## Re: [xsl] How to compare two sequences, where order matters and length matters?

 Subject: Re: [xsl] How to compare two sequences, where order matters and length matters? From: "David Carlisle d.p.carlisle@xxxxxxxxx" Date: Tue, 21 Nov 2017 23:27:41 -0000
```deep-equal?

On 21 November 2017 at 17:21, Costello, Roger L. costello@xxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hi Folks,
>
> Consider this XML:
>
> <sequences>
>     <sequence/>
>     <sequence>
>         <item>A</item>
>     </sequence>
>     <sequence>
>         <item>B</item>
>     </sequence>
>     <sequence>
>         <item>A</item>
>         <item>A</item>
>     </sequence>
>     <sequence>
>         <item>A</item>
>         <item>B</item>
>     </sequence>
>     <sequence>
>         <item>B</item>
>         <item>A</item>
>     </sequence>
>     <sequence>
>         <item>B</item>
>         <item>B</item>
>     </sequence>
> </sequences>
>
> Suppose that \$item has this value:
>
>     <item>A</item>
>
> And suppose the root element, <sequences>, is the context node.
>
> Then, this evaluates to true (thanks David):
>
>     sequence[2] = (sequence[1], \$item)
>
> Unfortunately, this also evaluates to true:
>
>     sequence[4] = (sequence[1], \$item)
>
> sequence[4] is this:
>
>     <sequence>
>         <item>A</item>
>         <item>A</item>
>     </sequence>
>
> And this also evaluates to true:
>
>     sequence[5] = (sequence[1], \$item)
>
> sequence[5] is this:
>
>     <sequence>
>         <item>B</item>
>         <item>A</item>
>     </sequence>
>
> Eek!
>
> I don't want that. I only want these two sequences to match: sequence[2] and (sequence[1], \$item).
>
> For this comparison:
>
>     Blah/item *compare-operator* (Bar/item, \$item)
>
> It should only return true if:
>
> 1. The number of <item> elements are the same on the left and right side of compare-operator.
>
> 2. The value of item[1] of the left sequence equals the value of item[1] of the right sequence.
> The value of item[2] of the left sequence equals the value of item[2] of the right sequence.
> Etc.
>
> In other words, in the comparison the order of the items in the left and right sequences matters and the number of the items in the left and right sequences matter.
>
> What XPath expression will do such a comparison?
>
> Note: I'd like the XPath expression to *not* use a for-each loop.
>
> /Roger

```