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https://github.com/Mikaela/Limnoria.git
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Math: Rewrite calc functions with a proper evaluator.
Instead of hacking around eval(), which everyone knows is a bad idea even with prior expression sanitizing.
This commit is contained in:
Valentin Lorentz
parent
5e2343f717
commit
3848ae78de
169
plugins/Math/evaluator.py
Normal file
169
plugins/Math/evaluator.py
Normal file
@ -0,0 +1,169 @@
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###
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# Copyright (c) 2019, Valentin Lorentz
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions, and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions, and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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# * Neither the name of the author of this software nor the name of
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# contributors to this software may be used to endorse or promote products
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# derived from this software without specific prior written consent.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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###
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import ast
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import math
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import cmath
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import operator
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class InvalidNode(Exception):
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pass
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def filter_module(module, safe_names):
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return dict([
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(name, getattr(module, name))
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for name in safe_names
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if hasattr(module, name)
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])
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UNARY_OPS = {
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ast.UAdd: lambda x: x,
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ast.USub: lambda x: -x,
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}
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BIN_OPS = {
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ast.Add: operator.add,
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ast.Sub: operator.sub,
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ast.Mult: operator.mul,
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ast.Div: operator.truediv,
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ast.Pow: operator.pow,
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ast.BitXor: operator.xor,
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ast.BitOr: operator.or_,
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ast.BitAnd: operator.and_,
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}
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MATH_CONSTANTS = 'e inf nan pi tau'.split()
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SAFE_MATH_FUNCTIONS = (
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'acos acosh asin asinh atan atan2 atanh copysign cos cosh degrees erf '
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'erfc exp expm1 fabs fmod frexp fsum gamma hypot ldexp lgamma log log10 '
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'log1p log2 modf pow radians remainder sin sinh tan tanh'
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).split()
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SAFE_CMATH_FUNCTIONS = (
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'acos acosh asin asinh atan atanh cos cosh exp inf infj log log10 '
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'nanj phase polar rect sin sinh tan tanh tau'
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).split()
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SAFE_ENV = filter_module(math, MATH_CONSTANTS + SAFE_MATH_FUNCTIONS)
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SAFE_ENV.update(filter_module(cmath, SAFE_CMATH_FUNCTIONS))
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def _sqrt(x):
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if isinstance(x, complex) or x < 0:
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return cmath.sqrt(x)
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else:
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return math.sqrt(x)
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def _cbrt(x):
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return math.pow(x, 1.0/3)
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def _factorial(x):
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if x<=10000:
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return float(math.factorial(x))
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else:
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raise Exception('factorial argument too large')
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SAFE_ENV.update({
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'i': 1j,
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'abs': abs,
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'max': max,
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'min': min,
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'round': lambda x, y=0: round(x, int(y)),
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'factorial': _factorial,
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'sqrt': _sqrt,
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'cbrt': _cbrt,
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'ceil': lambda x: float(math.ceil(x)),
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'floor': lambda x: float(math.floor(x)),
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})
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UNSAFE_ENV = SAFE_ENV.copy()
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# Add functions that return integers
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UNSAFE_ENV.update(filter_module(math, 'ceil floor factorial gcd'.split()))
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# It would be nice if ast.literal_eval used a visitor so we could subclass
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# to extend it, but it doesn't, so let's reimplement it entirely.
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class SafeEvalVisitor(ast.NodeVisitor):
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def __init__(self, allow_ints):
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self._allow_ints = allow_ints
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self._env = UNSAFE_ENV if allow_ints else SAFE_ENV
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def _convert_num(self, x):
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"""Converts numbers to complex if ints are not allowed."""
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if self._allow_ints:
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return x
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else:
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x = complex(x)
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if x.imag == 0:
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x = x.real
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# Need to use string-formatting here instead of str() because
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# use of str() on large numbers loses information:
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# str(float(33333333333333)) => '3.33333333333e+13'
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# float('3.33333333333e+13') => 33333333333300.0
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return float('%.16f' % x)
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else:
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return x
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def visit_Expression(self, node):
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return self.visit(node.body)
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def visit_Num(self, node):
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return self._convert_num(node.n)
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def visit_Name(self, node):
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id_ = node.id.lower()
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if id_ in self._env:
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return self._env[id_]
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else:
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raise NameError(node.id)
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def visit_Call(self, node):
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func = self.visit(node.func)
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args = map(self.visit, node.args)
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# TODO: keywords?
