Implement the functions and operators casting rules for types.

[rhdunn]

This is needed for providing static analysis and syntax highlighting for cast expressions. It can also be used for validating the values of the context item and variables in run configurations.

• Casting from primitive types to primitive types
• Casting to derived types
• Casting from derived types to parent types
• Casting within a branch of the type hierarchy
• Casting across the type hierarchy
• Casting to union types
• Casting to list types
• xs:untyped

Primitive types

• xs:untypedAtomic
• xs:string
• xs:float
• xs:double
• xs:decimal
• xs:integer
• xs:duration
• xs:yearMonthDuration
• xs:dayTimeDuration
• xs:dateTime
• xs:time
• xs:date
• xs:gYearMonth
• xs:gYear
• xs:gMonthDay
• xs:gDay
• xs:gMonth
• xs:boolean
• xs:base64Binary
• xs:hexBinary
• xs:anyURI
• xs:QName
• xs:NOTATION

Derived types

• xs:integer types (min/max range checking)
• xs:normalizedString
• xs:token
• xs:language
• xs:Name
• xs:NCName
• xs:ENTITY
• xs:ID
• xs:IDREF
• xs:NMTOKEN
• xs:dateTimeStamp