/// <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 = cursor.GetOwnProperties().Select(x => x.Key).ToArray();
foreach (var p in keys)
{
if (processedKeys.Contains(p))
{
continue;
}
processedKeys.Add(p);
// collection might be modified by inner statement
if (!cursor.HasOwnProperty(p))
{
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);
}
private void EmitForInStatement(ForInStatement s)
{
if (s.Each)
{
throw new NotImplementedException();
}
else
{
Write("for (");
if (s.Left is VariableDeclaration)
{
var decl = s.Left as VariableDeclaration;
Emit(decl.Declarations.First());
}
else
{
Emit(s.Left);
}
Write(" in ");
Emit(s.Right);
Write(") ");
}
Emit(s.Body);
}