[jira] [Commented] (DAFFODIL-2043) fn:round-half-to-even returns decimal string

["Steve Lawrence (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DAFFODIL-2043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16733018#comment-16733018 ] 

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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