large operators have limits in displays; relations have limits always (#1748)

crates/typst-library/src/math/attach.rs

@@ -216,10 +216,16 @@ pub enum Limits {
 impl Limits {
     /// The default limit configuration if the given character is the base.
     pub fn for_char(c: char) -> Self {
-        if Self::DEFAULT_TO_LIMITS.contains(&c) {
+        match unicode_math_class::class(c) {
-            Limits::Display
+            Some(MathClass::Large) => {
-        } else {
+                if is_integral_char(c) {
                     Limits::Never
+                } else {
+                    Limits::Display
+                }
+            }
+            Some(MathClass::Relation) => Limits::Always,
+            _ => Limits::Never,
         }
     }
 
@@ -231,18 +237,6 @@ impl Limits {
             Self::Never => false,
         }
     }
-
-    /// Unicode codepoints that should show attachments as limits in display
-    /// mode.
-    #[rustfmt::skip]
-    const DEFAULT_TO_LIMITS: &[char] = &[
-        /* ∏ */ '\u{220F}', /* ∐ */ '\u{2210}', /* ∑ */ '\u{2211}',
-        /* ⋀ */ '\u{22C0}', /* ⋁ */ '\u{22C1}',
-        /* ⋂ */ '\u{22C2}', /* ⋃ */ '\u{22C3}',
-        /* ⨀ */ '\u{2A00}', /* ⨁ */ '\u{2A01}', /* ⨂ */ '\u{2A02}',
-        /* ⨃ */ '\u{2A03}', /* ⨄ */ '\u{2A04}',
-        /* ⨅ */ '\u{2A05}', /* ⨆ */ '\u{2A06}',
-    ];
 }
 
 macro_rules! measure {
@@ -444,6 +438,11 @@ fn compute_shifts_up_and_down(
     (shift_up, shift_down)
 }
 
+/// Determines if the character is one of a variety of integral signs
+fn is_integral_char(c: char) -> bool {
+    ('∫'..='∳').contains(&c) || ('⨋'..='⨜').contains(&c)
+}
+
 /// Whether the fragment consists of a single character or atomic piece of text.
 fn is_character_box(fragment: &MathFragment) -> bool {
     match fragment {

tests/typ/math/attach-p3.typ

@@ -22,3 +22,21 @@ $ attach(A, t: #locate(it => oops)) $
 #show math.iota: math.limits.with(inline: false)
 #eq
 $iota_a^b$
+
+---
+// Test default of limit attachments on relations at all sizes
+#set page(width: auto)
+$ a =^"def" b quad a lt.eq_"really" b quad  a arrow.r.long.squiggly^"slowly" b $
+$a =^"def" b quad a lt.eq_"really" b quad a arrow.r.long.squiggly^"slowly" b$
+
+$a scripts(=)^"def" b quad a scripts(lt.eq)_"really" b quad a scripts(arrow.r.long.squiggly)^"slowly" b$
+
+---
+// Test default of scripts attachments on integrals at display size
+$ integral.sect_a^b  quad \u{2a1b}_a^b quad limits(\u{2a1b})_a^b $
+$integral.sect_a^b quad \u{2a1b}_a^b quad limits(\u{2a1b})_a^b$
+
+---
+// Test default of limit attachments on large operators at display size only
+$ tack.t.big_0^1 quad \u{02A0A}_0^1 quad join_0^1 $
+$tack.t.big_0^1 quad \u{02A0A}_0^1 quad join_0^1$