Class AtomicValue

java.lang.Object
net.sf.saxon.value.Value
net.sf.saxon.value.AtomicValue
All Implemented Interfaces:
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:

  • Constructor Details

    • AtomicValue

      public AtomicValue()

  • Method Details

    • 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

    • getStringValueCS

      public CharSequence getStringValueCS()
      Get the value of the item as a CharSequence. This is in some cases more efficient than the version of the method that returns a String.
      Specified by:
      getStringValueCS in interface Item
      Specified by:
      getStringValueCS in interface ValueRepresentation
      Overrides:
      getStringValueCS in class Value
      Returns:
      the string value of the item
      See Also:

    • 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

    • getCardinality

      public final int getCardinality()
      Determine the static cardinality
      Specified by:
      getCardinality in interface Expression
      Overrides:
      getCardinality in class Value
      Returns:
      code identifying the cardinality
      See Also:

    • 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

    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the value (this simply returns the value unchanged)
      Specified by:
      evaluateItem in interface Expression
      Overrides:
      evaluateItem in class Value
      Parameters:
      context - the evaluation context (not used in this implementation)
      Returns:
      the value, unchanged
      Throws:
      XPathException

    • 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 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 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:

    • 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 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, 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 -