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return func(*args)
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def visit_UnaryOp(self, node):
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op = UNARY_OPS.get(node.op.__class__)
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if op:
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return op(self.visit(node.operand))
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else:
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raise InvalidNode('illegal operator %s' % node.op.__class__.__name__)
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def visit_BinOp(self, node):
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op = BIN_OPS.get(node.op.__class__)
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if op:
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return op(self.visit(node.left), self.visit(node.right))
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else:
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raise InvalidNode('illegal operator %s' % node.op.__class__.__name__)
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def generic_visit(self, node):
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raise InvalidNode('illegal construct %s' % node.__class__.__name__)
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def safe_eval(text, allow_ints):
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node = ast.parse(text, mode='eval')
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return SafeEvalVisitor(allow_ints).visit(node)
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@ -44,6 +44,7 @@ from supybot.i18n import PluginInternationalization, internationalizeDocstring
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_ = PluginInternationalization('Math')
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from .local import convertcore
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from .evaluator import safe_eval, InvalidNode, SAFE_ENV
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baseArg = ('int', 'base', lambda i: i <= 36)
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@ -97,36 +98,6 @@ class Math(callbacks.Plugin):
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return str(number)
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return self._convertDecimalToBase(number, toBase)
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_mathEnv = {'__builtins__': types.ModuleType('__builtins__'), 'i': 1j}
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_mathEnv.update(math.__dict__)
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_mathEnv.update(cmath.__dict__)
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def _sqrt(x):
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if isinstance(x, complex) or x < 0:
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return cmath.sqrt(x)
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else:
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return math.sqrt(x)
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def _cbrt(x):
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return math.pow(x, 1.0/3)
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def _factorial(x):
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if x<=10000:
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return float(math.factorial(x))
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else:
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raise Exception('factorial argument too large')
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_mathEnv['sqrt'] = _sqrt
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_mathEnv['cbrt'] = _cbrt
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_mathEnv['abs'] = abs
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_mathEnv['max'] = max
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_mathEnv['min'] = min
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_mathEnv['round'] = lambda x, y=0: round(x, int(y))
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_mathSafeEnv = dict([(x,y) for x,y in _mathEnv.items()])
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_mathSafeEnv['factorial'] = _factorial
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_mathRe = re.compile(r'((?:(?<![A-Fa-f\d)])-)?'
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r'(?:0x[A-Fa-f\d]+|'
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r'0[0-7]+|'
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r'\d+\.\d+|'
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r'\.\d+|'
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r'\d+\.|'
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r'\d+))')
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def _floatToString(self, x):
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if -1e-10 < x < 1e-10:
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return '0'
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@ -157,17 +128,6 @@ class Math(callbacks.Plugin):
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else:
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return '%s%s' % (realS, imagS)
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_calc_match_forbidden_chars = re.compile('[_\[\]]')
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_calc_remover = utils.str.MultipleRemover('_[] \t')
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###
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# So this is how the 'calc' command works:
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# First, we make a nice little safe environment for evaluation; basically,
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# the names in the 'math' and 'cmath' modules. Then, we remove the ability
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# of a random user to get ints evaluated: this means we have to turn all
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# int literals (even octal numbers and hexadecimal numbers) into floats.
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# Then we delete all square brackets, underscores, and whitespace, so no
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# one can do list comprehensions or call __...__ functions.
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###
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@internationalizeDocstring
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def calc(self, irc, msg, args, text):
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"""<math expression>
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@ -178,57 +138,17 @@ class Math(callbacks.Plugin):
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crash to the bot with something like '10**10**10**10'. One consequence
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is that large values such as '10**24' might not be exact.
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"""
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try:
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text = str(text)
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except UnicodeEncodeError:
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irc.error(_("There's no reason you should have fancy non-ASCII "
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"characters in your mathematical expression. "
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"Please remove them."))
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return
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if self._calc_match_forbidden_chars.match(text):
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# Note: this is important to keep this to forbid usage of
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# __builtins__
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irc.error(_('There\'s really no reason why you should have '
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'underscores or brackets in your mathematical '
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'expression. Please remove them.'))
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return
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text = self._calc_remover(text)
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if 'lambda' in text:
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irc.error(_('You can\'t use lambda in this command.'))
