Merge pull request #2069 from Silvertree2010/fix/h839-field-arithmetic-rejects-followe

Evaluate * and / left to right in field arithmetic

crates/doc/src/lib.rs

@@ -270,17 +270,22 @@ impl Unit {
 fn parse_measure(s: &str, default: Unit) -> Option<f64> {
     let s = s.trim();
     // Simple arithmetic on the right (Illustrator fields accept "10+5", "100/2", "3in*2").
-    for op in ['+', '-', '*', '/'] {
+    // `*` and `/` share one precedence level, so they split at the last of either (left to right).
+    for ops in [&['+'][..], &['-'][..], &['*', '/'][..]] {
         // Past the first character, so a leading sign isn't an operator.
         let skip = s.chars().next().map_or(0, char::len_utf8);
         // A `+` or `-` right after another operator is the sign of its operand (`10*-2`, `5--3`).
-        let is_sign = |i: usize| matches!(op, '+' | '-') && s.get(..i).and_then(|l| l.trim_end().chars().last()).is_some_and(|c| "+-*/".contains(c));
-        let found = s.char_indices().rev().find(|&(i, c)| i >= skip && c == op && !is_sign(i));
+        let is_sign = |i: usize| {
+            s.get(i..).and_then(|r| r.chars().next()).is_some_and(|c| matches!(c, '+' | '-'))
+                && s.get(..i).and_then(|l| l.trim_end().chars().last()).is_some_and(|c| "+-*/".contains(c))
+        };
+        let found = s.char_indices().rev().find(|&(i, c)| i >= skip && ops.contains(&c) && !is_sign(i));
         if let Some(i) = found.map(|(i, _)| i) {
             let (l, r) = (&s[..i], &s[i + 1..]);
             if l.trim().is_empty() {
                 continue;
             }
+            let Some(op) = s[i..].chars().next() else { continue };
             return match op {
                 '+' => Some(parse_measure(l, default)? + parse_measure(r, default)?),
                 '-' => Some(parse_measure(l, default)? - parse_measure(r, default)?),

crates/doc/src/tests_units.rs

@@ -77,3 +77,12 @@ fn a_negative_operand_after_an_operator_is_a_sign() {
     assert_eq!(Unit::Points.parse("10-2"), Some(8.0));
     assert_eq!(super::parse_number("90*-1"), Some(-90.0));
 }
+
+#[test]
+fn mixed_mul_div() {
+    // `*` and `/` share one precedence level and run left to right.
+    assert_eq!(Unit::Points.parse("10/2*5"), Some(25.0));
+    assert_eq!(crate::parse_number("100*3/4"), Some(75.0));
+    assert_eq!(Unit::Points.parse("10*2/5"), Some(4.0));
+    assert_eq!(Unit::Points.parse("10*2/5 px"), Some(Unit::Pixels.to_pt(4.0)));
+}