Re: ECMAScript: Automatic Semicolon Insertion

[Ricky]

Your syntax implies that [\n] should be treated as [;]. So why not use [\n] as 
alternative?

Cheers,
Ricky

> On Dec 6, 2016, at 4:23 PM, Simon Richter <address@hidden> wrote:
> 
> Hi,
> 
> I'm still building an ECMAScript parser, it's mostly running, except for
> the Automatic Semicolon Insertion rule in the language: if a token stream
> is invalid, but can be made valid by inserting a semicolon in front of the
> current token, pretend that a semicolon is there.
> 
> For example inside a function:
> 
>    function f() {
>        i = 5
>    }
> 
> the semicolon at the end of the assignment is implied, because a closing
> brace is unexpected there. Similarly,
> 
>    var foo = 4
>    var bar = 5
> 
> is legal, because the "var" token after the 4 is unexpected. At the same
> time, if I make the semicolon optional, I'm in shift/reduce hell as the
> next token could be unary or binary minus (as well as some other things).
> 
> Is there a way to create a last-resort alternative that always loses any
> conflict, so I can do something similar to
> 
>    variable_statement:
>        "var" variable_declaration_list ";"     %prec WIN |
>        "var" variable_declaration_list         %prec LOSE;
> 
> The expected result would be that anything that can be used to continue a
> variable_declaration_list should go into it, anything that cannot be used
> would terminate it, and a semicolon would terminate it nonetheless.
> 
> Alternatively, can I somehow use YYBACKUP or the error symbol here, by
> allowing error productions instead of a semicolon, and inserting a
> semicolon token as the next lookahead?
> 
>   Simon
> 
> _______________________________________________
> address@hidden https://lists.gnu.org/mailman/listinfo/help-bison