XML模式；有效属性值列表中的倍数 [英] XML schema; multiple from a list of valid attribute values

问题描述

我刚开始使用XML模式，因此，如果这比我本人认为的琐碎小事，请原谅我的无能.

I'm reasonably new to working with XML schemas, so excuse my incompetence if this is more trivial than I myself believe it must be.

我正在尝试创建一个必需属性，该属性必须包含列表中的1个或多个用空格分隔的字符串值.该列表是4种典型的HTTP请求方法. get，post，put和delete.

I'm trying to create a required attribute that must contain 1 or more white-space-separated string values from a list. The list is the 4 typical HTTP request methods; get, post, put, and delete.

因此有效的元素应包括:

So valid elements would include:

<rule methods="get" />
<rule methods="get post" />
<rule methods="post put delete" />

无效元素包括:

<rule methods="get get" />
<rule methods="foobar post" />
<rule methods="get;post;put" />

我尝试用枚举和长度愚弄，但是我不相信我正在理解我需要做的事情(或实际上是否可行，尽管看起来似乎应该这样做是)

I've tried fooling with enumerations and length, but I don't believe I'm understanding what I need to do (or for that matter if it is in fact possible, though it seems as though it should be)

这是我现在的位置，这要感谢@tdrury:

This is where I'm at now, thanks to @tdrury:

<xs:attribute name="methods" use="required">
    <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:whiteSpace value="collapse" />
            <xs:pattern value="(?:(?:get|post|put|delete)\s?){1,4}" />
        </xs:restriction>
    </xs:simpleType>
</xs:attribute>

除了重复(，例如get get或post post post )和缺少空白(，例如getpost或postputdelete )以外，其他方法都可以使用

Which works, except for repetition (such as get get or post post post) and absent whitespace (such as getpost or postputdelete)

修改:

玩了一点之后，我想到了一个主意:对所有可能的序列进行枚举.幸运的是，此列表(暂时)固定为四种常见的传输方法，分别是get，post，put和delete，因此我想出了:

After playing around with this a bit, I came up with an idea: an enumeration of all possible sequences. Thankfully, this list is (for the time being) fixed to the four usual transport methods, get, post, put, and delete, so I figured:

<xs:restriction base="xs:string">
    <xs:whiteSpace value="collapse" />
    <xs:enumeration value="delete" />
    <xs:enumeration value="put" />
    <xs:enumeration value="put delete" />
    <xs:enumeration value="post" />
    <xs:enumeration value="post delete" />
    <xs:enumeration value="post put" />
    <xs:enumeration value="post put delete" />
    <xs:enumeration value="get" />
    <xs:enumeration value="get delete" />
    <xs:enumeration value="get put" />
    <xs:enumeration value="get put delete" />
    <xs:enumeration value="get post" />
    <xs:enumeration value="get post delete" />
    <xs:enumeration value="get post put" />
    <xs:enumeration value="get post put delete" />
</xs:restriction>

有人能看到一个不是是个好主意的原因吗?

Can anyone see a reason that this would not be a good idea?

推荐答案

定期解决这个问题之后，我想到了这种模式. PCRE漂亮印刷中的第一个:

After periodically screwing around with this, I came up with this hulk of a pattern; first in PCRE pretty-print:

^
(
  (get     (\s post)?    (\s put)?     (\s delete)?  (\s head)?    (\s options)?)
| (post    (\s put)?     (\s delete)?  (\s head)?    (\s options)?)
| (put     (\s delete)?  (\s head)?    (\s options)?)
| (delete  (\s head)?    (\s options)?)
| (head    (\s options)?)
| (options)
)
$

与XML兼容:

((get(\spost)?(\sput)?(\sdelete)?(\shead)?(\soptions)?)|(post(\sput)?(\sdelete)?(\shead)?(\soptions)?)|(put(\sdelete)?(\shead)?(\soptions)?)|(delete(\shead)?(\soptions)?)|(head(\soptions)?)|(options))

这将成功匹配get post put delete head和options的任何排列，进一步要求它们正确排序(也很不错 )

This will successfully match any permutation of get post put delete head and options, further requiring that they be correctly ordered (which is kinda nice too)

无论如何，总结:

"get post put delete head options" // match

"get put delete options"           // match

"get get post put"                 // fail; double get

"get foo post put"                 // fail; invalid token, foo

"post delete"                      // match

"options get"                      // fail; ordering

由于每个组都需要包含每个新的令牌"，因此该模式的使用范围不是最大，但是鉴于问题域是HTTP方法，因此无法预见的变化，我认为它应该可以正常工作.

This pattern doesn't scale the greatest, as each new "token" needs to be included in every group, but given the problem domain is HTTP methods, change is unforeseeable and I figure it should work just fine.

此外，这是一个用于生成模式的快速脚本(PHP):

Also, here's a quick script (PHP) to generate the pattern:

$tokens = ['get', 'post', 'put', 'delete', 'head', 'options'];

echo implode('|', array_map(function ($token) use (&$tokens) {
    return sprintf('(%s%s)', array_shift($tokens),
        implode(null, array_map(function ($token) {
            return sprintf('(\s%s)?', $token);
        }, $tokens)));
}, $tokens));

它省略了最外面的()，因为我认为这不是必需的.

It omits the outermost () because I don't think it's necessary.

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