add CompileWithNS

[tingstad]

Related to discussion in antchfx/xmlquery#15

This pull-request proposes a function;

func CompileWithNS(expr string, namespaces map[string]string) (*Expr, error)

as an alternative to

func Compile(expr string) (*Expr, error)

This allows for more readable xpath expressions without relying on prefix values. For example:

<tags>
    <a:tag xmlns:a="example.com/tag" />
    <b:tag xmlns:b="example.com/tag" />
</tags>

Using Compile("//a:tag") is not desirable because a: is not guaranteed to not change, and does not match b:. Namespaces in XML says:

Note that the prefix functions only as a placeholder for a namespace name. Applications SHOULD use the namespace name, not the prefix, in constructing names whose scope extends beyond the containing document.

A current workaround is Compile("//*[local-name()='tag' and namespace-uri()='example.com/tag']") which quickly gets messy.

I propose CompileWithNS("//e:tag", map[string]string{"e": "example.com/tag"}) which scales better since namespace bindings can be reused.

[tingstad]

@zhengchun What are the chances of this PR, or something similar, making its way to master/release? And, if so, in what time frame? Thanks.

[zhengchun]

Sorry for late, merged, thanks.

A few days ago I was thinking if there was a way to return the all namespaceURL with it's prefix name on xmlquery package, let user to write a prefix xpath without namespace map.

[tingstad]

Awesome, @zhengchun! Do you know when the next release will be out?

[zhengchun]

Released v1.2.4 Richard H. Tingstad ***@***.***> 于 2023年2月15日周三 下午6:59写道：

…

Awesome, @zhengchun <https://github.com/zhengchun>! Do you know when the next release will be out? — Reply to this email directly, view it on GitHub <#82 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABG4O4DJQKXP44UN4JGY7QLWXSZK5ANCNFSM6AAAAAAUQHLRL4> . You are receiving this because you were mentioned.Message ID: ***@***.***>