解析 YAML，即使在有序映射中也能获取行号

我需要获取 YAML 文件中某些键的行号。

请注意，这个答案没有解决问题：我确实使用鲁梅尔.yaml，并且答案不适用于有序地图。

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from ruamel import yaml

data = yaml.round_trip_load("""
key1: !!omap
  - key2: item2
  - key3: item3
  - key4: !!omap
    - key5: item5
    - key6: item6
""")

print(data)

结果我得到这个：

CommentedMap([('key1', CommentedOrderedMap([('key2', 'item2'), ('key3', 'item3'), ('key4', CommentedOrderedMap([('key5', 'item5'), ('key6', 'item6')]))]))])

什么不允许访问行号，除了!!omap keys:

print(data['key1'].lc.line)  # output: 1
print(data['key1']['key4'].lc.line)  # output: 4

but:

print(data['key1']['key2'].lc.line)  # output: AttributeError: 'str' object has no attribute 'lc'

Indeed, data['key1']['key2] is a str.

我找到了一个解决方法：

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from ruamel import yaml

DATA = yaml.round_trip_load("""
key1: !!omap
  - key2: item2
  - key3: item3
  - key4: !!omap
    - key5: item5
    - key6: item6
""")


def get_line_nb(data):
    if isinstance(data, dict):
        offset = data.lc.line
        for i, key in enumerate(data):
            if isinstance(data[key], dict):
                get_line_nb(data[key])
            else:
                print('{}|{} found in line {}\n'
                      .format(key, data[key], offset + i + 1))


get_line_nb(DATA)

output:

key2|item2 found in line 2

key3|item3 found in line 3

key5|item5 found in line 5

key6|item6 found in line 6

但这看起来有点“脏”。有更合适的方法吗？

编辑：这种解决方法不仅脏，而且只适用于像上面这样的简单情况，并且一旦存在嵌套列表就会给出错误的结果

这个问题不是你使用的!omap并且它不会像“正常”映射那样为您提供行号。从你从做得到 4 的事实中应该可以清楚地看出这一点print(data['key1']['key4'].lc.line) (where key4是一把钥匙在外面!omap).

As this答案表明，

您可以访问收藏品的财产信用证

的价值data['key1']['key4']是一个收藏品（另一个!omap），但值data['key1']['key2']不是一个集合项，而是一个内置的 python 字符串，它没有槽来存储lc属性。

为了得到一个.lc非集合上的属性（例如字符串）您必须对其进行子类化RoundTripConstructor，使用类似中的类scalarstring.py (with __slots__调整以接受lc属性，然后将节点中可用的行信息传递给该属性，然后设置行、列信息：

import sys
import ruamel.yaml

yaml_str = """
key1: !!omap
  - key2: item2
  - key3: item3
  - key4: !!omap
    - key5: 'item5'
    - key6: |
        item6
"""

class Str(ruamel.yaml.scalarstring.ScalarString):
    __slots__ = ('lc')

    style = ""

    def __new__(cls, value):
        return ruamel.yaml.scalarstring.ScalarString.__new__(cls, value)

class MyPreservedScalarString(ruamel.yaml.scalarstring.PreservedScalarString):
    __slots__ = ('lc')

class MyDoubleQuotedScalarString(ruamel.yaml.scalarstring.DoubleQuotedScalarString):
    __slots__ = ('lc')

class MySingleQuotedScalarString(ruamel.yaml.scalarstring.SingleQuotedScalarString):
    __slots__ = ('lc')

class MyConstructor(ruamel.yaml.constructor.RoundTripConstructor):
    def construct_scalar(self, node):
        # type: (Any) -> Any
        if not isinstance(node, ruamel.yaml.nodes.ScalarNode):
            raise ruamel.yaml.constructor.ConstructorError(
                None, None,
                "expected a scalar node, but found %s" % node.id,
                node.start_mark)

        if node.style == '|' and isinstance(node.value, ruamel.yaml.compat.text_type):
            ret_val = MyPreservedScalarString(node.value)
        elif bool(self._preserve_quotes) and isinstance(node.value, ruamel.yaml.compat.text_type):
            if node.style == "'":
                ret_val = MySingleQuotedScalarString(node.value)
            elif node.style == '"':
                ret_val = MyDoubleQuotedScalarString(node.value)
            else:
                ret_val = Str(node.value)
        else:
            ret_val = Str(node.value)
        ret_val.lc = ruamel.yaml.comments.LineCol()
        ret_val.lc.line = node.start_mark.line
        ret_val.lc.col = node.start_mark.column
        return ret_val


yaml = ruamel.yaml.YAML()
yaml.Constructor = MyConstructor

data = yaml.load(yaml_str)
print(data['key1']['key4'].lc.line)
print(data['key1']['key2'].lc.line)
print(data['key1']['key4']['key6'].lc.line)

请注意最后一次调用的输出print是 6，因为文字标量字符串以|.

如果你也想转储data，你需要做一个Representer意识到那些My.... types.