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Refactor array iterator creation helper #210

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Refactor array iterator creation helper #210

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80 changes: 13 additions & 67 deletions src/Asynkron.JsEngine/StdLib/StandardLibrary.Array.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,18 @@
{
private const long MaxArrayLength = 9007199254740991L; // 2^53 - 1

private static double ToLengthValue(object? candidate)
{
var num = JsOps.ToNumber(candidate);
if (double.IsNaN(num) || double.IsInfinity(num) || num <= 0)
{
return 0;
}

var truncated = Math.Floor(num);
return Math.Min(truncated, (double)MaxArrayLength); // 2^53 - 1
}

public static void AddArrayMethods(IJsPropertyAccessor array, RealmState? realm = null,
JsObject? prototypeOverride = null)
{
Expand Down Expand Up @@ -109,72 +121,6 @@
});
return;

static double ToLengthValue(object? candidate)
{
var num = JsOps.ToNumber(candidate);
if (double.IsNaN(num) || double.IsInfinity(num) || num <= 0)
{
return 0;
}

var truncated = Math.Floor(num);
return Math.Min(truncated, (double)MaxArrayLength); // 2^53 - 1
}

static object CreateArrayIterator(object? thisValue, IJsPropertyAccessor accessor,
Func<uint, object?> projector)
{
var iterator = new JsObject();
var iteratorSymbol = TypedAstSymbol.For("Symbol.iterator");
var iteratorKey = $"@@symbol:{iteratorSymbol.GetHashCode()}";

uint index = 0;
var exhausted = false;

iterator.SetHostedProperty("next", Next);

iterator.SetHostedProperty(iteratorKey, ReturnIterator);
return iterator;

object? Next(object? _, IReadOnlyList<object?> __)
{
if (exhausted)
{
var doneResult = new JsObject();
doneResult.SetProperty("value", Symbol.Undefined);
doneResult.SetProperty("done", true);
return doneResult;
}

uint length = 0;
if (accessor.TryGetProperty("length", out var lengthValue))
{
length = (uint)ToLengthValue(lengthValue);
}

var result = new JsObject();
if (index < length)
{
result.SetProperty("value", projector(index));
result.SetProperty("done", false);
index++;
}
else
{
result.SetProperty("value", Symbol.Undefined);
result.SetProperty("done", true);
exhausted = true;
}

return result;
}

object? ReturnIterator(object? _, IReadOnlyList<object?> __)
{
return iterator;
}
}

HostFunction DefineArrayIteratorFunction(string name,
Func<IJsPropertyAccessor, object?, Func<uint, object?>> projectorFactory)
{
Expand All @@ -197,7 +143,7 @@
}

var projector = projectorFactory(accessor, thisValue);
return CreateArrayIterator(thisValue, accessor, projector);
return CreateArrayIterator(accessor, projector);
}) { IsConstructor = false };

fn.DefineProperty("name",
Expand Down Expand Up @@ -873,7 +819,7 @@
var toKey = ToIndexString(resultIndex);
if (TryGetExistingElement(spreadAccessor, fromKey, out var value))
{
result.SetProperty(toKey, value);

Check warning on line 822 in src/Asynkron.JsEngine/StdLib/StandardLibrary.Array.cs

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Dereference of a possibly null reference.
}
else if (result is not null)
{
Expand All @@ -890,11 +836,11 @@
throw ThrowTypeError("Array length exceeds 2^53 - 1", realm: realm);
}

result.SetProperty(ToIndexString(resultIndex++), sourceValue);

Check warning on line 839 in src/Asynkron.JsEngine/StdLib/StandardLibrary.Array.cs

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Dereference of a possibly null reference.
}
}

SetArrayLikeLength(result, resultIndex);

Check warning on line 843 in src/Asynkron.JsEngine/StdLib/StandardLibrary.Array.cs

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Possible null reference argument for parameter 'target' in 'void StandardLibrary.SetArrayLikeLength(IJsPropertyAccessor target, long length)'.
return result;
}

