Add spacing capabilities to stack function

- Named argument `spacing` controls spacing between any two template arguments
- Arbitrary linears in the list can produce arbitrary spacing

4 files changed, 101 insertions, 64 deletions

diff --git a/src/library/layout.rs b/src/library/layout.rs
index e958f3a3..87cedd99 100644
--- a/src/library/layout.rs
+++ b/src/library/layout.rs
@@ -188,8 +188,22 @@ pub fn pad(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 
 /// `stack`: Stack children along an axis.
 pub fn stack(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    enum Child {
+        Spacing(Linear),
+        Any(Template),
+    }
+
+    castable! {
+        Child: "linear or template",
+        Value::Length(v) => Self::Spacing(v.into()),
+        Value::Relative(v) => Self::Spacing(v.into()),
+        Value::Linear(v) => Self::Spacing(v),
+        Value::Template(v) => Self::Any(v),
+    }
+
     let dir = args.named("dir")?;
-    let children: Vec<Template> = args.all().collect();
+    let spacing = args.named("spacing")?;
+    let list: Vec<Child> = args.all().collect();
 
     Ok(Value::Template(Template::from_block(move |state| {
         let mut dirs = Gen::new(None, dir).unwrap_or(state.dirs);
@@ -208,10 +222,27 @@ pub fn stack(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
             aligns = Gen::new(aligns.block, aligns.inline);
         }
 
-        let children = children
-            .iter()
-            .map(|child| StackChild::Any(child.to_stack(state).into(), aligns))
-            .collect();
+        let mut children = vec![];
+        let mut delayed = None;
+
+        // Build the list of stack children.
+        for child in &list {
+            match child {
+                Child::Spacing(v) => {
+                    children.push(StackChild::Spacing(*v));
+                    delayed = None;
+                }
+                Child::Any(template) => {
+                    if let Some(v) = delayed {
+                        children.push(StackChild::Spacing(v));
+                    }
+
+                    let node = template.to_stack(state).into();
+                    children.push(StackChild::Any(node, aligns));
+                    delayed = spacing;
+                }
+            }
+        }
 
         StackNode { dirs, children }
     })))
@@ -219,27 +250,45 @@ pub fn stack(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 
 /// `grid`: Arrange children into a grid.
 pub fn grid(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    castable! {
+        Vec<TrackSizing>: "array of autos, linears, and fractionals",
+        Value::Int(count) => vec![TrackSizing::Auto; count.max(0) as usize],
+        Value::Array(values) => values
+            .into_iter()
+            .filter_map(|v| v.cast().ok())
+            .collect(),
+    }
+
+    castable! {
+        TrackSizing: "auto, linear, or fractional",
+        Value::Auto => Self::Auto,
+        Value::Length(v) => Self::Linear(v.into()),
+        Value::Relative(v) => Self::Linear(v.into()),
+        Value::Linear(v) => Self::Linear(v),
+        Value::Fractional(v) => Self::Fractional(v),
+    }
+
     let columns = args.named("columns")?.unwrap_or_default();
     let rows = args.named("rows")?.unwrap_or_default();
+    let tracks = Gen::new(columns, rows);
+
+    let column_dir = args.named("column-dir")?;
+    let row_dir = args.named("row-dir")?;
 
     let gutter_columns = args.named("gutter-columns")?;
     let gutter_rows = args.named("gutter-rows")?;
-    let default = args
+    let gutter_default = args
         .named("gutter")?
         .map(|v| vec![TrackSizing::Linear(v)])
         .unwrap_or_default();
 
-    let column_dir = args.named("column-dir")?;
-    let row_dir = args.named("row-dir")?;
-
-    let children: Vec<Template> = args.all().collect();
-
-    let tracks = Gen::new(columns, rows);
     let gutter = Gen::new(
-        gutter_columns.unwrap_or_else(|| default.clone()),
-        gutter_rows.unwrap_or(default),
+        gutter_columns.unwrap_or_else(|| gutter_default.clone()),
+        gutter_rows.unwrap_or(gutter_default),
     );
 
