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(debugger-make-xrefs): Optimize by (1) using skip-syntax-forward

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rather than regexp search and (2) copying text properties
already set up on text unchanged from the previous backtrace.
(debugger-previous-backtrace): New variable.
This commit is contained in:
Richard M. Stallman 2001-12-16 03:48:41 +00:00
parent b5cf8df800
commit 25c58854c7
1 changed files with 68 additions and 7 deletions
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75
lisp/emacs-lisp/debug.el
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@ -64,6 +64,10 @@ the middle is discarded, and just the beginning and end are displayed."
(defvar debugger-old-buffer nil
"This is the buffer that was current when the debugger was entered.")
(defvar debugger-previous-backtrace nil
"The contents of the previous backtrace (including text properties).
This is to optimize `debugger-make-xrefs'.")
(defvar debugger-outer-match-data)
(defvar debugger-outer-load-read-function)
(defvar debugger-outer-overriding-local-map)
@ -271,16 +275,73 @@ That buffer should be current already."
(debugger-make-xrefs))
(defun debugger-make-xrefs (&optional buffer)
"Create cross-references in the debugger buffer."
"Attach cross-references to symbol names in the `*Backtrace*' buffer."
(interactive "b")
(save-excursion
(set-buffer (or buffer (current-buffer)))
(goto-char (point-min))
(let ((buffer-read-only nil))
(while (re-search-forward "\\(\\(\\sw\\|\\s_\\)+\\)" nil t)
(let* ((sym (intern-soft (match-string 1)))
(file (symbol-file sym)))
(when file (help-xref-button 1 'help-function-def sym file)))))))
(setq buffer (current-buffer))
(let ((buffer-read-only nil)
(old-end 1) (new-end 1))
;; If we saved an old backtrace, find the common part
;; between the new and the old.
;; Compare line by line, starting from the end,
;; because that's the part that is likely to be unchanged.
(if debugger-previous-backtrace
(let (old-start new-start (all-match t))
(goto-char (point-max))
(with-temp-buffer
(insert debugger-previous-backtrace)
(while (and all-match (not (bobp)))
(setq old-end (point))
(forward-line -1)
(setq old-start (point))
(with-current-buffer buffer
(setq new-end (point))
(forward-line -1)
(setq new-start (point)))
(if (not (zerop
(compare-buffer-substrings
(current-buffer) old-start old-end
buffer new-start new-end)))
(setq all-match nil))))
;; Now new-end is the position of the start of the
;; unchanged part in the current buffer, and old-end is
;; the position of that same text in the saved old
;; backtrace. But we must subtract 1 since strings are
;; indexed in origin 0.
;; Replace the unchanged part of the backtrace
;; with the text from debugger-previous-backtrace,
;; since that already has the proper xrefs.
;; With this optimization, we only need to scan
;; the changed part of the backtrace.
(delete-region new-end (point-max))
(goto-char (point-max))
(insert (substring debugger-previous-backtrace (1- old-end)))
;; Make the unchanged part of the backtrace inaccessible
;; so it won't be scanned.
(narrow-to-region (point-min) new-end)))
;; Scan the new part of the backtrace, inserting xrefs.
(goto-char (point-min))
(while (progn
(skip-syntax-forward "^w_")
(not (eobp)))
(let* ((beg (point))
(end (progn (skip-syntax-forward "w_") (point)))
(sym (intern-soft (buffer-substring-no-properties
beg end)))
(file (and sym (symbol-file sym))))
(message "sym %s, file %s" sym file)
(recursive-edit)
(when file
(goto-char beg)
;; help-xref-button needs to operate on something matched
;; by a regexp, so set that up for it.
(re-search-forward "\\(\\(\\sw\\|\\s_\\)+\\)")
(help-xref-button 1 'help-function-def sym file))))
(widen))
(setq debugger-previous-backtrace (buffer-string))))
(defun debugger-step-through ()
"Proceed, stepping through subexpressions of this expression.