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

["Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

The deep-equal() function MIGHT meet your requirement. But your requirement
isn't described in enough detail to be sure (you've only specified it by
showing examples of some operands that are equal and some that aren't). For a
full specification you need to say how to handle comments, whitespace,
in-scope namespaces, base URI, schema type annotations, etc etc etc.

Michael Kay
Saxonica

> On 21 Nov 2017, at 23:21, 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