Hi,
The bash parser uses global variables and it also uses lexical freeback.
For example, to deal with heredoc in bash, the grammar rule will change the
variable `need_here_doc` via `push_heredoc()`.
```
| LESS_LESS WORD
{
source.dest = 0;
redir.filename = $2;
$$ = make_redirection (source, r_reading_until, redir, 0);
push_heredoc ($$);
}
```
http://git.savannah.gnu.org/cgit/bash.git/tree/parse.y#n539
```
static void
push_heredoc (r)
REDIRECT *r;
{
if (need_here_doc >= HEREDOC_MAX)
{
last_command_exit_value = EX_BADUSAGE;
need_here_doc = 0;
report_syntax_error (_("maximum here-document count exceeded"));
reset_parser ();
exit_shell (last_command_exit_value);
}
redir_stack[need_here_doc++] = r;
}
```
http://git.savannah.gnu.org/cgit/bash.git/tree/parse.y#n2794
`need_here_doc` is used in `read_token()`, which is called by
`yylex()`. This makes the behavior of `yylex()` non-automomous.
It seems to me that the parsing code could be made simpler by making
the parser reentrant. So there can be a parser parses anything not
heredoc and another parser just parse heredoc. And there should
different lexers for non-heredoc and heredoc. Is it so?
Does anybody have any suggestions on how to make the parsing code more
manageable?
````
if (need_here_doc)
gather_here_documents ();
````
http://git.savannah.gnu.org/cgit/bash.git/tree/parse.y#n3285
````
current_token = read_token (READ);
````
http://git.savannah.gnu.org/cgit/bash.git/tree/parse.y#n2761
--
Regards,
Peng
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