def do_rule(rule, sexps, nsi):
"""
Applies a Pure rule to tuple of elements. The codomain tuple
is always mapped to the same size of the domain tuple.
For example a rule to commute addition maps 1-tuples to
1-tuples.
`(Addition x y) → (Addition y x)`
A rule to add an element to both sides of an equation maps
2-tuples to 2-tuples but one element of the image is null.
`( (Equation lhs rhs) , x ) → ( (Equation lhs+x rhs+x) , pass )`
In this case the 'pass' element tells the worksheet to do
not expect a new element in the image of the rule and leave
that element inplace.
"""
# Build the Pure expression from the given sexps
args = map(translate.parse_sexp, sexps)
pargs = map(translate.python_to_pure, args)
# Build the rule and apply it to the Pure expression
ref = rules[rule]()
_pure_expr = ref.reduce_with(*pargs)
# Convert to prefix form for conversion back to Python
result = i2p(_pure_expr)
# Create the uid generator and walk the new expression to
# return the JSON
uid = uidgen(int(nsi))
expr_tree = translate.parse_pure_exp(result)
# Walk the tree with the UID generator
expr_tree.uid_walk(uid, overwrite=True)
_html = html(expr_tree)
_json = json_flat(expr_tree)
_nsi = uid.next()[3:]
return json.dumps({
'new_html' : [_html],
'new_json' : [_json],
'namespace_index' : _nsi
})
def do_eval(code, sexps, nsi):
# Block the execution of any code which could alter the
# interpreter, this is marginally improves security
if any([s in code for s in blacklist]):
# Raise a warning since this could be a hacking attempt
# TODO: at some point tie this into django-axes and cut
# the user off if they try too much of this stuff
logging.warning('Attempt to use Pure keyword: ' + code)
return json.dumps({'error': 'Invalid keyword'})
try:
pure_expr = PureInterface().eval(code)
result = i2p(pure_expr)
except Exception as e:
error = str(e.value)
return json.dumps({'error':error})
# Create the uid generator and walk the new expression to
# return the JSON
uid = uidgen(int(nsi))
try:
expr_tree = translate.parse_pure_exp(result)
except exception.NoWrapper as e:
unknown = e.value
return json.dumps({'error': 'Unknown symbol: %s' % unknown})
expr_tree.uid_walk(uid, overwrite=True)
_html = html(expr_tree)
_json = json_flat(expr_tree)
_nsi = uid.next()[3:]
return json.dumps({
'new_html' : [_html],
'new_json' : [_json],
'namespace_index' : _nsi
})