Always output styles in consistent order (Bold, Italic, Underline)

Keep it independent of Python's set implementation.

2 files changed, 7 insertions, 3 deletions

diff --git a/screenplain/export/fdx.py b/screenplain/export/fdx.py
index 0f92cf9..85cc0ab 100644
--- a/screenplain/export/fdx.py
+++ b/screenplain/export/fdx.py
@@ -30,7 +30,7 @@ def _write_text_element(out, styles, text):
 def write_text(out, rich, trailing_linebreak):
     """Writes <Text Style="..."> elements."""
     for seg_no, segment in enumerate(rich.segments):
-        fdx_styles = set(style_names[n] for n in segment.styles)
+        fdx_styles = [style_names[n] for n in segment.get_ordered_styles()]
         if trailing_linebreak and seg_no == len(rich.segments) - 1:
             _write_text_element(out, fdx_styles, segment.text + '\n')
         else:
diff --git a/screenplain/richstring.py b/screenplain/richstring.py
index c602966..43f5949 100644
--- a/screenplain/richstring.py
+++ b/screenplain/richstring.py
@@ -81,7 +81,7 @@ class Segment(object):
     def __repr__(self):
         return '(%s)(%r)' % (
             '+'.join(
-                style.name() for style in self.styles
+                style.name() for style in self.get_ordered_styles()
             ) or 'plain',
             self.text
         )
@@ -101,8 +101,12 @@ class Segment(object):
             self.text != other.text or self.styles != other.styles
         )
 
+    def get_ordered_styles(self):
+        """Get the styles in this segment in a deterministic order."""
+        return [style for style in all_styles if style in self.styles]
+
     def to_html(self):
-        ordered_styles = list(self.styles)
+        ordered_styles = self.get_ordered_styles()
         return (
             ''.join(style.start_html for style in ordered_styles) +
             cgi.escape(self.text).encode('ascii', 'xmlcharrefreplace') +