Defines a class to keep track of a stack for
template arguments and variables.
This has been changed from the previous incarnations of this
class to be fairly low level.
clearLocalSlots
public void clearLocalSlots(int start,
int len)
Use this to clear the variables in a section of the stack. This is
used to clear the parameter section of the stack, so that default param
values can tell if they've already been set. It is important to note that
this function has a 1K limitation.
start
- The start position, relative to the current local stack frame.len
- The number of slots to be cleared.
clone
public Object clone()
throws CloneNotSupportedException
Returns a clone of this variable stack.
- a clone of this variable stack.
elementAt
public XObject elementAt(int i)
Get the element at the given index, regardless of stackframe.
i
- index from zero.
- The item at the given index.
getGlobalVariable
public XObject getGlobalVariable(XPathContext xctxt,
int index)
throws TransformerException
Get a global variable or parameter from the global stack frame.
xctxt
- The XPath context, which must be passed in order to
lazy evaluate variables.index
- Global variable index relative to the global stack
frame bottom.
- The value of the variable.
TransformerException
-
getGlobalVariable
public XObject getGlobalVariable(XPathContext xctxt,
int index,
boolean destructiveOK)
throws TransformerException
Get a global variable or parameter from the global stack frame.
xctxt
- The XPath context, which must be passed in order to
lazy evaluate variables.index
- Global variable index relative to the global stack
frame bottom.
- The value of the variable.
TransformerException
-
getLocalVariable
public XObject getLocalVariable(int index,
int frame)
throws TransformerException
Get a local variable or parameter in the current stack frame.
index
- Local variable index relative to the given
frame bottom.
NEEDSDOC @param frame
- The value of the variable.
TransformerException
-
getLocalVariable
public XObject getLocalVariable(XPathContext xctxt,
int index)
throws TransformerException
Get a local variable or parameter in the current stack frame.
xctxt
- The XPath context, which must be passed in order to
lazy evaluate variables.index
- Local variable index relative to the current stack
frame bottom.
- The value of the variable.
TransformerException
-
getLocalVariable
public XObject getLocalVariable(XPathContext xctxt,
int index,
boolean destructiveOK)
throws TransformerException
Get a local variable or parameter in the current stack frame.
xctxt
- The XPath context, which must be passed in order to
lazy evaluate variables.index
- Local variable index relative to the current stack
frame bottom.
- The value of the variable.
TransformerException
-
getStackFrame
public int getStackFrame()
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.
- The current stack frame position.
getVariableOrParam
public XObject getVariableOrParam(XPathContext xctxt,
QName qname)
throws TransformerException
Get a variable based on it's qualified name.
This is for external use only.
xctxt
- The XPath context, which must be passed in order to
lazy evaluate variables.qname
- The qualified name of the variable.
- The evaluated value of the variable.
TransformerException
-
isLocalSet
public boolean isLocalSet(int index)
throws TransformerException
Tell if a local variable has been set or not.
index
- Local variable index relative to the current stack
frame bottom.
- true if the value at the index is not null.
TransformerException
-
link
public int link(int size)
Allocates memory (called a stackframe) on the stack; used to store
local variables and parameter arguments.
I use the link/unlink concept because of distant
Motorola 68000 assembler memories.
size
- The size of the stack frame allocation. This ammount should
normally be the maximum number of variables that you can have allocated
at one time in the new stack frame.
- The bottom of the stack frame, from where local variable addressing
should start from.
reset
public void reset()
Reset the stack to a start position.
setGlobalVariable
public void setGlobalVariable(int index,
XObject val)
Set a global variable or parameter in the global stack frame.
index
- Local variable index relative to the global stack frame
bottom.val
- The value of the variable that is being set.
setLocalVariable
public void setLocalVariable(int index,
XObject val)
Set a local variable or parameter in the current stack frame.
index
- Local variable index relative to the current stack
frame bottom.val
- The value of the variable that is being set.
setLocalVariable
public void setLocalVariable(int index,
XObject val,
int stackFrame)
Set a local variable or parameter in the specified stack frame.
index
- Local variable index relative to the current stack
frame bottom.
NEEDSDOC @param stackFrameval
- The value of the variable that is being set.
setStackFrame
public void setStackFrame(int sf)
Set the current stack frame.
sf
- The new stack frame position.
size
public int size()
Get size of the stack.
- the total size of the execution stack.
unlink
public void unlink()
Free up the stack frame that was last allocated with
link(int size)
.
unlink
public void unlink(int currentFrame)
Free up the stack frame that was last allocated with
link(int size)
.
currentFrame
- The current frame to set to
after the unlink.