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Commit 70635d54 authored by Stefan Marr's avatar Stefan Marr
Browse files

Added Bytecodes class



- this is slightly different from what the Java implementation does
- the main reason is that Python does not have a switch/case statement, but this approach here is also more declarative, a little nicer, and less redundant
Signed-off-by: default avatarStefan Marr <git@stefan-marr.de>
parent 78e818e9
class Bytecodes(object):
# Bytecodes used by the Simple Object Machine (SOM)
halt = 0
dup = 1
push_local = 2
push_argument = 3
push_field = 4
push_block = 5
push_constant = 6
push_global = 7
pop = 8
pop_local = 9
pop_argument = 10
pop_field = 11
send = 12
super_send = 13
return_local = 14
return_non_local = 15
_num_bytecodes = 16
_bytecode_length = {halt : 1,
dup : 1,
push_local : 3,
push_argument : 3,
push_field : 2,
push_block : 2,
push_constant : 2,
push_global : 2,
pop : 1,
pop_local : 3,
pop_argument : 3,
pop_field : 2,
send : 2,
super_send : 2,
return_local : 1,
return_non_local : 1 }
_stack_effect_depends_on_message = object()
_bytecode_stack_effect = {halt : 0,
dup : 1,
push_local : 1,
push_argument : 1,
push_field : 1,
push_block : 1,
push_constant : 1,
push_global : 1,
pop : -1,
pop_local : -1,
pop_argument : -1,
pop_field : -1,
send : _stack_effect_depends_on_message,
super_send : _stack_effect_depends_on_message,
return_local : 0,
return_non_local : 0 }
@classmethod
def get_bytecode_length(cls, bytecode):
return cls._bytecode_length[bytecode]
@classmethod
def get_stack_effect(cls, bytecode, number_of_arguments_of_message_send = 0):
if cls.stack_effect_depends_on_send(bytecode):
return -number_of_arguments_of_message_send + 1 # +1 in order to account for the return value
else:
return cls._stack_effect_depends_on_message[bytecode]
@classmethod
def stack_effect_depends_on_send(cls, bytecode):
return cls._stack_effect_depends_on_message[bytecode] is cls._stack_effect_depends_on_message
@classmethod
def as_str(cls, bytecode):
if not isinstance(bytecode, int):
raise ValueError('bytecode is expected to be an integer.')
for key, val in cls.__dict__:
if val == bytecode:
return key.upper()
raise ValueError('No defined defined for the value %d.' % bytecode)
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