Add method to output mpd as a string, and associated test (#22)

* Add method to output mpd as a string, and associated test

* Add debugging option in test to see whats happening on Python2.6

* provide own xml prettyprint work round bug in minidom 2.6

* import xml_utils correctly

* Rename xml_utils to something more sensible

mpegdash/parser.py

@@ -8,6 +8,7 @@
 
 from mpegdash.nodes import MPEGDASH
 from mpegdash.utils import parse_child_nodes, write_child_node
+from mpegdash.prettyprinter import pretty_print
 
 
 class MPEGDASHParser(object):
@@ -30,8 +31,16 @@ def parse(cls, string_or_url):
         return parse_child_nodes(xml_root_node, 'MPD', MPEGDASH)[0]
 
     @classmethod
-    def write(cls, mpd, filepath):
+    def get_as_doc(cls, mpd):
         xml_doc = minidom.Document()
         write_child_node(xml_doc, 'MPD', mpd)
+        return xml_doc
+
+    @classmethod
+    def write(cls, mpd, filepath):
         with open(filepath, 'w') as f:
-            xml_doc.writexml(f, indent='    ', addindent='    ', newl='\n')
+            cls.get_as_doc(mpd).writexml(f, indent='    ', addindent='    ', newl='\n')
+
+    @classmethod
+    def toprettyxml(cls, mpd):
+        return pretty_print(cls.get_as_doc(mpd).toxml())

mpegdash/prettyprinter.py

@@ -0,0 +1,59 @@
+
+# inspired by https://gist.github.com/sente/1083506
+# The MIT License (MIT)
+
+# Copyright (c) 2016 Stuart Powers
+
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import re
+
+def pretty_print(xmlstr, indent='    ', newl='\n'):
+    # python2 doesn't have nonlocal
+    current = [0]
+
+    def indentline(line):
+        addition = 0
+
+        if re.match('.+<\/\w[^>]*>$', line):
+            # single line text element, don't change indentation
+            addition = 0
+        elif re.match('^<\/\w', line) and current[0] > 0:
+            # end of element and have padding, decrement identation by one
+            current[0] -= 1
+        elif re.match('^<\w[^>]*[^\/]>.*$', line):
+            # start of element, increment indentation by one
+            addition = 1
+        else:
+            # single line element, don't change indentation
+            addition = 0
+
+        # update and store current indentation in outer function
+        current[0] += addition
+
+        # pad the line and return
+        return (indent * (current[0] - addition)) + line
+
+    # split the document into line, indent each line, then rejoin lines
+    return (newl).join(
+        map(
+            indentline,
+            re.sub('(>)(<)(\/*)', r'\1\n\2\3', xmlstr).split('\n')
+        )
+    )

tests/test_mpdtoxml.py

@@ -27,3 +27,18 @@ def test_mpd2xml(self):
 
         self.assertTrue(len(all_reprs) == 5)
         self.assertTrue(len(all_reprs) == len(all_reprs2))
+
+    def test_mpd2xmlstr(self):
+        # set maxDiff to None for Python2.6
+        self.maxDiff = None
+        with open('./tests/mpd-samples/sample-001.mpd') as f:
+            # read the test MPD
+            mpd = MPEGDASHParser.parse(f.read())
+            # get the MPD as an XML string
+            xmlstrout = MPEGDASHParser.toprettyxml(mpd)
+            # then parse that string
+            mpd2 = MPEGDASHParser.parse(xmlstrout)
+            # get the reparsed MPD as a string
+            xmlstrout2 = MPEGDASHParser.toprettyxml(mpd2)
+            # and check the are equal
+            self.assertEqual(xmlstrout, xmlstrout2)