Trying to change the prefix parsing a bit.

parso/python/prefix.py

@@ -4,10 +4,12 @@ from parso.tokenize import group
 
 
 class PrefixPart(object):
-    def __init__(self, leaf, typ, value, start_pos):
+    def __init__(self, leaf, typ, value, spacing='', start_pos=None):
+        assert start_pos is not None
         self.parent = leaf
         self.type = typ
         self.value = value
+        self.spacing = spacing
         self.start_pos = start_pos
 
     @property
@@ -16,6 +18,13 @@ class PrefixPart(object):
             return self.start_pos[0] + 1, 0
         return self.start_pos[0], self.start_pos[1] + len(self.value)
 
+    def create_spacing_part(self):
+        column = self.start_pos[1] - len(self.spacing)
+        return PrefixPart(
+            self.parent, 'spacing', self.spacing,
+            start_pos=(self.start_pos[0], column)
+        )
+
     def __repr__(self):
         return '%s(%s, %s, %s)' % (
             self.__class__.__name__,
@@ -27,35 +36,53 @@ class PrefixPart(object):
 
 _comment = r'#[^\n\r\f]*'
 _backslash = r'\\\r?\n'
-_indentation = r'[ \t]+'
 _newline = r'\r?\n'
 _form_feed = r'\f'
+_only_spacing = '$'
+_spacing = r'[ \t]*'
 
-_regex = group(_comment, _backslash, _indentation, _newline, _form_feed)
-_regex = re.compile(_regex)
+_regex = group(
+    _comment, _backslash, _newline, _form_feed, _only_spacing,
+    capture=True
+)
+_regex = re.compile(group(_spacing, capture=True) + _regex)
 
 
 _types = {
-    ' ': 'indentation',
     '#': 'comment',
     '\\': 'backslash',
     '\f': 'formfeed',
     '\n': 'newline',
     '\r': 'newline',
-    '\t': 'indentation',
 }
 
 
 def split_prefix(leaf, start_pos):
     line, column = start_pos
     start = 0
+    value = spacing = ''
     while start != len(leaf.prefix):
         match =_regex.match(leaf.prefix, start)
-        value = match.group(0)
-        typ = _types[value[0]]
-        yield PrefixPart(leaf, typ, value, (line, column + start))
+        spacing = match.group(1)
+        value = match.group(2)
+        if not value:
+            break
+        type_ = _types[value[0]]
+        print(repr(spacing), repr(value), column)
+        yield PrefixPart(
+            leaf, type_, value, spacing,
+            start_pos=(line, column + start + len(spacing))
+        )
 
         start = match.end(0)
         if value.endswith('\n'):
             line += 1
             column = -start
+
+    print('x', repr(value), repr(spacing))
+    if value:
+        spacing = ''
+    yield PrefixPart(
+        leaf, 'spacing', spacing,
+        start_pos=(line, column + start)
+    )