Expand Down Expand Up @@ -1262,7 +1208,7 @@
result?.Delete(key);
}

SetArrayLikeLength(result, length);

Check warning on line 1211 in src/Asynkron.JsEngine/StdLib/StandardLibrary.Array.cs

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GitHub Actions / build-and-test 

Possible null reference argument for parameter 'target' in 'void StandardLibrary.SetArrayLikeLength(IJsPropertyAccessor target, long length)'.
return result;
}

Expand Down Expand Up @@ -2498,7 +2444,7 @@
private static IJsObjectLike CreateArrayLikeReceiverForConstructor(IJsCallable constructor, RealmState? realm,
long length)
{
var proto = ResolveConstructPrototype(constructor, constructor, realm);

Check warning on line 2447 in src/Asynkron.JsEngine/StdLib/StandardLibrary.Array.cs

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GitHub Actions / build-and-test 

Possible null reference argument for parameter 'realmState' in 'JsObject? StandardLibrary.ResolveConstructPrototype(IJsCallable newTarget, IJsCallable target, RealmState realmState)'.
IJsObjectLike receiver;

if (constructor is HostFunction hostFunction && realm?.ArrayConstructor is not null &&
Expand Down
77 changes: 52 additions & 25 deletions src/Asynkron.JsEngine/StdLib/StandardLibrary.IteratorHelpers.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ public static HostFunction CreateGetAsyncIteratorHelper(JsEngine engine)

if (iterable is JsArray jsArray)
{
var iteratorObj = CreateArrayIterator(jsArray);
var iteratorObj = CreateArrayIterator(jsArray, idx => jsArray.GetElement((int)idx));
engine.WriteAsyncIteratorTrace(
$"getAsyncIterator: branch=array length={jsArray.Length}");
return iteratorObj;
Expand Down Expand Up @@ -104,37 +104,64 @@ static JsObject CreateStringIterator(string str)
}
}

static JsObject CreateArrayIterator(JsArray array)
static bool HasCallableNext(object? candidate)
{
var iteratorObj = new JsObject();
var index = 0;
iteratorObj.SetHostedProperty("next", Next);
return iteratorObj;
return candidate is JsObject obj &&
obj.TryGetProperty("next", out var nextProp) &&
nextProp is IJsCallable;
}
}
}

object? Next(IReadOnlyList<object?> _)
{
var result = new JsObject();
if (index < array.Length)
{
result.SetProperty("value", array.GetElement(index));
result.SetProperty("done", false);
index++;
}
else
{
result.SetProperty("done", true);
}
private static JsObject CreateArrayIterator(IJsPropertyAccessor accessor, Func<uint, object?> projector)
{
var iterator = new JsObject();
var iteratorSymbol = TypedAstSymbol.For("Symbol.iterator");
var iteratorKey = $"@@symbol:{iteratorSymbol.GetHashCode()}";

return result;
}
uint index = 0;
var exhausted = false;

iterator.SetHostedProperty("next", Next);
iterator.SetHostedProperty(iteratorKey, ReturnIterator);
return iterator;

object? Next(object? _, IReadOnlyList<object?> __)
{
if (exhausted)
{
var doneResult = new JsObject();
doneResult.SetProperty("value", Symbol.Undefined);
doneResult.SetProperty("done", true);
return doneResult;
}

static bool HasCallableNext(object? candidate)
uint length = 0;
if (accessor.TryGetProperty("length", out var lengthValue))
{
return candidate is JsObject obj &&
obj.TryGetProperty("next", out var nextProp) &&
nextProp is IJsCallable;
length = (uint)ToLengthValue(lengthValue);
}

var result = new JsObject();
if (index < length)
{
result.SetProperty("value", projector(index));
result.SetProperty("done", false);
index++;
}
else
{
result.SetProperty("value", Symbol.Undefined);
result.SetProperty("done", true);
exhausted = true;
}

return result;
}

object? ReturnIterator(object? _, IReadOnlyList<object?> __)
{
return iterator;
}
}

Expand Down
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