Re: [Emacs-diffs] scratch/widen-less a4ba846: Replace prog-widen with consolidating widen calls

[Stefan Monnier <monnier@iro.umontreal.ca>]

>     Replace prog-widen with consolidating widen calls

So, IIUC the idea is that the multi-major-mode framework will *have* to
use narrowing to indicate to the sub-modes the boundaries of the current
chunk, right?


        Stefan


> ---
>  doc/lispref/text.texi       | 45 +++++----------------------------------------
>  etc/NEWS                    |  8 ++++----
>  lisp/indent.el              | 12 +++++++++---
>  lisp/progmodes/prog-mode.el | 28 ++--------------------------
>  lisp/progmodes/python.el    | 34 ++++++++--------------------------
>  lisp/progmodes/ruby-mode.el |  1 -
>  lisp/vc/add-log.el          |  4 +++-
>  7 files changed, 31 insertions(+), 101 deletions(-)

> diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
> index 1e19f75..5a63e5b 100644
> --- a/doc/lispref/text.texi
> +++ b/doc/lispref/text.texi
> @@ -2407,42 +2407,17 @@ such multi-mode indentation.
>  This variable, when non-@code{nil}, holds the indentation context for
>  the sub-mode's indentation engine provided by the superior major mode.
>  The value should be a list of the form @code{(@var{first-column}
> -@w{(@var{start} . @var{end})} @code{prev-chunk})}.  The members of the
> -list have the following meaning:
> +@code{...rest})}.  The members of the list have the following meaning:
 
>  @table @var
>  @item first-column
>  The column to be used for top-level constructs.  This replaces the
>  default value of the top-level column used by the sub-mode, usually
>  zero.
> -@item start
> -@itemx end
> -The region of the code chunk to be indented by the sub-mode.  The
> -value of @var{end} can be @code{nil}, which stands for the value of
> -@code{point-max}.
> -@item prev-chunk
> -If this is non-@code{nil}, it should provide the sub-mode's
> -indentation engine with a virtual context of the code chunk.  Valid
> -values include:
> -
> -@itemize @minus
> -@item
> -A string whose contents is the text the sub-mode's indentation engine
> -should consider to precede the code chunk.  The sub-mode's indentation
> -engine can add text properties to that string, to be reused in
> -repeated calls with the same string, thus using it as a cache.  An
> -example where this is useful is code chunks that need to be indented
> -as function bodies, but lack the function's preamble---the string
> -could then include that missing preamble.
> -@item
> -A function.  It is expected to be called with the start position of
> -the current chunk, and should return a cons cell
> -@w{@code{(@var{prev-start} . @var{prev-end})}} that specifies the
> -region of the previous code chunk, or @code{nil} if there is no previous
> -chunk.  This is useful in literate-programming sources, where code is
> -split into chunks, and correct indentation needs to access previous
> -chunks.
> -@end itemize
> +@item rest
> +Reserved for future use.  The intent is to provide the sub-mode's
> +indentation engine with a virtual context of the code chunk.  Working
> +patches that use this in a significant fashion are welcome.
>  @end table
>  @end defvar
 
> @@ -2457,16 +2432,6 @@ function's value is the column number to use for top-level constructs.
>  When no superior mode is in effect, this function returns zero.
>  @end defun
 
> -@defun prog-widen
> -Call this function instead of @code{widen} to remove any restrictions
> -imposed by the mode's indentation engine and restore the restrictions
> -recorded in @code{prog-indentation-context}.  This prevents the
> -indentation engine of a sub-mode from inadvertently operating on text
> -outside of the chunk it was supposed to indent, and preserves the
> -restriction imposed by the superior mode.  When no superior mode is in
> -effect, this function just calls @code{widen}.
> -@end defun
> -
 
>  @node Region Indent
>  @subsection Indenting an Entire Region
> diff --git a/etc/NEWS b/etc/NEWS
> index 4ccf468..6e1561d 100644
> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -1108,10 +1108,10 @@ programming languages in the same buffer, like literate programming
>  environments or ANTLR programs with embedded Python code.
 
