Dry-clean visitor with a macro 🏜

6 files changed, 172 insertions, 175 deletions

diff --git a/src/eval/capture.rs b/src/eval/capture.rs
index 054b64ab..42b617a7 100644
--- a/src/eval/capture.rs
+++ b/src/eval/capture.rs
@@ -15,32 +15,60 @@ impl<'a> CapturesVisitor<'a> {
     pub fn new(external: &'a Scopes) -> Self {
         Self { external, internal: Scopes::default() }
     }
+
+    /// Define an internal variable.
+    fn define(&mut self, ident: &Ident) {
+        self.internal.def_mut(ident.as_str(), Value::None);
+    }
 }
 
-impl<'a> Visitor<'a> for CapturesVisitor<'a> {
-    fn visit_scope_pre(&mut self) {
-        self.internal.push();
+impl<'ast> Visit<'ast> for CapturesVisitor<'_> {
+    fn visit_expr(&mut self, item: &'ast mut Expr) {
+        match item {
+            Expr::Ident(ident) => {
+                // Find out whether the identifier is not locally defined, but
+                // captured, and if so, replace it with its value.
+                if self.internal.get(ident).is_none() {
+                    if let Some(value) = self.external.get(ident) {
+                        *item = Expr::Captured(Rc::clone(&value));
+                    }
+                }
+            }
+            expr => visit_expr(self, expr),
+        }
     }
 
-    fn visit_scope_post(&mut self) {
+    fn visit_block(&mut self, item: &'ast mut ExprBlock) {
+        // Blocks create a scope except if directly in a template.
+        if item.scopes {
+            self.internal.push();
+        }
+        visit_block(self, item);
+        if item.scopes {
+            self.internal.pop();
+        }
+    }
+
+    fn visit_template(&mut self, item: &'ast mut ExprTemplate) {
+        // Templates always create a scope.
+        self.internal.push();
+        visit_template(self, item);
         self.internal.pop();
     }
 
-    fn visit_def(&mut self, id: &mut Ident) {
-        self.internal.def_mut(id.as_str(), Value::None);
+    fn visit_let(&mut self, item: &'ast mut ExprLet) {
+        self.define(&item.pat.v);
+        visit_let(self, item);
     }
 
-    fn visit_expr(&mut self, expr: &'a mut Expr) {
-        if let Expr::Ident(ident) = expr {
-            // Find out whether the identifier is not locally defined, but
-            // captured, and if so, replace it with its value.
-            if self.internal.get(ident).is_none() {
-                if let Some(value) = self.external.get(ident) {
-                    *expr = Expr::Captured(Rc::clone(&value));
-                }
+    fn visit_for(&mut self, item: &'ast mut ExprFor) {
+        match &mut item.pat.v {
+            ForPattern::Value(value) => self.define(value),
+            ForPattern::KeyValue(key, value) => {
+                self.define(key);
+                self.define(value);
             }
-        } else {
-            walk_expr(self, expr);
         }
+        visit_for(self, item);
     }
 }
diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 4f8961cc..cfd1c808 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -23,6 +23,7 @@ use crate::diag::Pass;
 use crate::env::Env;
 use crate::geom::{Angle, Length, Relative, Spec};
 use crate::layout::{self, Expansion, NodeSpacing, NodeStack};
+use crate::syntax::visit::Visit;
 use crate::syntax::*;
 
 /// Evaluate a syntax tree into a layout tree.
diff --git a/src/export/pdf.rs b/src/export/pdf.rs
index e5124c21..b2a6bbfd 100644
--- a/src/export/pdf.rs
+++ b/src/export/pdf.rs
@@ -130,11 +130,11 @@ impl<'a> PdfExporter<'a> {
         let mut content = Content::new();
 
         for (pos, element) in &page.elements {
+            let x = pos.x.to_pt() as f32;
             match element {
                 Element::Image(image) => {
                     let name = format!("Im{}", self.images.map(image.res));
                     let size = image.size;
-                    let x = pos.x.to_pt() as f32;
                     let y = (page.size.height - pos.y - size.height).to_pt() as f32;
                     let w = size.width.to_pt() as f32;
                     let h = size.height.to_pt() as f32;
@@ -151,16 +151,14 @@ impl<'a> PdfExporter<'a> {
                     match geometry.fill {
                         Fill::Color(Color::Rgba(c)) => {
                             content.fill_rgb(
-                                c.r as f32 / 255.,
-                                c.g as f32 / 255.,
-                                c.b as f32 / 255.,
+                                c.r as f32 / 255.0,
+                                c.g as f32 / 255.0,
+                                c.b as f32 / 255.0,
                             );
                         }
                         Fill::Image(_) => todo!(),
                     }
 
