From 18f9ac7d44bd2b9b2ce80177b4ac071669a00e6e Mon Sep 17 00:00:00 2001
From: Philip Eisenlohr <eisenlohr@egr.msu.edu>
Date: Mon, 14 Feb 2022 12:11:01 -0500
Subject: [PATCH] outsource tail-repacking of characters into string
 (util.tail_repack)

---
 python/damask/_vtk.py |  7 +------
 python/damask/util.py | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/python/damask/_vtk.py b/python/damask/_vtk.py
index 49c7d5d79..16b72e98d 100644
--- a/python/damask/_vtk.py
+++ b/python/damask/_vtk.py
@@ -408,14 +408,9 @@ class VTK:
             Comments.
 
         """
-        if isinstance(comments,list):
-            i = 0
-            while -i < len(comments) and len(comments[i-1]) == 1: i -= 1        # repack any trailing characters
-            comments = comments[:i] + [''.join(comments[i:])]                   # that resulted from autosplitting of str to list
-
         s = vtk.vtkStringArray()
         s.SetName('comments')
-        for c in [comments] if isinstance(comments,str) else comments:
+        for c in util.tail_repack(comments,self.comments):
             s.InsertNextValue(c)
         self.vtk_data.GetFieldData().AddArray(s)
 
diff --git a/python/damask/util.py b/python/damask/util.py
index fc3f8ea8f..96c6f46a6 100644
--- a/python/damask/util.py
+++ b/python/damask/util.py
@@ -33,7 +33,8 @@ __all__=[
          'extend_docstring', 'extended_docstring',
          'Bravais_to_Miller', 'Miller_to_Bravais',
          'DREAM3D_base_group', 'DREAM3D_cell_data_group',
-         'dict_prune', 'dict_flatten'
+         'dict_prune', 'dict_flatten',
+         'tail_repack',
         ]
 
 # https://svn.blender.org/svnroot/bf-blender/trunk/blender/build_files/scons/tools/bcolors.py
@@ -722,6 +723,36 @@ def dict_flatten(d: Dict) -> Dict:
 
 
 
+def tail_repack(extended: Union[str, Sequence[str]],
+                existing: List[str] = []) -> List[str]:
+    """
+    Repack tailing characters into single string if all are new.
+
+    Parameters
+    ----------
+    extended : str or list of str
+        Extended string list with potentially autosplitted tailing string relative to `existing`.
+    existing : list of str
+        Base string list.
+
+    Returns
+    -------
+    repacked : list of str
+        Repacked version of `extended`.
+
+    Examples
+    --------
+    >>> tail_repack(['a','new','e','n','t','r','y'],['a','new'])
+        ['a','new','entry']
+    >>> tail_repack(['a','new','shiny','e','n','t','r','y'],['a','new'])
+        ['a','new','shiny','e','n','t','r','y']
+
+    """
+    return [extended] if isinstance(extended,str) else existing + \
+         ([''.join(extended[len(existing):])] if np.prod([len(i) for i in extended[len(existing):]]) == 1 else
+          list(extended[len(existing):]))
+
+
 ####################################################################################################
 # Classes
 ####################################################################################################