/// <summary>
/// http://www.ecma-international.org/ecma-262/5.1/#sec-12.6.4
/// </summary>
/// <param name="forInStatement"></param>
/// <returns></returns>
public Completion ExecuteForInStatement(ForInStatement forInStatement)
{
Identifier identifier = forInStatement.Left.Type == SyntaxNodes.VariableDeclaration
? forInStatement.Left.As <VariableDeclaration>().Declarations.First().Id
: forInStatement.Left.As <Identifier>();
var varRef = _engine.EvaluateExpression(identifier) as Reference;
var exprRef = _engine.EvaluateExpression(forInStatement.Right);
var experValue = _engine.GetValue(exprRef);
if (experValue == Undefined.Instance || experValue == Null.Instance)
{
return(new Completion(Completion.Normal, null, null));
}
var obj = TypeConverter.ToObject(_engine, experValue);
JsValue v = Null.Instance;
// keys are constructed using the prototype chain
var cursor = obj;
var processedKeys = new HashSet <string>();
while (cursor != null)
{
var keys = _engine.Object.GetOwnPropertyNames(Undefined.Instance, Arguments.From(cursor)).AsArray();
for (var i = 0; i < keys.GetLength(); i++)
{
var p = keys.GetOwnProperty(i.ToString()).Value.AsString();
if (processedKeys.Contains(p))
{
continue;
}
processedKeys.Add(p);
// collection might be modified by inner statement
if (cursor.GetOwnProperty(p) == PropertyDescriptor.Undefined)
{
continue;
}
var value = cursor.GetOwnProperty(p);
if (!value.Enumerable.HasValue || !value.Enumerable.Value)
{
continue;
}
_engine.PutValue(varRef, p);
var stmt = ExecuteStatement(forInStatement.Body);
if (stmt.Value != null)
{
v = stmt.Value;
}
if (stmt.Type == Completion.Break)
{
return(new Completion(Completion.Normal, v, null));
}
if (stmt.Type != Completion.Continue)
{
if (stmt.Type != Completion.Normal)
{
return(stmt);
}
}
}
cursor = cursor.Prototype;
}
return(new Completion(Completion.Normal, v, null));
}