Prune derives

1 files changed, 129 insertions, 0 deletions

diff --git a/src/eval/walk.rs b/src/eval/walk.rs
new file mode 100644
index 00000000..4c6a1605
--- /dev/null
+++ b/src/eval/walk.rs
@@ -0,0 +1,129 @@
+use std::fmt::Write;
+use std::rc::Rc;
+
+use super::{Eval, EvalContext, Template, Value};
+use crate::diag::TypResult;
+use crate::geom::Gen;
+use crate::layout::{ParChild, ParNode, StackChild, StackNode};
+use crate::syntax::*;
+use crate::util::EcoString;
+
+/// Walk a syntax node and fill the currently built template.
+pub trait Walk {
+    /// Walk the node.
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()>;
+}
+
+impl Walk for SyntaxTree {
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()> {
+        for node in self.iter() {
+            node.walk(ctx)?;
+        }
+        Ok(())
+    }
+}
+
+impl Walk for SyntaxNode {
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()> {
+        match self {
+            Self::Space => ctx.template.space(),
+            Self::Linebreak(_) => ctx.template.linebreak(),
+            Self::Parbreak(_) => ctx.template.parbreak(),
+            Self::Strong(_) => ctx.template.modify(|s| s.font_mut().strong ^= true),
+            Self::Emph(_) => ctx.template.modify(|s| s.font_mut().emph ^= true),
+            Self::Text(text) => ctx.template.text(text),
+            Self::Raw(raw) => raw.walk(ctx)?,
+            Self::Heading(heading) => heading.walk(ctx)?,
+            Self::List(list) => list.walk(ctx)?,
+            Self::Enum(enum_) => enum_.walk(ctx)?,
+            Self::Expr(expr) => match expr.eval(ctx)? {
+                Value::None => {}
+                Value::Int(v) => ctx.template.text(v.to_string()),
+                Value::Float(v) => ctx.template.text(v.to_string()),
+                Value::Str(v) => ctx.template.text(v),
+                Value::Template(v) => ctx.template += v,
+                // For values which can't be shown "naturally", we print the
+                // representation in monospace.
+                other => ctx.template.monospace(other.to_string()),
+            },
+        }
+        Ok(())
+    }
+}
+
+impl Walk for RawNode {
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()> {
+        if self.block {
+            ctx.template.parbreak();
+        }
+
+        ctx.template.monospace(&self.text);
+
+        if self.block {
+            ctx.template.parbreak();
+        }
+
+        Ok(())
+    }
+}
+
+impl Walk for HeadingNode {
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()> {
+        let level = self.level;
+        let body = self.body.eval(ctx)?;
+
+        ctx.template.parbreak();
+        ctx.template.save();
+        ctx.template.modify(move |state| {
+            let font = state.font_mut();
+            let upscale = 1.6 - 0.1 * level as f64;
+            font.size *= upscale;
+            font.strong = true;
+        });
+        ctx.template += body;
+        ctx.template.restore();
+        ctx.template.parbreak();
+
+        Ok(())
+    }
+}
+
+impl Walk for ListNode {
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()> {
+        let body = self.body.eval(ctx)?;
+        walk_item(ctx, '•'.into(), body);
+        Ok(())
+    }
+}
+
+impl Walk for EnumNode {
+    fn walk(&self, ctx: &mut EvalContext) -> TypResult<()> {
+        let body = self.body.eval(ctx)?;
+        let mut label = EcoString::new();
+        write!(&mut label, "{}.", self.number.unwrap_or(1)).unwrap();
+        walk_item(ctx, label, body);
+        Ok(())
+    }
+}
+
+fn walk_item(ctx: &mut EvalContext, label: EcoString, body: Template) {
+    ctx.template += Template::from_block(move |state| {
+        let label = ParNode {
+            dir: state.dirs.cross,
+            line_spacing: state.line_spacing(),
+            children: vec![ParChild::Text(
+                label.clone(),
+                state.aligns.cross,
+                Rc::clone(&state.font),
+            )],
+        };
+        StackNode {
+            dirs: Gen::new(state.dirs.main, state.dirs.cross),
+            children: vec![
+                StackChild::Any(label.into(), Gen::default()),
+                StackChild::Spacing((state.font.size / 2.0).into()),
+                StackChild::Any(body.to_stack(&state).into(), Gen::default()),
+            ],
+        }
+    });
+}