Nick/dnm hint - do not merge, just using jenkins

CHANGELOG.rst

@@ -23,6 +23,8 @@ LMS: Support adding students to a cohort via the instructor dashboard. TNL-163
 
 LMS: Show cohorts on the new instructor dashboard. TNL-161
 
+LMS: Extended hints feature
+
 LMS: Mobile API available for courses that opt in using the Course Advanced
 Setting "Mobile Course Available" (only used in limited closed beta).
 

common/lib/capa/capa/capa_problem.py

@@ -162,6 +162,8 @@ def __init__(self, problem_text, id, capa_system, state=None, seed=None):
         # parse problem XML file into an element tree
         self.tree = etree.XML(problem_text)
 
+        self.make_xml_compatible(self.tree)
+
         # handle any <include file="foo"> tags
         self._process_includes()
 
@@ -191,6 +193,48 @@ def __init__(self, problem_text, id, capa_system, state=None, seed=None):
 
         self.extracted_tree = self._extract_html(self.tree)
 
+    def make_xml_compatible(self, tree):
+        """
+        Adjust tree xml in-place for compatibility, such as
+        supporting an old xml format by translating it to a new format.
+        """
+        # <additional_answer> compatibility translation:
+        # old:    <additional_answer>ANSWER</additional_answer>
+        # convert to
+        # new:    <additional_answer answer="ANSWER">OPTIONAL-HINT</addional_answer>
+        # the new format is the form used at runtime and by this conversion we support
+        # the old format
+        additionals = tree.xpath('//stringresponse/additional_answer')
+        for additional in additionals:
+            answer = additional.get('answer')
+            text = additional.text
+            if not answer and text:  # trigger of old->new conversion
+                additional.set('answer', text)
+                additional.text = ''
+
+        # <optioninput> compatibility translation:
+        # optioninput uses option= like this:
+        #   <optioninput options="('yellow','blue','green')" correct="blue" />
+        # With extended hints there is a new <option> tag, like this
+        #   <option correct="True">blue <optionhint>sky color</optionhint> </option>
+        # This translation takes in the new format and synthesizes the old option= attribute
+        # so all downstream logic works unchanged with the new <option> tag format.
+        for optioninput in tree.xpath('//optioninput'):
+            correct_option = None
+            child_options = []
+            for option_element in optioninput.findall('./option'):
+                option_name = option_element.text.strip()
+                if option_element.get('correct').upper() == 'TRUE':
+                    correct_option = option_name
+                child_options.append("'" + option_name + "'")
+
+            if len(child_options) > 0:
+                options_string = '(' + ','.join(child_options) + ')'
+                optioninput.attrib.update({'options': options_string})
+                if correct_option:
+                    optioninput.attrib.update({'correct': correct_option})
+
+
     def do_reset(self):
         """
         Reset internal state to unfinished, with no answers

common/lib/capa/capa/inputtypes.py

@@ -483,15 +483,17 @@ def extract_choices(element, i18n):
         _ = i18n.ugettext
 
         for choice in element:
-            if choice.tag != 'choice':
-                msg = u"[capa.inputtypes.extract_choices] {error_message}".format(
-                    # Translators: '<choice>' is a tag name and should not be translated.
-                    error_message=_("Expected a <choice> tag; got {given_tag} instead").format(
-                        given_tag=choice.tag
+            if choice.tag == 'choice':
+                choices.append((choice.get("name"), stringify_children(choice)))
+            else:
+                if choice.tag != 'compoundhint':
+                    msg = u'[capa.inputtypes.extract_choices] {error_message}'.format(
+                        # Translators: '<choice>' and '<compoundhint>' are tag names and should not be translated.
+                        error_message=_('Expected a <choice> or <compoundhint> tag; got {given_tag} instead').format(
+                            given_tag=choice.tag
+                        )
                     )
-                )
-                raise Exception(msg)
-            choices.append((choice.get("name"), stringify_children(choice)))
+                    raise Exception(msg)
         return choices
 
     def get_user_visible_answer(self, internal_answer):