Make align not behave box-like and smarter 📦

Doesn't layout contents into a box anymore, instead layouting inline in the parent context. Also makes axis inferring for center alignents smarter (just because I had fun doing it). It's unsure whether we want to keep it because it might be confusing.

src/library/align.rs

@@ -5,16 +5,19 @@ use super::*;
 /// # Positional arguments
 /// - At most two of `left`, `right`, `top`, `bottom`, `center`.
 ///
+/// When `center` is used as a positional argument, it is automatically inferred
+/// which axis it should apply to depending on further arguments, defaulting
+/// to the axis, text is set along.
+///
 /// # Keyword arguments
 /// - `horizontal`: Any of `left`, `right` or `center`.
 /// - `vertical`: Any of `top`, `bottom` or `center`.
 ///
 /// There may not be two alignment specifications for the same axis.
-pub async fn align(_: Span, mut args: TableValue, mut ctx: LayoutContext<'_>) -> Pass<Value> {
+pub async fn align(_: Span, mut args: TableValue, ctx: LayoutContext<'_>) -> Pass<Value> {
     let mut f = Feedback::new();
 
     let content = args.take::<SyntaxTree>();
-
     let h = args.take_key::<Spanned<SpecAlign>>("horizontal", &mut f);
     let v = args.take_key::<Spanned<SpecAlign>>("vertical", &mut f);
     let all = args
@@ -23,40 +26,69 @@ pub async fn align(_: Span, mut args: TableValue, mut ctx: LayoutContext<'_>) ->
         .chain(h.into_iter().map(|align| (Some(Horizontal), align)))
         .chain(v.into_iter().map(|align| (Some(Vertical), align)));
 
+    let mut aligns = ctx.align;
     let mut had = [false; 2];
-    for (axis, align) in all {
-        let axis = axis.unwrap_or_else(|| align.v.axis().unwrap_or_else(|| {
-            let primary = ctx.axes.primary.axis();
-            if !had[primary as usize] {
-                primary
-            } else {
-                ctx.axes.secondary.axis()
-            }
-        }));
+    let mut deferred_center = false;
 
-        if align.v.axis().map(|a| a != axis).unwrap_or(false) {
-            error!(
-                @f, align.span,
-                "invalid alignment {} for {} axis", align.v, axis,
-            );
-        } else if had[axis as usize] {
-            error!(@f, align.span, "duplicate alignment for {} axis", axis);
+    for (axis, align) in all {
+        // Check whether we know which axis this alignment belongs to. We don't
+        // if the alignment is `center` for a positional argument. Then we set
+        // `deferred_center` to true and handle the situation once we know more.
+        if let Some(axis) = axis {
+            if align.v.axis().map(|a| a != axis).unwrap_or(false) {
+                error!(
+                    @f, align.span,
+                    "invalid alignment {} for {} axis", align.v, axis,
+                );
+            } else if had[axis as usize] {
+                error!(@f, align.span, "duplicate alignment for {} axis", axis);
+            } else {
+                let gen_align = align.v.to_generic(ctx.axes);
+                *aligns.get_mut(axis.to_generic(ctx.axes)) = gen_align;
+                had[axis as usize] = true;
+            }
         } else {
+            if had == [true, true] {
+                error!(@f, align.span, "duplicate alignment");
+            } else if deferred_center {
+                // We have two unflushed centers, meaning we know that both axes
+                // are to be centered.
+                had = [true, true];
+                aligns = LayoutAlign::new(Center, Center);
+            } else {
+                deferred_center = true;
+            }
+        }
+
+        // Flush a deferred center alignment if we know have had at least one
+        // known alignment.
+        if deferred_center && had != [false, false] {
+            let axis = if !had[Horizontal as usize] {
+                Horizontal
+            } else {
+                Vertical
+            };
+
+            *aligns.get_mut(axis.to_generic(ctx.axes)) = Center;
+
             had[axis as usize] = true;
-            let gen_axis = axis.to_generic(ctx.axes);
-            let gen_align = align.v.to_generic(ctx.axes);
-            *ctx.align.get_mut(gen_axis) = gen_align;
+            deferred_center = false;
         }
     }
 
+    // If center has not been flushed by known, it is the only argument and then
+    // we default to applying it to the primary axis.
+    if deferred_center {
+        aligns.primary = Center;
+    }
+
     let commands = match content {
-        Some(tree) => {
-            ctx.base = ctx.spaces[0].size;
-            let layouted = layout(&tree, ctx).await;
-            f.extend(layouted.feedback);
-            vec![AddMultiple(layouted.output)]
-        }
-        None => vec![SetAlignment(ctx.align)],
+        Some(tree) => vec![
+            SetAlignment(aligns),
+            LayoutSyntaxTree(tree),
+            SetAlignment(ctx.align),
+        ],
+        None => vec![SetAlignment(aligns)],
     };
 
     args.unexpected(&mut f);

tests/coma.typ

@@ -7,7 +7,7 @@
     Dr. Max Mustermann \
     Ola Nordmann, John Doe
 ]
-[align: right][
+[align: right >> box][
     *WiSe 2019/2020* \
     Woche 3
 ]