-                    let x = pos.x.to_pt() as f32;
-
                     match &geometry.shape {
                         Shape::Rect(r) => {
                             let w = r.width.to_pt() as f32;
diff --git a/src/library/layout.rs b/src/library/layout.rs
index 2812a48f..e4839953 100644
--- a/src/library/layout.rs
+++ b/src/library/layout.rs
@@ -175,7 +175,16 @@ impl Display for Alignment {
 /// # Named arguments
 /// - Width of the box:  `width`, of type `linear` relative to parent width.
 /// - Height of the box: `height`, of type `linear` relative to parent height.
+/// - Main layouting direction: `main-dir`, of type `direction`.
+/// - Cross layouting direction: `cross-dir`, of type `direction`.
 /// - Background color of the box: `color`, of type `color`.
+///
+/// # Relevant types and constants
+/// - Type `direction`
+///     - `ltr` (left to right)
+///     - `rtl` (right to left)
+///     - `ttb` (top to bottom)
+///     - `btt` (bottom to top)
 pub fn box_(ctx: &mut EvalContext, args: &mut Args) -> Value {
     let snapshot = ctx.state.clone();
 
@@ -210,13 +219,12 @@ pub fn box_(ctx: &mut EvalContext, args: &mut Args) -> Value {
     if let Some(color) = color {
         ctx.push(NodeBackground {
             fill: Fill::Color(color),
-            child: Node::Any(fixed_node.into()),
+            child: fixed_node.into(),
         })
     } else {
         ctx.push(fixed_node);
     }
 
-
     ctx.state = snapshot;
     Value::None
 }
diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index af6715c6..8bb6931a 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -12,7 +12,6 @@ pub use ident::*;
 pub use node::*;
 pub use span::*;
 pub use token::*;
-pub use visit::Visitor;
 
 use crate::pretty::{Pretty, Printer};
 
diff --git a/src/syntax/visit.rs b/src/syntax/visit.rs
index 6f0e7ef3..2e4391ac 100644
--- a/src/syntax/visit.rs
+++ b/src/syntax/visit.rs
@@ -2,184 +2,147 @@
 
 use super::*;
 
-/// Visits syntax tree nodes in a depth-first manner.
-pub trait Visitor<'a>: Sized {
-    /// Visit a variable definition.
-    fn visit_def(&mut self, _ident: &'a mut Ident) {}
-
-    /// Visit the start of a scope.
-    fn visit_scope_pre(&mut self) {}
-
-    /// Visit the end of a scope.
-    fn visit_scope_post(&mut self) {}
+macro_rules! visit {
+    ($(fn $name:ident($v:ident, $item:ident: &mut $ty:ty) $body:block)*) => {
+        /// Traverses the syntax tree.
+        pub trait Visit<'ast> {
+            $(fn $name(&mut self, $item: &'ast mut $ty) {
+                $name(self, $item);
+            })*
+        }
 
-    fn visit_node(&mut self, node: &'a mut Node) {
-        walk_node(self, node)
-    }
-    fn visit_expr(&mut self, expr: &'a mut Expr) {
-        walk_expr(self, expr)
-    }
-    fn visit_array(&mut self, array: &'a mut ExprArray) {
-        walk_array(self, array)
-    }
-    fn visit_dict(&mut self, dict: &'a mut ExprDict) {
-        walk_dict(self, dict)
-    }
-    fn visit_template(&mut self, template: &'a mut ExprTemplate) {
-        walk_template(self, template)
-    }
-    fn visit_group(&mut self, group: &'a mut ExprGroup) {
-        walk_group(self, group)
-    }
-    fn visit_block(&mut self, block: &'a mut ExprBlock) {
-        walk_block(self, block)
-    }
-    fn visit_binary(&mut self, binary: &'a mut ExprBinary) {
-        walk_binary(self, binary)
-    }
-    fn visit_unary(&mut self, unary: &'a mut ExprUnary) {
-        walk_unary(self, unary)
-    }
-    fn visit_call(&mut self, call: &'a mut ExprCall) {
-        walk_call(self, call)
+        $(visit! {
+            @concat!("Walk a node of type [`", stringify!($ty), "`]."),
+            pub fn $name<'ast, V>($v: &mut V, $item: &'ast mut $ty)
+            where
+                V: Visit<'ast> + ?Sized
+            $body
+        })*
+    };
+    (@$doc:expr, $($tts:tt)*) => {
+        #[doc = $doc]
+        $($tts)*
     }
-    fn visit_arg(&mut self, arg: &'a mut Argument) {
-        walk_arg(self, arg)
-    }
-    fn visit_let(&mut self, expr_let: &'a mut ExprLet) {
-        walk_let(self, expr_let)
-    }
-    fn visit_if(&mut self, expr_if: &'a mut ExprIf) {
-        walk_if(self, expr_if)
-    }
-    fn visit_for(&mut self, expr_for: &'a mut ExprFor) {
-        walk_for(self, expr_for)
-    }
-}
 
