branch: elpa/haskell-tng-mode
commit 6a05d122d38400079e302a5f8d7091c1776a2b7c
Author: Tseen She <ts33n....@gmail.com>
Commit: Tseen She <ts33n....@gmail.com>
planning for indentation
---
haskell-tng-smie.el | 40 ++++++++++++++++++++++++++++++++++++----
1 file changed, 36 insertions(+), 4 deletions(-)
diff --git a/haskell-tng-smie.el b/haskell-tng-smie.el
index 5bb86c5..ebbef4f 100644
--- a/haskell-tng-smie.el
+++ b/haskell-tng-smie.el
@@ -8,9 +8,11 @@
;; SMIE precedence table, providing s-expression navigation, and indentation
;; rules.
;;
-;; Note that we don't support every aspect of the Haskell language. e.g. if we
-;; had access to the fixity of operators in scope we could create
file-specific
-;; rules.
+;; Although SMIE provides the primary indentation suggest (when the user types
+;; RETURN), we cycle through alternative candidates on TAB. The philosophy is
+;; not to try and get indentation right 100% of the time, but to get it right
+;; 90% of the time and make it so easy to fix it that it doesn't get in the
+;; way.
;;
;; Users may consult the SMIE manual to customise their indentation rules:
;; https://www.gnu.org/software/emacs/manual/html_mono/elisp.html#SMIE
@@ -85,7 +87,7 @@
;;
https://github.com/elixir-editors/emacs-elixir/blob/master/test/test-helper.el#L52-L63
(defun haskell-tng-smie:rules (method arg)
;; see docs for `smie-rules-function'
- ;; FIXME implement and test indentation
+ ;; TODO implement indentation
(pcase (cons method arg)
(`(:elem . basic) smie-indent-basic)
(`(,_ . ",") (smie-rule-separator method))
@@ -96,6 +98,36 @@
(and (not (smie-rule-bolp)) (smie-rule-prev-p "else")
(smie-rule-parent)))))
+;; FIXME tests for indentation, including the cycled choices
+
+;; TODO decide either to set indent-line-function or to wrap around
+;; smie-indent-calculate with
+
+;; (add-hook 'smie-indent-functions
+;; #'haskell-tng:smie-indent nil 'local)
+
+(defvar haskell-tng:smie-indent-nested-call nil)
+
+(defun haskell-tng:smie-indent ()
+ (cond
+ ;; When we're not in the top-level call to smie-indent-calculate, so just do
+ ;; nothing and let the other rules do their job.
+ (haskell-tng:smie-indent-nested-call nil)
+ ;; When cycling, return the next indentation.
+ ((eq this-command last-command)
+ (haskell-tng:return-next-stashed-indentation-column))
+ ;; When we're in the top-level call to smie-indent-calculate, take control
+ ;; and return a non-nil value to prevent the other rules from being used.
+ (t
+ (let ((haskell-tng:smie-indent-nested-call t)
+ (n (haskell-tng:get-number-of-closing-braces-at-bol))
+ (indentations ()))
+ (dotimes (i n)
+ (haskell-tng:tell-lexer-there-are-N-closing-braces-at-bol i)
+ (push (smie-indent-calculate) indentations))
+ (haskell-tng:stash-indentation-columns indentations)
+ (haskell-tng:return-next-stashed-indentation-column)))))
+
(defun haskell-tng-smie:setup ()
(setq-local smie-indent-basic 2)
