text.py

                    % location)

        self.matchers = [
                parse_matcher(
                    vctx,
                    "%s, answer %d" % (location, i+1),
                    answer)
                for i, answer in enumerate(page_desc.answers)]

        if not any(matcher.correct_answer_text() is not None
                for matcher in self.matchers):
            raise ValidationError(
                    string_concat(
                        "%s: ",
                        _("no matcher is able to provide a plain-text "
                        "correct answer"))
                    % location)

    def required_attrs(self):
        return super(TextQuestion, self).required_attrs() + (
                ("answers", list),
                )

    def allowed_attrs(self):
        return super(TextQuestion, self).allowed_attrs() + (
                ("answer_explanation", "markup"),
                )

    def get_validators(self):
        return self.matchers

    def grade(self, page_context, page_data, answer_data, grade_data):
        if answer_data is None:
            return AnswerFeedback(correctness=0,
                    feedback=gettext("No answer provided."))

        answer = answer_data["answer"]

        # Must start with 'None' to allow matcher to set feedback for zero
        # correctness.
        afb = None

        for matcher in self.matchers:
            try:
                matcher.validate(answer)
            except forms.ValidationError:
                continue

            matcher_afb = matcher.grade(answer)
            if matcher_afb.correctness is not None:
                if afb is None:
                    afb = matcher_afb
                elif matcher_afb.correctness > afb.correctness:
                    afb = matcher_afb

        if afb is None:
            afb = AnswerFeedback(0)

        return afb

    def correct_answer(self, page_context, page_data, answer_data, grade_data):
        # FIXME: Could use 'best' match to answer

        unspec_correct_answer_text = None
        for matcher in self.matchers:  # pragma: no branch
            unspec_correct_answer_text = matcher.correct_answer_text()
            if unspec_correct_answer_text is not None:
                break

        assert unspec_correct_answer_text

        result = CORRECT_ANSWER_PATTERN % unspec_correct_answer_text

        if hasattr(self.page_desc, "answer_explanation"):
            result += markup_to_html(page_context, self.page_desc.answer_explanation)

        return result

    def _is_case_sensitive(self):
        return any(matcher.is_case_sensitive for matcher in self.matchers)

# }}}


# {{{ human-graded text question

class HumanGradedTextQuestion(TextQuestionBase, PageBaseWithValue,
        PageBaseWithHumanTextFeedback, PageBaseWithCorrectAnswer):
    """
    A page asking for a textual answer

    .. attribute:: id

        |id-page-attr|

    .. attribute:: type

        ``HumanGradedTextQuestion``

    .. attribute:: is_optional_page

        |is-optional-page-attr|

    .. attribute:: access_rules

        |access-rules-page-attr|

    .. attribute:: title

        |title-page-attr|

    .. attribute:: value

        |value-page-attr|

    .. attribute:: prompt

        The page's prompt, written in :ref:`markup`.

    .. attribute:: widget

        |text-widget-page-attr|

    .. attribute:: initial_text

        Text with which to prepopulate the input widget.

    .. attribute:: validators

        Optional.
        TODO

    .. attribute:: correct_answer

        Optional.
        Content that is revealed when answers are visible
        (see :ref:`flow-permissions`). Written in :ref:`markup`.

    .. attribute:: rubric

        Required.
        The grading guideline for this question, in :ref:`markup`.
    """

    def __init__(self, vctx, location, page_desc):
        super(HumanGradedTextQuestion, self).__init__(vctx, location, page_desc)

        self.validators = [
                parse_validator(
                    vctx,
                    "%s, validator %d" % (location, i+1),
                    answer)
                for i, answer in enumerate(
                    getattr(page_desc, "validators", []))]

    def allowed_attrs(self):
        return super(HumanGradedTextQuestion, self).allowed_attrs() + (
                ("validators", list),
                )

    def human_feedback_point_value(self, page_context, page_data):
        return self.max_points(page_data)

    def get_validators(self):
        return self.validators

# }}}

# vim: foldmethod=marker