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https://issues.apache.org/jira/browse/DAFFODIL-2043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16733018#comment-16733018
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Steve Lawrence commented on DAFFODIL-2043:
------------------------------------------
The difference here is subtle, and certainly a bug in Daffodil. The first two
expression (which compile to the same thing), compile to the following XML
representation:
{code:xml}
<CompiledDPath>
<FNRoundHalfToEven1>
<CompiledDPath>
<Literal>0.1</Literal>
</CompiledDPath>
</FNRoundHalfToEven1>
<NumericToString/>
<StringToLong/>
<LongToInt/>
</CompiledDPath>
{code}
Note that the result of fn:round-half-to-even is a numeric, so that numeric
must be converted to an int. This is done by converting the numeric to a
string, then converting the string to a long (implemented via the String.toLong
method), which is finally converted to an Int. However, the
fn:round-half-to-even method can return a decimal, in which case the
String.toLong method will fail.
If we look at the working expression, it's compiled XML representation is the
following:
{code:xml}
{code}
> fn:round-half-to-even returns decimal string
> --------------------------------------------
>
> Key: DAFFODIL-2043
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2043
> Project: Daffodil
> Issue Type: Bug
> Reporter: Brandon Sloane
> Priority: Major
> Attachments: test.dfdl.xsd
>
>
> fn:round-half-to-even() appears to be returning a decimal string, which
> causes issues when an integer type is expected.
> The following elements both trigger a schema definition error
> <xs:element name="a" type="xs:int"
> dfdl:inputValueCalc="\{ (fn:round-half-to-even( 0.1 )) }"
> />
> <xs:element name="a" type="xs:int"
> dfdl:inputValueCalc="\{ xs:int(fn:round-half-to-even( 0.1 )) }"
> />
> [error] Schema Definition Error: Cannot convert '0.0' from String type to
> Long (Cannot convert to type long: For input string: "0.0").
> In contrast, casting to a double, as below, appears to work as expected:
> <xs:element name="a" type="xs:int"
> dfdl:inputValueCalc="\{ xs:double(fn:round-half-to-even( 0.1 )) }"
> />
>
> What appears to be happening is that fn:round-half-to-even( 0.1 ) returns the
> string "0.0", and the type="xs:int" on the element triggers an implicit cast
> to an integer type. Since "0.0" contains a decimal point, this cast fail.
> However, an explict cast to xs:double can succeed, and then the explicit cast
> to an int from the double works as expected.
> Complete example schema attached
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