7 nov. 2022 kl. 21.35 skrev Yuan Fu <casouri@gmail.com>:
> fast_c_string_match_ignore_case (Lisp_Object regexp,
> const char *string, ptrdiff_t len)
> {
> regexp = string_make_unibyte (regexp);
This is expensive and not obviously correct when it makes a difference. Ie, no
longer "fast", and may hide bugs.
Something should be done about that.
> // Why do we need to unwind stack?
> specpdl_ref count = SPECPDL_INDEX ();
Because freeze_pattern pushes an unwind-protect on the specpdl.
> struct regexp_cache *cache_entry
> = compile_pattern (regexp, 0, Vascii_canon_table, 0, 0);
`Vascii_canon_table` is what makes it case-insensitive; you want to use Qnil
(but you probably already know that now).
Since this is the only thing that differs from your intended use, I suggest you
generalise this subroutine with a boolean parameter.
> // What does freezing a pattern do?
> freeze_pattern (cache_entry);
It locks the compiled pattern record to make the regexp engine reentrant (but
here it also seems to be used for GC purposes; not sure about that).
> // What is re_match_object for? I see that it can be t, nil or a string.
> re_match_object = Qt;
Described in regex-emacs.h:
> /* The string or buffer being matched.
> It is used for looking up syntax properties.
>
> If the value is a Lisp string object, match text in that string; if
> it's nil, match text in the current buffer; if it's t, match text
> in a C string.
>
> This value is effectively another parameter to re_search_2 and
> re_match_2. No calls into Lisp or thread switches are allowed
> before setting re_match_object and calling into the regex search
> and match functions. These functions capture the current value of
> re_match_object into gl_state on entry.
>
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