public final class PathExpression extends SlashExpression implements ContextMappingFunction
This class inherits from SlashExpression; it is used in the common case where the SlashExpression is known to return nodes rather than atomic values.
This class is not responsible for sorting the results into document order or removing duplicates. That is done by a DocumentSorter expression which is wrapped around the path expression. However, this class does contain the logic for deciding statically whether the DocumentSorter is needed or not.
start, step
EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD
Constructor and Description |
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PathExpression(Expression start,
Expression step)
Constructor
|
Modifier and Type | Method and Description |
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(package private) Expression |
addDocumentSorter()
Add a document sorting node to the expression tree, if needed
|
int |
computeSpecialProperties()
Get the static properties of this expression (other than its type).
|
Expression |
copy()
Copy an expression.
|
void |
explain(ExpressionPresenter destination)
Diagnostic print of expression structure.
|
String |
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.
|
Expression |
getRemainingSteps()
Get all steps after the first.
|
boolean |
isAbsolute(TypeHierarchy th)
Test whether a path expression is an absolute path - that is, a path whose first step selects a
document node
|
boolean |
isHybrid()
Determine whether this expression is capable (as far as static analysis is concerned)
of returning a mixture of nodes and atomic values.
|
SequenceIterator |
iterate(XPathContext context)
Iterate the path-expression in a given context
|
Expression |
optimize(ExpressionVisitor visitor,
ItemType contextItemType)
Optimize the expression and perform type analysis
|
Expression |
promote(PromotionOffer offer,
Expression parent)
Promote this expression if possible
|
Expression |
simplify(ExpressionVisitor visitor)
Simplify an expression
|
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.
|
PathExpression |
tryToMakeAbsolute(TypeHierarchy th)
Test whether a path expression is an absolute path - that is, a path whose first step selects a
document node; if not, see if it can be converted to an absolute path.
|
Expression |
typeCheck(ExpressionVisitor visitor,
ItemType contextItemType)
Perform type analysis
|
addToPathMap, computeCardinality, computeDependencies, equals, getControlledExpression, getControllingExpression, getFirstStep, getItemType, getLastStep, getLeadingSteps, hashCode, hasLoopingSubexpression, iterateSameFocusSubExpressions, iterateSubExpressions, map, promoteFocusIndependentSubexpressions, replaceSubExpression, setStartExpression, setStepExpression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
map
public PathExpression(Expression start, Expression step)
start
- A node-set expression denoting the absolute or relative set of nodes from which the
navigation path should start.step
- The step to be followed from each node in the start expression to yield a new
node-setpublic boolean isHybrid()
SlashExpression
isHybrid
in class SlashExpression
Expression addDocumentSorter()
public Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify
in class SlashExpression
visitor
- the expression visitorXPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
typeCheck
in class SlashExpression
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
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
optimize
in class SlashExpression
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
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
promote
in class SlashExpression
offer
- details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expressionXPathException
- if any error is detectedpublic Expression copy()
copy
in class SlashExpression
public int computeSpecialProperties()
computeSpecialProperties
in class SlashExpression
public Expression getRemainingSteps()
getRemainingSteps
in class SlashExpression
public boolean isAbsolute(TypeHierarchy th)
th
- the type hierarchy cachepublic PathExpression tryToMakeAbsolute(TypeHierarchy th)
th
- the type hierarchy cachepublic SequenceIterator iterate(XPathContext context) throws XPathException
iterate
in interface SequenceIterable
iterate
in class SlashExpression
context
- the evaluation contextXPathException
- if any dynamic error occurs evaluating the
expressionpublic String toString()
toString
in class SlashExpression
public String getExpressionName()
getExpressionName
in class Expression
public void explain(ExpressionPresenter destination)
explain
in class SlashExpression
destination
- the expression presenter used to display the structure