RuntimeError from XPath union expression

[uogbuji]

Pretty simple. I tried to do the following:

import amara 

RDFA11_EXAMPLE = """\
<div vocab="http://schema.org/"
     typeof="Person">
  <span property="name">Manu Sporny</span>
  <img rel="image" src="manu.jpg" />

  <span property="jobTitle">CEO</span>

  <div rel="address">
    <span property="streetAddress">
     1700 Kraft Drive, Suite 2408
    </span>
    ...
  </div>

  <a rel="url"
     href="http://manu.sporny.org/">
       manu.sporny.org
  </a>
</div>
"""

doc = amara.parse(RDFA11_EXAMPLE)
doc.xml_select(u'//*[@property|@resource|@rel]')

Throws the following exception:

Traceback (most recent call last):
  File "/tmp/foo.py", line 26, in <module>
    doc.xml_select(u'//*[@property|@resource|@rel]')
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/util.py", line 52, in simple_evaluate
    return ctx.evaluate(expr)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/__init__.py", line 224, in evaluate
    return parsed.evaluate(self)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/__init__.py", line 65, in evaluate
    return self.evaluate(context)
  File "<ast-0>", line 0, in evaluate
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 161, in _boolean
    if expr.evaluate_as_boolean(context):
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/__init__.py", line 70, in evaluate_as_boolean
    self.compile_as_boolean(compiler)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 155, in compile_as_boolean
    path.compile_as_boolean(compiler)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 78, in compile_as_boolean
    return self._make_loop(compiler, found, empty)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 44, in _make_loop
    for block in self._make_block(compiler):
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 24, in _make_block
    'LOAD_ATTR', 'size',
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 41, in emit
    for opname in instructions:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 159, in _boolean
    for node in nodes:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 161, in _boolean
    if expr.evaluate_as_boolean(context):
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/__init__.py", line 70, in evaluate_as_boolean
    self.compile_as_boolean(compiler)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 155, in compile_as_boolean
    path.compile_as_boolean(compiler)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 78, in compile_as_boolean
    return self._make_loop(compiler, found, empty)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 44, in _make_loop
    for block in self._make_block(compiler):
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/nodesets.py", line 24, in _make_block
    'LOAD_ATTR', 'size',
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 41, in emit
    for opname in instructions:
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/locationpaths/predicates.py", line 161, in _boolean
    if expr.evaluate_as_boolean(context):
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/expressions/__init__.py", line 72, in evaluate_as_boolean
    docstring=unicode(self))
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/__init__.py", line 45, in compile
    firstlineno)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 60, in assemble
    stacksize = self._compute_stack_size()
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 202, in _compute_stack_size
    return walk(self.entry, 0, 0)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 192, in walk
    maxsize = walk(instr.target, size, maxsize)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 198, in walk
    maxsize = walk(block.next, size, maxsize)
  File "/Users/uche/.local/lib/python2.7/site-packages/amara/xpath/compiler/assembler.py", line 187, in walk
    raise RuntimeError("unhandled instruction: %r" % instr)
RuntimeError: unhandled instruction: <instr at 0x10b236940: opname='<block 1, offset 0>', oparg=None, target=None>

This only seems to happen when the union expression is used. You can do any of the following without the error:

• doc.xml_select(u'//*[@property]')
• doc.xml_select(u'//*[@resource]')
• doc.xml_select(u'//*[@rel]')

But any combination of 2 of the attributes in a union expression does trigger the exception.