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master fab2332 1/2: cc-mode: add ‘c-lineup-ternary-bodies’ (bug#41061)
From: |
Micha? Nazarewicz |
Subject: |
master fab2332 1/2: cc-mode: add ‘c-lineup-ternary-bodies’ (bug#41061) |
Date: |
Sat, 9 May 2020 06:34:53 -0400 (EDT) |
branch: master
commit fab23328512e47a50caced8d074e86e583cc8a9f
Author: Michal Nazarewicz <address@hidden>
Commit: Michal Nazarewicz <address@hidden>
cc-mode: add ‘c-lineup-ternary-bodies’ (bug#41061)
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 f9c9f5e..16eac48 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 9c71752..12406ee 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 f30477d..c49bdc5 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 0729841..ad7a52b 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