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Remove print state objects, and ports-with-print-state

The goal was that, as part of a print operation, all nested prints of
contained data would be able to use the same parameters (e.g. write or
not), and also detect cycles, highlight objects, etc.  The mechanism was
a heap-allocated data structure.  However, given that:

  1. Nobody accessed print states from Scheme

  2. `write` and `display` should move to Scheme anyway, in order to be
     suspendable

  3. The "fancyp" and "highlight" options were unused

  4. A simple stack-allocated data structure with a per-thread key could
     do the trick just as well, without needing the weird freelist
     structure

  5. Ports-with-print-states were a source of bugs

In the end we switch print states to be something completely internal to
print.c.  There are no more SCM print-state objects, and no more
ports-with-print-state.

* libguile/print.h: Remove print state from API.
* libguile/print.c (struct scm_print_state): Move definition here.
(scm_print_opts): Remove "highlight-prefix" and "highlight-suffix"
options, as they were not used.
(ENTER_NESTED_DATA): Remove "fancyp" case.
(init_print_state_key, get_print_state, push_print_state)
(maybe_push_print_state, pop_print_state): New facility to manage stack
of active print states.
(scm_iprin1, print_vector): No more fancyp.
(iprin1): Access "writingp" member directly.  Don't make ports with
print states.
(scm_prin1): Manage print state stack.
(scm_iprlist): No more fancyp.
(scm_valid_oport_value_p): Remove; valid outports are SCM_OPOUTPORTP.
* libguile/backtrace.c:
* libguile/filesys.c:
* libguile/fports.c:
* libguile/goops.c:
* libguile/ioext.c:
* libguile/ports.c:
* libguile/posix.c:
* libguile/promises.c:
* libguile/socket.c:
* libguile/struct.c: Remove cases that dealt with
ports-with-print-states.
* libguile/private-options.h: Remove highlight options.
* module/ice-9/ports.scm (inherit-print-state): Deprecate.
* libguile/deprecated.c:
* libguile/deprecated.h: Add deprecation shims for print states, as far
as that is possible.
This commit is contained in:
Andy Wingo 2025-06-17 08:33:47 +02:00
parent d1b548033c
commit 3cf4ca187c
16 changed files with 181 additions and 425 deletions

View file

@ -295,13 +295,8 @@ SCM_DEFINE (scm_class_of, "class-of", 1, 0, 0,
return class_procedure;
case scm_tc7_smob:
{
scm_t_bits type = SCM_TYP16 (x);
if (type != scm_tc16_port_with_ps)
return scm_i_smob_class[SCM_TC2SMOBNUM (type)];
x = SCM_PORT_WITH_PS_PORT (x);
/* fall through to ports */
}
return scm_i_smob_class[SCM_TC2SMOBNUM (SCM_TYP16 (x))];
case scm_tc7_port:
{
scm_t_port_type *ptob = SCM_PORT_TYPE (x);