The choiceDirectDispatchKey is a DFDL expression. In order to return a
string value from an expression, you need to wrap it in quotes,
otherwise it looks like a path. For example, in this expression:
{ rounded }
There are no quotes, so it looks like a path, and so will return the
value of the infoset element with name "rounded". On the otherhand, when
there are quotes like this expression:
{ 'rounded' }
That will returns the literal string "rounded", but without the quotes.
So when we compare the value against choice branch key, were compare
against the string value without quotes.
On 6/7/19 11:35 AM, Costello, Roger L. wrote:
> Steve wrote:
>
> 2) Have a more complex dispatch expression, something like:
>
> dfdl:choiceDispatchKey="{
>
> if (./num eq 1) then 'rounded'
>
> else if (./num eq 2) then 'square'
>
> else 'none' }"
>
> And change your choiceBranchKeys to "rounded", "square", and "none".
>
> Wow!
>
> I really like that solution.
>
> I implemented it and it works great. But it raises a question. Here is the
> DFDL
> schema:
>
> <xs:elementname="input">
> <xs:complexType>
> <xs:sequencedfdl:separator="%NL;"dfdl:separatorPosition="infix">
> <xs:elementname="num"type="xs:integer"/>
> <xs:choicedfdl:choiceDispatchKey="{ if (./num eq 1) then 'rounded' else if
> (./num eq 2) then 'square' else 'none' }">
> <xs:elementname="A"type="xs:string"
> dfdl:initiator="("dfdl:terminator=")"
> dfdl:choiceBranchKey="rounded"/>
> <xs:elementname="B"type="xs:string"
> dfdl:initiator="["dfdl:terminator="]"
> dfdl:choiceBranchKey="square"/>
> <xs:elementname="C"type="xs:string"
> dfdl:initiator="%WSP*;"dfdl:terminator="%NL;"
> dfdl:choiceBranchKey="none"/>
> </xs:choice>
> </xs:sequence>
> </xs:complexType>
> </xs:element>
>
> Notice that there are quotes around round, square, and none in the expression
> for dfdl:choiceDispatchKey but there are no quotes around them in
> dfdl:choiceBranchKey. I initially did this:
>
> dfdl:choiceBranchKey=" 'rounded' "
>
> Notice the single quotes within the double quotes. That resulted in an error.
>
> Why don’t I need those single quotes to indicate that we are matching to a
> _/string/_?
>
> /Roger
>
> -----Original Message-----
> From: Steve Lawrence <[email protected]>
> Sent: Friday, June 7, 2019 10:47 AM
> To: [email protected]
> Subject: [EXT] Re: A choiceBranchKey that specifies multiple value?
>
> A few ways to handle this:
>
> 1) Daffodil has an extension to allow a space separated list of
> choiceBranchKeys, so if you know all the keys for the third branch you can do
> this:
>
> dfdl:choiceBranchKey="3 4 5 6"
>
> But if you need it to be portable to other DFDL implementations (e.g.
>
> IBM), or if you need something more generic (e.g. all nums greater than
>
> 3 should have no parents) then you need to go a different route.
>
> 2) Have a more complex dispatch expression, something like:
>
> dfdl:choiceDispatchKey="{
>
> if (./num eq 1) then 'rounded'
>
> else if (./num eq 2) then 'square'
>
> else 'none' }"
>
> And change your choiceBranchKeys to "rounded", "square", and "none".
>
> This works well if there aren't too many different keys/branches, but if
> there
> are, then the if else expression can get pretty complicated, so we sometimes
> use
> the next alternative.
>
> 3) Nested choices act sort of like a default if the dispatch doesn't match
> anything:
>
> <xs:choice>
>
> <xs:choice dfdl:choiceDispatchKey="{ ./num }">
>
> <xs:element name="A" dfdl:choiceBranchKey="1" ... />
>
> <xs:element name="B" dfdl:choiceBranchKey="2" ... />
>
> </xs:choice>
>
> <xs:element name="C" ... />
>
> </xs:choice>
>
> So we first try the first branch of the outer choice, which is a choice
> dispatch. If the dispatch key doesn't match any of the branch keys, then we
> try
> the second branch of the outer choice. Which in this case is our element C
> with
> no parens.
>
> On 6/7/19 10:28 AM, Costello, Roger L. wrote:
>
> > Hello DFDL community,
>
> >
>
> > My input file has a number (num), followed by a comma-separated pair
>
> > of values, enclosed within either round parentheses, square parentheses,
> or
> no parentheses.
>
> >
>
> > * If num=1 then the initiator and terminator are rounded parentheses.
>
> > * If num=2 then the initiator and terminator are square parentheses.
>
> > * If num=3, 4, 5, … then there is no parentheses.
>
> >
>
> > The below DFDL schema works for num=1, num=2, and num=3. But it is
>
> > silent on other values of num (4, 5, …). Is there a way to have a
>
> > choiceBranchKey for multiple values, e.g.,
>
> >
>
> > dfdl:choiceBranchKey="3…infinity"
>
> >
>
> > <xs:element name="input">
>
> > <xs:complexType>
>
> > <xs:sequence dfdl:separator="%NL;" dfdl:separatorPosition="infix">
>
> > <xs:element name="num" type="xs:integer" />
>
> > <xs:choice dfdl:choiceDispatchKey="{ ./num }">
>
> > <xs:element name="A" type="xs:string"
>
> > dfdl:initiator="(" dfdl:terminator=")"
>
> > dfdl:choiceBranchKey="1" />
>
> > <xs:element name="B" type="xs:string"
>
> > dfdl:initiator="[" dfdl:terminator="]"
>
> > dfdl:choiceBranchKey="2" />
>
> > <xs:element name="C" type="xs:string"
>
> > dfdl:initiator="%WSP*;"
> dfdl:terminator="%NL;"
>
> > dfdl:choiceBranchKey="3" />
>
> > </xs:choice>
>
> > </xs:sequence>
>
> > </xs:complexType>
>
> > </xs:element>
>
> >
>
