xdmp：電子郵件過濾掉的電子郵件地址，沒有通過謂詞

Question

比方說，我有一個謂語：

declare function local:should-send-email($email-address) { 
    ... fn:true() ... 
    ... fn:false() ... 
}; 

然後，我對使用一個電子郵件元素與xdmp:email：

<em:Message 
xmlns:em="URN:ietf:params:email-xml:" 
xmlns:rf="URN:ietf:params:rfc822:"> 
    <rf:subject>Test</rf:subject> 
    <rf:from> 
    <em:Address> 
     <em:name>Test Name</em:name> 
     <em:adrs>test-from@test000.com</em:adrs> 
    </em:Address> 
    </rf:from> 
    <rf:to> 
    <em:Address> 
     <em:name>Test Name</em:name> 
     <em:adrs>test-to-1@test000.com</em:adrs> 
    </em:Address> 
    <em:Address> 
     <em:name>Test Name</em:name> 
     <em:adrs>test-to-2@test000.com</em:adrs> 
    </em:Address> 
    </rf:to> 
    <em:content>Hello World</em:content> 
</em:Message> 

可以說，其中一個地址通過謂詞，一個不會。什麼是一個有效的方式來刪除em：地址元素爲不通過的？

Answer 1

假定你打算開始與完整<em:Message>元素，你可以使用遞歸typeswitch過濾掉無效的電子郵件地址 - 邏輯非常相似，XSLT：

declare function local:filter-addresses(
    $node as node() 
) as item()* 
{ 
    typeswitch ($node) 
    case element(em:Address) return 
    if (not(local:should-send-email($node/em:adrs))) 
    then() (: Filter :) 
    else $node 
    case element() return (: Passthrough :) 
    element { node-name($node) } { 
     $node/@*, 
     for $child in $node/node() 
     return local:filter-addresses($child) 
    } 
    default return $node 
};