def load_cnf(s, varname='x'):
"""Parse an input string in DIMACS CNF format, and return an expression."""
m = _CNF_PREAMBLE_RE.match(s)
if m:
nvars = int(m.group(1))
ncls = int(m.group(2))
else:
raise SyntaxError("incorrect preamble")
ps, fs = s[:m.end()], s[m.end():]
line = ps.count('\n') + 1
gtoks = _iter_tokens(fs, line)
X = bitvec(varname, (1, nvars + 1))
clauses = [[]]
try:
while True:
tok = _expect_token(gtoks, _CNF_FORMULA_TOKS)
if tok.typ == 'ZERO':
clauses.append([])
elif tok.typ == 'NOT':
tok = _expect_token(gtoks, {'POSINT'})
assert tok.val <= len(X)
clauses[-1].append(-X[tok.val])
elif tok.typ == 'POSINT':
assert tok.val <= len(X)
clauses[-1].append(X[tok.val])
except StopIteration:
pass
assert len(clauses) == ncls
return And(*[Or(*clause) for clause in clauses])
def load_sat(s, varname='x'):
"""Parse an input string in DIMACS SAT format, and return an expression."""
m = _SAT_PREAMBLE_RE.match(s)
if m:
fmt = m.group(1)
nvars = int(m.group(2))
else:
raise SyntaxError("incorrect preamble")
ps, fs = s[:m.end()], s[m.end():]
line = ps.count('\n') + 1
gtoks = _iter_tokens(fs, line)
types = {'POSINT', 'LPAREN'} | _SAT_OP_TOKS[fmt]
X = bitvec(varname, (1, nvars + 1))
try:
tok = _expect_token(gtoks, types)
return _sat_formula(gtoks, tok, fmt, X)
except StopIteration:
raise SyntaxError("incomplete formula")
from pyeda.expr import (
factor, simplify,
var,
Or, And, Not, Xor, Xnor, Equal, Implies, ITE,
Nor, Nand, OneHot0, OneHot,
f_not, f_or, f_nor, f_and, f_nand, f_xor, f_xnor, f_equal, f_implies, f_ite
)
from pyeda.vexpr import bitvec
import nose
MAJOR = sys.version_info.major
MINOR = sys.version_info.minor
a, b, c, d, e, p, q, s = map(var, 'abcdepqs')
X = bitvec('x', 16)
Y = bitvec('y', 16, 16, 16)
def test_ops():
# __sub__, __rsub__
assert (a - 0) == 1
assert (0 - a) == -a
assert (a - 1) == a
assert (1 - a) == 1
assert (a - b).equivalent(a + -b)
# xor, equal, ite
assert a.xor(b, c).equivalent(-a * -b * c + -a * b * -c + a * -b * -c + a * b * c)
assert a.equal(b, c).equivalent(-a * -b * -c + a * b * c)
assert s.ite(a, b).equivalent(s * a + -s * b)
def test_factor():
"""
Test DIMACS load/dump methods
"""
from pyeda.vexpr import bitvec
from pyeda.dimacs import load_cnf, dump_cnf, load_sat, dump_sat
from pyeda.expr import Xor, Equal
import nose
X = bitvec('x', (1, 16))
F1 = (X[1] + -X[2] + X[3]) * (-X[4] + X[5]) * -X[6]
F2 = (-X[1] * X[2] * -X[3]) + (X[4] * -X[5]) + X[6]
F3 = X[1] + Xor(-X[2], X[3], -X[4] * X[5]) + -X[6]
F4 = X[1] + Equal(-X[2], X[3], -X[4] * X[5]) + -X[6]
F5 = X[1] + Xor(-X[2], X[3], Equal(-X[4], X[5])) + -X[6]
CNF_NO_PREAMBLE = \
"""c comment
1 -2 3 0 -4 5 0 -6
"""
CNF_INCORRECT_PREAMBLE_1 = \
"""c comment
p
1 -2 3 0 -4 5 0 -6
"""
CNF_INCORRECT_PREAMBLE_2 = \
"""c comment
