class PushInterpreter:
"""An interpreter capable of running Push programs.
Parameters
----------
instruction_set : Union[InstructionSet, str], optional
The ``InstructionSet`` to use for executing programs. Default is "core"
which instantiates an ``InstructionSet`` using all the core instructions.
Attributes
----------
instruction_set : InstructionSet
The ``InstructionSet`` to use for executing programs.
state : PushState
The current ``PushState``. Contains one stack for each ``PushType``
mentioned by the instructions in the instruction set.
status : PushInterpreterStatus
A string denoting if the interpreter has encountered a situation
where non-standard termination was required.
"""
def __init__(self,
instruction_set: Union[InstructionSet, str] = "core",
reset_on_run: bool = True):
self.reset_on_run = reset_on_run
# If no instruction set given, create one and register all instructions.
if instruction_set == "core":
self.instruction_set = InstructionSet(register_core=True)
else:
self.instruction_set = instruction_set
self.type_library = self.instruction_set.type_library
# Initialize the PushState and status
self.state: PushState = None
self.status: PushInterpreterStatus = None
self._validate()
def _validate(self):
library_type_names = set(self.type_library.keys())
required_stacks = self.instruction_set.required_stacks() - {
"stdout", "exec", "untyped"
}
if not required_stacks <= library_type_names:
raise ValueError(
"PushInterpreter instruction_set and type_library are incompatible. {iset} vs {tlib}. Diff: {d}"
.format(
iset=required_stacks,
tlib=library_type_names,
d=required_stacks - library_type_names,
))
def _evaluate_instruction(self, instruction: Instruction,
config: PushConfig):
self.state = instruction.evaluate(self.state, config)
def untyped_to_typed(self):
"""Infer ``PushType`` of items on state's untyped queue and push to corresponding stacks."""
while len(self.state.untyped) > 0:
el = self.state.untyped.popleft()
push_type = self.type_library.push_type_of(el,
error_on_not_found=True)
self.state[push_type.name].push(el)
@tap
def evaluate_atom(self, atom: Atom, config: PushConfig):
"""Evaluate an ``Atom``.
Parameters
----------
atom : Atom
The Atom (``Literal``, ``InstructionMeta``, ``Input``, or ``CodeBlock``) to
evaluate against the current ``PushState``.
config : PushConfig
The configuration of the Push program being run.
"""
try:
if isinstance(atom, InstructionMeta):
self._evaluate_instruction(self.instruction_set[atom.name],
config)
elif isinstance(atom, Input):
input_value = self.state.inputs[atom.input_index]
self.state.untyped.append(input_value)
elif isinstance(atom, CodeBlock):
for a in atom[::-1]:
self.state["exec"].push(a)
elif isinstance(atom, Literal):
self.state[atom.push_type.name].push(atom.value)
elif isinstance(atom, Closer):
raise PushError(
"Closers should not be in push programs. Only genomes.")
else:
raise PushError(
"Cannot evaluate {t}, require a subclass of Atom".format(
t=type(atom)))
self.untyped_to_typed()
except Exception as e:
err_type = type(e).__name__
err_msg = str(e)
raise PushError(
"{t} raised while evaluating {atom}. Original message: \"{m}\""
.format(t=err_type, atom=atom, m=err_msg))
@tap
def run(self,
program: Program,
inputs: list,
print_trace: bool = False) -> list:
"""Run a Push ``Program`` given some inputs and desired output ``PushTypes``.
The general flow of this method is:
1. Create a new push state
2. Load the program and inputs.
3. If the exec stack is empty, return the outputs.
4. Else, pop the exec stack and process the atom.
5. Return to step 3.
Parameters
----------
program : Program
Program to run.
inputs : list
A sequence of values to use as inputs to the push program.
print_trace : bool
If True, each step of program execution will be summarized in stdout.
Returns
-------
Sequence
A sequence of values pulled from the final push state. May contain
pyshgp.utils.Token.no_stack_item if output stacks are empty.
"""
push_config = program.signature.push_config
if self.reset_on_run or self.state is None:
self.state = PushState(self.type_library, push_config)
self.status = PushInterpreterStatus.normal
# Setup
self.state.load_code(program.code)
self.state.load_inputs(inputs)
stop_time = time.time() + push_config.runtime_limit
steps = 0
if print_trace:
print("Initial State:")
self.state.pretty_print()
# Iterate atom evaluation until entire program is evaluated.
while len(self.state["exec"]) > 0:
# Stopping conditions
if steps > push_config.step_limit:
self.status = PushInterpreterStatus.step_limit_exceeded
break
if time.time() > stop_time:
self.status = PushInterpreterStatus.runtime_limit_exceeded
break
# Next atom in the program to evaluate.
next_atom = self.state["exec"].pop()
if print_trace:
start = time.time()
print("\nCurrent Atom: " + str(next_atom))
# Evaluate atom.
old_size = self.state.size()
self.evaluate_atom(next_atom, push_config)
if self.state.size() > old_size + push_config.growth_cap:
self.status = PushInterpreterStatus.growth_cap_exceeded
break
if print_trace:
duration = time.time() - start
print("Current State (step {step}):".format(step=steps))
self.state.pretty_print()
print("Step duration:", duration)
steps += 1
if print_trace:
print("Finished program evaluation.")
return self.state.observe_stacks(program.signature.output_stacks)
def test_load_program(self, state: PushState, atoms):
prog = CodeBlock([atoms["5"], atoms["5"], atoms["add"]])
state.load_code(prog)
assert state.size() == 1
assert len(state["exec"].top()) == 3