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:element name="input">
<xs:complexType>
<xs:sequence dfdl:separator="%NL;" dfdl:separatorPosition="infix">
<xs:element name="num" type="xs:integer" />
<xs:choice dfdl:choiceDispatchKey="{ if (./num eq 1) then 'rounded'
else if (./num eq 2) then 'square' else 'none' }">
<xs:element name="A" type="xs:string"
dfdl:initiator="(" dfdl:terminator=")"
dfdl:choiceBranchKey="rounded" />
<xs:element name="B" type="xs:string"
dfdl:initiator="[" dfdl:terminator="]"
dfdl:choiceBranchKey="square" />
<xs:element name="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>
>
