From 61a8c195566f1f68a250e5132a37f4600909eccb Mon Sep 17 00:00:00 2001
From: Luke <luke.wilde@live.co.uk>
Date: Fri, 18 Jun 2021 03:57:53 +0100
Subject: [PATCH] LibJS: Add %TypedArray%.prototype.find

---
 .../LibJS/Runtime/TypedArrayPrototype.cpp     |  15 +++
 .../LibJS/Runtime/TypedArrayPrototype.h       |   1 +
 .../TypedArray/TypedArray.prototype.find.js   | 108 ++++++++++++++++++
 3 files changed, 124 insertions(+)
 create mode 100644 Userland/Libraries/LibJS/Tests/builtins/TypedArray/TypedArray.prototype.find.js

diff --git a/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp b/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp
index 598339b1ec..123b79447b 100644
--- a/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp
@@ -27,6 +27,7 @@ void TypedArrayPrototype::initialize(GlobalObject& object)
     define_native_accessor(vm.names.byteOffset, byte_offset_getter, nullptr, Attribute::Configurable);
     define_native_function(vm.names.at, at, 1, attr);
     define_native_function(vm.names.every, every, 1, attr);
+    define_native_function(vm.names.find, find, 1, attr);
 }
 
 TypedArrayPrototype::~TypedArrayPrototype()
@@ -139,6 +140,20 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::every)
     return Value(result);
 }
 
+// 23.2.3.10 %TypedArray%.prototype.find ( predicate [ , thisArg ] ), https://tc39.es/ecma262/#sec-%typedarray%.prototype.find
+JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::find)
+{
+    auto result = js_undefined();
+    for_each_item(vm, global_object, "find", [&](auto, auto value, auto callback_result) {
+        if (callback_result.to_boolean()) {
+            result = value;
+            return IterationDecision::Break;
+        }
+        return IterationDecision::Continue;
+    });
+    return result;
+}
+
 // 23.2.3.1 get %TypedArray%.prototype.buffer, https://tc39.es/ecma262/#sec-get-%typedarray%.prototype.buffer
 JS_DEFINE_NATIVE_GETTER(TypedArrayPrototype::buffer_getter)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.h b/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.h
index f0e225077f..be4c44d8b8 100644
--- a/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.h
@@ -26,6 +26,7 @@ private:
 
     JS_DECLARE_NATIVE_FUNCTION(at);
     JS_DECLARE_NATIVE_FUNCTION(every);
+    JS_DECLARE_NATIVE_FUNCTION(find);
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/TypedArray/TypedArray.prototype.find.js b/Userland/Libraries/LibJS/Tests/builtins/TypedArray/TypedArray.prototype.find.js
new file mode 100644
index 0000000000..5eb85af952
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/TypedArray/TypedArray.prototype.find.js
@@ -0,0 +1,108 @@
+const TYPED_ARRAYS = [
+    Uint8Array,
+    Uint16Array,
+    Uint32Array,
+    Int8Array,
+    Int16Array,
+    Int32Array,
+    Float32Array,
+    Float64Array,
+];
+
+const BIGINT_TYPED_ARRAYS = [BigUint64Array, BigInt64Array];
+
+test("length is 1", () => {
+    TYPED_ARRAYS.forEach(T => {
+        expect(T.prototype.find).toHaveLength(1);
+    });
+
+    BIGINT_TYPED_ARRAYS.forEach(T => {
+        expect(T.prototype.find).toHaveLength(1);
+    });
+});
+
+describe("errors", () => {
+    function errorTests(T) {
+        test(`requires at least one argument (${T.name})`, () => {
+            expect(() => {
+                new T().find();
+            }).toThrowWithMessage(
+                TypeError,
+                "TypedArray.prototype.find() requires at least one argument"
+            );
+        });
+
+        test(`callback must be a function (${T.name})`, () => {
+            expect(() => {
+                new T().find(undefined);
+            }).toThrowWithMessage(TypeError, "undefined is not a function");
+        });
+    }
+
+    TYPED_ARRAYS.forEach(T => errorTests(T));
+    BIGINT_TYPED_ARRAYS.forEach(T => errorTests(T));
+});
+
+describe("normal behaviour", () => {
+    test("basic functionality", () => {
+        TYPED_ARRAYS.forEach(T => {
+            const typedArray = new T([1, 2, 3]);
+
+            expect(typedArray.find(value => value === 1)).toBe(1);
+            expect(typedArray.find(value => value === 2)).toBe(2);
+            expect(typedArray.find(value => value === 3)).toBe(3);
+            expect(typedArray.find((value, index) => index === 1)).toBe(2);
+            expect(typedArray.find(value => value == "1")).toBe(1);
+            expect(typedArray.find(value => value === 10)).toBeUndefined();
+        });
+
+        BIGINT_TYPED_ARRAYS.forEach(T => {
+            const typedArray = new T([1n, 2n, 3n]);
+
+            expect(typedArray.find(value => value === 1n)).toBe(1n);
+            expect(typedArray.find(value => value === 2n)).toBe(2n);
+            expect(typedArray.find(value => value === 3n)).toBe(3n);
+            expect(typedArray.find((value, index) => index === 1)).toBe(2n);
+            expect(typedArray.find(value => value == 1)).toBe(1n);
+            expect(typedArray.find(value => value == "1")).toBe(1n);
+            expect(typedArray.find(value => value === 1)).toBeUndefined();
+        });
+    });
+
+    test("never calls callback with empty array", () => {
+        function emptyTest(T) {
+            var callbackCalled = 0;
+            expect(
+                new T().find(() => {
+                    callbackCalled++;
+                })
+            ).toBeUndefined();
+            expect(callbackCalled).toBe(0);
+        }
+
+        TYPED_ARRAYS.forEach(T => emptyTest(T));
+        BIGINT_TYPED_ARRAYS.forEach(T => emptyTest(T));
+    });
+
+    test("calls callback once for every item", () => {
+        TYPED_ARRAYS.forEach(T => {
+            var callbackCalled = 0;
+            expect(
+                new T([1, 2, 3]).find(() => {
+                    callbackCalled++;
+                })
+            ).toBeUndefined();
+            expect(callbackCalled).toBe(3);
+        });
+
+        BIGINT_TYPED_ARRAYS.forEach(T => {
+            var callbackCalled = 0;
+            expect(
+                new T([1n, 2n, 3n]).find(() => {
+                    callbackCalled++;
+                })
+            ).toBeUndefined();
+            expect(callbackCalled).toBe(3);
+        });
+    });
+});