Gud LLDB completions (bug#66604)

* etc/emacs_lldb.py: Remove xcomplete.
* lisp/progmodes/gud.el: Implement lldb command completions.
* src/.lldbinit: Remove settings done in Gud.

etc/emacs_lldb.py

@@ -203,35 +203,6 @@ def xdebug_print(debugger, command, result, internal_dict):
     """Print Lisp_Objects using safe_debug_print()"""
     debugger.HandleCommand(f"expr safe_debug_print({command})")
 
-# According to SBCommanInterpreter.cpp, the return value of
-# HandleCompletions is as follows:
-#
-# Index 1 to the end contain all the completions.
-#
-# At index 0:
-#
-# If all completions have a common prefix, this is the shortest
-# completion, with the common prefix removed from it.
-#
-# If it is the completion for a whole word, a space is added at the
-# end.
-#
-# So, the prefix is what could be added to make the command partially
-# complete.
-#
-# If there is no common prefix, index 0 has an empty string "".
-
-def xcomplete(debugger, command, result, internal_dict):
-    """Print completions for COMMAND."""
-    interpreter = debugger.GetCommandInterpreter()
-    string_list = lldb.SBStringList()
-    interpreter.HandleCompletion(command, len(command), len(command),
-                                 -1, string_list)
-    list = ""
-    for i in range(string_list.GetSize()):
-        list += '"' + string_list.GetStringAtIndex(i) + '" '
-    result.AppendMessage("(" + list + ")")
-
 
 ########################################################################
 #                             Formatters
@@ -336,7 +307,6 @@ def enable_type_category(debugger, category):
 def __lldb_init_module(debugger, internal_dict):
     define_command(debugger, xbacktrace)
     define_command(debugger, xdebug_print)
-    define_command(debugger, xcomplete)
     define_type_summary(debugger, "Lisp_Object", type_summary_Lisp_Object)
     define_type_synthetic(debugger, "Lisp_Object", Lisp_Object_Provider)
     enable_type_category(debugger, "Emacs")

lisp/progmodes/gud.el

@@ -3850,7 +3850,7 @@ so they have been disabled."))
 
 
 ;; 'gud-lldb-history' and 'gud-gud-lldb-command-name' are required
-;; because gud-symbol uses their values if they are present.  Their
+;; because 'gud-symbol' uses their values if they are present.  Their
 ;; names are deduced from the minor-mode name.
 (defvar gud-lldb-history nil)
 
@@ -3859,7 +3859,7 @@ so they have been disabled."))
   :type 'string)
 
 (defun gud-lldb-marker-filter (string)
-  "Deduce interesting stuff from output STRING."
+  "Deduce interesting stuff from process output STRING."
   (cond (;; Process 72668 stopped
          ;; * thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
          ;;     frame #0: ...) at emacs.c:1310:9 [opt]
@@ -3879,6 +3879,96 @@ so they have been disabled."))
          (setq gud-overlay-arrow-position nil)))
   string)
 
+;; According to SBCommanInterpreter.cpp, the return value of
+;; HandleCompletions is as follows:
+;;
+;; Index 1 to the end contain all the completions.
+;;
+;; At index 0:
+;;
+;; If all completions have a common prefix, this is the shortest
+;; completion, with the common prefix removed from it.
+;;
+;; If it is the completion for a whole word, a space is added at the
+;; end.
+;;
+;; So, the prefix is what could be added to make the command partially
+;; complete.
+;;
+;; If there is no common prefix, index 0 has an empty string "".
+
+(defun gud-lldb-fetch-completions (context command)
+  "Return the data to complete the LLDB command before point.
+This is what the Python function we installed at initialzation
+time returns, as a Lisp list."
+  (let* ((process (get-buffer-process gud-comint-buffer))
+         (to-complete (concat context command))
+         (output-buffer (get-buffer-create "*lldb-completions*")))
+    ;; Send the completion command with output to our buffer
+    (with-current-buffer output-buffer
+      (erase-buffer))
+    (comint-redirect-send-command-to-process
+     (format "script --language python -- gud_complete('%s')"
+             to-complete)
+     output-buffer process nil t)
+    ;; Wait for output
+    (unwind-protect
+        (while (not comint-redirect-completed)
+          (accept-process-output process))
+      (comint-redirect-cleanup))
+    ;; Process the completion output.
+    (with-current-buffer output-buffer
+      (goto-char (point-min))
+      (when (search-forward "gud-completions:" nil t)
+        (read (current-buffer))))))
+
+(defun gud-lldb-completions (context command)
+  "Completion table for LLDB commands."
+  (let ((completions (gud-lldb-fetch-completions context command)))
+    ;; If this is a cmpletion for w whole word, return a completion
+    ;; list that contains that word only, with a space appended.
+    (if (string-suffix-p " " (car completions))
+        (list (concat (cadr completions) " "))
+      (cdr completions))))
+
+(defun gud-lldb-completion-at-point ()
+  "Return the data to complete the LLDB command before point."
+  (let* ((end (point))
+         (line-start (comint-line-beginning-position))
+         (start (save-excursion
+                  (skip-chars-backward "^ " line-start)
+                  (point)))
+         (context (buffer-substring line-start start)))
+    (list (copy-marker start t)
+          end
+          (completion-table-dynamic
+           (apply-partially #'gud-lldb-completions context)))))
+
+(defvar gud-lldb-def-python-completion-function
+  "
+def gud_complete(s):
+    interpreter = lldb.debugger.GetCommandInterpreter()
+    string_list = lldb.SBStringList()
+    interpreter.HandleCompletion(s, len(s), len(s), -1, string_list)
+    print('gud-completions: (')
+    for i in range(string_list.GetSize()):
+        print(f'\"{string_list.GetStringAtIndex(i)}\" ')
+    print(')')
+"
+  "LLDB command to define a Python function for completion.")
+
+(defun gud-lldb-send-python (python)
+  (gud-basic-call "script --language python --")
+  (mapc #'gud-basic-call (split-string python "\n"))
+  (gud-basic-call "exit()"))
+
+(defun gud-lldb-initialize ()
+  "Initialize the LLDB process as needed for this debug session."
+  (gud-lldb-send-python gud-lldb-def-python-completion-function)
+  (gud-basic-call "settings set stop-line-count-before 0")
+  (gud-basic-call "settings set stop-line-count-after 0")
+  (gud-basic-call "script --language python -- print('Gud initialized')"))
+
 ;;;###autoload
 (defun lldb (command-line)
   "Run lldb passing it COMMAND-LINE as arguments.
@@ -3979,11 +4069,17 @@ the buffer in which this command was invoked."
 	   nil
            "Run the program.")
 
+  (add-hook 'completion-at-point-functions
+            #'gud-lldb-completion-at-point
+            nil 'local)
+  (keymap-local-set "<tab>" #'completion-at-point)
+
   (gud-set-repeat-map-property 'gud-gdb-repeat-map)
   (setq comint-prompt-regexp (rx line-start "(lldb)" (0+ blank)))
+  (setq comint-process-echoes t)
   (setq paragraph-start comint-prompt-regexp)
   (setq gud-running nil)
-  (setq gud-filter-pending-text nil)
+  (gud-lldb-initialize)
   (run-hooks 'lldb-mode-hook))
 
 (provide 'gud)

src/.lldbinit

@@ -33,8 +33,4 @@ command script import emacs_lldb
 # Print with children provider, depth 2.
 command alias xprint frame variable -P 2
 
-# This is for M-x lldb: don't show source lines when stopping.
-settings set stop-line-count-before 0
-settings set stop-line-count-after 0
-
 # end.