Package net.sf.saxon.value
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
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:
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Field Summary
Fields inherited from class net.sf.saxon.value.Value
EMPTY_CLASS_ARRAY
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
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 AtomicValue
convert
(int requiredType, XPathContext context) Convert the value to a given type.convert
(AtomicType targetType, XPathContext context, boolean validate) Convert the value to a given type.abstract AtomicValue
convertPrimitive
(BuiltInAtomicType requiredType, boolean validate, XPathContext context) Convert a value to another primitive data type, with control over how validation is handled.final void
display
(int level, PrintStream out, Configuration config) Diagnostic print of expression structureboolean
effectiveBooleanValue
(XPathContext context) Get the effective boolean value of the valuefinal String
evaluateAsString
(XPathContext context) Evaluate as a stringevaluateItem
(XPathContext context) Evaluate the value (this simply returns the value unchanged)final int
Determine the static cardinalitygetComponent
(int component) Method to extract components of a value.int
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().final int
Get the length of the sequenceGet the primitive value (the value in the value space).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 itemboolean
Test whether the type of this atomic value is a built-in type.final SequenceIterator
iterate
(XPathContext context) Iterate over the (single) item in the sequencevoid
process
(XPathContext context) Process the instruction, without returning any tail callstoString()
Get string value.Methods inherited from class net.sf.saxon.value.Value
asItem, asIterator, asValue, convert, convertJavaObjectToXPath, convertToJava, equals, getDependencies, getItemType, getIterator, getParentExpression, getSpecialProperties, hashCode, itemAt, iterateSubExpressions, makeQNameValue, optimize, promote, reduce, simplify, stringToNumber, typeCheck
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Constructor Details
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AtomicValue
public AtomicValue()
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Method Details
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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 interfaceExpression
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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:
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process
Process the instruction, without returning any tail calls- Specified by:
process
in interfaceExpression
- Overrides:
process
in classValue
- Parameters:
context
- The dynamic context, giving access to the current node, the current variables, etc.- Throws:
XPathException
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getCardinality
public final int getCardinality()Determine the static cardinality- Specified by:
getCardinality
in interfaceExpression
- Overrides:
getCardinality
in classValue
- Returns:
- code identifying the cardinality
- See Also:
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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:
requiredType
- type code of the required atomic typecontext
-- 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
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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 typevalidate
- 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.
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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 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 convertedcontext
- provides access to conversion contextvalidate
- 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.
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getLength
public final int getLength()Get the length of the sequence -
evaluateItem
Evaluate the value (this simply returns the value unchanged)- Specified by:
evaluateItem
in interfaceExpression
- Overrides:
evaluateItem
in classValue
- Parameters:
context
- the evaluation context (not used in this implementation)- Returns:
- the value, unchanged
- Throws:
XPathException
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iterate
Iterate over the (single) item in the sequence- Specified by:
iterate
in interfaceExpression
- Parameters:
context
- the evaluation context (not used in this implementation)- Returns:
- a SequenceIterator that iterates over the single item in this value
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evaluateAsString
Evaluate as a string- Specified by:
evaluateAsString
in interfaceExpression
- Overrides:
evaluateAsString
in classValue
- 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 "".
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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:
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getTypedValue
Get the typed value of this item- Specified by:
getTypedValue
in interfaceItem
- Returns:
- the typed value of the expression (which is this value)
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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 byType.isPrimitiveType(int)
It may also return a RestrictedStringValue, because that is a subclass of StringValue. -
effectiveBooleanValue
Get the effective boolean value of the value- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classValue
- 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
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getComponent
Method to extract components of a value. Implemented by some subclasses, but defined at this level for convenience- Throws:
XPathException
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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 interfaceExpression
- 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
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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. -
display
Diagnostic print of expression structure- Specified by:
display
in interfaceExpression
- Overrides:
display
in classValue
- Parameters:
level
- the indentation level of the outputout
-config
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