lexing__get_next_char ?

Ian T Zimmerman (itz@rahul.net)
Thu, 17 Oct 1996 20:40:55 -0700

Date: Thu, 17 Oct 1996 20:40:55 -0700
Message-Id: <199610180340.UAA12614@kronstadt.rahul.net>
From: Ian T Zimmerman <itz@rahul.net>
To: caml-list@inria.fr
Subject: lexing__get_next_char ?

Hello camellers --- this is a hacker question.
In the caml-light sources, in src/runtime/lexing.c, the primitive
get_next_char is defined as follows:

struct lexer_buffer {
value refill_buff;
value lex_buffer;
value lex_abs_pos;
value lex_start_pos;
value lex_curr_pos;
value lex_last_pos;
value lex_last_action;
};

value get_next_char(lexbuf) /* ML */
struct lexer_buffer * lexbuf;
{
mlsize_t buffer_len, curr_pos;

buffer_len = string_length(lexbuf->lex_buffer);
...

How can this work, when lexer buffers are ML records on the heap, as
the following piece of src/lib/lexing.ml seems to show:

let create_lexer f =
{ refill_buff = lex_refill f;
lex_buffer = create_string 2048;
lex_abs_pos = - 2048;
lex_start_pos = 2048;
lex_curr_pos = 2048;
lex_last_pos = 2048;
lex_last_action = dummy_action }
...

Shouldn't get_next_char be something like

value get_next_char(lexbuf) /* ML */
value lexbuf;
{
mlsize_t buffer_len, curr_pos;
assert(Is_block(lexbuf));
buffer_len = string_length(Field(lexbuf,1));
...

Thanks for your explanation!

-- 
Ian T Zimmerman                        <itz@rahul.net>
Days spent working only for oneself are twice wasted; 
it would have been better not to work at all.