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return
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text = text.lower()
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def handleMatch(m):
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s = m.group(1)
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if s.startswith('0x'):
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i = int(s, 16)
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elif s.startswith('0') and '.' not in s:
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try:
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i = int(s, 8)
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except ValueError:
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i = int(s)
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else:
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i = float(s)
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x = complex(i)
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if x.imag == 0:
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x = x.real
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# Need to use string-formatting here instead of str() because
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# use of str() on large numbers loses information:
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# str(float(33333333333333)) => '3.33333333333e+13'
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# float('3.33333333333e+13') => 33333333333300.0
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return '%.16f' % x
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return str(x)
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text = self._mathRe.sub(handleMatch, text)
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try:
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self.log.info('evaluating %q from %s', text, msg.prefix)
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x = complex(eval(text, self._mathSafeEnv, self._mathSafeEnv))
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x = complex(safe_eval(text, allow_ints=False))
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irc.reply(self._complexToString(x))
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except OverflowError:
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maxFloat = math.ldexp(0.9999999999999999, 1024)
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irc.error(_('The answer exceeded %s or so.') % maxFloat)
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except TypeError:
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irc.error(_('Something in there wasn\'t a valid number.'))
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except InvalidNode as e:
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irc.error(_('Invalid syntax: %s') % e.args[0])
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except NameError as e:
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irc.error(_('%s is not a defined function.') % str(e).split()[1])
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irc.error(_('%s is not a defined function.') % e.args[0])
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except Exception as e:
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irc.error(str(e))
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calc = wrap(calc, ['text'])
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@ -241,28 +161,15 @@ class Math(callbacks.Plugin):
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math, and can thus cause the bot to suck up CPU. Hence it requires
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the 'trusted' capability to use.
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"""
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if self._calc_match_forbidden_chars.match(text):
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# Note: this is important to keep this to forbid usage of
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# __builtins__
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irc.error(_('There\'s really no reason why you should have '
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'underscores or brackets in your mathematical '
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'expression. Please remove them.'))
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return
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# This removes spaces, too, but we'll leave the removal of _[] for
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# safety's sake.
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text = self._calc_remover(text)
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if 'lambda' in text:
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irc.error(_('You can\'t use lambda in this command.'))
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return
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text = text.replace('lambda', '')
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try:
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self.log.info('evaluating %q from %s', text, msg.prefix)
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irc.reply(str(eval(text, self._mathEnv, self._mathEnv)))
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x = safe_eval(text, allow_ints=True)
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irc.reply(str(x))
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except OverflowError:
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maxFloat = math.ldexp(0.9999999999999999, 1024)
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irc.error(_('The answer exceeded %s or so.') % maxFloat)
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except TypeError:
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irc.error(_('Something in there wasn\'t a valid number.'))
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except InvalidNode as e:
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irc.error(_('Invalid syntax: %s') % e.args[0])
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except NameError as e:
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irc.error(_('%s is not a defined function.') % str(e).split()[1])
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except Exception as e:
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@ -286,8 +193,8 @@ class Math(callbacks.Plugin):
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x = abs(x)
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stack.append(x)
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except ValueError: # Not a float.
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if arg in self._mathSafeEnv:
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f = self._mathSafeEnv[arg]
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if arg in SAFE_ENV:
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f = SAFE_ENV[arg]
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if callable(f):
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called = False
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arguments = []
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@ -310,7 +217,7 @@ class Math(callbacks.Plugin):
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arg1 = stack.pop()
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s = '%s%s%s' % (arg1, arg, arg2)
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try:
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stack.append(eval(s, self._mathSafeEnv, self._mathSafeEnv))
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stack.append(safe_eval(s, allow_ints=False))
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except SyntaxError:
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irc.error(format(_('%q is not a defined function.'),
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arg))
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@ -91,9 +91,6 @@ class MathTestCase(PluginTestCase):
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self.assertError('base 4 4')
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self.assertError('base 10 12 A')
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print()
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print("If we have not fixed a bug with Math.base, the following ")
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print("tests will hang the test-suite.")
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self.assertRegexp('base 2 10 [base 10 2 -12]', '-12')
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self.assertRegexp('base 16 2 [base 2 16 -110101]', '-110101')
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@ -117,7 +114,10 @@ class MathTestCase(PluginTestCase):
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self.assertError('calc factorial(20000)')
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def testCalcNoNameError(self):
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self.assertNotRegexp('calc foobar(x)', 'NameError')
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self.assertRegexp('calc foobar(x)', 'foobar is not a defined function')
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def testCalcInvalidNode(self):
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self.assertRegexp('calc {"foo": "bar"}', 'Illegal construct Dict')
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def testCalcImaginary(self):
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self.assertResponse('calc 3 + sqrt(-1)', '3+i')
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