-pub fn walk_node<'a, V: Visitor<'a>>(v: &mut V, node: &'a mut Node) {
-    match node {
-        Node::Strong => {}
-        Node::Emph => {}
-        Node::Space => {}
-        Node::Linebreak => {}
-        Node::Parbreak => {}
-        Node::Text(_) => {}
-        Node::Heading(_) => {}
-        Node::Raw(_) => {}
-        Node::Expr(expr) => v.visit_expr(expr),
-    }
 }
 
-pub fn walk_expr<'a, V: Visitor<'a>>(v: &mut V, expr: &'a mut Expr) {
-    match expr {
-        Expr::None => {}
-        Expr::Ident(_) => {}
-        Expr::Bool(_) => {}
-        Expr::Int(_) => {}
-        Expr::Float(_) => {}
-        Expr::Length(_, _) => {}
-        Expr::Angle(_, _) => {}
-        Expr::Percent(_) => {}
-        Expr::Color(_) => {}
-        Expr::Str(_) => {}
-        Expr::Array(e) => v.visit_array(e),
-        Expr::Dict(e) => v.visit_dict(e),
-        Expr::Template(e) => v.visit_template(e),
-        Expr::Group(e) => v.visit_group(e),
-        Expr::Block(e) => v.visit_block(e),
-        Expr::Unary(e) => v.visit_unary(e),
-        Expr::Binary(e) => v.visit_binary(e),
-        Expr::Call(e) => v.visit_call(e),
-        Expr::Let(e) => v.visit_let(e),
-        Expr::If(e) => v.visit_if(e),
-        Expr::For(e) => v.visit_for(e),
-        Expr::Captured(_) => {}
+visit! {
+    fn visit_tree(v, item: &mut Tree) {
+        for node in item {
+            v.visit_node(&mut node.v);
+        }
     }
-}
 
-pub fn walk_array<'a, V: Visitor<'a>>(v: &mut V, array: &'a mut ExprArray) {
-    for expr in array {
-        v.visit_expr(&mut expr.v);
+    fn visit_node(v, item: &mut Node) {
+        match item {
+            Node::Strong => {}
+            Node::Emph => {}
+            Node::Space => {}
+            Node::Linebreak => {}
+            Node::Parbreak => {}
+            Node::Text(_) => {}
+            Node::Heading(n) => v.visit_tree(&mut n.contents),
+            Node::Raw(_) => {}
+            Node::Expr(expr) => v.visit_expr(expr),
+        }
     }
-}
 
-pub fn walk_dict<'a, V: Visitor<'a>>(v: &mut V, dict: &'a mut ExprDict) {
-    for named in dict {
-        v.visit_expr(&mut named.expr.v);
+    fn visit_expr(v, item: &mut Expr) {
+        match item {
+            Expr::None => {}
+            Expr::Ident(_) => {}
+            Expr::Bool(_) => {}
+            Expr::Int(_) => {}
+            Expr::Float(_) => {}
+            Expr::Length(_, _) => {}
+            Expr::Angle(_, _) => {}
+            Expr::Percent(_) => {}
+            Expr::Color(_) => {}
+            Expr::Str(_) => {}
+            Expr::Array(e) => v.visit_array(e),
+            Expr::Dict(e) => v.visit_dict(e),
+            Expr::Template(e) => v.visit_template(e),
+            Expr::Group(e) => v.visit_group(e),
+            Expr::Block(e) => v.visit_block(e),
+            Expr::Unary(e) => v.visit_unary(e),
+            Expr::Binary(e) => v.visit_binary(e),
+            Expr::Call(e) => v.visit_call(e),
+            Expr::Let(e) => v.visit_let(e),
+            Expr::If(e) => v.visit_if(e),
+            Expr::For(e) => v.visit_for(e),
+            Expr::Captured(_) => {}
+        }
     }
-}
 
-pub fn walk_template<'a, V: Visitor<'a>>(v: &mut V, template: &'a mut ExprTemplate) {
-    v.visit_scope_pre();
-    for node in template {
-        v.visit_node(&mut node.v);
+    fn visit_array(v, item: &mut ExprArray) {
+        for expr in item {
+            v.visit_expr(&mut expr.v);
+        }
     }
-    v.visit_scope_post();
-}
 
