net.sf.saxon.trans

Interface GlobalVariableManager

All Known Implementing Classes:

PrincipalStylesheetModule

public interface GlobalVariableManager

This interface provides access to a collection of global variables. This abstraction is used by the optimizer to handle the rather different ways that global variables are managed in XSLT and XQuery, as a result of XSLT packaging.

Method Summary

Modifier and Type	Method and Description
void	addGlobalVariable(GlobalVariable variable) Add a global variable to the collection
GlobalVariable	getEquivalentVariable(Expression select) Get an existing global variable whose initializer is a given expression, if there is one.

Method Detail

getEquivalentVariable

GlobalVariable getEquivalentVariable(Expression select)

Get an existing global variable whose initializer is a given expression, if there is one. Note that this depends on the logic for detecting equivalence of expressions, which is necessarily approximate. Expressions with dependencies on the static context should never be considered equivalent. If no equivalent global variable is found, return null. An implementation can always return null if it wants to avoid a lengthy search.

Returns:

an existing global variable with the same select expression, if one can be found; otherwise null.

addGlobalVariable

void addGlobalVariable(GlobalVariable variable)
                throws XPathException

Add a global variable to the collection

Parameters:

variable - the variable to be added

Throws:

XPathException - if errors occur (some implementations of the method have side-effects, such as causing the variable declaration to be compiled)