From b2d6a9f44109c22f1bb96558411c7d910cfe8eaf Mon Sep 17 00:00:00 2001
From: Marek L <nospam.keram@gmail.com>
Date: Thu, 2 Feb 2023 19:54:57 +0000
Subject: [PATCH] Make idris-format compatible with emacs 25*

---
 idris-compat.el | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 idris-format.el | 12 +++++++-----
 2 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/idris-compat.el b/idris-compat.el
index d248d7f8..9f0dc28f 100644
--- a/idris-compat.el
+++ b/idris-compat.el
@@ -41,5 +41,51 @@ attention to case differences."
       (concat (apply 'concat (mapcar 'file-name-as-directory dirs))
               (car (reverse components))))))
 
+(if (fboundp 'string-limit)
+    (defalias 'idris-string-limit 'string-limit)
+  ;; Extracted from Emacs 28* 'subr-x
+  (defun idris-string-limit (string length &optional end coding-system)
+    "Return a substring of STRING that is (up to) LENGTH characters long.
+If STRING is shorter than or equal to LENGTH characters, return the
+entire string unchanged.
+
+If STRING is longer than LENGTH characters, return a substring
+consisting of the first LENGTH characters of STRING.  If END is
+non-nil, return the last LENGTH characters instead.
+
+If CODING-SYSTEM is non-nil, STRING will be encoded before
+limiting, and LENGTH is interpreted as the number of bytes to
+limit the string to.  The result will be a unibyte string that is
+shorter than LENGTH, but will not contain \"partial\" characters,
+even if CODING-SYSTEM encodes characters with several bytes per
+character.
+
+When shortening strings for display purposes,
+`truncate-string-to-width' is almost always a better alternative
+than this function."
+    (unless (natnump length)
+      (signal 'wrong-type-argument (list 'natnump length)))
+    (if coding-system
+        (let ((result nil)
+              (result-length 0)
+              (index (if end (1- (length string)) 0)))
+          (while (let ((encoded (encode-coding-char
+                                 (aref string index) coding-system)))
+                   (and (<= (+ (length encoded) result-length) length)
+                        (progn
+                          (push encoded result)
+                          (cl-incf result-length (length encoded))
+                          (setq index (if end (1- index)
+                                        (1+ index))))
+                        (if end (> index -1)
+                          (< index (length string)))))
+            ;; No body.
+            )
+          (apply #'concat (if end result (nreverse result))))
+      (cond
+       ((<= (length string) length) string)
+       (end (substring string (- (length string) length)))
+       (t (substring string 0 length))))))
+
 (provide 'idris-compat)
 ;;; idris-compat.el ends here
diff --git a/idris-format.el b/idris-format.el
index cb04513b..4ef2f36f 100644
--- a/idris-format.el
+++ b/idris-format.el
@@ -25,13 +25,14 @@
 (require 'rx)
 (require 'subr-x)
 (require 'cl-seq)
+(require 'idris-compat)
 
 (defun idris-split-line-to-lhs-rhs (line)
   "Split LINE string to two parts starting at first occurence of equal sign (=).
 The equal sign is part of the right hand side. If no equal sign found
 the `car' of result (LHS) is empty string and `cdr' of result (RHS) the LINE."
   (let* ((lhs-length (or (string-match "=" line) 0))
-         (lhs (string-trim-right (string-limit line lhs-length)))
+         (lhs (string-trim-right (idris-string-limit line lhs-length)))
          (rhs (substring line lhs-length)))
     (cons lhs rhs)))
 
@@ -106,9 +107,10 @@ Example: (idris-split-words \"foo (S k) k\")
      (lambda (lhs-rhs)
        (if (and prev-lhs-delta (null (car lhs-rhs)))
            (concat (make-string prev-lhs-delta ? ) (cdr lhs-rhs))
-         (let ((new-lhs (string-join (idris-mapcar-with-index (lambda (word j)
-                                                                (string-pad word (nth j mvl)))
-                                                              (car lhss-words))
+         (let ((new-lhs (string-join (idris-mapcar-with-index
+                                      (lambda (word j)
+                                        (concat word (make-string (nth j mvl) ?\s)))
+                                      (car lhss-words))
                                      " ")))
            (setq prev-lhs-delta (- (length new-lhs) (length (car lhs-rhs))))
            (setq lhss-words (cdr lhss-words))
@@ -159,7 +161,7 @@ before line containing colon symbol (:) that contains equal sign (=)."
     (let* ((start (idris-beginning-of-clause))
            (end (idris-end-of-clause))
            (indent (make-string (idris-clause-point-column start) ? ))
-           (lines (string-lines (buffer-substring-no-properties start end)))
+           (lines (split-string (buffer-substring-no-properties start end) "\n"))
            (padded-lines (mapcar (lambda (line) (concat indent line))
                                  (idris-pad-lines lines)))
            (new-region (string-join padded-lines "\n")))