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#!/usr/bin/python3
import re
from prolog.core import *
from prolog.util import *
class Atom(object):
__slots__ = 'ref'
def __init__(self, src=None, ref=None):
if ref != None:
self.ref = ref
else:
self.ref = PL_new_atom(bytes(src, encoding=encoding))
class Term(object):
__slots__ = 'ref'
def __init__(self, src=None, ref=None):
if ref != None:
self.ref = ref
else:
self.ref = PL_new_term_ref()
if isinstance(src, str):
if not PL_chars_to_term(bytes(src, encoding=encoding), self.ref):
raise ValueError("invalid compound term")
elif isinstance(src, int):
PL_put_integer(self.ref, src)
elif isinstance(src, float):
PL_put_float(self.ref, src)
elif isinstance(src, list):
PL_put_nil(self.ref)
for t in src:
PL_cons_list(self.ref, t.ref, self.ref)
elif isinstance(src, tuple) and len(src) == 2:
name = PL_new_atom(bytes(src[0], encoding=encoding))
args = src[1]
PL_cons_functor_v(self.ref, PL_new_functor(name, len(args)), args.ref)
elif isinstance(src, Atom):
PL_put_atom(self.ref, src.ref)
def __str__(self):
ptr = c_char_p()
if PL_get_chars(self.ref, byref(ptr), CVT_WRITE|BUF_RING):
return str(ptr.value, encoding=encoding)
class Termv(object):
__slots__ = 'ref', 'size'
def __init__(self, terms):
self.size = len(terms)
self.ref = PL_new_term_refs(self.size)
for i in range(len(terms)):
PL_put_term(self.ref+i, terms[i].ref)
def __len__(self):
return self.size
def __getitem__(self, i):
if not isinstance(i, int) or len(self) == 0 or i < 0 or i >= len(self):
raise TypeError
return Term(ref=self.ref+i)
def __iter__(self):
for i in range(len(self)):
yield Term(ref=self.ref+i)
return
def __str__(self):
return '[' + ','.join([str(term) for term in self]) + ']'
class PrologEngine(object):
def __init__(self):
# initialize Prolog library
args = ['./', '-q', '--nosignals']
if SWI_HOME_DIR is not None:
args.append('--home={0}'.format(SWI_HOME_DIR))
s_plargs = len(args)
plargs = (c_char_p*s_plargs)()
for i in range(s_plargs):
plargs[i] = bytes(args[i], encoding)
if not PL_initialise(s_plargs, plargs):
raise EnvironmentError('Could not initialize Prolog environment.'
'PL_initialise returned {0}'.format(result))
# construct needed predicates
self.p = {
'assertz': PL_predicate(b'assertz', 2, None),
'erase': PL_predicate(b'erase', 1, None),
'call_with_depth_limit': PL_predicate(b'call_with_depth_limit', 3, None),
'call_with_time_limit': PL_predicate(b'call_with_time_limit', 2, None),
'consult': PL_predicate(b'consult', 1, None),
'read_term_from_atom': PL_predicate(b'read_term_from_atom', 3, None),
'safe_goal': PL_predicate(b'safe_goal', 1, None),
'set_prolog_stack': PL_predicate(b'set_prolog_stack', 2, None)
}
self.err_flags = PL_Q_NODEBUG|PL_Q_CATCH_EXCEPTION
# database of current asserts; each load gets a new index
self.refs = {}
self.max_index = 0
PL_call_predicate(None, self.err_flags, self.p['set_prolog_stack'],
Termv([Term('global'), Term('limit(2*10**9)')]).ref)
PL_call_predicate(None, self.err_flags, self.p['set_prolog_stack'],
Termv([Term('local'), Term('limit(2*10**9)')]).ref)
def consult(self, filename):
args = Termv([Term(Atom(filename))])
out = PL_call_predicate(None, self.err_flags, self.p['consult'], args.ref)
return out == 1
def load(self, program, module=None):
tokens = tokenize(program)
refs = []
try:
start = 0
for idx in range(len(tokens)):
if tokens[idx] != ('PERIOD', '.') or idx - start <= 1:
continue
rule = stringify(tokens[start:idx])
start = idx + 1
if module != None:
rule = module + ':(' + rule + ')'
args = Termv([Term(rule), Term('Ref')])
out = PL_call_predicate(None, self.err_flags, self.p['assertz'], args.ref)
refs.append(args[1])
except:
# unload already loaded rules (hacky, mustfix, todo)
for ref in refs:
args = Termv([ref])
out = PL_call_predicate(None, self.err_flags, self.p['erase'], args.ref)
return None
self.max_index += 1
self.refs[self.max_index] = refs
return self.max_index
def unload(self, index):
for ref in self.refs[index]:
args = Termv([ref])
out = PL_call_predicate(None, self.err_flags, self.p['erase'], args.ref)
del self.refs[index]
def query(self, q, module=None):
if module != None:
q = module + ':(' + q + ')'
fid = PL_open_foreign_frame()
goal = Term()
var_list = Term()
options = Term([Term(('variable_names', Termv([var_list])))])
# parse term
if not PL_call_predicate(None, self.err_flags, self.p['read_term_from_atom'],
Termv([Term(Atom(q)), goal, options]).ref):
sys.stderr.write('WARNING: Could not read term from {}\n'.format(q))
return None
# check if goal is safe with currently loaded rules
if not PL_call_predicate(None, self.err_flags, self.p['safe_goal'],
Termv([goal]).ref):
sys.stderr.write('WARNING: Unsafe goal: {}\n'.format(q))
return None
solutions = []
#depth_limit = Term(('call_with_depth_limit', Termv([goal, Term(50), Term('_')])))
qid = PL_open_query(None, self.err_flags, self.p['call_with_time_limit'],
Termv([Term(0.01), goal]).ref)
while len(solutions) < 10:
if PL_next_solution(qid):
# get variable values in this solution as strings
variables = {}
head, tail = Term(), Term()
while PL_get_list(var_list.ref, head.ref, tail.ref):
name, value = Term(), Term()
PL_get_arg(1, head.ref, name.ref)
PL_get_arg(2, head.ref, value.ref)
variables[str(name)] = str(value)
var_list = tail
solutions += [variables]
else:
ex = PL_exception(qid)
if ex != None:
ex = Term(ref=PL_exception(qid))
if ex != None:
message_to_string = PL_predicate(b'message_to_string', 2, None)
args = Termv([ex, Term()])
if PL_call_predicate(None, self.err_flags, message_to_string, args.ref):
sys.stderr.write('Error: ' + str(args[1]) + '\n')
else:
sys.stderr.write('Unknown error\n')
break
PL_close_query(qid)
PL_discard_foreign_frame(fid)
return solutions
|
