        // We might want to issue a warning or error for content that wasn't
+        // handled (e.g. a pagebreak in a flow building process). However, we
+        // don't have the spans here at the moment.
+        Ok(())
+    }
+
+    fn show(&mut self, node: &ShowNode, styles: StyleChain<'a>) -> SourceResult<()> {
+        if let Some(mut realized) = styles.apply(self.world, Target::Node(node))? {
+            let mut map = StyleMap::new();
+            let barrier = Barrier::new(node.id());
+            map.push(StyleEntry::Barrier(barrier));
+            map.push(StyleEntry::Barrier(barrier));
+            realized = realized.styled_with_map(map);
+            let stored = self.scratch.templates.alloc(realized);
+            self.accept(stored, styles)?;
+        }
+        Ok(())
+    }
+
+    fn styled(
+        &mut self,
+        (content, map): &'a (Content, StyleMap),
+        styles: StyleChain<'a>,
+    ) -> SourceResult<()> {
+        let stored = self.scratch.styles.alloc(styles);
+        let styles = map.chain(stored);
+        let intr = map.interruption();
+
+        if let Some(intr) = intr {
+            self.interrupt(intr, styles, false)?;
+        }
+
+        self.accept(content, styles)?;
+
+        if let Some(intr) = intr {
+            self.interrupt(intr, styles, true)?;
+        }
+
+        Ok(())
+    }
+
+    fn interrupt(
+        &mut self,
+        intr: Interruption,
+        styles: StyleChain<'a>,
+        keep: bool,
+    ) -> SourceResult<()> {
+        if intr >= Interruption::List && !self.list.is_empty() {
+            mem::take(&mut self.list).finish(self)?;
+        }
+
+        if intr >= Interruption::Par {
+            if !self.par.is_empty() {
+                mem::take(&mut self.par).finish(self);
+            }
+        }
+
+        if intr >= Interruption::Page {
+            if let Some(doc) = &mut self.doc {
+                if !self.flow.is_empty() || (doc.keep_next && keep) {
+                    mem::take(&mut self.flow).finish(doc, styles);
+                }
+                doc.keep_next = !keep;
+            }
+        }
+
+        Ok(())
+    }
+
+    fn sequence(
+        &mut self,
+        seq: &'a [Content],
+        styles: StyleChain<'a>,
+    ) -> SourceResult<()> {
+        for content in seq {
+            self.accept(content, styles)?;
+        }
+        Ok(())
+    }
+}
+
+/// Accepts pagebreaks and pages.
+struct DocBuilder<'a> {
+    /// The page runs built so far.
+    pages: StyleVecBuilder<'a, PageNode>,
+    /// Whether to keep a following page even if it is empty.
+    keep_next: bool,
+}
+
+impl<'a> DocBuilder<'a> {
+    fn accept(&mut self, content: &'a Content, styles: StyleChain<'a>) {
+        match content {
+            Content::Pagebreak { weak } => {
+                self.keep_next = !weak;
+            }
+            Content::Page(page) => {
+                self.pages.push(page.clone(), styles);
+                self.keep_next = false;
+            }
+            _ => {}
+        }
+    }
+}
+
+impl Default for DocBuilder<'_> {
+    fn default() -> Self {
+        Self {
+            pages: StyleVecBuilder::new(),
+            keep_next: true,
+        }
+    }
+}
+
+/// Accepts flow content.
+#[derive(Default)]
+struct FlowBuilder<'a>(CollapsingBuilder<'a, FlowChild>);
+
+impl<'a> FlowBuilder<'a> {
+    fn accept(&mut self, content: &'a Content, styles: StyleChain<'a>) -> bool {
+        // Weak flow elements:
+        // Weakness | Element
+        //    0     | weak colbreak
+        //    1     | weak fractional spacing
+        //    2     | weak spacing
+        //    3     | generated weak spacing
+        //    4     | generated weak fractional spacing
+        //    5     | par spacing
+
+        match content {
+            Content::Parbreak => {}
+            Content::Colbreak { weak } => {
+                if *weak {
+                    self.0.weak(FlowChild::Colbreak, styles, 0);
+                } else {
+                    self.0.destructive(FlowChild::Colbreak, styles);
+                }
+            }
+            &Content::Vertical { amount, weak, generated } => {
+                let child = FlowChild::Spacing(amount);
+                let frac = amount.is_fractional();
+                if weak {
+                    let weakness = 1 + u8::from(frac) + 2 * u8::from(generated);
+                    self.0.weak(child, styles, weakness);
+                } else if frac {
+                    self.0.destructive(child, styles);
+                } else {
+                    self.0.ignorant(child, styles);
+                }
+            }
+            Content::Block(node) => {
+                let child = FlowChild::Node(node.clone());
+                if node.is::<PlaceNode>() {
+                    self.0.ignorant(child, styles);
+                } else {
+                    self.0.supportive(child, styles);
+                }
+            }
+            _ => return false,
+        }
+
+        true
+    }
+
+    fn par(&mut self, par: ParNode, styles: StyleChain<'a>, indent: bool) {
+        let amount = if indent && !styles.get(ParNode::SPACING_AND_INDENT) {
+            styles.get(ParNode::LEADING).into()
+        } else {
+            styles.get(ParNode::SPACING).into()
+        };
+
+        self.0.weak(FlowChild::Spacing(amount), styles, 5);
+        self.0.supportive(FlowChild::Node(par.pack()), styles);
+        self.0.weak(FlowChild::Spacing(amount), styles, 5);
+    }
+
+    fn finish(self, doc: &mut DocBuilder<'a>, styles: StyleChain<'a>) {
+        let (flow, shared) = self.0.finish();
+        let styles = if flow.is_empty() { styles } else { shared };
+        let node = PageNode(FlowNode(flow).pack());
+        doc.pages.push(node, styles);
+    }
+
+    fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+/// Accepts paragraph content.
