org.apache.xpath
Class VariableStack

java.lang.Object
  |
  +--java.util.AbstractCollection
        |
        +--java.util.AbstractList
              |
              +--java.util.Vector
                    |
                    +--java.util.Stack
                          |
                          +--org.apache.xpath.VariableStack

public class VariableStack

extends java.util.Stack

**For internal use only** Defines a class to keep track of a stack for template arguments and variables. The VariableStack extends Stack, and each element in the stack is a stack frame, i.e. a Stack itself. The zero element is the global stack frame. Note: Someone recently made the suggestion that the globals should not be kept at the bottom of the stack, but should be implemented in a hash table.

See Also:

Serialized Form

Constructor Summary

VariableStack()
Constructor for a variable stack.

Method Summary

int	getContextPos() Get the current context position.
Arg	getParamArg(QName qname) Get the variable argument.
int	getSearchStart() Get the position to start the search, or -1 if the search should start from the top.
int	getSearchStartOrTop() Get the position from where the search should start, which is either the searchStart property, or the top of the stack if that value is -1.
XObject	getVariable(XPathContext xctxt, QName name) Given a name, return an object representing the value.
void	markGlobalStackFrame() Mark the top of the global stack frame.
void	popContextPosition() Pop the current context position onto the contextPositions.
void	popCurrentContext() Pop the current context from the current context stack.
void	popElemFrame() Pop the current context from the current context stack.
void	pushContextMarker() Push the current top of the stack as a context marker into the variables stack to let us know when to stop searching for a var.
void	pushContextPosition(int pos) Push a context marker onto the contextPositions stack to let us know when to stop searching for a var.
void	pushElemFrame() Push an argument onto the stack.
void	pushOrReplaceVariable(QName qname, XObject xval) Push an argument onto the stack, or replace it if it already exists.
void	pushVariable(QName qname, XObject val) Push an argument onto the stack.
void	pushVariableArg(Arg arg) Push an argument onto the stack.
void	remarkParams() Re-mark the variables in the current frame as all being parameters.
void	setSearchStart(int startPos) Set where to start the current search for a variable.
boolean	variableIsDeclared(QName qname) Tell if a variable or parameter is already declared, either in the current context or in the global space.

Methods inherited from class java.util.Stack

empty, peek, pop, push, search

Methods inherited from class java.util.Vector

add, add, addAll, addAll, addElement, capacity, clear, clone, contains, containsAll, copyInto, elementAt, elements, ensureCapacity, equals, firstElement, get, hashCode, indexOf, indexOf, insertElementAt, isEmpty, lastElement, lastIndexOf, lastIndexOf, remove, remove, removeAll, removeAllElements, removeElement, removeElementAt, retainAll, set, setElementAt, setSize, size, subList, toArray, toArray, toString, trimToSize

Methods inherited from class java.util.AbstractList

iterator, listIterator, listIterator

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

VariableStack

public VariableStack()

Constructor for a variable stack.

Method Detail

setSearchStart

public void setSearchStart(int startPos)

Set where to start the current search for a variable. If this is -1, the search should start at the top of the stack.

Parameters:

startPos - The position to start the search, or -1 if the search should start from the top.

getSearchStartOrTop

public int getSearchStartOrTop()

Get the position from where the search should start, which is either the searchStart property, or the top of the stack if that value is -1.

Returns:

The position from where the search should start, which is always greater than or equal to zero.

getSearchStart

public int getSearchStart()

Get the position to start the search, or -1 if the search should start from the top.

Returns:

The position to start the search, or -1 if the search should start from the top.

markGlobalStackFrame

public void markGlobalStackFrame()

Mark the top of the global stack frame.

pushContextPosition

public void pushContextPosition(int pos)

Push a context marker onto the contextPositions stack to let us know when to stop searching for a var. This operation usually corresponds to the start of a template.

popContextPosition

public void popContextPosition()

Pop the current context position onto the contextPositions. This operation usually corresponds to the ending of a template.

getContextPos

public int getContextPos()

Get the current context position.

Returns:

The context marker into the stack to let us know when to stop searching for a var.

pushContextMarker

public void pushContextMarker()

Push the current top of the stack as a context marker into the variables stack to let us know when to stop searching for a var. This operation usually corresponds to the start of a template.

popCurrentContext

public void popCurrentContext()

Pop the current context from the current context stack.

pushOrReplaceVariable

public void pushOrReplaceVariable(QName qname,
                                  XObject xval)

Push an argument onto the stack, or replace it if it already exists. Don't forget to call startContext before pushing a series of arguments for a given macro call.

Parameters:

qname - The qualified name of the variable.

val - The wrapped value of the variable.

remarkParams

public void remarkParams()

Re-mark the variables in the current frame as all being parameters.

pushVariable

public void pushVariable(QName qname,
                         XObject val)

Push an argument onto the stack. Don't forget to call startContext before pushing a series of arguments for a given macro call.

Parameters:

qname - The qualified name of the variable.

val - The wrapped value of the variable.

pushVariableArg

public void pushVariableArg(Arg arg)

Push an argument onto the stack. Don't forget to call startContext before pushing a series of arguments for a given macro call.

Parameters:

arg - The variable argument.

variableIsDeclared

public boolean variableIsDeclared(QName qname)
                           throws TransformerException

Tell if a variable or parameter is already declared, either in the current context or in the global space.

Parameters:

qname - The qualified name of the variable.

Returns:

true if the variable is already declared.

Throws:

TransformerException -

getParamArg

public Arg getParamArg(QName qname)
                throws TransformerException

Get the variable argument.

Parameters:

qname - The qualified name of the variable.

Returns:

the argument object.

Throws:

TransformerException -

getVariable

public XObject getVariable(XPathContext xctxt,
                           QName name)
                    throws TransformerException

Given a name, return an object representing the value.

Parameters:

qname - The qualified name of the variable.

Returns:

The wrapped value of the variable.

Throws:

TransformerException -

pushElemFrame

public void pushElemFrame()

Push an argument onto the stack. Don't forget to call startContext before pushing a series of arguments for a given macro call.

popElemFrame

public void popElemFrame()

Pop the current context from the current context stack.