>  A major mode can provide indentation context for a sub-mode through
> -the 'prog-indentation-context' variable.  To support this, modes that
> -provide indentation should use 'prog-widen' instead of 'widen' and
> -'prog-first-column' instead of a literal zero.  See the node
> -"(elisp) Mode-Specific Indent" in the ELisp manual for more details.
> +the 'prog-indentation-context' variable.  To support this, modes
> +should use 'prog-first-column' instead of a literal zero and never
> +call 'widen' in their indentation functions.  See the node "(elisp)
> +Mode-Specific Indent" in the ELisp manual for more details.
 
>  ** ERC
 
> diff --git a/lisp/indent.el b/lisp/indent.el
> index d5ba0bd..ccf0e99 100644
> --- a/lisp/indent.el
> +++ b/lisp/indent.el
> @@ -69,6 +69,8 @@ variable is `indent-relative' or `indent-relative-maybe', handle
>  it specially (since those functions are used for tabbing); in
>  that case, indent by aligning to the previous non-blank line."
>    (interactive)
> +  (save-restriction
> +    (widen)
>    (syntax-propertize (line-end-position))
>    (if (memq indent-line-function
>  	    '(indent-relative indent-relative-maybe))
> @@ -84,7 +86,7 @@ that case, indent by aligning to the previous non-blank line."
>  	    (indent-line-to column)
>  	  (save-excursion (indent-line-to column))))
>      ;; The normal case.
> -    (funcall indent-line-function)))
> +    (funcall indent-line-function))))
 
>  (defun indent--default-inside-comment ()
>    (unless (or (> (current-column) (current-indentation))
> @@ -144,7 +146,9 @@ prefix argument is ignored."
>            (indent--default-inside-comment)
>            (when (or (<= (current-column) (current-indentation))
>                      (not (eq tab-always-indent 'complete)))
> -            (funcall (default-value 'indent-line-function))))
> +            (save-restriction
> +              (widen)
> +              (funcall (default-value 'indent-line-function)))))
 
>        (cond
>         ;; If the text was already indented right, try completion.
> @@ -538,7 +542,9 @@ column to indent to; if it is nil, use one of the three methods above."
>  	  (forward-line 1)))))
>     ;; Use indent-region-function is available.
>     (indent-region-function
> -    (funcall indent-region-function start end))
> +    (save-restriction
> +      (widen)
> +      (funcall indent-region-function start end)))
>     ;; Else, use a default implementation that calls indent-line-function on
>     ;; each line.
>     (t (indent-region-line-by-line start end)))
> diff --git a/lisp/progmodes/prog-mode.el b/lisp/progmodes/prog-mode.el
> index f727e45..b36d242 100644
> --- a/lisp/progmodes/prog-mode.el
> +++ b/lisp/progmodes/prog-mode.el
> @@ -64,37 +64,13 @@ mode, it should bind this variable to non-nil around the call.
 
>  The non-nil value should be a list of the form:
 
> -   (FIRST-COLUMN (START . END) PREVIOUS-CHUNKS)
> +   (FIRST-COLUMN ...REST)
 
>  FIRST-COLUMN is the column the indentation engine of the sub-mode
>  should use for top-level language constructs inside the code
>  chunk (instead of 0).
 
> -START and END specify the region of the code chunk.  END can be
> -nil, which stands for the value of `point-max'.  The function
> -`prog-widen' uses this to restore restrictions imposed by the
> -sub-mode's indentation engine.
> -
> -PREVIOUS-CHUNKS, if non-nil, provides the indentation engine of
> -the sub-mode with the virtual context of the code chunk.  Valid
> -values are:
> -
> - - A string containing text which the indentation engine can
> -   consider as standing in front of the code chunk.  To cache the
> -   string's calculated syntactic information for repeated calls
> -   with the same string, the sub-mode can add text-properties to
> -   the string.
> -
> -   A typical use case is for grammars with code chunks which are
> -   to be indented like function bodies -- the string would contain
> -   the corresponding function preamble.
> -
> - - A function, to be called with the start position of the current
> -   chunk.  It should return either the region of the previous chunk
> -   as (PREV-START . PREV-END), or nil if there is no previous chunk.
> -
> -   A typical use case are literate programming sources -- the
> -   function would successively return the previous code chunks.")
> +REST is currently unused, but can be defined in future versions.")
 
