""" This has custom renderers: classes that know how to render certain problem tags (e.g. and ) to html. These tags do not have state, so they just get passed the system (for access to render_template), and the xml element. """ from registry import TagRegistry import logging import re import shlex # for splitting quoted strings import json from lxml import etree import xml.sax.saxutils as saxutils from registry import TagRegistry log = logging.getLogger(__name__) registry = TagRegistry() #----------------------------------------------------------------------------- class MathRenderer(object): tags = ['math'] def __init__(self, system, xml): ''' Render math using latex-like formatting. Examples: $\displaystyle U(r)=4 U_0 $ $r_0$ We convert these to [mathjax]...[/mathjax] and [mathjaxinline]...[/mathjaxinline] TODO: use shorter tags (but this will require converting problem XML files!) ''' self.system = system self.xml = xml mathstr = re.sub('\$(.*)\$', r'[mathjaxinline]\1[/mathjaxinline]', xml.text) mtag = 'mathjax' if not r'\displaystyle' in mathstr: mtag += 'inline' else: mathstr = mathstr.replace(r'\displaystyle', '') self.mathstr = mathstr.replace('mathjaxinline]', '%s]' % mtag) def get_html(self): """ Return the contents of this tag, rendered to html, as an etree element. """ # TODO: why are there nested html tags here?? Why are there html tags at all, in fact? html = '%s%s' % ( self.mathstr, saxutils.escape(self.xml.tail)) try: xhtml = etree.XML(html) except Exception as err: if self.system.DEBUG: msg = '

Error %s

' % ( str(err).replace('<', '<')) msg += ('

Failed to construct math expression from 

%s

' % html.replace('<', '<')) msg += "
" log.error(msg) return etree.XML(msg) else: raise return xhtml registry.register(MathRenderer) #----------------------------------------------------------------------------- class SolutionRenderer(object): ''' A solution is just a ... which is given an ID, that is used for displaying an extended answer (a problem "solution") after "show answers" is pressed. Note that the solution content is NOT rendered and returned in the HTML. It is obtained by an ajax call. ''' tags = ['solution'] def __init__(self, system, xml): self.system = system self.id = xml.get('id') def get_html(self): context = {'id': self.id} html = self.system.render_template("solutionspan.html", context) return etree.XML(html) registry.register(SolutionRenderer)