Fix inconsistency between text and idents in math

src/ide/highlight.rs

@@ -260,6 +260,7 @@ fn highlight_ident(node: &LinkedNode) -> Option<Category> {
     if let Some(next) = &next_leaf {
         if node.range().end == next.offset()
             && matches!(next.kind(), SyntaxKind::LeftParen | SyntaxKind::LeftBracket)
+            && matches!(next.parent_kind(), Some(SyntaxKind::Args | SyntaxKind::Params))
         {
             return Some(Category::Function);
         }

src/syntax/parser.rs

@@ -230,9 +230,11 @@ fn math_expr(p: &mut Parser) {
 
 fn math_expr_prec(p: &mut Parser, min_prec: usize, stop: SyntaxKind) {
     let m = p.marker();
+    let mut continuable = false;
     match p.current() {
         SyntaxKind::Hashtag => embedded_code_expr(p),
         SyntaxKind::MathIdent => {
+            continuable = true;
             p.eat();
             while p.directly_at(SyntaxKind::Text)
                 && p.current_text() == "."
@@ -245,30 +247,41 @@ fn math_expr_prec(p: &mut Parser, min_prec: usize, stop: SyntaxKind) {
                 p.convert(SyntaxKind::Ident);
                 p.wrap(m, SyntaxKind::FieldAccess);
             }
-            if p.directly_at(SyntaxKind::Text) && p.current_text() == "(" {
+            if min_prec < 3 && p.directly_at(SyntaxKind::Text) && p.current_text() == "("
+            {
                 math_args(p);
                 p.wrap(m, SyntaxKind::FuncCall);
+                continuable = false;
             }
         }
 
         SyntaxKind::Text | SyntaxKind::Shorthand => {
-            if math_class(p.current_text()) == Some(MathClass::Fence) {
-                math_delimited(p, MathClass::Fence)
-            } else if math_class(p.current_text()) == Some(MathClass::Opening) {
-                math_delimited(p, MathClass::Closing)
-            } else {
-                p.eat()
+            continuable = matches!(
+                math_class(p.current_text()),
+                None | Some(MathClass::Alphabetic)
+            );
+            if !maybe_delimited(p, true) {
+                p.eat();
             }
         }
 
-        SyntaxKind::Linebreak
-        | SyntaxKind::Escape
-        | SyntaxKind::MathAlignPoint
-        | SyntaxKind::Str => p.eat(),
+        SyntaxKind::Linebreak | SyntaxKind::MathAlignPoint => p.eat(),
+        SyntaxKind::Escape | SyntaxKind::Str => {
+            continuable = true;
+            p.eat();
+        }
 
         _ => p.expected("expression"),
     }
 
+    if continuable
+        && min_prec < 3
+        && p.prev_end() == p.current_start()
+        && maybe_delimited(p, false)
+    {
+        p.wrap(m, SyntaxKind::Math);
+    }
+
     while !p.eof() && !p.at(stop) {
         let Some((kind, stop, assoc, mut prec)) = math_op(p.current()) else {
             break;
@@ -302,6 +315,18 @@ fn math_expr_prec(p: &mut Parser, min_prec: usize, stop: SyntaxKind) {
     }
 }
 
+fn maybe_delimited(p: &mut Parser, allow_fence: bool) -> bool {
+    if allow_fence && math_class(p.current_text()) == Some(MathClass::Fence) {
+        math_delimited(p, MathClass::Fence);
+        true
+    } else if math_class(p.current_text()) == Some(MathClass::Opening) {
+        math_delimited(p, MathClass::Closing);
+        true
+    } else {
+        false
+    }
+}
+
 fn math_delimited(p: &mut Parser, stop: MathClass) {
     let m = p.marker();
     p.eat();
@@ -361,10 +386,10 @@ fn math_class(text: &str) -> Option<MathClass> {
 fn math_op(kind: SyntaxKind) -> Option<(SyntaxKind, SyntaxKind, ast::Assoc, usize)> {
     match kind {
         SyntaxKind::Underscore => {
-            Some((SyntaxKind::MathAttach, SyntaxKind::Hat, ast::Assoc::Right, 2))
+            Some((SyntaxKind::MathAttach, SyntaxKind::Hat, ast::Assoc::Right, 3))
         }
         SyntaxKind::Hat => {
-            Some((SyntaxKind::MathAttach, SyntaxKind::Underscore, ast::Assoc::Right, 2))
+            Some((SyntaxKind::MathAttach, SyntaxKind::Underscore, ast::Assoc::Right, 3))
         }
         SyntaxKind::Slash => {
             Some((SyntaxKind::MathFrac, SyntaxKind::Eof, ast::Assoc::Left, 1))

tests/typ/compiler/highlight.typ

@@ -5,7 +5,7 @@
 #set hello()
 #set hello.world()
 #set hello.my.world()
-
+#let foo(x) = x * 2
 #show heading: func
 #show module.func: func
 #show module.func: it => {}
@@ -30,6 +30,7 @@ $ hello.my.world $
 $ hello.my.world() $
 $ hello.my().world $
 $ hello.my().world() $
+$ f_zeta(x), f_zeta(x)/1 $
 
 $ emph(hello) $
 $ emph(hello()) $

tests/typ/math/attach.typ

@@ -6,8 +6,9 @@ $f_x + t^b + V_1^2
  + attach(A, top: alpha, bottom: beta)$
 
 ---
-// Test text vs ident parsing.
-$pi_1(Y), a_f(x) != a_zeta(x)$
+// Test function call after subscript.
+$pi_1(Y), a_f(x), a^zeta(x) \
+ a^subset.eq(x), a_(zeta(x)), pi_(1(Y))$
 
 ---
 // Test associativity and scaling.

tests/typ/math/frac.typ

@@ -8,10 +8,6 @@ $ x = 1/2 = a/(a h) = a/a = a/(1/2) $
 // Test parenthesis removal.
 $ (|x| + |y|)/2 < [1+2]/3 $
 
----
-// Test associativity.
-$ 1/2/3 = (1/2)/3 = 1/(2/3) $
-
 ---
 // Test large fraction.
 $ x = (-b plus.minus sqrt(b^2 - 4a c))/(2a) $
@@ -23,3 +19,14 @@ $ binom(circle, square) $
 ---
 // Error: 8-13 missing argument: lower index
 $ binom(x^2) $
+
+---
+// Test associativity.
+$ 1/2/3 = (1/2)/3 = 1/(2/3) $
+
+---
+// Test precedence.
+$ a_1/b_2, 1/f(x), zeta(x)/2, "foo"[|x|]/2 \
+  🏳️‍🌈[x]/2, f [x]/2, phi [x]/2, 🏳️‍🌈 [x]/2 \
+  +[x]/2, 1(x)/2, 2[x]/2 \
+  (a)b/2, b(a)[b]/2 $