>  (defun prog-indent-sexp (&optional defun)
>    "Indent the expression after point.
> diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
> index d4226e5..104889a 100644
> --- a/lisp/progmodes/python.el
> +++ b/lisp/progmodes/python.el
> @@ -287,10 +287,6 @@
>  ;;; 24.x Compat
>  \f
 
> -(unless (fboundp 'prog-widen)
> -  (defun prog-widen ()
> -    (widen)))
> -
>  (unless (fboundp 'prog-first-column)
>    (defun prog-first-column ()
>      0))
> @@ -785,7 +781,7 @@ work on `python-indent-calculate-indentation' instead."
>    (interactive)
>    (save-excursion
>      (save-restriction
> -      (prog-widen)
> +      (widen)
>        (goto-char (point-min))
>        (let ((block-end))
>          (while (and (not block-end)
> @@ -883,8 +879,6 @@ keyword
>  :at-dedenter-block-start
>   - Point is on a line starting a dedenter block.
>   - START is the position where the dedenter block starts."
> -  (save-restriction
> -    (prog-widen)
>      (let ((ppss (save-excursion
>                    (beginning-of-line)
>                    (syntax-ppss))))
> @@ -1022,7 +1016,7 @@ keyword
>                        (looking-at (python-rx block-ender)))
>                      :after-block-end)
>                     (t :after-line))
> -             (point)))))))))
> +             (point))))))))
 
>  (defun python-indent--calculate-indentation ()
>    "Internal implementation of `python-indent-calculate-indentation'.
> @@ -1030,8 +1024,6 @@ May return an integer for the maximum possible indentation at
>  current context or a list of integers.  The latter case is only
>  happening for :at-dedenter-block-start context since the
>  possibilities can be narrowed to specific indentation points."
> -  (save-restriction
> -    (prog-widen)
>      (save-excursion
>        (pcase (python-indent-context)
>          (`(:no-indent . ,_) (prog-first-column)) ; usually 0
> @@ -1081,7 +1073,7 @@ possibilities can be narrowed to specific indentation points."
>          (`(,(or :inside-paren-newline-start-from-block) . ,start)
>           ;; Add two indentation levels to make the suite stand out.
>           (goto-char start)
> -         (+ (current-indentation) (* python-indent-offset 2)))))))
> +         (+ (current-indentation) (* python-indent-offset 2))))))
 
>  (defun python-indent--calculate-levels (indentation)
>    "Calculate levels list given INDENTATION.
> @@ -4589,8 +4581,6 @@ To this:
>  Optional argument INCLUDE-TYPE indicates to include the type of the defun.
>  This function can be used as the value of `add-log-current-defun-function'
>  since it returns nil if point is not inside a defun."
> -  (save-restriction
> -    (prog-widen)
>      (save-excursion
>        (end-of-line 1)
>        (let ((names)
> @@ -4644,7 +4634,7 @@ since it returns nil if point is not inside a defun."
>              (and (= (current-indentation) 0) (throw 'exit t))))
>          (and names
>               (concat (and type (format "%s " type))
> -                     (mapconcat 'identity names ".")))))))
> +                     (mapconcat 'identity names "."))))))
 
