Question

使用PyYAML将包含值YES，NO的字典转储到YAML时，YES / NO被引用为'YES'或'NO'。如何在没有报价的情况下获得YES或NO？

Answer 1

如果您要将YES / yes / Yes和NO / no / No转储为非引用的标量，必须制作一个解析器（该代码由PyYAML转储器和PyYAML加载器使用），与my answer here类似，阻止从YAML加载这些值作为布尔值。

import re
import yaml as yaml
from yaml.resolver import BaseResolver, Resolver
from yaml.emitter import Emitter
from yaml.serializer import Serializer
from yaml.representer import Representer as Repr


class MyResolver(BaseResolver):
    pass

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:bool',
    re.compile(u'''^(?:true|True|TRUE|false|False|FALSE)$''', re.X),
    list(u'tTfF'))

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:float',
    re.compile(u'''^(?:
     [-+]?(?:[0-9][0-9_]*)\\.[0-9_]*(?:[eE][-+]?[0-9]+)?
    |[-+]?(?:[0-9][0-9_]*)(?:[eE][-+]?[0-9]+)
    |\\.[0-9_]+(?:[eE][-+][0-9]+)?
    |[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]*
    |[-+]?\\.(?:inf|Inf|INF)
    |\\.(?:nan|NaN|NAN))$''', re.X),
    list(u'-+0123456789.'))

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:int',
    re.compile(u'''^(?:[-+]?0b[0-1_]+
    |[-+]?[0-9]+
    |[-+]?0o?[0-7_]+
    |[-+]?(?:0|[1-9][0-9_]*)
    |[-+]?0x[0-9a-fA-F_]+
    |[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$''', re.X),
    list(u'-+0123456789'))

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:merge',
    re.compile(u'^(?:<<)$'),
    [u'<'])

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:null',
    re.compile(u'''^(?: ~
    |null|Null|NULL
    | )$''', re.X),
    [u'~', u'n', u'N', u''])

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:timestamp',
    re.compile(u'''^(?:[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]
    |[0-9][0-9][0-9][0-9] -[0-9][0-9]? -[0-9][0-9]?
    (?:[Tt]|[ \\t]+)[0-9][0-9]?
    :[0-9][0-9] :[0-9][0-9] (?:\\.[0-9]*)?
    (?:[ \\t]*(?:Z|[-+][0-9][0-9]?(?::[0-9][0-9])?))?)$''', re.X),
    list(u'0123456789'))

MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:value',
    re.compile(u'^(?:=)$'),
    [u'='])

# The following resolver is only for documentation purposes. It cannot work
# because plain scalars cannot start with '!', '&', or '*'.
MyResolver.add_implicit_resolver(
    u'tag:yaml.org,2002:yaml',
    re.compile(u'^(?:!|&|\\*)$'),
    list(u'!&*'))


class MySafeDumper(Emitter, Serializer, Repr, MyResolver):
    def __init__(self, stream,
                 default_style=None, default_flow_style=None,
                 canonical=None, indent=None, width=None,
                 allow_unicode=None, line_break=None,
                 encoding=None, explicit_start=None, explicit_end=None,
                 version=None, tags=None):
        Emitter.__init__(self, stream, canonical=canonical,
                         indent=indent, width=width,
                         allow_unicode=allow_unicode, line_break=line_break)
        Serializer.__init__(self, encoding=encoding,
                            explicit_start=explicit_start,
                            explicit_end=explicit_end,
                            version=version, tags=tags)
        Repr.__init__(self, default_style=default_style,
                                 default_flow_style=default_flow_style)
        MyResolver.__init__(self)

print(yaml.dump(dict(sampe='Yes'), Dumper=MySafeDumper))

这给出了：

{sampe: Yes}

正如您在评论中指出的那样。如果您希望能够将其作为字符串加载，则应使用上面链接的答案中的构造函数代码，两个答案的解析器部分相同。

是或否在PyYAML中倾倒为'是'或'否'

1 个答案: