Updated CaptionList to handle list operations.

pycaption/base.py

@@ -242,11 +242,37 @@ def _format_timestamp(self, value, msec_separator=None):
 
 class CaptionList(list):
     """ A list of captions with a layout object attached to it """
-    def __init__(self, layout_info=None):
+    def __init__(self, iterable=None, layout_info=None):
         """
+        :param iterator: An iterator used to populate the caption list
         :param Layout layout_info: A Layout object with the positioning info
         """
         self.layout_info = layout_info
+        args = [iterable] if iterable else []
+        super(CaptionList, self).__init__(*args)
+
+    def __getslice__(self, i, j):
+        return CaptionList(
+            list.__getslice__(self, i, j), layout_info=self.layout_info)
+
+    def __add__(self, other):
+        add_is_safe = (
+            not hasattr(other, 'layout_info') or
+            not other.layout_info or
+            self.layout_info == other.layout_info
+        )
+        if add_is_safe:
+            return CaptionList(
+                list.__add__(self, other), layout_info=self.layout_info)
+        else:
+            raise ValueError(
+                "Cannot add CaptionList objects with different layout_info")
+
+    def __mul__(self, other):
+        return CaptionList(
+            list.__mul__(self, other), layout_info=self.layout_info)
+
+    __rmul__ = __mul__
 
 
 class CaptionSet(object):

pycaption/dfxp/base.py

@@ -98,20 +98,19 @@ def _get_dfxp_parser_class():
         return LayoutAwareDFXPParser
 
     def _translate_div(self, div):
-        captions = CaptionList(div.layout_info)
-        for p_tag in div.find_all(u'p'):
-            captions.append(self._translate_p_tag(p_tag))
-        return captions
+        return CaptionList(
+            [self._translate_p_tag(p_tag) for p_tag in div.find_all(u'p')],
+            div.layout_info
+        )
 
     def _translate_p_tag(self, p_tag):
         start, end = self._find_times(p_tag)
         self.nodes = []
         self._translate_tag(p_tag)
         styles = self._translate_style(p_tag)
 
-        caption = Caption(start, end, self.nodes, style=styles,
-                          layout_info=p_tag.layout_info)
-        return caption
+        return Caption(
+            start, end, self.nodes, style=styles, layout_info=p_tag.layout_info)
 
     def _find_times(self, p_tag):
         start = self._translate_time(p_tag[u'begin'])

pycaption/sami.py

@@ -182,7 +182,7 @@ def _translate_lang(self, language, sami_soup, parent_layout):
 
         :rtype: list
         """
-        captions = CaptionList(parent_layout)
+        captions = CaptionList(layout_info=parent_layout)
         milliseconds = 0
 
         for p in sami_soup.select(u'p[lang|=%s]' % language):

tests/test_base.py

@@ -0,0 +1,42 @@
+import unittest
+
+from pycaption.base import CaptionList
+
+
+class CaptionListTestCase(unittest.TestCase):
+
+    def setUp(self):
+        self.layout_info = "My Layout"
+        self.caps = CaptionList([1, 2, 3], layout_info=self.layout_info)
+
+    def test_splice(self):
+        newcaps = self.caps[1:]
+        self.assertTrue(isinstance(newcaps, CaptionList))
+        self.assertTrue(newcaps.layout_info == self.layout_info)
+
+    def test_mul(self):
+        newcaps = self.caps * 2
+        self.assertTrue(isinstance(newcaps, CaptionList))
+        self.assertTrue(newcaps.layout_info == self.layout_info)
+
+    def test_rmul(self):
+        newcaps = 2 * self.caps
+        self.assertTrue(isinstance(newcaps, CaptionList))
+        self.assertTrue(newcaps.layout_info == self.layout_info)
+
+    def test_add_list_to_caption_list(self):
+        newcaps = self.caps + [9, 8, 7]
+        self.assertTrue(isinstance(newcaps, CaptionList))
+        self.assertTrue(newcaps.layout_info == self.layout_info)
+
+    def test_add_two_caption_lists(self):
+        newcaps = self.caps + CaptionList([4], layout_info=None)
+        self.assertTrue(isinstance(newcaps, CaptionList))
+        self.assertTrue(newcaps.layout_info == self.layout_info)
+
+        newcaps = self.caps + CaptionList([4], layout_info=self.layout_info)
+        self.assertTrue(isinstance(newcaps, CaptionList))
+        self.assertTrue(newcaps.layout_info == self.layout_info)
+
+        with self.assertRaises(ValueError):
+            newcaps = self.caps + CaptionList([4], layout_info="Other Layout")