>  (defun python-info-current-symbol (&optional replace-self)
>    "Return current symbol using dotty syntax.
> @@ -4788,12 +4778,10 @@ likely an invalid python file."
>    "Message the first line of the block the current statement closes."
>    (let ((point (python-info-dedenter-opening-block-position)))
>      (when point
> -      (save-restriction
> -        (prog-widen)
>          (message "Closes %s" (save-excursion
>                                 (goto-char point)
>                                 (buffer-substring
> -                                (point) (line-end-position))))))))
> +                                (point) (line-end-position)))))))
 
>  (defun python-info-dedenter-statement-p ()
>    "Return point if current statement is a dedenter.
> @@ -4809,8 +4797,6 @@ statement."
>    "Return non-nil if current line ends with backslash.
>  With optional argument LINE-NUMBER, check that line instead."
>    (save-excursion
> -    (save-restriction
> -      (prog-widen)
>        (when line-number
>          (python-util-goto-line line-number))
>        (while (and (not (eobp))
> @@ -4819,14 +4805,12 @@ With optional argument LINE-NUMBER, check that line instead."
>                    (not (equal (char-before (point)) ?\\)))
>          (forward-line 1))
>        (when (equal (char-before) ?\\)
> -        (point-marker)))))
> +        (point-marker))))
 
>  (defun python-info-beginning-of-backslash (&optional line-number)
>    "Return the point where the backslashed line start.
>  Optional argument LINE-NUMBER forces the line number to check against."
>    (save-excursion
> -    (save-restriction
> -      (prog-widen)
>        (when line-number
>          (python-util-goto-line line-number))
>        (when (python-info-line-ends-backslash-p)
> @@ -4835,15 +4819,13 @@ Optional argument LINE-NUMBER forces the line number to check against."
>                   (python-syntax-context 'paren))
>            (forward-line -1))
>          (back-to-indentation)
> -        (point-marker)))))
> +        (point-marker))))
 
>  (defun python-info-continuation-line-p ()
>    "Check if current line is continuation of another.
>  When current line is continuation of another return the point
>  where the continued line ends."
>    (save-excursion
> -    (save-restriction
> -      (prog-widen)
>        (let* ((context-type (progn
>                               (back-to-indentation)
>                               (python-syntax-context-type)))
> @@ -4869,7 +4851,7 @@ where the continued line ends."
>                 (python-util-forward-comment -1)
>                 (when (and (equal (1- line-start) (line-number-at-pos))
>                            (python-info-line-ends-backslash-p))
> -                 (point-marker))))))))
> +                 (point-marker)))))))
 
>  (defun python-info-block-continuation-line-p ()
>    "Return non-nil if current line is a continuation of a block."
> diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
> index dc1b0f8..7c10114 100644
> --- a/lisp/progmodes/ruby-mode.el
> +++ b/lisp/progmodes/ruby-mode.el
> @@ -1364,7 +1364,6 @@ delimiter."
>                                               "\\)\\>")))
>                      (eq (ruby-deep-indent-paren-p t) 'space)
>                      (not (bobp)))
> -                   (widen)
>                     (goto-char (or begin parse-start))
>                     (skip-syntax-forward " ")
>                     (current-column))
> diff --git a/lisp/vc/add-log.el b/lisp/vc/add-log.el
> index 392147b..9da8abc 100644
> --- a/lisp/vc/add-log.el
> +++ b/lisp/vc/add-log.el
> @@ -1133,6 +1133,8 @@ identifiers followed by `:' or `='.  See variables
>  Has a preference of looking backwards."
>    (condition-case nil
>        (save-excursion
> +        (save-restriction
> +          (widen)
>  	(if add-log-current-defun-function
>  	    (funcall add-log-current-defun-function)
>  	  ;; If all else fails, try heuristics
> @@ -1147,7 +1149,7 @@ Has a preference of looking backwards."
>  	      (when (string-match "\\([^ \t\n\r\f].*[^ \t\n\r\f]\\)"
>  				  result)
>  		(setq result (match-string-no-properties 1 result)))
> -	      result))))
> +	      result)))))
>      (error nil)))
 
>  (defvar change-log-get-method-definition-md)

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