+    let children: Vec<Template> = args.all().collect();
+
     Ok(Value::Template(Template::from_block(move |state| {
         // If the directions become aligned, try to fix up the direction which
         // is not user-defined.
@@ -269,24 +318,3 @@ pub fn grid(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
         }
     })))
 }
-
-/// Defines size of rows and columns in a grid.
-type Tracks = Vec<TrackSizing>;
-
-castable! {
-    Tracks: "array of `auto`s, linears, and fractionals",
-    Value::Int(count) => vec![TrackSizing::Auto; count.max(0) as usize],
-    Value::Array(values) => values
-        .into_iter()
-        .filter_map(|v| v.cast().ok())
-        .collect(),
-}
-
-castable! {
-    TrackSizing: "`auto`, linear, or fractional",
-    Value::Auto => TrackSizing::Auto,
-    Value::Length(v) => TrackSizing::Linear(v.into()),
-    Value::Relative(v) => TrackSizing::Linear(v.into()),
-    Value::Linear(v) => TrackSizing::Linear(v),
-    Value::Fractional(v) => TrackSizing::Fractional(v),
-}
diff --git a/src/library/text.rs b/src/library/text.rs
index b8b3afcd..0deda6e4 100644
--- a/src/library/text.rs
+++ b/src/library/text.rs
@@ -3,6 +3,33 @@ use crate::layout::{Decoration, LineDecoration, LineKind, Paint};
 
 /// `font`: Configure the font.
 pub fn font(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    struct FontDef(Rc<Vec<FontFamily>>);
+    struct FamilyDef(Rc<Vec<String>>);
+
+    castable! {
+        FontDef: "font family or array of font families",
+        Value::Str(string) => Self(Rc::new(vec![FontFamily::Named(string.to_lowercase())])),
+        Value::Array(values) => Self(Rc::new(
+            values
+                .into_iter()
+                .filter_map(|v| v.cast().ok())
+                .collect()
+        )),
+        @family: FontFamily => Self(Rc::new(vec![family.clone()])),
+    }
+
+    castable! {
+        FamilyDef: "string or array of strings",
+        Value::Str(string) => Self(Rc::new(vec![string.to_lowercase()])),
+        Value::Array(values) => Self(Rc::new(
+            values
+                .into_iter()
+                .filter_map(|v| v.cast().ok())
+                .map(|string: Str| string.to_lowercase())
+                .collect()
+        )),
+    }
+
     let list = args.named("family")?.or_else(|| {
         let families: Vec<_> = args.all().collect();
         (!families.is_empty()).then(|| FontDef(Rc::new(families)))
@@ -81,34 +108,6 @@ pub fn font(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     })
 }
 
-struct FontDef(Rc<Vec<FontFamily>>);
-
-castable! {
-    FontDef: "font family or array of font families",
-    Value::Str(string) => Self(Rc::new(vec![FontFamily::Named(string.to_lowercase())])),
-    Value::Array(values) => Self(Rc::new(
-        values
-            .into_iter()
-            .filter_map(|v| v.cast().ok())
-            .collect()
-    )),
-    @family: FontFamily => Self(Rc::new(vec![family.clone()])),
-}
-
-struct FamilyDef(Rc<Vec<String>>);
-
-castable! {
-    FamilyDef: "string or array of strings",
-    Value::Str(string) => Self(Rc::new(vec![string.to_lowercase()])),
-    Value::Array(values) => Self(Rc::new(
-        values
-            .into_iter()
-            .filter_map(|v| v.cast().ok())
-            .map(|string: Str| string.to_lowercase())
-            .collect()
-    )),
-}
-
 /// `par`: Configure paragraphs.
 pub fn par(ctx: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     let par_spacing = args.named("spacing")?;
diff --git a/tests/ref/layout/stack.png b/tests/ref/layout/stack.png
index bc0eb48b..13438d07 100644
--- a/tests/ref/layout/stack.png
+++ b/tests/ref/layout/stack.png
diff --git a/tests/typ/layout/stack.typ b/tests/typ/layout/stack.typ
index 384f574f..aee66d6a 100644
--- a/tests/typ/layout/stack.typ
+++ b/tests/typ/layout/stack.typ
@@ -24,7 +24,17 @@
 #stack(dir: ltr, ..items)
 
 ---
-// Test overflowing stack.
+// Test spacing.
+#page(width: 50pt, margins: 0pt)
+#par(spacing: 5pt)
+
+#let x = square(length: 10pt, fill: eastern)
+#stack(dir: rtl, spacing: 5pt, x, x, x)
+#stack(dir: ltr, x, 20%, x, 20%, x)
+#stack(dir: ltr, spacing: 5pt, x, x, 7pt, 3pt, x)
+
+---
+// Test overflow.
 #page(width: 50pt, height: 30pt, margins: 0pt)
 #box(stack(
   rect(width: 40pt, height: 20pt, fill: conifer),