net.sf.saxon.expr.instruct

Class Bindery

java.lang.Object

net.sf.saxon.expr.instruct.Bindery

public final class Bindery
extends java.lang.Object

The Bindery class holds information about variables and their values. It is used only for global variables: local variables are held in the XPathContext object.

Variables are identified by a GlobalVariable object. Values will always be of class Sequence.

The Bindery is a run-time object, but slot numbers within the bindery are allocated to global variables at compile time. Because XSLT packages can be separately compiled, each package needs to have its own bindery.

From Saxon 9.7 there is one Bindery for the global variables in each separately-compiled package. The Bindery is no longer used to hold supplied values of global parameters, but it does hold their values after initialization, treating them as normal global variables. Management of dependencies among global variables, and checking for dynamic circularities, has been moved to the Controller.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Bindery.FailureValue A value that can be saved in a global variable to indicate that evaluation failed, and that subsequent attempts at evaluation should also fail

Constructor Summary

Constructors

Constructor and Description
Bindery(PackageData pack)

Method Summary

Modifier and Type	Method and Description
GroundedValue<?>	getGlobalVariable(int slot) Get the value of a global variable whose slot number is known
GroundedValue[]	getGlobalVariables() Get all the global variables, as an array.
GroundedValue<?>	getGlobalVariableValue(GlobalVariable binding) Get the value of a global variable
GroundedValue<?>	saveGlobalVariableValue(GlobalVariable binding, GroundedValue<?> value) Save the value of a global variable, and mark evaluation as complete.
boolean	setExecuting(GlobalVariable binding) Set/Unset a flag to indicate that a particular global variable is currently being evaluated.
void	setGlobalVariable(GlobalVariable binding, GroundedValue<?> value) Provide a value for a global variable
void	setNotExecuting(GlobalVariable binding) Indicate that a global variable is not currently being evaluated

Methods inherited from class java.lang.Object

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

Constructor Detail

Bindery

public Bindery(PackageData pack)

Method Detail

setGlobalVariable

public void setGlobalVariable(GlobalVariable binding,
                              GroundedValue<?> value)

Provide a value for a global variable

Parameters:

binding - identifies the variable

value - the value of the variable

setExecuting

public boolean setExecuting(GlobalVariable binding)
                     throws XPathException

Set/Unset a flag to indicate that a particular global variable is currently being evaluated. Note that this code is not synchronized, so there is no absolute guarantee that two threads will not both evaluate the same global variable; however, apart from wasted time, it is harmless if they do.

Parameters:

binding - the global variable in question

Returns:

true if evaluation of the variable should proceed; false if it is found that the variable has now been evaluated in another thread.

Throws:

XPathException - If an attempt is made to set the flag when it is already set, this means the definition of the variable is circular.

setNotExecuting

public void setNotExecuting(GlobalVariable binding)

Indicate that a global variable is not currently being evaluated

Parameters:

binding - the global variable

saveGlobalVariableValue

public GroundedValue<?> saveGlobalVariableValue(GlobalVariable binding,
                                                GroundedValue<?> value)

Save the value of a global variable, and mark evaluation as complete.

Parameters:

binding - the global variable in question

value - the value that this thread has obtained by evaluating the variable

Returns:

the value actually given to the variable. Exceptionally this will be different from the supplied value if another thread has evaluated the same global variable concurrently. The returned value should be used in preference, to ensure that all threads agree on the value. They could be different if for example the variable is initialized using the collection() function.

getGlobalVariableValue

public GroundedValue<?> getGlobalVariableValue(GlobalVariable binding)

Get the value of a global variable

Parameters:

binding - the Binding that establishes the unique instance of the variable

Returns:

the Value of the variable if defined, null otherwise.

getGlobalVariable

public GroundedValue<?> getGlobalVariable(int slot)

Get the value of a global variable whose slot number is known

Parameters:

slot - the slot number of the required variable

Returns:

the Value of the variable if defined, null otherwise.

getGlobalVariables

public GroundedValue[] getGlobalVariables()

Get all the global variables, as an array. This is provided for use by debuggers. The meaning of the result can be determined by use of data held in the corresponding PackageData.

Returns:

the array of global variables.