+#[derive(Default)]
+struct ParBuilder<'a>(CollapsingBuilder<'a, ParChild>);
+
+impl<'a> ParBuilder<'a> {
+    fn accept(&mut self, content: &'a Content, styles: StyleChain<'a>) -> bool {
+        // Weak par elements:
+        // Weakness | Element
+        //    0     | weak fractional spacing
+        //    1     | weak spacing
+        //    2     | space
+
+        match content {
+            Content::Space => {
+                self.0.weak(ParChild::Text(' '.into()), styles, 2);
+            }
+            &Content::Linebreak { justify } => {
+                let c = if justify { '\u{2028}' } else { '\n' };
+                self.0.destructive(ParChild::Text(c.into()), styles);
+            }
+            &Content::Horizontal { amount, weak } => {
+                let child = ParChild::Spacing(amount);
+                let frac = amount.is_fractional();
+                if weak {
+                    let weakness = u8::from(!frac);
+                    self.0.weak(child, styles, weakness);
+                } else if frac {
+                    self.0.destructive(child, styles);
+                } else {
+                    self.0.ignorant(child, styles);
+                }
+            }
+            &Content::Quote { double } => {
+                self.0.supportive(ParChild::Quote { double }, styles);
+            }
+            Content::Text(text) => {
+                self.0.supportive(ParChild::Text(text.clone()), styles);
+            }
+            Content::Inline(node) => {
+                self.0.supportive(ParChild::Node(node.clone()), styles);
+            }
+            _ => return false,
+        }
+
+        true
+    }
+
+    fn finish(self, parent: &mut Builder<'a>) {
+        let (mut children, shared) = self.0.finish();
+        if children.is_empty() {
+            return;
+        }
+
+        // Paragraph indent should only apply if the paragraph starts with
+        // text and follows directly after another paragraph.
+        let indent = shared.get(ParNode::INDENT);
+        if !indent.is_zero()
+            && children
+                .items()
+                .find_map(|child| match child {
+                    ParChild::Spacing(_) => None,
+                    ParChild::Text(_) | ParChild::Quote { .. } => Some(true),
+                    ParChild::Node(_) => Some(false),
+                })
+                .unwrap_or_default()
+            && parent
+                .flow
+                .0
+                .items()
+                .rev()
+                .find_map(|child| match child {
+                    FlowChild::Spacing(_) => None,
+                    FlowChild::Node(node) => Some(node.is::<ParNode>()),
+                    FlowChild::Colbreak => Some(false),
+                })
+                .unwrap_or_default()
+        {
+            children.push_front(ParChild::Spacing(indent.into()));
+        }
+
+        parent.flow.par(ParNode(children), shared, !indent.is_zero());
+    }
+
+    fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+/// Accepts list / enum items, spaces, paragraph breaks.
+struct ListBuilder<'a> {
+    /// The list items collected so far.
+    items: StyleVecBuilder<'a, ListItem>,
+    /// Whether the list contains no paragraph breaks.
+    tight: bool,
+    /// Whether the list can be attached.
+    attachable: bool,
+    /// Trailing content for which it is unclear whether it is part of the list.
+    staged: Vec<(&'a Content, StyleChain<'a>)>,
+}
+
+impl<'a> ListBuilder<'a> {
+    fn accept(&mut self, content: &'a Content, styles: StyleChain<'a>) -> bool {
+        if self.items.is_empty() {
+            match content {
+                Content::Space => {}
+                Content::Item(_) => {}
+                Content::Parbreak => self.attachable = false,
+                _ => self.attachable = true,
+            }
+        }
+
+        match content {
+            Content::Item(item)
+                if self
+                    .items
+                    .items()
+                    .next()
+                    .map_or(true, |first| item.kind() == first.kind()) =>
+            {
+                self.items.push(item.clone(), styles);
+                self.tight &= self.staged.drain(..).all(|(t, _)| *t != Content::Parbreak);
+            }
+            Content::Space | Content::Parbreak if !self.items.is_empty() => {
+                self.staged.push((content, styles));
+            }
+            _ => return false,
+        }
+
+        true
+    }
+
+    fn finish(self, parent: &mut Builder<'a>) -> SourceResult<()> {
+        let (items, shared) = self.items.finish();
+        let kind = match items.items().next() {
+            Some(item) => item.kind(),
+            None => return Ok(()),
+        };
+
+        let tight = self.tight;
+        let attached = tight && self.attachable;
+        let content = match kind {
+            LIST => Content::show(ListNode::<LIST> { tight, attached, items }),
+            ENUM => Content::show(ListNode::<ENUM> { tight, attached, items }),
+            DESC | _ => Content::show(ListNode::<DESC> { tight, attached, items }),
+        };
+
+        let stored = parent.scratch.templates.alloc(content);
+        parent.accept(stored, shared)?;
+
+        for (content, styles) in self.staged {
+            parent.accept(content, styles)?;
+        }
+
+        parent.list.attachable = true;
+
+        Ok(())
+    }
+
+    fn is_empty(&self) -> bool {
+        self.items.is_empty()
+    }
+}
+
+impl Default for ListBuilder<'_> {
+    fn default() -> Self {
+        Self {
+            items: StyleVecBuilder::default(),
+            tight: true,
+            attachable: true,
+            staged: vec![],
+        }
+    }
+}