Make indentation work

plantuml-mode.el

@@ -396,32 +396,41 @@ Uses prefix (as PREFIX) to choose where to display it:
 ;; indentation
 
 
-(defun plantuml-current-block-indentation ()
+(defun plantuml-current-block-depth ()
+  "Trace the current block indentation level by recursively looking back line by line."
   (save-excursion
     (let ((relative-depth 0))
-      (while (>= relative-depth 0)
-        (forward-line -1)
+      (beginning-of-line)
+      (forward-line -1)
+      (setq bob-visited? nil)
+      (while (and (>= relative-depth 0)
+                  (not bob-visited?))
         (if (bobp)
-            (setq relative-depth -2))   ;end fast
+            (setq bob-visited? t))
         (if (looking-at plantuml-indent-regexp-end)
-            (setq relative-depth (1+ relative-depth)))
+            (setq relative-depth (1- relative-depth)))
         (if (looking-at plantuml-indent-regexp-start)
-            (setq relative-depth (1- relative-depth))))
+            (setq relative-depth (1+ relative-depth)))
+        (forward-line -1))
 
-      (if (= -2 relative-depth)
+      (if (<= relative-depth 0)
           0
-        (+ tab-width (current-indentation))))))
+        relative-depth))))
 
 (defun plantuml-indent-line ()
+  "Indent the current line to its desired indentation level."
   (interactive)
-  (save-excursion
-    (beginning-of-line)
-    (if (bobp)
-        (indent-line-to 0)
-      (let ((offset (plantuml-current-block-indentation)))
-        (when (looking-at plantuml-indent-regexp-end)
-          (setq offset (max (- offset tab-width) 0)))
-        (indent-line-to offset)))))
+  (let ((original-indentation (current-indentation)))
+    (save-excursion
+      (beginning-of-line)
+      (if (bobp)
+          (indent-line-to 0)
+        (let ((depth (plantuml-current-block-depth)))
+          (when (looking-at plantuml-indent-regexp-end)
+            (setq depth (max (1- depth) 0)))
+          (indent-line-to (* tab-width depth)))))
+    (forward-char (- (current-indentation)
+                     original-indentation))))
 
 
 ;;;###autoload

test/plantuml-indentation-test.el

@@ -10,6 +10,44 @@
 
 ;;; Code:
 
+(defun add-text-and-position-cursor (txt)
+  "Add TXT into the buffer, move cursor to the position of the marker | and delete the marker."
+  (insert txt)
+  (goto-char (point-min))
+  (search-forward "|")
+  (delete-char -1))
+
+(defun assert-block-depth (expected txt)
+  "Assert the EXPECTED indentation level for the given TXT."
+  (with-temp-buffer
+    (add-text-and-position-cursor txt)
+    (let ((actual (plantuml-current-block-depth)))
+      (should (equal expected actual)))))
+
+(ert-deftest test-plantuml-current-block-depth ()
+  (setq-local plantuml-jar-path plantuml-test-jar-path)
+  (plantuml-init-once)
+
+  (assert-block-depth 0 "
+A |-> B")
+
+  (assert-block-depth 0 "
+pac|kage Foo {
+A -> B
+}")
+
+  (assert-block-depth 1 "
+package APackage {
+|A -> B
+}")
+
+
+  (assert-block-depth 1 "
+alt choice 1
+|A -> B
+end
+"))
+
 ;; This is taken from https://github.com/clojure-emacs/clojure-mode/blob/master/test/clojure-mode-indentation-test.el
 (defmacro check-indentation (description before after &optional var-bindings)
   "Declare an ert test for indentation behaviour.
@@ -36,11 +74,12 @@ values of customisable variables."
            (setq-local plantuml-jar-path plantuml-test-jar-path)
            (plantuml-init-once)
 
-           (insert ,before)
-           (goto-char (point-min))
-           (search-forward "|")
-           (delete-char -1)
+           (add-text-and-position-cursor ,before)
            (plantuml-mode)
+
+           ;; use 2 spaces instead of one tab for indentation
+           (setq-local indent-tabs-mode nil)
+           (setq-local tab-width 2)
            (indent-according-to-mode)
 
            (should (equal expected-state (buffer-string)))
@@ -53,7 +92,8 @@ values of customisable variables."
 (check-indentation package-block
                    "package APackage {
 |A -> B
-}" "package APackage {
+}"
+                   "package APackage {
   |A -> B
 }")