From 618863ecf14b99e12ad9a055f91db2fe74d651a9 Mon Sep 17 00:00:00 2001
From: vigneshrajan94 <vrajan@terpmail.umd.edu>
Date: Wed, 27 May 2026 17:06:16 +0530
Subject: [PATCH] Fix median sort, set-op duplicates, and unescape Unicode
 range
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Fixes three independent bugs:

- Arithmetic.mjs (median): sort was only applied for even-length arrays;
  odd-length inputs returned the middle element of the unsorted array.
  Sort is now unconditional. Fixes #2239.

- SetDifference / SetIntersection: plain .filter() on array a preserved
  duplicate entries from the first input, violating set semantics.
  Deduplicate a via [...new Set(a)] before filtering. Fixes #2241.

- UnescapeUnicodeCharacters: regex quantifier was hardcoded to {4} for
  all prefixes. U+ notation allows 4-6 hex digits (e.g. U+1F600 for 😀);
  \u and %u remain at exactly {4} per their respective specs. Fixes #2242.
---
 src/core/lib/Arithmetic.mjs                       | 9 +++++----
 src/core/operations/SetDifference.mjs             | 2 +-
 src/core/operations/SetIntersection.mjs           | 2 +-
 src/core/operations/UnescapeUnicodeCharacters.mjs | 3 ++-
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/core/lib/Arithmetic.mjs b/src/core/lib/Arithmetic.mjs
index 7c10855f..a1c2e181 100644
--- a/src/core/lib/Arithmetic.mjs
+++ b/src/core/lib/Arithmetic.mjs
@@ -108,10 +108,11 @@ export function mean(data) {
  * @returns {BigNumber}
  */
 export function median(data) {
-    if ((data.length % 2) === 0 && data.length > 0) {
-        data.sort(function(a, b) {
-            return a.minus(b);
-        });
+    if (data.length === 0) return data[0];
+    data.sort(function(a, b) {
+        return a.minus(b);
+    });
+    if ((data.length % 2) === 0) {
         const first = data[Math.floor(data.length / 2)];
         const second = data[Math.floor(data.length / 2) - 1];
         return mean([first, second]);
diff --git a/src/core/operations/SetDifference.mjs b/src/core/operations/SetDifference.mjs
index dc46c079..1c14a289 100644
--- a/src/core/operations/SetDifference.mjs
+++ b/src/core/operations/SetDifference.mjs
@@ -75,7 +75,7 @@ class SetDifference extends Operation {
      * @returns {Object[]}
      */
     runSetDifference(a, b) {
-        return a
+        return [...new Set(a)]
             .filter((item) => {
                 return b.indexOf(item) === -1;
             })
diff --git a/src/core/operations/SetIntersection.mjs b/src/core/operations/SetIntersection.mjs
index 7e6dbe10..27a36aa7 100644
--- a/src/core/operations/SetIntersection.mjs
+++ b/src/core/operations/SetIntersection.mjs
@@ -75,7 +75,7 @@ class SetIntersection extends Operation {
      * @returns {Object[]}
      */
     runIntersect(a, b) {
-        return a
+        return [...new Set(a)]
             .filter((item) => {
                 return b.indexOf(item) > -1;
             })
diff --git a/src/core/operations/UnescapeUnicodeCharacters.mjs b/src/core/operations/UnescapeUnicodeCharacters.mjs
index 02d16662..f7759c78 100644
--- a/src/core/operations/UnescapeUnicodeCharacters.mjs
+++ b/src/core/operations/UnescapeUnicodeCharacters.mjs
@@ -56,7 +56,8 @@ class UnescapeUnicodeCharacters extends Operation {
      */
     run(input, args) {
         const prefix = prefixToRegex[args[0]],
-            regex = new RegExp(prefix+"([a-f\\d]{4})", "ig");
+            quantifier = args[0] === "U+" ? "{4,6}" : "{4}",
+            regex = new RegExp(prefix+"([a-f\\d]"+quantifier+")", "ig");
         let output = "",
             m,
             i = 0;