Bug 2025779 - Implement Iterator Includes; r=arai

Differential Revision: https://phabricator.services.mozilla.com/D295349

Author: dminor

js/public/friend/ErrorNumbers.msg

@@ -845,6 +845,7 @@ MSG_DEF(JSMSG_BAD_WEAKREF_TARGET,                        0, JSEXN_TYPEERR, "cann
 MSG_DEF(JSMSG_NEGATIVE_LIMIT,                            0, JSEXN_RANGEERR, "Iterator limits cannot be negative")
 MSG_DEF(JSMSG_INVALID_CHUNKSIZE,                         0, JSEXN_RANGEERR, "Iterator chunkSize must be an integer between 1 and 2**32-1 inclusive")
 MSG_DEF(JSMSG_INVALID_WINDOWSIZE,                        0, JSEXN_RANGEERR, "Iterator windowSize must be an integer between 1 and 2**32-1 inclusive")
+MSG_DEF(JSMSG_INVALID_SKIP_COUNT,                        0, JSEXN_TYPEERR, "Iterator skippedElements must be +Infinity, -Infinity, or an integral Number")
 MSG_DEF(JSMSG_INVALID_UNDERSIZED_OPTION_VALUE,           2, JSEXN_TYPEERR, "invalid value for \"{0}\" option: {1}")
 MSG_DEF(JSMSG_ITERATOR_ZIP_INVALID_OPTION_TYPE,          2, JSEXN_TYPEERR, "invalid type for \"{0}\" option: {1}")
 MSG_DEF(JSMSG_ITERATOR_ZIP_INVALID_OPTION_VALUE,         2, JSEXN_TYPEERR, "invalid value for \"{0}\" option: {1}")

js/src/builtin/Iterator.js

@@ -2168,4 +2168,77 @@ function* IteratorWindowsGenerator(iterator, nextMethod, windowSize, undersized)
 function IteratorJoin(separator) {
 	return false;
 }
+
+/**
+ *  Iterator.prototype.includes ( searchElement [ , skippedElements ] )
+ *
+ *  https://tc39.es/proposal-iterator-includes
+ */
+function IteratorIncludes(searchElement, skippedElements = undefined) {
+  // Step 1. Let O be the this value.
+  var O = this;
+
+  // Step 2. If O is not an Object, throw a TypeError exception.
+  if (!IsObject(O)) {
+    ThrowTypeError(JSMSG_OBJECT_REQUIRED, O === null ? "null" : typeof O);
+  }
+
+  // Step 3. Let iterated be the Iterator Record
+  //         { [[Iterator]]: O, [[NextMethod]]: undefined, [[Done]]: false }.
+
+  // Step 4. If skippedElements is undefined, then
+  // Step 4.a. Let toSkip be 0.
+  var toSkip = 0;
+  // Step 5. Else, (skippedElements is not undefined)
+  if (skippedElements !== undefined) {
+    // Step 5.a. If skippedElements is not one of +∞𝔽, -∞𝔽, or an integral Number, then
+    if (!(Number_isInteger(skippedElements) ||
+          (typeof skippedElements === "number" &&
+           !Number_isFinite(skippedElements) &&
+           !Number_isNaN(skippedElements)))) {
+      // Step 5.a.i-ii. Let error be ThrowCompletion(...). Return ? IteratorClose(iterated, error).
+      try {
+        IteratorClose(O);
+      } catch {}
+      ThrowTypeError(JSMSG_INVALID_SKIP_COUNT);
+    }
+    // Step 5.b. Let toSkip be the extended mathematical value of skippedElements.
+    toSkip = skippedElements;
+  }
+
+  // Step 6. If toSkip < 0, then
+  // Step 6.a. Let error be ThrowCompletion(a newly created RangeError object).
+  // Step 6.b. Return ? IteratorClose(iterated, error).
+  if (toSkip < 0) {
+    try {
+      IteratorClose(O);
+    } catch {}
+    ThrowRangeError(JSMSG_NEGATIVE_LIMIT);
+  }
+
+  // Step 7. Let skipped be 0.
+  var skipped = 0;
+
+  // Step 8. Set iterated to ? GetIteratorDirect(O).
+  // (Inlined call to GetIteratorDirect.)
+  var nextMethod = O.next;
+
+  // Step 9. Repeat,
+  // Step 9.a. Let value be ? IteratorStepValue(iterated).
+  for (var value of allowContentIterWithNext(O, nextMethod)) {
+    // Step 9.c. If skipped < toSkip, then
+    if (skipped < toSkip) {
+      // Step 9.c.i. Set skipped to skipped + 1.
+      skipped++;
+    // Step 9.d. Else if SameValueZero(value, searchElement) is true, then
+    } else if (value === searchElement || (Number_isNaN(value) && Number_isNaN(searchElement))) {
+      // Step 9.d.i. Return ? IteratorClose(iterated, NormalCompletion(true)).
+      return true;
+    }
+  }
+
+  // Step 9.b. If value is done, return false.
+  return false;
+}
+
 #endif

js/src/vm/Iteration.cpp

@@ -1977,6 +1977,7 @@ static const JSFunctionSpec iterator_methods[] = {
     JS_SELF_HOSTED_FN("chunks", "IteratorChunks", 1, 0),
     JS_SELF_HOSTED_FN("windows", "IteratorWindows", 2, 0),
     JS_SELF_HOSTED_FN("join", "IteratorJoin", 1, 0),
+    JS_SELF_HOSTED_FN("includes", "IteratorIncludes", 2, 0),
 #endif
     JS_FS_END,
 };