net.sf.saxon.expr
Class ContextItemExpression
- EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator
public class ContextItemExpression
This class represents the expression "(dot)", which always returns the context item.
This may be a AtomicValue or a Node.
addToPathMap , adoptChildExpression , checkPermittedContents , computeCardinality , computeDependencies , computeSpecialProperties , computeStaticProperties , copy , display , doPromotion , dynamicError , effectiveBooleanValue , evaluateAsString , evaluateItem , explain , explain , findParentOf , getCardinality , getColumnNumber , getConstructType , getContainer , getDependencies , getExecutable , getHostLanguage , getImplementationMethod , getInstructionInfo , getIntrinsicDependencies , getItemType , getLineNumber , getLocationId , getLocationProvider , getPublicId , getSlotsUsed , getSpecialProperties , getSystemId , hasLoopingSubexpression , implementsStaticTypeCheck , iterate , iterateEvents , iterateSubExpressions , markTailFunctionCalls , optimize , process , promote , replaceSubExpression , resetLocalStaticProperties , setContainer , setFiltered , setFlattened , setLocationId , simplify , staticTypeCheck , suppressValidation , toString , typeCheck , typeError |
ContextItemExpression
public ContextItemExpression()
Create the expression
addToPathMap
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodeSet)
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.
- addToPathMap in interface Expression
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the PathMapNodeSet to which the paths embodied in this expression should be added
- the pathMapNodeSet representing the points in the source document that are both reachable by this
expression, and that represent possible results of this 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.
copy
public Expression copy()
Create a clone copy of this expression
- copy in interface Expression
- a copy of this expression
equals
public boolean equals(Object other)
Is this expression the same as another expression?
explain
public void explain(ExpressionPresenter destination)
Diagnostic print of expression structure. The abstract expression tree
is written to the supplied output destination.
- explain in interface Expression
getErrorCodeForUndefinedContext
protected String getErrorCodeForUndefinedContext()
getIntrinsicDependencies
public int getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived
from the dependencies of its subexpressions. For example, position() has an intrinsic dependency
on the context position, while (position()+1) does not. The default implementation
of the method returns 0, indicating "no dependencies".
- getIntrinsicDependencies in interface Expression
- a set of bit-significant flags identifying the "intrinsic"
dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
hashCode
public int hashCode()
get HashCode for comparing two expressions
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)
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