addExternalFunctionCallToPathMap
public PathMap.PathMapNodeSet addExternalFunctionCallToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodes)
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
by an expression in a source tree.
The default implementation of this method assumes that an expression does no navigation other than
the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the
same context as the containing expression. The method must be overridden for any expression
where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression,
and RootExpression (because they perform navigation), and for the doc(), document(), and collection()
functions because they create a new navigation root. Implementations also exist for PathExpression and
FilterExpression because they have subexpressions that are evaluated in a different context from the
calling expression.
pathMap
- the PathMap to which the expression should be addedpathMapNodes
- the node in the PathMap representing the focus at the point where this expression
is called. Set to null if this expression appears at the top level, in which case the expression, if it
is registered in the path map at all, must create a new path map root.
- the pathMapNode representing the focus established by this expression, in the case where this
expression is the first operand of a path expression or filter expression. For an expression that does
navigation, it represents the end of the arc in the path map that describes the navigation route. For other
expressions, it is the same as the input pathMapNode.
checkArgumentCount
protected int checkArgumentCount(int min,
int max,
ExpressionVisitor visitor)
throws XPathException
Check number of arguments.
A convenience routine for use in subclasses.
min
- the minimum number of arguments allowedmax
- the maximum number of arguments allowedvisitor
- an expression visitor
- the actual number of arguments
checkArguments
protected abstract void checkArguments(ExpressionVisitor visitor)
throws XPathException
Method supplied by each class of function to check arguments during parsing, when all
the argument expressions have been read
visitor
- the expression visitor
equals
public boolean equals(Object o)
Determine whether two expressions are equivalent
explain
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree
is written to the supplied output destination.
- explain in interface Expression
getArguments
public Expression[] getArguments()
Get the expressions supplied as actual arguments to the function
- the array of expressions supplied in the argument list of the function call
getDisplayName
public final String getDisplayName()
Get the name of the function for display in messages
- the name of the function as a lexical QName
getFunctionName
public StructuredQName getFunctionName()
Get the qualified of the function being called
getNumberOfArguments
public final int getNumberOfArguments()
Determine the number of actual arguments supplied in the function call
- the arity (the number of arguments)
hashCode
public int hashCode()
Get hashCode in support of equals() method
iterateSubExpressions
public Iterator iterateSubExpressions()
Get the immediate subexpressions of this expression
- iterateSubExpressions in interface Expression
optimize
public Expression optimize(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
Perform optimisation of an expression and its subexpressions.
This method is called after all references to functions and variables have been resolved
to the declaration of the function or variable, and after all type checking has been done.
- optimize in interface Expression
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
- the original expression, rewritten if appropriate to optimize execution
XPathException
- if an error is discovered during this phase
(typically a type error)
preEvaluate
public Expression preEvaluate(ExpressionVisitor visitor)
throws XPathException
Pre-evaluate a function at compile time. Functions that do not allow
pre-evaluation, or that need access to context information, can override this method.
visitor
- an expression visitor
- the result of the early evaluation, or the original expression, or potentially
a simplified expression
replaceSubExpression
public boolean replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression
- replaceSubExpression in interface Expression
original
- the original subexpressionreplacement
- the replacement subexpression
- true if the original subexpression is found
setArguments
public void setArguments(Expression[] args)
Method called by the expression parser when all arguments have been supplied
args
- the expressions contained in the argument list of the function call
setFunctionName
public final void setFunctionName(StructuredQName name)
Set the name of the function being called
name
- the name of the function
simplifyArguments
protected final Expression simplifyArguments(ExpressionVisitor visitor)
throws XPathException
Simplify the arguments of the function.
Called from the simplify() method of each function.
visitor
- an expression visitor
- the result of simplifying the arguments of the expression
toString
public String toString()
The toString() method for an expression attempts to give a representation of the expression
in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
- toString in interface Expression
typeCheck
public Expression typeCheck(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
Type-check the expression. This also calls preEvaluate() to evaluate the function
if all the arguments are constant; functions that do not require this behavior
can override the preEvaluate method.
- typeCheck in interface Expression