mirror of
https://github.com/bikini/patchwork
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bikini
43 lines
1.4 KiB
Python
43 lines
1.4 KiB
Python
from __future__ import annotations
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import ast
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import random
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class OpaquePredicateInjector(ast.NodeTransformer):
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def __init__(self, rng: random.Random, seed_name: str, prob: float=0.5):
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self.rng = rng
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self.seed_name = seed_name
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self.prob = prob
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self.injected = False
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def visit_If(self, node: ast.If) -> ast.AST:
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self.generic_visit(node)
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if self.rng.random() < self.prob:
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node.test = self._wrap(node.test)
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self.injected = True
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return node
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def visit_While(self, node: ast.While) -> ast.AST:
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self.generic_visit(node)
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if self.rng.random() < self.prob * 0.4:
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node.test = self._wrap(node.test)
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self.injected = True
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return node
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def _wrap(self, test: ast.expr) -> ast.expr:
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return ast.BoolOp(op=ast.And(), values=[test, self._tautology()])
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def _tautology(self) -> ast.expr:
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s = self.seed_name
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kind = self.rng.choice(('parity', 'flt3', 'flt5'))
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if kind == 'parity':
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src = f'({s} * ({s} + 1)) % 2 == 0'
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elif kind == 'flt3':
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src = f'({s} * {s} * {s} - {s}) % 3 == 0'
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else:
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src = f'({s} * {s} * {s} * {s} * {s} - {s}) % 5 == 0'
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return ast.parse(src, mode='eval').body
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def build_seed_stmt(seed_name: str) -> ast.stmt:
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return ast.parse(f'{seed_name} = id(int) & 0xFFFFFFFF').body[0]
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