operator.py 文件源码

def __new__(cls, *args, **old_assumptions):
        from sympy.physics.quantum.state import KetBase, BraBase

        if len(args) != 2:
            raise ValueError('2 parameters expected, got %d' % len(args))

        ket_expr = expand(args[0])
        bra_expr = expand(args[1])

        if (isinstance(ket_expr, (KetBase, Mul)) and
                isinstance(bra_expr, (BraBase, Mul))):
            ket_c, kets = ket_expr.args_cnc()
            bra_c, bras = bra_expr.args_cnc()

            if len(kets) != 1 or not isinstance(kets[0], KetBase):
                raise TypeError('KetBase subclass expected'
                                ', got: %r' % Mul(*kets))

            if len(bras) != 1 or not isinstance(bras[0], BraBase):
                raise TypeError('BraBase subclass expected'
                                ', got: %r' % Mul(*bras))

            if not kets[0].dual_class() == bras[0].__class__:
                raise TypeError(
                    'ket and bra are not dual classes: %r, %r' %
                    (kets[0].__class__, bras[0].__class__)
                    )

            # TODO: make sure the hilbert spaces of the bra and ket are
            # compatible
            obj = Expr.__new__(cls, *(kets[0], bras[0]), **old_assumptions)
            obj.hilbert_space = kets[0].hilbert_space
            return Mul(*(ket_c + bra_c)) * obj

        op_terms = []
        if isinstance(ket_expr, Add) and isinstance(bra_expr, Add):
            for ket_term in ket_expr.args:
                for bra_term in bra_expr.args:
                    op_terms.append(OuterProduct(ket_term, bra_term,
                                                 **old_assumptions))
        elif isinstance(ket_expr, Add):
            for ket_term in ket_expr.args:
                op_terms.append(OuterProduct(ket_term, bra_expr,
                                             **old_assumptions))
        elif isinstance(bra_expr, Add):
            for bra_term in bra_expr.args:
                op_terms.append(OuterProduct(ket_expr, bra_term,
                                             **old_assumptions))
        else:
            raise TypeError(
                'Expected ket and bra expression, got: %r, %r' %
                (ket_expr, bra_expr)
                )

        return Add(*op_terms)