def parse(s, globals=None, conditional_context=None, expression=True,
autovariables=False):
if not isinstance(s, basestring):
return s
# this prevents any function named something ending in "if"
str_to_parse = s.replace('if(', 'where(')
str_to_parse = and_re.sub(r'\1&\2', str_to_parse)
str_to_parse = or_re.sub(r'\1|\2', str_to_parse)
str_to_parse = not_re.sub(r'\1~', str_to_parse)
mode = 'eval' if expression else 'exec'
try:
c = compile(str_to_parse, '<expr>', mode)
except SyntaxError:
# SyntaxError are clearer if left unmodified since they already contain
# the faulty string
# Instances of this class have attributes filename, lineno, offset and
# text for easier access to the details. str() of the exception
# instance returns only the message.
raise
except Exception, e:
raise add_context(e, s)
# field/link actually exist in the context it is used.
# the Token class above was my first naive try at doing that, however,
# it's not as easy as I first thought because functions need to be
# delayed too.
if conditional_context is not None:
for var in c.co_names:
if var in conditional_context:
context.update(conditional_context[var])
context.update(functions)
if globals is not None:
context.update(globals)
context['__builtins__'] = None
if expression:
try:
return eval(c, context)
#IOError and such. Those are clearer when left unmodified.
except EnvironmentError:
raise
except Exception, e:
raise add_context(e, s)
else:
exec c in context
# cleanup result
del context['__builtins__']
for funcname in functions.keys():
del context[funcname]
return context
