sympy_parser.py 文件源码

def visit_BinOp(self, node):
        if node.op.__class__ in self.operators:
            sympy_class = self.operators[node.op.__class__]
            right = self.visit(node.right)
            left = self.visit(node.left)
            if isinstance(node.left, ast.UnaryOp) and (isinstance(node.right, ast.UnaryOp) == 0) and sympy_class in ('Mul',):
                left, right = right, left
            if isinstance(node.op, ast.Sub):
                right = ast.UnaryOp(op=ast.USub(), operand=right)
            if isinstance(node.op, ast.Div):
                if isinstance(node.left, ast.UnaryOp):
                    if isinstance(node.right,ast.UnaryOp):
                        left, right = right, left
                    left = ast.Call(
                    func=ast.Name(id='Pow', ctx=ast.Load()),
                    args=[left, ast.UnaryOp(op=ast.USub(), operand=ast.Num(1))],
                    keywords=[ast.keyword(arg='evaluate', value=ast.Name(id='False', ctx=ast.Load()))],
                    starargs=None,
                    kwargs=None
                )
                else:
                    right = ast.Call(
                    func=ast.Name(id='Pow', ctx=ast.Load()),
                    args=[right, ast.UnaryOp(op=ast.USub(), operand=ast.Num(1))],
                    keywords=[ast.keyword(arg='evaluate', value=ast.Name(id='False', ctx=ast.Load()))],
                    starargs=None,
                    kwargs=None
                )

            new_node = ast.Call(
                func=ast.Name(id=sympy_class, ctx=ast.Load()),
                args=[left, right],
                keywords=[ast.keyword(arg='evaluate', value=ast.Name(id='False', ctx=ast.Load()))],
                starargs=None,
                kwargs=None
            )

            if sympy_class in ('Add', 'Mul'):
                # Denest Add or Mul as appropriate
                new_node.args = self.flatten(new_node.args, sympy_class)

            return new_node
        return node