branch: elpa/rust-mode
commit 4659aeedcb009016c8fac135878b7d624446f257
Merge: 186583d f292554
Author: Alex Crichton <[email protected]>
Commit: Alex Crichton <[email protected]>
rollup merge of #19913: KOMON/rust-mode-emacs-indentation
I added an option to auto-indent method chains to line up along their '.'
operators. Like so:
```
let input = io::stdin().readline()
.ok()
.expect("Failed to read line");
```
The old default would indent like so:
```
let input = io::stdin().readme()
.ok()
.expect("Failed to read line");
```
The Rust guide explicitly condones the former, so I thought it would be
nice for the emacs mode to support it. It's off by default, you have to set
```rust-indent-method-chain``` to ```t``` via your .emacs or the customize menu
---
rust-mode.el | 33 ++++++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)
diff --git a/rust-mode.el b/rust-mode.el
index f25a590..dae685f 100644
--- a/rust-mode.el
+++ b/rust-mode.el
@@ -54,6 +54,11 @@
:type 'integer
:group 'rust-mode)
+(defcustom rust-indent-method-chain nil
+ "Indent Rust method chains, aligned by the '.' operators"
+ :type 'boolean
+ :group 'rust-mode)
+
(defun rust-paren-level () (nth 0 (syntax-ppss)))
(defun rust-in-str-or-cmnt () (nth 8 (syntax-ppss)))
(defun rust-rewind-past-str-cmnt () (goto-char (nth 8 (syntax-ppss))))
@@ -73,10 +78,19 @@
;; open bracket ends the line
(when (not (looking-at "[[:blank:]]*\\(?://.*\\)?$"))
(when (looking-at "[[:space:]]")
- (forward-word 1)
- (backward-word 1))
+ (forward-word 1)
+ (backward-word 1))
(current-column))))
+(defun rust-align-to-method-chain ()
+ (save-excursion
+ (previous-line)
+ (end-of-line)
+ (backward-word 1)
+ (backward-char)
+ (when (looking-at "\\..+\(.*\)\n")
+ (- (current-column) rust-indent-offset))))
+
(defun rust-rewind-to-beginning-of-current-level-expr ()
(let ((current-level (rust-paren-level)))
(back-to-indentation)
@@ -99,10 +113,13 @@
;; the inside of it correctly relative to the outside.
(if (= 0 level)
0
+ (or
+ (when rust-indent-method-chain
+ (rust-align-to-method-chain))
(save-excursion
(backward-up-list)
(rust-rewind-to-beginning-of-current-level-expr)
- (+ (current-column) rust-indent-offset)))))
+ (+ (current-column) rust-indent-offset))))))
(cond
;; A function return type is indented to the corresponding
function arguments
((looking-at "->")
@@ -114,6 +131,16 @@
;; A closing brace is 1 level unindended
((looking-at "}") (- baseline rust-indent-offset))
+ ;;Line up method chains by their .'s
+ ((when (and rust-indent-method-chain
+ (looking-at "\..+\(.*\);?\n"))
+ (or
+ (let ((method-indent (rust-align-to-method-chain)))
+ (when method-indent
+ (+ method-indent rust-indent-offset)))
+ (+ baseline rust-indent-offset))))
+
+
;; Doc comments in /** style with leading * indent to line up
the *s
((and (nth 4 (syntax-ppss)) (looking-at "*"))
(+ 1 baseline))
