Take fields into account during text conversion

* lisp/cus-edit.el (Custom-mode): Enable text conversion, now
that fields are correctly treated.

* src/alloc.c (mark_frame): Mark f->conversion.field.

* src/androidterm.c (android_update_selection): Adjust
conversion region and selection position by the field start and
end.

* src/editfns.c (find_field): Export function.

* src/frame.c (make_frame): Clear f->conversion.field.

* src/frame.h (struct text_conversion_state) <field>: New field.

* src/lisp.h (find_fields, reset_frame_conversion): Export
functions.

* src/minibuf.c (Fread_from_minibuffer): Reset frame conversion
if Voverriding_text_conversion_style is set.

* src/textconv.c (textconv_query): Narrow to field.
(reset_frame_conversion): New function.
(reset_frame_state): Clear conversion field.
(really_delete_surrounding_text): Narrow to field.
(locate_and_save_position_in_field): New function.
(really_request_point_update, really_set_point_and_mark)
(complete_edit_check, handle_pending_conversion_events_1)
(handle_pending_conversion_events, get_conversion_field)
(set_composing_region, textconv_set_point_and_mark, replace_text)
(get_extracted_text, get_surrounding_text, report_point_change):
Compute, narrow to and offset by the currently active field
whenever point is updated or a command is received.
(syms_of_textconv): Revise doc strings.

* src/textconv.h (get_conversion_field): Export function.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/frame.h b/src/frame.h
index e03362361a7..63bcce259af 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -126,6 +126,10 @@ struct text_conversion_state
   /* Overlay representing the composing region.  */
   Lisp_Object compose_region_overlay;
 
+  /* Cons of (START END . WINDOW) holding the field to which text
+     conversion should be confined, or nil if no such field exists.  */
+  Lisp_Object field;
+
   /* The number of ongoing ``batch edits'' that are causing point
      reporting to be delayed.  */
   int batch_edit_count;