feat(lisp): insert space before opening paren after slurping

This prevents some weirdly formatted code like (foo)(bar)
becomnig (foo(bar)) instead of (foo (bar))

Fixes Fuco1#781

smartparens-config.el

@@ -70,9 +70,21 @@ ID, ACTION, CONTEXT."
  ;; do not consider punctuation
  (not (looking-at "[?.,;!]"))))))))
 
+(defun sp-lisp-insert-space-after-slurp (_id action _context)
+ (-let (((&plist :ok-orig :next-thing) sp-handler-context))
+ (when (and (eq action 'slurp-forward)
+ (sp-get ok-orig (/= :beg-in :end-in)))
+ (save-excursion
+ (sp-get ok-orig (goto-char :end-in))
+ (skip-syntax-backward " ")
+ (unless (looking-at-p (rx (or whitespace eol)))
+ (insert " "))))))
+
 ;; emacs is lisp hacking environment, so we set up some most common
 ;; lisp modes too
 (sp-with-modes sp-lisp-modes
+ (sp-local-pair "(" nil :post-handlers '(:add sp-lisp-insert-space-after-slurp))
+ (sp-local-pair "[" nil :post-handlers '(:add sp-lisp-insert-space-after-slurp))
  ;; disable ', it's the quote character!
  (sp-local-pair "'" nil :actions nil))
 

smartparens.el

@@ -7362,7 +7362,12 @@ Examples:
  (let ((n (abs (prefix-numeric-value arg)))
  (enc (sp-get-enclosing-sexp))
  (in-comment (sp-point-in-comment))
- next-thing ok)
+ next-thing ok
+ ;; At some places we mutate the value of `ok'
+ ;; destructively (updating the end). The original value
+ ;; is useful in the handlers for manipulating the
+ ;; surroundings, so we copy it here.
+ ok-orig)
  (when enc
  (save-excursion
  (if (sp--raw-argument-p arg)
@@ -7387,6 +7392,7 @@ Examples:
  (goto-char (sp-get next-thing :end-suf))
  (setq ok next-thing)
  (setq next-thing (sp-get-thing nil)))
+ (setq ok-orig (copy-sequence ok))
  ;; do not allow slurping into a different context from
  ;; inside a comment
  (if (and in-comment
@@ -7427,14 +7433,14 @@ Examples:
  (insert " "))))
  (sp--run-hook-with-args
  (sp-get enc :op) :pre-handlers 'slurp-forward
- (list :arg arg :enc enc :ok ok :next-thing next-thing))
+ (list :arg arg :enc enc :ok ok :ok-orig ok-orig :next-thing next-thing))
  (sp-get ok (insert :cl :suffix))
  (sp--indent-region (sp-get ok :beg-prf) (point))
  ;; HACK: update the "enc" data structure if ok==enc
  (when (= (sp-get enc :beg) (sp-get ok :beg)) (plist-put enc :end (point)))
  (sp--run-hook-with-args
  (sp-get enc :op) :post-handlers 'slurp-forward
- (list :arg arg :enc enc :ok ok :next-thing next-thing)))
+ (list :arg arg :enc enc :ok ok :ok-orig ok-orig :next-thing next-thing)))
  (setq n (1- n)))
  (sp-message :cant-slurp)
  (setq n -1))))))))

test/smartparens-elisp-test.el

@@ -25,3 +25,54 @@ punctuation was considered invalid."
  (sp-backward-delete-char)
  (sp-backward-delete-char)
  (sp-buffer-equals ";; `a-symbol-name'? I|")))
+
+(prog1 "#781"
+ (ert-deftest sp-test-slurp-insert-space-for-style--next-sexp-paren-no-space ()
+ (sp-test-with-temp-elisp-buffer "(foo|)(bar)"
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| (bar))")
+ (call-interactively 'sp-forward-barf-sexp)
+ (sp-buffer-equals "(foo|) (bar)")
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| (bar))")))
+
+ (ert-deftest sp-test-slurp-insert-space-for-style--next-sexp-paren-space ()
+ (sp-test-with-temp-elisp-buffer "(foo|) (bar)"
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| (bar))")
+ (call-interactively 'sp-forward-barf-sexp)
+ (sp-buffer-equals "(foo|) (bar)")
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| (bar))")))
+
+ (ert-deftest sp-test-slurp-insert-space-for-style--next-sexp-symbol-no-space ()
+ (sp-test-with-temp-elisp-buffer "(foo|)bar"
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| bar)")
+ (call-interactively 'sp-forward-barf-sexp)
+ (sp-buffer-equals "(foo|) bar")
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| bar)")))
+
+ (ert-deftest sp-test-slurp-insert-space-for-style--next-sexp-symbol-space ()
+ (sp-test-with-temp-elisp-buffer "(foo|) bar"
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| bar)")
+ (call-interactively 'sp-forward-barf-sexp)
+ (sp-buffer-equals "(foo|) bar")
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo| bar)")))
+
+ (ert-deftest sp-test-slurp-insert-space-for-style--no-extra-space-from-empty-sexp ()
+ (sp-test-with-temp-elisp-buffer "(|)foo"
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(|foo)")
+ (call-interactively 'sp-forward-barf-sexp)
+ (sp-buffer-equals "(|)foo")))
+
+ (ert-deftest sp-test-slurp-insert-space-for-style--next-on-new-line ()
+ (sp-test-with-temp-elisp-buffer "(foo|)\n(bar)"
+ (call-interactively 'sp-forward-slurp-sexp)
+ (sp-buffer-equals "(foo|\n (bar))")
+ (call-interactively 'sp-forward-barf-sexp)
+ (sp-buffer-equals "(foo|)\n(bar)"))))