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"""
PARENS: '(' (EXPR | ATOM) ')'
EXPR: (BINARY | PARENS | NOT)
BINARY: (ATOM | EXPR) BOPER (ATOM | EXPR)
UNITARY: UOPER (EXPR | ATOM)
ATOM: (VAR | NUM)
VAR: 't'
NUM: <integer>
Order of ops:
()
~
* / %
+ -
<< >>
&
^
|
TODO: allow negative numbers?
"""
hexchr = "0123456789ABCDEFabcdef"
raw_opers = "+ - * / % << >> & | ^ ~".split()
binary_opers = list("+-*/%lr&|^")
unitary_opers = list("~+-")
binaryoper_priority = (
tuple("|"),
tuple("^"),
tuple("&"),
tuple("rl"),
tuple("+-"),
tuple("*/%"),
)
def cons(a, l):
return [a, ] + l
def car(l):
return l[0]
def cdr(l):
return l[1:]
def preparse(l, depth=0):
"""
match parens and set types
"""
ret = []
for i in range(len(l)):
if l[i] == '(':
#print "%sleft: %s" % (" "*depth, ret)
middle, remains = preparse(l[i+1:], depth+1)
#print "%smiddle: %s" % (" "*depth, middle)
right, moreright = preparse(remains, depth)
#print "%sright: %s" % (" "*depth, right)
return ret + [tuple(cons('PARENS', middle))] + right, moreright
elif l[i] == ')':
if depth == 0:
Exception("preparse: unexpected parens")
return ret, l[i+1:]
else:
if type(l[i]) == int:
ret.append(('NUM', l[i]))
elif l[i] == '~':
ret.append(('NOTOPER',))
elif l[i] in binary_opers:
ret.append(('OPER', l[i]))
elif l[i] == 't':
ret.append(('VAR',))
else:
raise Exception("prepase: unexpected token: %s" % l[i])
if depth > 0:
raise Exception("preparse: unmatched parens")
return ret, []
def parse(l):
#print l
if not l or len(l) == 0:
return []
if len(l) == 1:
if car(car(l)) in ('VAR', 'NUM'):
return ('ATOM', car(l))
elif car(car(l)) == 'PARENS':
return parse(cdr(car(l)))
else:
raise Exception("parse error: %s" % l)
# ~ has highest priority
if ('NOTOPER',) in l:
i = l.index(('NOTOPER',))
if i == len(l)-1:
raise Exception("parse error: trailing ~")
return parse(l[:i] + ('NOT', parse(l[i+1])) + l[i+2:])
# helper function
def hunt_opers(l, operlist):
for i in range(1, len(l) - 1):
if car(l[i]) == 'OPER' and l[i][1] in operlist:
left = parse(l[:i])
right = parse(l[i+1:])
if not car(left) in ['ATOM', 'BINARY', 'NOT']:
raise Exception("parse error: not a binary operand: %s" %
left)
if not car(right) in ['ATOM', 'BINARY', 'NOT']:
raise Exception("parse error: not a binary operand: %s" %
right)
return ('BINARY', l[i][1], left, right)
for operlist in binaryoper_priority:
match = hunt_opers(l, operlist)
if match:
return match
raise Exception("parse error: %s" % [l])
def schemify(ast):
if car(ast) == 'BINARY':
return "(%s %s %s)" % (ast[1], schemify(ast[2]), schemify(ast[3]))
elif car(ast) == 'NOT':
return "(~ %s)" % schemify(ast[1])
elif car(ast) == 'ATOM':
return "%s" % ast[1][1]
else:
raise Exception("schemify: bad type: %s" % ast)
def test_parse():
"""
()
~~1
"""
def tokenize(s):
s = s.strip()
if not s or len(s) is 0:
return []
if car(s) in ['t', 'i']:
# accept i, but tokenize as t
return cons('t', tokenize(cdr(s)))
if car(s) in raw_opers or car(s) in ['(', ')']:
return cons(car(s), tokenize(cdr(s)))
if len(s) >= 2 and s[:2] == '>>':
return cons('r', tokenize(s[2:]))
if len(s) >= 2 and s[:2] == '<<':
return cons('l', tokenize(s[2:]))
if len(s) >= 3 and s[:2] == "0x" and s[2] in hexchr:
num = s[:3]
for c in s[3:]:
if c in hexchr:
num += c
else:
break
return cons(int(num, 16), tokenize(s[len(num):]))
if car(s).isdigit():
num = car(s)
for c in s[1:]:
if c.isdigit():
num += c
else:
break
return cons(int(num), tokenize(s[len(num):]))
# default
raise Exception("tokenization error: %s" % s)
def execute(ast, t):
if car(ast) == 'ATOM':
if car(ast[1]) == 'VAR':
return t
if car(ast[1]) == 'NUM':
return ast[1][1]
elif car(ast) == 'NOT':
return ~ execute(ast[1], t)
elif car(ast) == 'BINARY':
# UGH
oper, left, right = ast[1:4]
left = execute(ast[2], t)
right = execute(ast[3], t)
if oper == '+':
return left + right
elif oper == '-':
return left - right
elif oper == '*':
return left * right
elif oper == '/':
return left / right
elif oper == '%':
return left % right
elif oper == 'r':
return left >> right
elif oper == 'l':
return left << right
elif oper == '|':
return left | right
elif oper == '^':
return left ^ right
elif oper == '&':
return left & right
raise Exception("execute: unexpected node: %s" % car(ast))
# ==============================
def test_tokenize():
assert tokenize("(t>>4)") == ['(','t','r',4,')']
assert tokenize("t") == ['t']
assert tokenize("i") == ['t']
assert tokenize("tt123i") == ['t','t',123,'t']
assert tokenize("12345") == [12345]
assert tokenize("0xF") == [15]
assert tokenize("<<") == ['l']
assert tokenize(">>") == ['r']
assert tokenize("~") == ['~']
assert tokenize("444 444") == [444,444]
assert tokenize("t*(((t>>12)|(t>>8))&(63&(t>>4)))") == \
['t','*','(','(','(','t','r',12,')','|','(','t','r',8,')',')',
'&','(',63,'&','(','t','r',4,')',')',')']
try:
assert tokenize("1.0") is "TOKENIZE ERROR"
except:
pass
try:
assert tokenize("t,(") is "TOKENIZE ERROR"
except:
pass
try:
assert tokenize("0x") is "TOKENIZE ERROR"
except:
pass
try:
assert tokenize("1230x123") is "TOKENIZE ERROR"
except:
pass
try:
assert tokenize("x123") is "TOKENIZE ERROR"
except:
pass
|
