correctly highlight lines with tabs

line.py

@@ -1,3 +1,6 @@
+import constants
+
+
 class Line:
     def __init__(self, byte_offset: int, byte_end: int, line: str):
         self._byte_offset = byte_offset
@@ -24,12 +27,37 @@ class Line:
         prefix_chars = prefix_bytes.decode("utf8", errors="ignore")
         return len(prefix_chars)
 
+    def column_to_char(self, column_in_line: int) -> int:
+        i = 0
+        result = 0
+        while i < column_in_line:
+            char = self._line[result]
+            if char == "\t":
+                i = i + constants.tab_width - 1  # jump the additional 7 columns of the tab width
+                if i >= column_in_line:
+                    break;
+            i = i + 1
+            result = result + 1
+
+        return result
+
+    def char_to_column(self, char_in_line: int) -> int:
+        result = 0
+        i = 0
+        while i < char_in_line:
+            if i < len(self._line) and self._line[i] == "\t":
+                result = result + constants.tab_width
+            else:
+                result = result + 1
+            i = i + 1
+        return result
+
     def includes_byte(self, byte: int) -> bool:
         return self._byte_offset <= byte <= self._byte_end
 
     def intersects(self, start_byte: int, end_byte: int):
         result = start_byte < self._byte_end and end_byte > self._byte_offset
-        #print("%d,%d in %d,%d" % (start_byte, end_byte, self._byte_offset, self._byte_end))
+        # print("%d,%d in %d,%d" % (start_byte, end_byte, self._byte_offset, self._byte_end))
         return result
 
     def prefix(self, index: int) -> str: