def env_with_prelude():
"""Return a fresh environment where the prelude has already been
evaluated.
"""
# todo: document TRIFLEPATH
# todo: should we inline the prelude, so changing TRIFLEPATH doens't break this?
trifle_path = getenv_llimpl("TRIFLEPATH") or "."
prelude_path = os.path.join(trifle_path, "prelude.tfl")
# Trifle equivalent of PYTHONPATH.
try:
code = get_contents(prelude_path)
except OSError:
# TODO: work out which error occurred (not found/wrong
# permissions/other) and be more helpful.
print "Could not find prelude.tfl. Have you set TRIFLEPATH?"
raise
# TODO: either of these could return errors, and we should handle that.
lexed_tokens = lex(code)
parse_tree = parse(lexed_tokens)
env = fresh_environment()
result = evaluate_all(parse_tree, env)
assert not is_thrown_exception(result, error), "Error when evaluating prelude: %s" % result
return env
def eval(self, program):
"""Evaluate this program in a fresh environment with the prelude
already included. Returns the result of the last expression.
"""
# Fresh copy of the environment so tests don't interfere with one another.
env = Environment([Scope({})])
global_scope = self.env.scopes[0]
for key, value in global_scope.bindings.iteritems():
# We do a deep copy of mutable values.
if isinstance(value, List):
env.set(key, deepcopy(value))
elif isinstance(value, String):
env.set(key, deepcopy(value))
elif isinstance(value, Bytestring):
env.set(key, deepcopy(value))
else:
env.set(key, value)
parse_tree = parse(lex(program))
if isinstance(parse_tree, TrifleExceptionInstance):
self.fail("Parse error on: %r" % program)
result = NULL
for expression in parse_tree.values:
result = evaluate(expression, env)
if is_thrown_exception(result, error):
return result
return result
def entry_point(argv):
"""Either a file name:
$ ./trifle ~/files/foo.tfl
A code snippet:
$ ./trifle -i '1 2'
"""
if len(argv) == 2:
# open the file
filename = argv[1]
if not os.path.exists(filename):
print 'No such file: %s' % filename
return 2
try:
env = env_with_prelude()
except OSError:
return 2
code = get_contents(filename)
lexed_tokens = lex(code)
if is_thrown_exception(lexed_tokens, error):
print u'Uncaught error: %s: %s' % (
lexed_tokens.exception_type.name,
lexed_tokens.message)
return 1
parse_tree = parse(lexed_tokens)
try:
result = evaluate_all(parse_tree, env)
if is_thrown_exception(result, error):
# TODO: a proper stack trace.
print u'Uncaught error: %s: %s' % (result.exception_type.name,
result.message)
return 1
except SystemExit:
return 0
return 0
elif len(argv) == 3:
if argv[1] == '-i':
try:
env = env_with_prelude()
except OSError:
return 2
code_snippet = argv[2].decode('utf-8')
lexed_tokens = lex(code_snippet)
if is_thrown_exception(lexed_tokens, error):
print u'Uncaught error: %s: %s' % (
lexed_tokens.exception_type.name,
lexed_tokens.message)
return 1
parse_tree = parse(lexed_tokens)
try:
result = evaluate_all(parse_tree, env)
if is_thrown_exception(result, error):
# TODO: a proper stack trace.
print u'Uncaught error: %s: %s' % (result.exception_type.name,
result.message)
return 1
else:
print result.repr().encode('utf-8')
except SystemExit:
return 0
return 0
print USAGE
return 1
