Package net.sf.saxon.value
Class AtomicValue
java.lang.Object
net.sf.saxon.value.Value
net.sf.saxon.value.AtomicValue
- All Implemented Interfaces:
Serializable
,PullEvent
,SequenceIterable
,GroundedValue
,Item
,ValueRepresentation
,ConversionResult
- Direct Known Subclasses:
Base64BinaryValue
,BooleanValue
,CalendarValue
,DurationValue
,HexBinaryValue
,NumericValue
,ObjectValue
,QualifiedNameValue
,StringValue
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 xs: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:
-
Field Summary
FieldsFields inherited from class net.sf.saxon.value.Value
EMPTY_CLASS_ARRAY, INDETERMINATE_ORDERING
Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionasAtomic()
Calling this method on a ConversionResult returns the AtomicValue that results from the conversion if the conversion was successful, and throws a ValidationException explaining the conversion error otherwise.void
checkPermittedContents
(SchemaType parentType, StaticContext env, boolean whole) Check statically that the results of the expression are capable of constructing the content of a given schema type.final ConversionResult
convert
(AtomicType targetType, boolean validate, XPathContext context) Convert the value to a given type.final AtomicValue
convert
(AtomicType schemaType, XPathContext context) Convert the value to a given type.protected abstract ConversionResult
convertPrimitive
(BuiltInAtomicType requiredType, boolean validate, XPathContext context) Convert a value to either (a) another primitive type, or (b) another built-in type derived from the current primitive type, with control over how validation is handled.abstract AtomicValue
copyAsSubType
(AtomicType typeLabel) Create a copy of this atomic value, with a different type labelboolean
Get the effective boolean value of the valueabstract boolean
The equals() methods on atomic values is defined to follow the semantics of eq when applied to two atomic values.final int
Determine the static cardinalitygetComponent
(int component) Method to extract components of a value.Determine the data type of the items in the expression, if possiblefinal int
Get the length of the sequenceabstract BuiltInAtomicType
Determine the primitive type of the value.abstract Comparable
Get a Comparable value that implements the XML Schema ordering comparison semantics for this value.abstract String
Convert the value to a string, using the serialization rules.Get the value of the item as a CharSequence.final SequenceIterator
Get the typed value of this itemDetermine the data type of the value.abstract Object
getXPathComparable
(boolean ordered, StringCollator collator, XPathContext context) Get an object value that implements the XPath equality and ordering comparison semantics for this value.boolean
isNaN()
Test whether the value is the double/float value NaNfinal Item
itemAt
(int n) Get the n'th item in the sequence (starting from 0).final SequenceIterator
iterate()
Iterate over the (single) item in the sequencevoid
process
(XPathContext context) Process the instruction, without returning any tail callsvoid
setTypeLabel
(AtomicType type) Set the type label on this atomic value.subsequence
(int start, int length) Get a subsequence of the valuetoString()
Get string value.Methods inherited from class net.sf.saxon.value.Value
asItem, asItem, asIterator, asValue, convertToJava, fromItem, getCanonicalLexicalRepresentation, getIterator, iterate, makeQNameValue, reduce, stringToNumber
-
Field Details
-
typeLabel
-
-
Constructor Details
-
AtomicValue
public AtomicValue()
-
-
Method Details
-
setTypeLabel
Set the type label on this atomic value. Note that this modifies the value, so it must only called if the caller is confident that the value is not shared. In other cases, usecopyAsSubType(net.sf.saxon.type.AtomicType)
- Parameters:
type
- the type label to be set
-
getSchemaComparable
Get a Comparable value that implements the XML Schema ordering comparison semantics for this value. An implementation must be provided for all atomic types.In the case of data types that are partially ordered, the returned Comparable extends the standard semantics of the compareTo() method by returning the value
Value.INDETERMINATE_ORDERING
when there is no defined order relationship between two given values. This value is also returned when two values of different types are compared.- Overrides:
getSchemaComparable
in classValue
- Returns:
- a Comparable that follows XML Schema comparison rules
-
getXPathComparable
public abstract Object getXPathComparable(boolean ordered, StringCollator collator, XPathContext context) throws NoDynamicContextException Get an object value that implements the XPath equality and ordering comparison semantics for this value. If the ordered parameter is set to true, the result will be a Comparable and will support a compareTo() method with the semantics of the XPath lt/gt operator, provided that the other operand is also obtained using the getXPathComparable() method. In all cases the result will support equals() and hashCode() methods that support the semantics of the XPath eq operator, again provided that the other operand is also obtained using the getXPathComparable() method. A context argument is supplied for use in cases where the comparison semantics are context-sensitive, for example where they depend on the implicit timezone or the default collation.- Parameters:
ordered
- true if an ordered comparison is required. In this case the result is null if the type is unordered; in other cases the returned value will be a Comparable.collator
- the collation to be used when comparing stringscontext
- the XPath dynamic evaluation context, used in cases where the comparison is context sensitive- Returns:
- an Object whose equals() and hashCode() methods implement the XPath comparison semantics with respect to this atomic value. If ordered is specified, the result will either be null if no ordering is defined, or will be a Comparable
- Throws:
NoDynamicContextException
- if the comparison depends on dynamic context information that is not available, for example implicit timezone
-
equals
The equals() methods on atomic values is defined to follow the semantics of eq when applied to two atomic values. When the other operand is not an atomic value, the result is undefined (may be false, may be an exception). When the other operand is an atomic value that cannot be compared with this one, the method must throw a ClassCastException.The hashCode() method is consistent with equals().
