From fab23328512e47a50caced8d074e86e583cc8a9f Mon Sep 17 00:00:00 2001 From: Michal Nazarewicz Date: Sun, 3 May 2020 16:32:47 +0100 Subject: [PATCH] =?utf8?q?cc-mode:=20add=20=E2=80=98c-lineup-ternary-bodie?= =?utf8?q?s=E2=80=99=20=20(bug#41061)?= MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Introduce ‘c-lineup-ternary-bodies’ function which, when used as a c lineup function, aligns question mark and colon of a ternary operator. For example: return arg % 2 == 0 ? arg / 2 : (3 * arg + 1); * lisp/progmodes/cc-align.el (c-lineup-ternary-bodies): New function. * doc/misc/cc-mode.texi (Operator Line-Up Functions): Document the new function. * test/lisp/progmodes/cc-mode-tests.el (c-lineup-ternary-bodies): New test case. --- doc/misc/cc-mode.texi | 20 +++++++++++++++++ etc/NEWS | 17 +++++++++++++++ lisp/progmodes/cc-align.el | 32 ++++++++++++++++++++++++++++ test/lisp/progmodes/cc-mode-tests.el | 21 ++++++++++++++++++ 4 files changed, 90 insertions(+) diff --git a/doc/misc/cc-mode.texi b/doc/misc/cc-mode.texi index f9c9f5e1830..16eac4828c7 100644 --- a/doc/misc/cc-mode.texi +++ b/doc/misc/cc-mode.texi @@ -6395,6 +6395,26 @@ function is the same as specifying a list @code{(c-lineup-assignments @comment ------------------------------------------------------------ +@defun c-lineup-ternary-bodies +@findex lineup-ternary-bodies @r{(c-)} +Line up true and false branches of a ternary operator +(i.e. @code{?:}). More precisely, if the line starts with a colon +which is a part of a said operator it with corresponding question +mark. For example: + +@example +@group +return arg % 2 == 0 ? arg / 2 + : (3 * arg + 1); @hereFn{c-lineup-ternary-bodies} +@end group +@end example + +@workswith @code{arglist-cont}, @code{arglist-cont-nonempty} and +@code{statement-cont}. +@end defun + +@comment ------------------------------------------------------------ + @defun c-lineup-cascaded-calls @findex lineup-cascaded-calls @r{(c-)} Line up ``cascaded calls'' under each other. If the line begins with diff --git a/etc/NEWS b/etc/NEWS index 9c71752b621..12406eea822 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -305,6 +305,23 @@ use ‘doxygen’ by default one might evaluate: or use it in a custom ‘c-style’. +*** Added support to line up ‘?’ and ‘:’ of a ternary operator. +The new ‘c-lineup-ternary-bodies’ function can be used as a lineup +function to align question mark and colon which are part of a ternary +operator (‘?:’). For example: + + return arg % 2 == 0 ? arg / 2 + : (3 * arg + 1); + +To enable, add it to appropriate entries in ‘c-offsets-alist’, e.g.: + + (c-set-offset 'arglist-cont '(c-lineup-ternary-bodies + c-lineup-gcc-asm-reg)) + (c-set-offset 'arglist-cont-nonempty '(c-lineup-ternary-bodies + c-lineup-gcc-asm-reg + c-lineup-arglist)) + (c-set-offset 'statement-cont '(c-lineup-ternary-bodies +)) + ** browse-url *** Added support for custom URL handlers diff --git a/lisp/progmodes/cc-align.el b/lisp/progmodes/cc-align.el index f30477dc787..c49bdc5c518 100644 --- a/lisp/progmodes/cc-align.el +++ b/lisp/progmodes/cc-align.el @@ -790,6 +790,38 @@ arglist-cont-nonempty." (or (c-lineup-assignments langelem) c-basic-offset)) +(defun c-lineup-ternary-bodies (langelem) + "Line up true and false branches of a ternary operator (i.e. ‘?:’). +More precisely, if the line starts with a colon which is a part of +a said operator it with corresponding question mark; otherwise return +nil. For example: + + return arg % 2 == 0 ? arg / 2 + : (3 * arg + 1); <- c-lineup-ternary-bodies + +Works with: arglist-cont, arglist-cont-nonempty and statement-cont. +" + (save-excursion + (back-to-indentation) + (when (and (eq ?: (char-after)) + (not (eq ?: (char-after (1+ (point)))))) + (let ((limit (c-langelem-pos langelem)) (depth 1)) + (catch 'done + (while (c-syntactic-skip-backward "^?:" limit t) + (goto-char (1- (point))) + (cond ((eq (char-after) ??) + ;; If we’ve found a question mark, decrease depth. If we’re + ;; reached zero, we’ve found the one we were looking for. + (when (zerop (setq depth (1- depth))) + (throw 'done (vector (current-column))))) + ((or (eq ?: (char-before)) (eq ?? (char-before))) + ;; Step over ‘::’ and ‘?:’ operators. We don’t have to + ;; handle ‘?:’ here but doing so saves an iteration. + (if (eq (point) limit) + (throw 'done nil) + (goto-char (1- (point))))) + ((setq depth (1+ depth)))))))))) ; Otherwise increase depth. + (defun c-lineup-cascaded-calls (langelem) "Line up \"cascaded calls\" under each other. If the line begins with \"->\" or \".\" and the preceding line ends diff --git a/test/lisp/progmodes/cc-mode-tests.el b/test/lisp/progmodes/cc-mode-tests.el index 0729841ce6f..ad7a52b40d9 100644 --- a/test/lisp/progmodes/cc-mode-tests.el +++ b/test/lisp/progmodes/cc-mode-tests.el @@ -78,4 +78,25 @@ (insert macro-string) (c-mode)))) +(ert-deftest c-lineup-ternary-bodies () + "Test for c-lineup-ternary-bodies function" + (with-temp-buffer + (c-mode) + (let* ((common-prefix "int value = condition ") + (expected-column (length common-prefix))) + (dolist (test '(("? a : \n b" . nil) + ("? a \n ::b" . nil) + ("a \n : b" . nil) + ("? a \n : b" . t) + ("? ::a \n : b" . t) + ("? (p ? q : r) \n : b" . t) + ("? p ?: q \n : b" . t) + ("? p ? : q \n : b" . t) + ("? p ? q : r \n : b" . t))) + (delete-region (point-min) (point-max)) + (insert common-prefix (car test)) + (should (equal + (and (cdr test) (vector expected-column)) + (c-lineup-ternary-bodies '(statement-cont . 1)))))))) + ;;; cc-mode-tests.el ends here -- 2.39.5