net.sf.saxon.expr.instruct

Class GlobalVariable

java.lang.Object

net.sf.saxon.expr.instruct.GeneralVariable

net.sf.saxon.expr.instruct.GlobalVariable

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, Binding, Container, Declaration, InstructionInfo, Locator

Direct Known Subclasses:

GlobalParam, UndeclaredVariable

public class GlobalVariable
extends GeneralVariable
implements Container, Declaration, InstructionInfo

A compiled global variable in a stylesheet or query.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected List<BindingReference>	references

Fields inherited from class net.sf.saxon.expr.instruct.GeneralVariable

evaluationMode, referenceCount, slotNumber, variableQName

Constructor Summary

Constructors

Constructor and Description
GlobalVariable() Create a global variable

Method Summary

Methods

Modifier and Type	Method and Description
protected Sequence	actuallyEvaluate(XPathContext context) Evaluate the global variable, and save its value for use in subsequent references.
void	compile(Executable exec, int slot) Create a compiled representation of this global variable
Sequence	evaluateVariable(XPathContext context) Evaluate the variable
int	getColumnNumber(long locationId) Get the column number within the document, entity, or module containing a particular location
int	getConstructType() Get the type of construct.
Container	getContainer() Get the container in which this expression is located.
int	getContainerGranularity() Get the granularity of the container.
Executable	getExecutable() Get the executable containing this global variable
int	getHostLanguage() Get the host language (XSLT, XQuery, XPath) used to implement the code in this container
int	getLineNumber() Get the line number where the declaration appears
int	getLineNumber(long locationId) Get the line number within the document, entity or module containing a particular location
StructuredQName	getObjectName() Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc.
GlobalVariable	getOriginalVariable() Get the original declaration of this variable
Iterator<String>	getProperties() Get an iterator over all the properties available.
Object	getProperty(String name) Get the value of a particular property of the instruction.
Sequence	getSelectValue(XPathContext context) Evaluate the variable.
String	getSystemId() Get the system ID of the module containing the variable declaration
GlobalVariable	getUltimateOriginalVariable() Get the original declaration of this variable, or its original declaration, transitively
boolean	isAssignable() Test whether it is permitted to assign to the variable using the saxon:assign extension element.
boolean	isGlobal() Is this a global variable?
boolean	isIndexedVariable() Ask whether this is an indexed variable
boolean	isPrivate() Ask whether this global variable is private
Iterator	iterateReferences() Iterate over the references to this variable
void	lookForCycles(Stack<Container> referees, XQueryFunctionLibrary globalFunctionLibrary) Check for cycles in this variable definition
void	registerReference(BindingReference ref) Register a variable reference that refers to this global variable
void	setAssignable(boolean assignable) Indicate whether this variable is assignable using saxon:assign
void	setContainsLocals(SlotManager map) The expression that initializes a global variable may itself use local variables.
protected static void	setDependencies(Bindery bindery, GlobalVariable var, XPathContext context) Get the variable that is immediately dependent on this one, and register the dependency, so that circularities can be detected across threads.
void	setExecutable(Executable executable) Set the containing executable
void	setIndexedVariable() Mark this as an indexed variable, to allow fast searching
void	setLineNumber(int lineNumber) Set the line number where the variable declaration appears in the source
void	setOriginalVariable(GlobalVariable var) Say that this (XQuery) variable is a copy of some originally declared variable.
void	setPrivate(boolean b) Say whether this global variable is a "parameter" (an external variable, in XQuery terminology)
void	setSystemId(String systemId) Set the system ID of the module where the variable declaration appears
void	typeCheck(ExpressionVisitor visitor) Type check the compiled representation of this global variable

Methods inherited from class net.sf.saxon.expr.instruct.GeneralVariable

addReference, checkAgainstRequiredType, computeEvaluationMode, copy, explain, getCardinality, getColumnNumber, getEvaluationMode, getInstructionNameCode, getIntegerBoundsForVariable, getLocalSlotNumber, getLocationId, getLocationProvider, getPublicId, getRequiredType, getSelectExpression, getSlotNumber, getSystemId, getVariableQName, init, isImplicitlyRequiredParam, isRequiredParam, isTunnelParam, iterateSubExpressions, optimize, replaceSubExpression, setContainer, setImplicitlyRequiredParam, setLocationId, setReferenceCount, setRequiredParam, setRequiredType, setSelectExpression, setSlotNumber, setTunnel, setVariableQName, simplify, typeCheck

