python_source_visitors.py 文件源码

def visit_infix_expression(node, operators={}):
    def interleave(*iterables):
        for values in itertools.zip_longest(*iterables, fillvalue=UnboundLocalError):
            for index, value in enumerate(values):
                if value != UnboundLocalError:
                    yield index, value

    tokens = [
        visit_node(operand_or_operator)
        if index == 0
        else operators.get(operand_or_operator, operand_or_operator)
        for index, operand_or_operator in interleave(node['operands'], node['operators'])
        ]
    # Transform product expressions into a lazy "and" expression in order to prevent a division by 0:
    if node['type'] == 'product_expression':
        tokens = concatv(
            interpose(
                el='and',
                seq=map(visit_node, node['operands']),
                ),
            ['and'],
            tokens,
            )
    return '({})'.format(' '.join(map(str, tokens)))


# Main visitor