Code cleanup for long line optimizations

This commit does not change any code, it merely renames functions
and clarifies the documentation, to make the code hopefully easier
to grasp.

* src/dispextern.h (struct it): Rename the 'narrowed_begv',
'narrowed_zv', 'locked_narrowing_begv', 'locked_narrowing_zv' to
'medium_narrowing_begv', 'medium_narrowing_zv',
'large_narrowing_begv', 'large_narrowing_zv'.  Clarify the
comments.
Update the prototypes of the functions renamed in xdisp.c.

* src/lisp.h: Update the prototypes of the functions renamed in
editfns.c.  Remove the prototype of
'safe_run_hooks_maybe_narrowed', which is used only in keyboard.c.

* src/xdisp.c
(get_small_narrowing_begv): Renamed from
'get_closer_narrowed_begv'.
(get_medium_narrowing_begv): Renamed from 'get_narrowed_begv'.
(get_medium_narrowing_zv): Renamed from 'get_narrowed_zv'.
(get_large_narrowing_begv): Renamed from 'get_locked_narrowing_begv'.
(get_large_narrowing_zv): Renamed from 'get_locked_narrowing_zv'.
(SET_WITH_NARROWED_BEGV): Use the new field names.
(handle_fontified_prop): Use the new function and new field names.
(back_to_previous_line_start): Use the new field name.
(back_to_previous_visible_line_start): Use the new field name.
(reseat): Use the new function and new field names.
(get_visually_first_element): Use the new field name.
(move_it_vertically_backward): Use the new function name.
(redisplay_internal): Use the new function name.
Also add a large comment to explain how Emacs deals with long lines.

* src/keyboard.c:
(safe_run_hooks_maybe_narrowed): Use the new function names from
xdisp.c and editfns.c.  Make the function static, and add a
prototype.

* src/editfns.c:
(labeled_restrictions): Renamed from 'narrowing_locks'.
(labeled_restrictions_add): Renamed from 'narrowing_locks_add'.
(labeled_restrictions_remove): Renamed from
'narrowing_locks_remove'.
(labeled_restrictions_get_bound): Renamed from
'narrowing_lock_get_bound'.
(labeled_restrictions_peek_label): Renamed from
'narrowing_lock_peek_tag'.
(labeled_restrictions_push): Renamed from 'narrowing_lock_push'.
(labeled_restrictions_pop): Renamed from 'narrowing_lock_pop'.
(unwind_reset_outermost_restriction): Renamed from
'unwind_reset_outermost_narrowing'.
(reset_outermost_restrictions): Renamed from
'reset_outermost_narrowings'.
(labeled_restrictions_save): Renamed from 'narrowing_locks_save'.
(labeled_restrictions_restore): Renamed from
'narrowing_locks_restore'.
(unwind_labeled_narrow_to_region): Renamed from
'unwind_narrow_to_region_locked'.
(labeled_narrow_to_region): Renamed from
'narrow_to_region_locked'.
(Finternal__label_restriction): Renamed from
'Finternal__lock_narrowing'.
(Finternal__unlabel_restriction): Renamed from
'Finternal__unlock_narrowing'.
(Fwiden): Use the new function names.
(Fnarrow_to_region): Use the new function names.
(save_restriction_save): Use the new function names.
(syms_of_editfns): Use the new function names.
<outermost-restriction>: Renamed from 'outermost-narrowing'.

* lisp/subr.el (internal--with-restriction): Use the new internal
function name.
(internal--without-restriction): Use the new internal function
name.

* src/composite.c (composition_compute_stop_pos):
(find_automatic_composition): Use the new function name.

* doc/lispref/positions.texi (Narrowing): Add index entry.

1 files changed, 2 insertions, 2 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index f82826e819c..ca1fc2886b4 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -3975,7 +3975,7 @@ same LABEL argument.
   "Helper function for `with-restriction', which see."
   (save-restriction
     (narrow-to-region start end)
-    (if label (internal--lock-narrowing label))
+    (if label (internal--label-restriction label))
     (funcall body)))
 
 (defmacro without-restriction (&rest rest)
@@ -3997,7 +3997,7 @@ are lifted.
 (defun internal--without-restriction (body &optional label)
   "Helper function for `without-restriction', which see."
   (save-restriction
-    (if label (internal--unlock-narrowing label))
+    (if label (internal--unlabel-restriction label))
     (widen)
     (funcall body)))