From 0ebce56b36ea2a875609949f4da81c9ca6a4a081 Mon Sep 17 00:00:00 2001
From: PgBiel <9021226+PgBiel@users.noreply.github.com>
Date: Tue, 5 Dec 2023 15:15:03 -0300
Subject: [PATCH] Implement lexicographic array comparison (#2827)

---
 crates/typst/src/eval/ops.rs       | 21 +++++++++++++++++++++
 tests/typ/compiler/ops-invalid.typ |  8 ++++++++
 tests/typ/compiler/ops.typ         | 12 ++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/crates/typst/src/eval/ops.rs b/crates/typst/src/eval/ops.rs
index cb830614e..8e8b6d293 100644
--- a/crates/typst/src/eval/ops.rs
+++ b/crates/typst/src/eval/ops.rs
@@ -551,6 +551,7 @@ pub fn compare(lhs: &Value, rhs: &Value) -> StrResult<Ordering> {
 
         (Duration(a), Duration(b)) => a.cmp(b),
         (Datetime(a), Datetime(b)) => try_cmp_datetimes(a, b)?,
+        (Array(a), Array(b)) => try_cmp_arrays(a.as_slice(), b.as_slice())?,
 
         _ => mismatch!("cannot compare {} and {}", lhs, rhs),
     })
@@ -568,6 +569,26 @@ fn try_cmp_datetimes(a: &Datetime, b: &Datetime) -> StrResult<Ordering> {
         .ok_or_else(|| eco_format!("cannot compare {} and {}", a.kind(), b.kind()))
 }
 
+/// Try to compare arrays of values lexicographically.
+fn try_cmp_arrays(a: &[Value], b: &[Value]) -> StrResult<Ordering> {
+    a.iter()
+        .zip(b.iter())
+        .find_map(|(first, second)| {
+            match compare(first, second) {
+                // Keep searching for a pair of elements that isn't equal.
+                Ok(Ordering::Equal) => None,
+                // Found a pair which either is not equal or not comparable, so
+                // we stop searching.
+                result => Some(result),
+            }
+        })
+        .unwrap_or_else(|| {
+            // The two arrays are equal up to the shortest array's extent,
+            // so compare their lengths instead.
+            Ok(a.len().cmp(&b.len()))
+        })
+}
+
 /// Test whether one value is "in" another one.
 pub fn in_(lhs: Value, rhs: Value) -> StrResult<Value> {
     if let Some(b) = contains(&lhs, &rhs) {
diff --git a/tests/typ/compiler/ops-invalid.typ b/tests/typ/compiler/ops-invalid.typ
index de8e62346..64e3a8786 100644
--- a/tests/typ/compiler/ops-invalid.typ
+++ b/tests/typ/compiler/ops-invalid.typ
@@ -37,6 +37,14 @@
 // Error: 3-22 cannot compare 2.2 with NaN
 #(2.2 <= float("nan"))
 
+---
+// Error: 3-26 cannot compare integer and string
+#((0, 1, 3) > (0, 1, "a"))
+
+---
+// Error: 3-42 cannot compare 3.5 with NaN
+#((0, "a", 3.5) <= (0, "a", float("nan")))
+
 ---
 // Error: 3-12 cannot divide by zero
 #(1.2 / 0.0)
diff --git a/tests/typ/compiler/ops.typ b/tests/typ/compiler/ops.typ
index 89ed3e5f7..64736228f 100644
--- a/tests/typ/compiler/ops.typ
+++ b/tests/typ/compiler/ops.typ
@@ -206,6 +206,18 @@
 #test(50% < 40% + 0pt, false)
 #test(40% + 0pt < 50% + 0pt, true)
 #test(1em < 2em, true)
+#test((0, 1, 2, 4) < (0, 1, 2, 5), true)
+#test((0, 1, 2, 4) < (0, 1, 2, 3), false)
+#test((0, 1, 2, 3.3) > (0, 1, 2, 4), false)
+#test((0, 1, 2) < (0, 1, 2, 3), true)
+#test((0, 1, "b") > (0, 1, "a", 3), true)
+#test((0, 1.1, 3) >= (0, 1.1, 3), true)
+#test((0, 1, datetime(day: 1, month: 12, year: 2023)) <= (0, 1, datetime(day: 1, month: 12, year: 2023), 3), true)
+#test(("a", 23, 40, "b") > ("a", 23, 40), true)
+#test(() <= (), true)
+#test(() >= (), true)
+#test(() <= (1,), true)
+#test((1,) <= (), false)
 
 ---
 // Test assignment operators.