-
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 interfaceItem
- Specified by:
getStringValueCS
in interfaceValueRepresentation
- Overrides:
getStringValueCS
in classValue
- Returns:
- the string value of the item
- See Also:
-
process
Process the instruction, without returning any tail calls- Overrides:
process
in classValue
- Parameters:
context
- The dynamic context, giving access to the current node, the current variables, etc.- Throws:
XPathException
-
itemAt
Get the n'th item in the sequence (starting from 0). This is defined for all Values, but its real benefits come for a sequence Value stored extensionally (or for a MemoClosure, once all the values have been read)- Specified by:
itemAt
in interfaceGroundedValue
- Overrides:
itemAt
in classValue
- Parameters:
n
- position of the required item, counting from zero.- Returns:
- the n'th item in the sequence, where the first item in the sequence is numbered zero. If n is negative or >= the length of the sequence, returns null.
-
getItemType
Determine the data type of the items in the expression, if possible- Overrides:
getItemType
in classValue
- Parameters:
th
- The TypeHierarchy. Can be null if the target is an AtomicValue, except in the case where it is an external ObjectValue.- Returns:
- for the default implementation: AnyItemType (not known)
-
getTypeLabel
Determine the data type of the value. This delivers the same answer asgetItemType(net.sf.saxon.type.TypeHierarchy)
, except in the case of external objects (instances ofObjectValue
, where the method may deliver a less specific type.- Returns:
- for the default implementation: AnyItemType (not known)
-
getPrimitiveType
Determine the primitive type of the value. This delivers the same answer as getItemType().getPrimitiveItemType(). The primitive types are the 19 primitive types of XML Schema, plus xs:integer, xs:dayTimeDuration and xs:yearMonthDuration, and xs:untypedAtomic. For external objects, the result is xs:anyAtomicType.- Returns:
- the primitive type
-
getCardinality
public final int getCardinality()Determine the static cardinality- Overrides:
getCardinality
in classValue
- Returns:
- code identifying the cardinality
- See Also:
-
convert
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:
schemaType
- the required atomic typecontext
- the XPath dynamic 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
protected abstract ConversionResult convertPrimitive(BuiltInAtomicType requiredType, boolean validate, XPathContext context) Convert a value to either (a) another primitive type, or (b) another built-in type derived from the current primitive type, with control over how validation is handled.- Parameters:
requiredType
- the required atomic type. This must either be a primitive type, or a built-in type derived from the same primitive type as this atomic value.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 xs:Name or similar types: it determines the NameChecker to be used.- Returns:
- the result of the conversion, if successful. If unsuccessful, the value returned will be a ValidationFailure. The caller must check for this condition. No exception is thrown, instead the exception information will be encapsulated within the ValidationFailure.
-
convert
public final ConversionResult convert(AtomicType targetType, boolean validate, XPathContext context) 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 convertedvalidate
- true if validation is required, false if the caller already knows that the value is validcontext
- provides access to conversion context- Returns:
- the value after conversion if successful; or a
ValidationFailure
if conversion failed. The caller must check for this condition. Validation may fail even if validation was not requested.
-
copyAsSubType
Create a copy of this atomic value, with a different type label- Parameters:
typeLabel
- the type label of the new copy. The caller is responsible for checking that the value actually conforms to this type.- Returns:
- the copied value
-
isNaN
public boolean isNaN()Test whether the value is the double/float value NaN- Returns:
- true if the value is float NaN or double NaN; otherwise false
-
getLength
public final int getLength()Get the length of the sequence -
iterate
Iterate over the (single) item in the sequence -
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 interfaceItem
- Specified by:
getStringValue
in interfaceValueRepresentation
- Overrides:
getStringValue
in classValue
- Returns:
- the string value of the item
- See Also:
-
getTypedValue
Get the typed value of this item- Specified by:
getTypedValue
in interfaceItem
- Returns:
- the typed value of the expression (which is this value)
-
effectiveBooleanValue
Get the effective boolean value of the value- Overrides:
effectiveBooleanValue
in classValue
- 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
Method to extract components of a value. Implemented by some subclasses, but defined at this level for convenience- Parameters:
component
- identifies the required component, as a constant defined in classComponent
, for exampleComponent.HOURS
- Returns:
- the value of the requested component of this value
- 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.- Overrides:
checkPermittedContents
in classValue
- Parameters:
parentType
- The schema typeenv
- the static contextwhole
- 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
-
asAtomic
Calling this method on a ConversionResult returns the AtomicValue that results from the conversion if the conversion was successful, and throws a ValidationException explaining the conversion error otherwise.Use this method if you are calling a conversion method that returns a ConversionResult, and if you want to throw an exception if the conversion fails.
- Specified by:
asAtomic
in interfaceConversionResult
- Returns:
- the atomic value that results from the conversion if the conversion was successful
-
subsequence
Get a subsequence of the value- Specified by:
subsequence
in interfaceGroundedValue
- Parameters:
start
- the index of the first item to be included in the result, counting from zero. A negative value is taken as zero. If the value is beyond the end of the sequence, an empty sequence is returnedlength
- the number of items to be included in the result. Specify Integer.MAX_VALUE to get the subsequence up to the end of the base sequence. If the value is negative, an empty sequence is returned. If the value goes off the end of the sequence, the result returns items up to the end of the sequence- Returns:
- the required subsequence. If min is
-
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.
-