[PATCH 7/9] StringList.get_indented(): Support indention by tabs

Support calculating indention with tabs, e.g. 1 tab = 8 spaces.
---
 docutils/docutils/statemachine.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/docutils/docutils/statemachine.py b/docutils/docutils/statemachine.py
index c1f07b57e..681563d19 100644
--- a/docutils/docutils/statemachine.py
+++ b/docutils/docutils/statemachine.py
@@ -1358,7 +1358,7 @@ def get_text_block(self, start, flush_left=False):
         return self[start:end]
 
     def get_indented(self, start=0, until_blank=False, strip_indent=True,
-                     block_indent=None, first_indent=None):
+                     block_indent=None, first_indent=None, tab_width=8):
         """
         Extract and return a StringList of indented lines of text.
 
@@ -1367,12 +1367,17 @@ def get_indented(self, start=0, until_blank=False, strip_indent=True,
         `strip_indent` is false), and return them. All lines up to but not
         including the first unindented line will be returned.
 
+        The indention is calculated for the logical text position.  That is
+        a tab character is `tab_width` spaces wide instead of 1.
+        See `logical_rslice()` for details.
+
         :Parameters:
           - `start`: The index of the first line to examine.
           - `until_blank`: Stop collecting at the first blank line if true.
           - `strip_indent`: Strip common leading indent if true (default).
           - `block_indent`: The indent of the entire block, if known.
           - `first_indent`: The indent of the first line, if known.
+          - `tab_width`: tab stop positions "1 tab = `tab_width` spaces"
 
         :Return:
           - a StringList of indented lines with minimum indent removed;
@@ -1388,7 +1393,7 @@ def get_indented(self, start=0, until_blank=False, strip_indent=True,
         last = len(self.data)
         while end < last:
             line = self.data[end]
-            if line and (line[0] != ' '
+            if line and ((line[0] not in ' \t')
                          or (block_indent is not None
                              and line[:block_indent].strip())):
                 # Line not indented or insufficiently indented.
@@ -1402,7 +1407,8 @@ def get_indented(self, start=0, until_blank=False, strip_indent=True,
                     blank_finish = 1
                     break
             elif block_indent is None:
-                line_indent = len(line) - len(stripped)
+                indent_chars = line[:-len(stripped)]
+                line_indent = len(indent_chars.expandtabs(tab_width))
                 if indent is None:
                     indent = line_indent
                 else:
@@ -1412,9 +1418,9 @@ def get_indented(self, start=0, until_blank=False, strip_indent=True,
             blank_finish = 1            # block ends at end of lines
         block = self[start:end]
         if first_indent is not None and block:
-            block.data[0] = block.data[0][first_indent:]
+            block.data[0] = logical_rslice(block.data[0], first_indent, tab_width)
         if indent and strip_indent:
-            block.trim_left(indent, start=(first_indent is not None))
+            block.trim_left(indent, start=(first_indent is not None), tab_width=tab_width)
         return block, indent or 0, blank_finish
 
     def get_2D_block(self, top, left, bottom, right, strip_indent=True):