Compare strings with numeric ordering for digits

1 files changed, 66 insertions, 10 deletions

diff --git a/systems/sheet/src/mapping.rs b/systems/sheet/src/mapping.rs
index 469e083..f509c0b 100644
--- a/systems/sheet/src/mapping.rs
+++ b/systems/sheet/src/mapping.rs
@@ -645,7 +645,7 @@ impl Ord for LocalMapping {
 /// Compare two `Vec<String>` according to a specific ordering:
 /// 1. ASCII symbols (excluding letters and digits)
 /// 2. Letters (Aa-Zz, case‑sensitive, uppercase before lowercase)
-/// 3. Digits (0‑9)
+/// 3. Digits (0‑9) - compared numerically
 /// 4. All other Unicode characters (in their natural order)
 ///
 /// The comparison is lexicographic: the first differing element determines the order.
@@ -664,15 +664,28 @@ fn compare_vec_string(a: &Vec<String>, b: &Vec<String>) -> std::cmp::Ordering {
 
 /// Compare two individual strings with the same ordering rules.
 fn compare_string(a: &str, b: &str) -> std::cmp::Ordering {
-    let mut a_chars = a.chars();
-    let mut b_chars = b.chars();
+    let mut a_chars = a.chars().peekable();
+    let mut b_chars = b.chars().peekable();
 
     loop {
-        match (a_chars.next(), b_chars.next()) {
-            (Some(ca), Some(cb)) => {
-                let ord = compare_char(ca, cb);
-                if ord != Ordering::Equal {
-                    return ord;
+        match (a_chars.peek(), b_chars.peek()) {
+            (Some(&ca), Some(&cb)) => {
+                if ca.is_ascii_digit() && cb.is_ascii_digit() {
+                    // Parse both numbers and compare numerically
+                    let a_num = parse_number(&mut a_chars);
+                    let b_num = parse_number(&mut b_chars);
+                    match a_num.cmp(&b_num) {
+                        Ordering::Equal => continue,
+                        ord => return ord,
+                    }
+                } else {
+                    // Non-digit comparison
+                    let ord = compare_char(ca, cb);
+                    if ord != Ordering::Equal {
+                        return ord;
+                    }
+                    a_chars.next();
+                    b_chars.next();
                 }
             }
             (None, Some(_)) => return Ordering::Less,
@@ -682,10 +695,26 @@ fn compare_string(a: &str, b: &str) -> std::cmp::Ordering {
     }
 }
 
+/// Parse a number from the character iterator.
+/// Consumes consecutive ASCII digits and returns the parsed u64.
+/// Assumes the first character is already verified to be a digit.
+fn parse_number<I: Iterator<Item = char>>(chars: &mut std::iter::Peekable<I>) -> u64 {
+    let mut num = 0;
+    while let Some(&c) = chars.peek() {
+        if c.is_ascii_digit() {
+            num = num * 10 + (c as u64 - '0' as u64);
+            chars.next();
+        } else {
+            break;
+        }
+    }
+    num
+}
+
 /// Compare two characters according to the ordering:
 /// 1. ASCII symbols (non‑letter, non‑digit)
 /// 2. Letters (A‑Z then a‑z)
-/// 3. Digits (0‑9)
+/// 3. Digits (0‑9) - note: digits are handled specially in compare_string
 /// 4. Other Unicode
 fn compare_char(a: char, b: char) -> std::cmp::Ordering {
     let group_a = char_group(a);
@@ -708,7 +737,11 @@ fn compare_char(a: char, b: char) -> std::cmp::Ordering {
                 a.cmp(&b)
             }
         }
-        CharGroup::Digit => a.cmp(&b), // Digits 0‑9
+        CharGroup::Digit => {
+            // Digits should be compared numerically, but this is only reached
+            // when comparing single digits (not part of a longer number).
+            a.cmp(&b)
+        }
         CharGroup::Other => a.cmp(&b), // Other Unicode (natural order)
     }
 }
@@ -741,3 +774,26 @@ fn test_compare_char_groups() {
     assert!(compare_string("a", "0") == Ordering::Less);
     assert!(compare_string("9", "你") == Ordering::Less);
 }
+
+#[test]
+fn test_numeric_ordering() {
+    // Test numeric ordering
+    assert!(compare_string("0", "1") == Ordering::Less);
+    assert!(compare_string("1", "0") == Ordering::Greater);
+    assert!(compare_string("9", "10") == Ordering::Less);
+    assert!(compare_string("10", "9") == Ordering::Greater);
+    assert!(compare_string("99", "100") == Ordering::Less);
+    assert!(compare_string("100", "99") == Ordering::Greater);
+    assert!(compare_string("001", "1") == Ordering::Equal); // "001" numerically equals "1"
+    assert!(compare_string("01", "1") == Ordering::Equal); // "01" numerically equals "1"
+
+    // Test mixed strings
+    assert!(compare_string("Frame-9", "Frame-10") == Ordering::Less);
+    assert!(compare_string("Frame-10", "Frame-9") == Ordering::Greater);
+    assert!(compare_string("Frame-99", "Frame-100") == Ordering::Less);
+    assert!(compare_string("Frame-100", "Frame-99") == Ordering::Greater);
+
+    // Test that numbers are compared as whole numbers, not digit-by-digit
+    assert!(compare_string("123", "23") == Ordering::Greater); // 123 > 23
+    assert!(compare_string("23", "123") == Ordering::Less); // 23 < 123
+}