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.saxon.expr.Container

getLocationProvider

Methods inherited from interface org.xml.sax.Locator

getColumnNumber, getPublicId

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getPublicId

Methods inherited from interface net.sf.saxon.event.LocationProvider

getSystemId

Field Detail

references

protected List<BindingReference> references

Constructor Detail

GlobalVariable

public GlobalVariable()

Create a global variable

Method Detail

getExecutable

public Executable getExecutable()

Get the executable containing this global variable

Specified by:

getExecutable in interface Container

Overrides:

getExecutable in class GeneralVariable

Returns:

the containing executable

setExecutable

public void setExecutable(Executable executable)

Set the containing executable

Parameters:

executable - the executable that contains this global variable

setOriginalVariable

public void setOriginalVariable(GlobalVariable var)

Say that this (XQuery) variable is a copy of some originally declared variable. It's a separate variable when imported into another module, but it retains the link to the original.

Parameters:

var - the variable in the imported module from which this variable is derived

getOriginalVariable

public GlobalVariable getOriginalVariable()

Get the original declaration of this variable

Returns:

the variable in the imported module from which this variable is derived

getUltimateOriginalVariable

public GlobalVariable getUltimateOriginalVariable()

Get the original declaration of this variable, or its original declaration, transitively

Returns:

the real variable declaration in some transitively imported module from which this variable is ultimately derived

setLineNumber

public void setLineNumber(int lineNumber)

Set the line number where the variable declaration appears in the source

Parameters:

lineNumber - the line number

getLineNumber

public int getLineNumber()

Get the line number where the declaration appears

Specified by:

getLineNumber in interface SourceLocator

Specified by:

getLineNumber in interface InstructionInfo

Specified by:

getLineNumber in interface Locator

Overrides:

getLineNumber in class GeneralVariable

Returns:

the line number of the expression within the containing module

getLineNumber

public int getLineNumber(long locationId)

Description copied from interface: LocationProvider

Get the line number within the document, entity or module containing a particular location

Specified by:

getLineNumber in interface LocationProvider

Parameters:

locationId - identifier of the location in question (as passed down the Receiver pipeline)

Returns:

the line number within the document, entity or module, or -1 if no information is available.

setSystemId

public void setSystemId(String systemId)

Set the system ID of the module where the variable declaration appears

Parameters:

systemId - the System ID (base URI)

getSystemId

public String getSystemId()

Get the system ID of the module containing the variable declaration

Specified by:

getSystemId in interface SourceLocator

Specified by:

getSystemId in interface InstructionInfo

Specified by:

getSystemId in interface Locator

Overrides:

getSystemId in class GeneralVariable

Returns:

the System ID (base URI)

getColumnNumber

public int getColumnNumber(long locationId)

Get the column number within the document, entity, or module containing a particular location

Specified by:

getColumnNumber in interface LocationProvider

Parameters:

locationId - identifier of the location in question (as passed down the Receiver pipeline)

Returns:

the column number within the document, entity, or module, or -1 if this is not available

isPrivate

public boolean isPrivate()

Ask whether this global variable is private

Returns:

true if this variable is private

setPrivate

public void setPrivate(boolean b)

Say whether this global variable is a "parameter" (an external variable, in XQuery terminology)

Parameters:

b - true if this variable is external

setAssignable

public void setAssignable(boolean assignable)

Indicate whether this variable is assignable using saxon:assign

Parameters:

assignable - true if this variable is assignable

isAssignable

public final boolean isAssignable()

Test whether it is permitted to assign to the variable using the saxon:assign extension element. This will only be true if the extra attribute saxon:assignable="yes" is present.

Specified by:

isAssignable in interface Binding

Overrides:

isAssignable in class GeneralVariable

Returns:

true if the binding is assignable

getConstructType

public int getConstructType()

Get the type of construct. This will either be the fingerprint of a standard XSLT instruction name (values in StandardNames: all less than 1024) or it will be a constant in class Location.

Specified by:

getConstructType in interface InstructionInfo

Returns:

an integer identifying the kind of construct

getObjectName

public StructuredQName getObjectName()

Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc. This is used only where the name is known statically.

Specified by:

getObjectName in interface InstructionInfo

Returns:

the QName of the object declared or manipulated by this instruction or expression

getProperty

public Object getProperty(String name)

Get the value of a particular property of the instruction. Properties of XSLT instructions are generally known by the name of the stylesheet attribute that defines them.

Specified by:

getProperty in interface InstructionInfo

Parameters:

name - The name of the required property

Returns:

The value of the requested property, or null if the property is not available

getProperties

public Iterator<String> getProperties()

Get an iterator over all the properties available. The values returned by the iterator will be of type String, and each string can be supplied as input to the getProperty() method to retrieve the value of the property. The iterator may return properties whose value is null.

