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java.lang.Objectnet.sf.saxon.expr.Expression
net.sf.saxon.expr.SlashExpression
net.sf.saxon.expr.SimpleStepExpression
public final class SimpleStepExpression
An SimpleStepExpression is a special case of a SlashExpression in which the start expression selects a single item (or nothing), and the step expression is a simple AxisExpression. This is designed to avoid the costs of creating a new dynamic context for expressions (common in XQuery) such as for $b in EXPR return $b/title
| Field Summary |
|---|
| Fields inherited from class net.sf.saxon.expr.Expression |
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EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD |
| Constructor Summary | |
|---|---|
SimpleStepExpression(Expression start,
Expression step)
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| Method Summary | |
|---|---|
Expression |
copy()
Copy an expression. |
SequenceIterator |
iterate(XPathContext context)
Evaluate the expression, returning an iterator over the result |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression |
| Methods inherited from class java.lang.Object |
|---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
| Constructor Detail |
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public SimpleStepExpression(Expression start,
Expression step)
| Method Detail |
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public Expression typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
throws XPathException
SlashExpression
typeCheck in class SlashExpressionvisitor - 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,
ExpressionVisitor.ContextItemType contextItemType)
throws XPathException
ExpressionThis 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 class SlashExpressionvisitor - 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 copy()
copy in class SlashExpression
public SequenceIterator iterate(XPathContext context)
throws XPathException
iterate in class SlashExpressioncontext - the evaluation context
XPathException - if any dynamic error occurs evaluating the
expression
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