My preference is the latter. I think expressions for delimiters should be
avoided if possible.
One may get better diagnostics here if in fact what is found in the data stream
is neither a "(" nor "[".
But, if you had a larger number of branch cases, one could argue in favor of
the expression for performance reasons.
________________________________
From: Costello, Roger L. <[email protected]>
Sent: Monday, June 3, 2019 9:07:21 AM
To: [email protected]
Subject: Best Practice: dynamically compute initiator/terminator or choice with
initiatedContent="yes"?
Hello DFDL community,
My input file has a number (num), followed by a comma-separated pair of values,
enclosed within either round parentheses or square parentheses. If num=1 then
the initiator and terminator are rounded parentheses. If num=2 then the
initiator and terminator are square parentheses.
Below are two solutions to the problem. The first solution dynamically computes
the initiator and terminator. The second solution uses a choice with
dfdl:initiatedContent="yes".
Which solution is better?
Solution #1 Dynamically Compute initiator and terminator
<xs:element name="input">
<xs:complexType>
<xs:sequence dfdl:separator="%NL;" dfdl:separatorPosition="infix">
<xs:element name="num" type="xs:integer" />
<xs:sequence dfdl:initiator="{if (num eq 1) then '(' else '[' }"
dfdl:terminator="{if (num eq 1) then ')' else ']' }"
dfdl:separator="," dfdl:separatorPosition="infix">
<xs:element name="A" type="xs:string" />
<xs:element name="B" type="xs:string" />
</xs:sequence>
</xs:sequence>
</xs:complexType>
</xs:element>
Solution #2 Choice with initiatedContent="yes"
<xs:element name="input">
<xs:complexType>
<xs:sequence dfdl:separator="%NL;" dfdl:separatorPosition="infix">
<xs:element name="num" type="xs:integer" />
<xs:choice dfdl:initiatedContent="yes">
<xs:element name="A" type="xs:string" dfdl:initiator="("
dfdl:terminator=")" />
<xs:element name="B" type="xs:string" dfdl:initiator="["
dfdl:terminator="]" />
</xs:choice>
</xs:sequence>
</xs:complexType>
</xs:element>
