Class TypeChecker10

  • public class TypeChecker10
    extends TypeChecker
    This class provides type checking capability with XPath 1.0 backwards compatibility enabled.
    • Constructor Detail

      • TypeChecker10

        public TypeChecker10()
    • Method Detail

      • staticTypeCheck

        public Expression staticTypeCheck​(Expression supplied,
                                          SequenceType req,
                                          java.util.function.Supplier<RoleDiagnostic> roleSupplier,
                                          ExpressionVisitor visitor)
                                   throws XPathException
        Description copied from class: TypeChecker
        Check an expression against a required type, modifying it if necessary.

        This method takes the supplied expression and checks to see whether it is known statically to conform to the specified type. There are three possible outcomes. If the static type of the expression is a subtype of the required type, the method returns the expression unchanged. If the static type of the expression is incompatible with the required type (for example, if the supplied type is integer and the required type is string) the method throws an exception (this results in a compile-time type error being reported). If the static type is a supertype of the required type, then a new expression is constructed that evaluates the original expression and checks the dynamic type of the result; this new expression is returned as the result of the method.

        The rules applied are those for function calling in XPath, that is, the rules that the argument of a function call must obey in relation to the signature of the function. Some contexts require slightly different rules (for example, operands of polymorphic operators such as "+"). In such cases this method cannot be used.

        Note that this method does not do recursive type-checking of the sub-expressions.

        staticTypeCheck in class TypeChecker
        supplied - The expression to be type-checked
        req - The required type for the context in which the expression is used
        roleSupplier - Information about the role of the subexpression within the containing expression, used to provide useful error messages
        visitor - An expression visitor
        The original expression if it is type-safe, or the expression wrapped in a run-time type checking expression if not.
        XPathException - if the supplied type is statically inconsistent with the required type (that is, if they have no common subtype)