Specified by:

getProperties in interface InstructionInfo

Returns:

an iterator over the properties.

getContainer

public Container getContainer()

Get the container in which this expression is located. This will usually be a top-level construct such as a function or global variable, and XSLT template, or an XQueryExpression. In the case of free-standing XPath expressions it will be the StaticContext object

Overrides:

getContainer in class GeneralVariable

Returns:

the expression's container

getHostLanguage

public int getHostLanguage()

Get the host language (XSLT, XQuery, XPath) used to implement the code in this container

Specified by:

getHostLanguage in interface Container

Returns:

typically Configuration.XSLT or Configuration.XQUERY

setIndexedVariable

public void setIndexedVariable()

Mark this as an indexed variable, to allow fast searching

isIndexedVariable

public boolean isIndexedVariable()

Ask whether this is an indexed variable

Returns:

true if this variable is indexed

getContainerGranularity

public int getContainerGranularity()

Get the granularity of the container.

Specified by:

getContainerGranularity in interface Container

Returns:

0 for a temporary container created during parsing; 1 for a container that operates at the level of an XPath expression; 2 for a container at the level of a global function or template

setContainsLocals

public void setContainsLocals(SlotManager map)

The expression that initializes a global variable may itself use local variables. In this case a stack frame needs to be allocated while evaluating the global variable

Parameters:

map - The stack frame map for local variables used while evaluating this global variable.

isGlobal

public boolean isGlobal()

Is this a global variable?

Specified by:

isGlobal in interface Binding

Overrides:

isGlobal in class GeneralVariable

Returns:

true (yes, it is a global variable)

registerReference

public void registerReference(BindingReference ref)

Register a variable reference that refers to this global variable

Parameters:

ref - the variable reference

iterateReferences

public Iterator iterateReferences()

Iterate over the references to this variable

Returns:

an iterator over the references: returns objects of class VariableReference

compile

public void compile(Executable exec,
           int slot)
             throws XPathException

Create a compiled representation of this global variable

Parameters:

exec - the executable

slot - the slot number allocated to this variable

Throws:

XPathException - if compile-time errors are found.

typeCheck

public void typeCheck(ExpressionVisitor visitor)
               throws XPathException

Type check the compiled representation of this global variable

Parameters:

visitor - an expression visitor

Throws:

XPathException - if compile-time errors are found.

lookForCycles

public void lookForCycles(Stack<Container> referees,
                 XQueryFunctionLibrary globalFunctionLibrary)
                   throws XPathException

Check for cycles in this variable definition

Parameters:

referees - the calls leading up to this one; it's an error if this variable is on the stack, because that means it calls itself directly or indirectly. The stack may contain variable definitions (GlobalVariable objects) and user-defined functions (UserFunction objects). It will never contain the same object more than once.

globalFunctionLibrary - the library containing all global functions

Throws:

XPathException - if cycles are found

getSelectValue

public Sequence getSelectValue(XPathContext context)
                        throws XPathException

Evaluate the variable. That is, get the value of the select expression if present or the content of the element otherwise, either as a tree or as a sequence

Overrides:

getSelectValue in class GeneralVariable

Parameters:

context - the XPath dynamic context

Returns:

the result of evaluating the variable

Throws:

XPathException - if evaluation of the select expression fails with a dynamic error

evaluateVariable

public Sequence evaluateVariable(XPathContext context)
                          throws XPathException

Evaluate the variable

Specified by:

evaluateVariable in interface Binding

Parameters:

context - the XPath dynamic evaluation context

Returns:

the result of evaluating the variable

Throws:

XPathException - if an error occurs while evaluating the variable

actuallyEvaluate

protected Sequence actuallyEvaluate(XPathContext context)
                             throws XPathException

Evaluate the global variable, and save its value for use in subsequent references.

Parameters:

context - the XPath dynamic context

Returns:

the value of the variable

Throws:

XPathException - if evaluation fails

setDependencies

protected static void setDependencies(Bindery bindery,
                   GlobalVariable var,
                   XPathContext context)
                               throws XPathException

Get the variable that is immediately dependent on this one, and register the dependency, so that circularities can be detected across threads. This relies on the fact that when the initialiser for variable X contains a reference to variable Y, then when Y is evaluated, a stack frame will be found on the context stack representing the evaluation of X. We don't set a dependency from X to Y if the value of Y was already available in the Bindery; it's not needed, because in this case we know that evaluation of Y is unproblematic, and can't lead to any circularities.

Parameters:

bindery - the Bindery

var - the global variable or parameter being evaluated

context - the dynamic evaluation context

Throws:

XPathException