Added support for superscripts in variables and fixed bug with normal…

Added support for superscripts in variables and fixed bug with normal subscripted variables raised to powers

Added support for superscripts in variables and fixed bug with normal…
Added support for superscripts in variables and fixed bug with normal subscripted variables raised to powers
66657db0 · Peter Baratta · 999ed17e · 66657db0
Commit 66657db0 authored Mar 04, 2013 by Peter Baratta
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lms/lib/symmath/formula.py
+60 -0

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--- a/lms/lib/symmath/formula.py
+++ b/lms/lib/symmath/formula.py
@@ -247,6 +247,65 @@ class formula(object):
                fix_hat(k)
        fix_hat(xml)

+        def flatten_pmathml(xml):
+            '''
+            Give the text version of PMathML elements
+            '''
+            tag = gettag(xml)
+            if tag == 'mn': return xml.text
+            elif tag == 'mi': return xml.text
+            # elif tag == 'msub': return '_'.join([flatten_pmathml(y) for y in xml])
+            # elif tag == 'msup': return '^'.join([flatten_pmathml(y) for y in xml])
+            elif tag == 'mrow': return ''.join([flatten_pmathml(y) for y in xml])
+            raise Exception, '[flatten_pmathml] unknown tag %s' % tag
+
+        # find "tagged" superscripts
+        # they have the character \u200b in the superscript
+        # replace them with a__b so snuggle doesn't get confused
+        def fix_superscripts(xml):
+            for k in xml:
+                tag = gettag(k)
+
+                # match node to a superscript
+                if (tag == 'msup' and
+                    len(k) == 2 and gettag(k[1]) == 'mrow' and
+                    gettag(k[1][0]) == 'mo' and k[1][0].text == u'\u200b'): # whew
+
+                    k[1].remove(k[1][0])
+                    newk = etree.Element('mi')
+                    newk.text = '%s__%s' % (flatten_pmathml(k[0]), flatten_pmathml(k[1]))
+                    xml.replace(k, newk)
+
+                if (tag == 'msubsup' and
+                    len(k) == 3 and gettag(k[2]) == 'mrow' and
+                    gettag(k[2][0]) == 'mo' and k[2][0].text == u'\u200b'): # whew
+
+                    k[2].remove(k[2][0])
+                    newk = etree.Element('mi')
+                    newk.text = '%s_%s__%s' % (flatten_pmathml(k[0]), flatten_pmathml(k[1]), flatten_pmathml(k[2]))
+                    xml.replace(k, newk)
+
+                fix_superscripts(k)
+        fix_superscripts(xml)
+
+        # Snuggle returns an error when it sees an <msubsup>
+        # replace such elements with an <msup>, except the first element is of
+        # the form a_b. I.e. map a_b^c => (a_b)^c
+        def fix_msubsup(parent):
+            for child in parent:
+                # fix msubsup
+                if (gettag(child) == 'msubsup' and len(child) == 3):
+                    newchild = etree.Element('msup')
+                    newbase = etree.Element('mi')
+                    newbase.text = '%s_%s' % (flatten_pmathml(child[0]), flatten_pmathml(child[1]))
+                    newexp = child[2]
+                    newchild.append(newbase)
+                    newchild.append(newexp)
+                    parent.replace(child, newchild)
+
+                fix_msubsup(child)
+        fix_msubsup(xml)
+
        self.xml = xml
        return self.xml

@@ -257,6 +316,7 @@ class formula(object):
        try:
            xml = self.preprocess_pmathml(self.expr)
        except Exception, err:
+            # print 'Err %s while preprocessing; expr=%s' % (err, self.expr)
            return "<html>Error! Cannot process pmathml</html>"
        pmathml = etree.tostring(xml, pretty_print=True)
        self.the_pmathml = pmathml