fix(emacs): support tabs in a file

Fix #226

src/emacs/lean-company.el

@@ -126,7 +126,7 @@
 
 (defun company-lean--findg-candidates (prefix)
   (let ((line-number (line-number-at-pos))
-        (column-number (current-column))
+        (column-number (lean-line-offset))
         pattern)
     (lean-server-send-cmd-sync (lean-cmd-wait) '(lambda () ()))
     (setq pattern (if current-prefix-arg
@@ -203,7 +203,6 @@ triggers a completion immediately."
 
 (defun company-lean--findp-candidates (prefix)
   (let ((line-number (line-number-at-pos))
-        (column-number (current-column))
         pattern)
     (lean-server-send-cmd-sync (lean-cmd-wait) '(lambda () ()))
     (lean-server-send-cmd-sync (lean-cmd-findp line-number prefix)

src/emacs/lean-info.el

@@ -456,13 +456,13 @@ Take out \"BEGININFO\" and \"ENDINFO\" and Use \"ACK\" as a delim."
   (save-excursion
     (forward-char 1)
     (backward-list 1)
-    `(,(line-number-at-pos) . ,(current-column))))
+    `(,(line-number-at-pos) . ,(lean-line-offset))))
 
 (defun lean-get-info-record-at-point (cont)
   "Get info-record at the current point"
   (let* ((file-name     (buffer-file-name))
          (line-number   (line-number-at-pos))
-         (column-number (current-column))
+         (column-number (lean-line-offset))
          (cmd           (cond ((looking-at "(")
                                (lean-cmd-info line-number column-number))
                               ;; TODO(soonhok): give information on '('

src/emacs/lean-server.el

@@ -480,7 +480,7 @@ If it's not the same with file-name (default: buffer-file-name), send VISIT cmd.
 
 (defun lean-server-get-info-record-at-pos (body)
   (let* ((file-name (buffer-file-name))
-         (column (current-column)))
+         (column (lean-line-offset)))
     (when (and (or (looking-at (rx (or white "," ")" "}" "]")))
                    (eolp))
                (> column 1))

src/emacs/lean-util.el

@@ -166,4 +166,15 @@
         (when id-beg
           (buffer-substring id-beg cur-pos))))))
 
+(defun lean-line-offset ()
+  "Return the byte-offset of current position, counting from the
+  beginning of the line"
+  (interactive)
+  (let ((bol-pos
+         (save-excursion
+           (beginning-of-line)
+           (point)))
+        (pos (point)))
+    (- pos bol-pos)))
+
 (provide 'lean-util)