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lexing__get_next_char ?
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Date: -- (:)
From: Ian T Zimmerman <itz@r...>
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.