Package net.sf.saxon.value

Class AtomicValue

  • All Implemented Interfaces:
    java.io.Serializable, Expression, Item, ValueRepresentation
    Direct Known Subclasses:
    Base64BinaryValue, BooleanValue, CalendarValue, DurationValue, HexBinaryValue, NumericValue, ObjectValue, QNameValue, StringValue
    public abstract class AtomicValue
extends Value
implements Item
    The AtomicValue class corresponds to the concept of an atomic value in the XPath 2.0 data model. Atomic values belong to one of the 19 primitive types defined in XML Schema; or they are of type xdt:untypedAtomic; or they are "external objects", representing a Saxon extension to the XPath 2.0 type system.

    The AtomicValue class contains some methods that are suitable for applications to use, and many others that are designed for internal use by Saxon itself. These have not been fully classified. At present, therefore, none of the methods on this class should be considered to be part of the public Saxon API.

    Author:
    Michael H. Kay
    See Also:
    Serialized Form

    • Constructor Detail

      • AtomicValue

        public AtomicValue()

    • Method Detail

      • hasBuiltInType

        public boolean hasBuiltInType()
        Test whether the type of this atomic value is a built-in type. Default implementation returns true.

      • getImplementationMethod

        public int getImplementationMethod()
        An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is prefered.
        Specified by:
        getImplementationMethod in interface Expression

      • process

        public void process​(XPathContext context)
             throws XPathException
        Process the instruction, without returning any tail calls
        Specified by:
        process in interface Expression
        Overrides:
        process in class Value
        Parameters:
        context - The dynamic context, giving access to the current node, the current variables, etc.
        Throws:
        XPathException

      • convert

        public final AtomicValue convert​(int requiredType,
                                 XPathContext context)
                          throws XPathException
        Convert the value to a given type. The result of the conversion will be an atomic value of the required type. This method works only where the target type is a built-in type.
        Parameters:
        requiredType - type code of the required atomic type
        context -
        Returns:
        the result of the conversion, if conversion was possible. This will always be an instance of the class corresponding to the type of value requested
        Throws:
        XPathException - if conversion is not allowed for this required type, or if the particular value cannot be converted

      • convertPrimitive

        public abstract AtomicValue convertPrimitive​(BuiltInAtomicType requiredType,
                                             boolean validate,
                                             XPathContext context)
        Convert a value to another primitive data type, with control over how validation is handled.
        Parameters:
        requiredType - type code of the required atomic type
        validate - true if validation is required. If set to false, the caller guarantees that the value is valid for the target data type, and that further validation is therefore not required. Note that a validation failure may be reported even if validation was not requested.
        context - The conversion context to be used. This is required at present only when converting to a date or time: it provides the implicit timezone.
        Returns:
        the result of the conversion, if successful. If unsuccessful, the value returned will be a ValidationErrorValue. The caller must check for this condition. No exception is thrown, instead the exception will be encapsulated within the ValidationErrorValue.

      • convert

        public AtomicValue convert​(AtomicType targetType,
                           XPathContext context,
                           boolean validate)
        Convert the value to a given type. The result of the conversion will be an atomic value of the required type. This method works where the target type is a built-in atomic type and also where it is a user-defined atomic type.
        Parameters:
        targetType - the type to which the value is to be converted
        context - provides access to conversion context
        validate - true if validation is required, false if the caller already knows that the value is valid
        Returns:
        the value after conversion if successful; or a ValidationErrorValue if conversion failed. The caller must check for this condition. Validation may fail even if validation was not requested.

      • getLength

        public final int getLength()
        Get the length of the sequence
        Overrides:
        getLength in class Value
        Returns:
        always 1 for an atomic value

      • iterate

        public final SequenceIterator iterate​(XPathContext context)
        Iterate over the (single) item in the sequence
        Specified by:
        iterate in interface Expression
        Parameters:
        context - the evaluation context (not used in this implementation)
        Returns:
        a SequenceIterator that iterates over the single item in this value

      • evaluateAsString

        public final java.lang.String evaluateAsString​(XPathContext context)
        Evaluate as a string
        Specified by:
        evaluateAsString in interface Expression
        Overrides:
        evaluateAsString in class Value
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the value of the expression, evaluated in the current context. The expression must return a string or (); if the value of the expression is (), this method returns "".

      • getStringValue

        public abstract java.lang.String getStringValue()
        Convert the value to a string, using the serialization rules. For atomic values this is the same as a cast; for sequence values it gives a space-separated list. This method is refined for AtomicValues so that it never throws an Exception.
        Specified by:
        getStringValue in interface Item
        Specified by:
        getStringValue in interface ValueRepresentation
        Overrides:
        getStringValue in class Value
        Returns:
        the string value of the item
        See Also:
        Item.getStringValueCS()

      • getTypedValue

        public final SequenceIterator getTypedValue()
        Get the typed value of this item
        Specified by:
        getTypedValue in interface Item
        Returns:
        the typed value of the expression (which is this value)

      • getPrimitiveValue

        public AtomicValue getPrimitiveValue()
        Get the primitive value (the value in the value space). This returns an AtomicValue of a Java class that would be used to represent the primitive value. In effect this means that for built-in types, it returns the value itself, but for user-defined type, it returns the primitive value minus the type annotation. Note that getItemType() when applied to the result of this function does not not necessarily return a primitive type: for example, this function may return a value of type xdt:dayTimeDuration, which is not a primitive type as defined by Type.isPrimitiveType(int) It may also return a RestrictedStringValue, because that is a subclass of StringValue.

      • effectiveBooleanValue

        public boolean effectiveBooleanValue​(XPathContext context)
                              throws XPathException
        Get the effective boolean value of the value
        Specified by:
        effectiveBooleanValue in interface Expression
        Overrides:
        effectiveBooleanValue in class Value
        Parameters:
        context - the evaluation context (not used in this implementation)
        Returns:
        true, unless the value is boolean false, numeric zero, or zero-length string
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression

      • getComponent

        public AtomicValue getComponent​(int component)
                         throws XPathException
        Method to extract components of a value. Implemented by some subclasses, but defined at this level for convenience
        Throws:
        XPathException

      • checkPermittedContents

        public void checkPermittedContents​(SchemaType parentType,
                                   StaticContext env,
                                   boolean whole)
                            throws XPathException
        Check statically that the results of the expression are capable of constructing the content of a given schema type.
        Specified by:
        checkPermittedContents in interface Expression
        Overrides:
        checkPermittedContents in class Value
        Parameters:
        parentType - The schema type
        env - the static context
        whole - true if this atomic value accounts for the entire content of the containing node
        Throws:
        XPathException - if the expression doesn't match the required content type

      • toString

        public java.lang.String toString()
        Get string value. In general toString() for an atomic value displays the value as it would be written in XPath: that is, as a literal if available, or as a call on a constructor function otherwise.
        Overrides:
        toString in class Value

      • display

        public final void display​(int level,
                          java.io.PrintStream out,
                          Configuration config)
        Diagnostic print of expression structure
        Specified by:
        display in interface Expression
        Overrides:
        display in class Value
        Parameters:
        level - the indentation level of the output
        out -
        config -