def _if(env, *args):
"""Evaluate and return true_case or false_case depending on cond."""
if len(args) != 3:
raise SException("if takes 3 parameters ({} given).".format(len(args)))
cond, true_case, false_case = args
if seval_tree(cond, env).value:
return seval_tree(true_case, env)
else:
return seval_tree(false_case, env)
def _quasiquote(env, elt):
"""Return the quoted expression, unquoting unquotes."""
if elt.type != 'list':
return elt
if (len(elt.value) > 0 and elt.value[0].type == 'id'
and elt.value[0].value == 'unquote'):
return seval_tree(elt.value[1], env)
result = []
for e in elt.value:
if (e.type != 'list' or not e.value
or e.value[0].value != 'unquote-splice'):
result.append(_quasiquote(env, e))
else:
result.extend(seval_tree(e.value[1], env).value)
return SNode('list', tuple(result))
def impl(dummy_env, *args):
if not restargs and len(params.value) != len(args):
raise SException("Expected {} args, got {}.".format(len(params.value), len(args)))
NON_SYMBOL_ERROR = "Trying to use a non-symbol as a parameter name!"
inner_env = SEnvironment(env)
for p, a in zip(nameargs.value, args):
if p.type != 'id':
raise SException(NON_SYMBOL_ERROR)
inner_env.define(p.value, a)
if restargs:
if params.value[1].type != 'id':
raise SException(NON_SYMBOL_ERROR)
rest = SNode('list', args[len(nameargs.value):])
inner_env.define(params.value[1].value, rest)
for c in code[:-1]:
seval_tree(c, inner_env)
return seval_tree(code[-1], inner_env)
def _define(env, *args):
"""Add the given name to the environment."""
if len(args) != 2:
raise SException("define takes 2 parameters ({} given).".format(len(args)))
name, value = args
if name.type != 'id':
raise SException("Trying to define a non-identifier!")
env.define(name.value, seval_tree(value, env))
return SNode('none', None)
def do_fuzz(program, env):
try:
sprint(program)
seval_tree(program, env)
except SException:
pass
def _eval(real_env, expr, env):
if env.type != 'env':
raise SException("Passed in value is not an environment.")
return seval_tree(expr, env.value)