-pub fn walk_group<'a, V: Visitor<'a>>(v: &mut V, group: &'a mut ExprGroup) {
-    v.visit_expr(&mut group.v);
-}
+    fn visit_dict(v, item: &mut ExprDict) {
+        for named in item {
+            v.visit_expr(&mut named.expr.v);
+        }
+    }
 
-pub fn walk_block<'a, V: Visitor<'a>>(v: &mut V, block: &'a mut ExprBlock) {
-    if block.scopes {
-        v.visit_scope_pre();
+    fn visit_template(v, item: &mut ExprTemplate) {
+        v.visit_tree(item);
     }
-    for expr in &mut block.exprs {
-        v.visit_expr(&mut expr.v);
+
+    fn visit_group(v, item: &mut ExprGroup) {
+        v.visit_expr(&mut item.v);
     }
-    if block.scopes {
-        v.visit_scope_post();
+
+    fn visit_block(v, item: &mut ExprBlock) {
+        for expr in &mut item.exprs {
+            v.visit_expr(&mut expr.v);
+        }
     }
-}
 
-pub fn walk_binary<'a, V: Visitor<'a>>(v: &mut V, binary: &'a mut ExprBinary) {
-    v.visit_expr(&mut binary.lhs.v);
-    v.visit_expr(&mut binary.rhs.v);
-}
+    fn visit_binary(v, item: &mut ExprBinary) {
+        v.visit_expr(&mut item.lhs.v);
+        v.visit_expr(&mut item.rhs.v);
+    }
 
-pub fn walk_unary<'a, V: Visitor<'a>>(v: &mut V, unary: &'a mut ExprUnary) {
-    v.visit_expr(&mut unary.expr.v);
-}
+    fn visit_unary(v, item: &mut ExprUnary) {
+        v.visit_expr(&mut item.expr.v);
+    }
 
-pub fn walk_call<'a, V: Visitor<'a>>(v: &mut V, call: &'a mut ExprCall) {
-    v.visit_expr(&mut call.callee.v);
-    for arg in &mut call.args.v {
-        v.visit_arg(arg);
+    fn visit_call(v, item: &mut ExprCall) {
+        v.visit_expr(&mut item.callee.v);
+        v.visit_args(&mut item.args.v);
     }
-}
 
-pub fn walk_arg<'a, V: Visitor<'a>>(v: &mut V, arg: &'a mut Argument) {
-    match arg {
-        Argument::Pos(expr) => v.visit_expr(&mut expr.v),
-        Argument::Named(named) => v.visit_expr(&mut named.expr.v),
+    fn visit_args(v, item: &mut ExprArgs) {
+        for arg in item {
+            v.visit_arg(arg);
+        }
     }
-}
 
-pub fn walk_let<'a, V: Visitor<'a>>(v: &mut V, expr_let: &'a mut ExprLet) {
-    v.visit_def(&mut expr_let.pat.v);
-    if let Some(init) = &mut expr_let.init {
-        v.visit_expr(&mut init.v);
+    fn visit_arg(v, item: &mut Argument) {
+        match item {
+            Argument::Pos(expr) => v.visit_expr(&mut expr.v),
+            Argument::Named(named) => v.visit_expr(&mut named.expr.v),
+        }
     }
-}
 
-pub fn walk_if<'a, V: Visitor<'a>>(v: &mut V, expr_if: &'a mut ExprIf) {
-    v.visit_expr(&mut expr_if.condition.v);
-    v.visit_expr(&mut expr_if.if_body.v);
-    if let Some(body) = &mut expr_if.else_body {
-        v.visit_expr(&mut body.v);
+    fn visit_let(v, item: &mut ExprLet) {
+        if let Some(init) = &mut item.init {
+            v.visit_expr(&mut init.v);
+        }
     }
-}
 
-pub fn walk_for<'a, V: Visitor<'a>>(v: &mut V, expr_for: &'a mut ExprFor) {
-    match &mut expr_for.pat.v {
-        ForPattern::Value(value) => v.visit_def(value),
-        ForPattern::KeyValue(key, value) => {
-            v.visit_def(key);
-            v.visit_def(value);
+    fn visit_if(v, item: &mut ExprIf) {
+        v.visit_expr(&mut item.condition.v);
+        v.visit_expr(&mut item.if_body.v);
+        if let Some(body) = &mut item.else_body {
+            v.visit_expr(&mut body.v);
         }
     }
-    v.visit_expr(&mut expr_for.iter.v);
-    v.visit_expr(&mut expr_for.body.v);
+
+    fn visit_for(v, item: &mut ExprFor) {
+        v.visit_expr(&mut item.iter.v);
+        v.visit_expr(&mut item.body.v);
+    }
 }