1 files changed, 81 insertions, 0 deletions
diff --git a/src/app/utils/set_utils.js b/src/app/utils/set_utils.js
new file mode 100644
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+++ b/src/app/utils/set_utils.js
@@ -0,0 +1,81 @@
+/**
+ * Operations on sets.
+ * @module app/utils/set_utils
+ */
+
+/**
+ * Determine if `set` contains `subset`
+ * @param  {Set}  set       the superset
+ * @param  {Set}  subset    the subset
+ * @return {Boolean}        true if set contains subset
+ */
+export function isSuperset(set, subset) {
+  for (let elem of subset) {
+    if (!set.has(elem)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+/**
+ * Return the union (A or B) of two sets
+ * @param  {Set}  setA      a set
+ * @param  {Set}  setB      a set
+ * @return {Boolean}        the union of the sets
+ */
+export function union(setA, setB) {
+  let _union = new Set(setA);
+  for (let elem of setB) {
+    _union.add(elem);
+  }
+  return _union;
+}
+
+/**
+ * Return the intersection (A and B) of two sets
+ * @param  {Set}  setA      a set
+ * @param  {Set}  setB      a set
+ * @return {Boolean}        the intersection of the sets
+ */
+export function intersection(setA, setB) {
+  let _intersection = new Set();
+  for (let elem of setB) {
+    if (setA.has(elem)) {
+      _intersection.add(elem);
+    }
+  }
+  return _intersection;
+}
+
+/**
+ * Return the symmetric difference (A xor B) of two sets
+ * @param  {Set}  setA      a set
+ * @param  {Set}  setB      a set
+ * @return {Boolean}        the symmetric difference of the sets
+ */
+export function symmetricDifference(setA, setB) {
+  let _difference = new Set(setA);
+  for (let elem of setB) {
+    if (_difference.has(elem)) {
+      _difference.delete(elem);
+    } else {
+      _difference.add(elem);
+    }
+  }
+  return _difference;
+}
+
+/**
+ * Return the difference (A not B) of two sets
+ * @param  {Set}  setA      a set
+ * @param  {Set}  setB      a set
+ * @return {Boolean}        the difference of the sets
+ */
+export function difference(setA, setB) {
+  let _difference = new Set(setA);
+  for (let elem of setB) {
+    _difference.delete(elem);
+  }
+  return _difference;
+}