Parsing Functions: Empty input

[ChristianGruen]

I was asked why some of the parsing functions allow empty input and others don’t:

Function	Input
fn:parse-integer	xs:string
fn:parse-uri	xs:string
fn:parse-ietf-date	xs:string?
fn:parse-QName	xs:string
fn:parse-xml	xs:string?
fn:parse-xml-fragment	xs:string?
fn:parse-html	(xs:string | xs:hexBinary | xs:base64Binary)?
fn:parse-json	xs:string?
fn:parse-csv	xs:string?

I would assume there is no rationale behind this, and that we should always allow empty input.

[michaelhkay]

Generally the specs are a pretty inconsistent mess as regards handling of empty sequence on input; it goes well beyond the parse-XX functions.

[ChristianGruen]

In the particular case, it seems that all pre-4.0 functions allow empty sequences, whereas only some of the new functions do. But it’s true, when cleaning this up we should probably consider the complete function set.

[michaelhkay]

See also #748