bool IsLet()
{
if (Type != TokenType.Name || Options.EcmaVersion < 6 || (string)Value != "let")
{
return(false);
}
var skip = SkipWhiteSpace.Match(_input, _pos.Index);
var next = _pos.Index + skip.Groups[0].Length;
var nextCh = _input[next];
if (nextCh == 91 || nextCh == 123)
{
return(true); // '{' and '['
}
if (IsIdentifierStart(nextCh, true))
{
var pos = next + 1;
while (IsIdentifierChar(_input.Get(pos), true))
{
++pos;
}
var ident = _input.Substring(next, pos - next);
if (!KeywordRelationalOperator.IsMatch(ident))
{
return(true);
}
}
return(false);
}
bool IsLet()
{
if (Type != TokenType.Name || !"let".Equals(Value))
{
return(false);
}
var skip = SkipWhiteSpace.Match(_input, _pos.Index);
var next = _pos.Index + skip.Groups[0].Length;
var nextCh = _input[next];
if (nextCh == CharCode.LeftSquareBracket || nextCh == CharCode.LeftCurlyBracket)
{
return(true); // '{' and '['
}
if (IsIdentifierStart(nextCh, true))
{
var pos = next + 1;
while (IsIdentifierChar(_input.Get(pos), true))
{
++pos;
}
var ident = _input.Substring(next, pos - next);
if (!KeywordRelationalOperator.IsMatch(ident))
{
return(true);
}
}
return(false);
}
// check 'async [no LineTerminator here] function'
// - 'async /*foo*/ function' is OK.
// - 'async /*\n*/ function' is invalid.
bool IsAsyncFunction()
{
if (Type != TokenType.Name || Options.EcmaVersion < 8 || (string)Value != "async")
{
return(false);
}
var skip = SkipWhiteSpace.Match(_input, _pos.Index);
var next = _pos.Index + skip.Groups[0].Length;
return(!LineBreak.IsMatch(_input.Substring(_pos.Index, next - _pos.Index)) &&
_input.Length >= next + 8 && _input.AsSpan(next, 8).SequenceEqual("function") &&
(next + 8 == _input.Length || !IsIdentifierChar(_input.Get(next + 8))));
}
