def eval(self, form, env, maxInstructions=None):
self.maxInstructions = maxInstructions
self.instructions = 0
try:
try:
return context.call({'SL-interp': self},
self.evalForm, form, env)
except:
# XXX This is _really_ not how it should be.
# Firstly, the thing that handles Python exceptions
# should be separate from the thing that handles
# Safelisp exceptions. Of course, that implies that
# Safelisp has its _own_ exception system. Then, of
# course, the arguments to *exc-handler* should be a
# Safelisp-representation of the exception and
# traceback objects.
exch = E.lookup(env, '*exc-handler*')
if exch:
if isinstance(exch, O.Function):
stuff = sys.exc_info()
errorclass = stuff[0].__name__
errormessage = str(stuff[1])
frames = self.frames[:]
context.call({'SL-interp': self},
exch.callFunc,
self,
O.List([errorclass, errormessage, frames]))
else:
exch(self)
self.frames = []
else:
self.frames = []
raise
finally:
self.maxInstructions = None
def evalForm(self, form, env):
"""
Evaluate a form in an environment
"""
assert context.get('SL-interp', None) is not None, "Only call evalForm from within eval!"
if self.maxInstructions:
self.instructions += 1
if self.instructions > self.maxInstructions:
raise TooManyInstructions("Your limit is %s, buddy." % self.maxInstructions)
# XXX This code is *riddled* with isinstance. What's a better solution?
if not isinstance(form, O.SLObject):
raise UnevaluableError("I cannot evaluate %s." % form)
if isinstance(form, O.Identifier):
return E.lookup(env, form.name)
if not isinstance(form, O.List):
return form
if isinstance(form, O.List):
value = form.pyvalue
if not value:
raise SyntaxError("Empty call.")
if isinstance(value[0], O.Identifier):
name = value[0].name
func = self.specials.get(name, None)
if func:
return func(self, form, env)
func = self.evalForm(value[0], env)
#print "GOT THE FUNC", func, "FROM", value
if isinstance(func, O.Macro):
return func.callMacro(self, env, value[1:])
# Must be a function call: LispEvaluate the
# elements of the list
args = [self.evalForm(x, env) for x in value[1:]]
if isinstance(func, O.Function):
return func.callFunc(self, O.List(args))
# must be a python extension...
r = context.call({'SL-env': env}, func, *args)
return r
raise RuntimeError("This is a bug. What the heck is %s?" % repr(form))