org.exist.xquery
Class SimpleStep
java.lang.Object
org.exist.xquery.AbstractExpression
org.exist.xquery.Step
org.exist.xquery.SimpleStep
- All Implemented Interfaces:
- Expression
- public class SimpleStep
- extends Step
Represents a primary expression in a simple path step like
foo//$x. The class is mainly used to wrap variable references inside
a path expression.
- Author:
- Wolfgang Meier (wolfgang@exist-db.org)
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait |
SimpleStep
public SimpleStep(XQueryContext context,
int axis,
Expression expression)
- Parameters:
context
- axis
-
analyze
public void analyze(AnalyzeContextInfo contextInfo)
throws XPathException
- Description copied from interface:
Expression
- Statically analyze the expression and its subexpressions.
During the static analysis phase, the query engine can detect
unknown variables and some type errors.
- Specified by:
analyze
in interface Expression
- Overrides:
analyze
in class Step
- Throws:
XPathException
eval
public Sequence eval(Sequence contextSequence,
Item contextItem)
throws XPathException
- Description copied from interface:
Expression
- Evaluate the expression represented by this object.
Depending on the context in which this expression is executed,
either the context sequence, the context item or both of them may
be set. An implementing class should know how to handle this.
The general contract is as follows: if the
Dependency.CONTEXT_ITEM
bit is set in the bit field returned by Expression.getDependencies()
, the eval method will
be called once for every item in the context sequence. The contextItem
parameter will be set to the current item. Otherwise, the eval method will only be called
once for the whole context sequence and contextItem will be null.
eXist tries to process the entire context set in one, single step whenever
possible. Thus, most classes only expect context to contain a list of
nodes which represents the current context of the expression.
The position() function in XPath is an example for an expression,
which requires both, context sequence and context item to be set.
The context sequence might be a node set, a sequence of atomic values or a single
node or atomic value.
- Specified by:
eval
in interface Expression
- Specified by:
eval
in class Step
- Throws:
XPathException
resetState
public void resetState()
- Description copied from interface:
Expression
- Called to inform an expression that it should reset to its initial state.
All cached data in the expression object should be dropped. For example,
the document() function calls this method whenever the input document
set has changed.
- Specified by:
resetState
in interface Expression
- Overrides:
resetState
in class Step
setContextDocSet
public void setContextDocSet(DocumentSet contextSet)
- Specified by:
setContextDocSet
in interface Expression
- Overrides:
setContextDocSet
in class AbstractExpression
setPrimaryAxis
public void setPrimaryAxis(int axis)
- Specified by:
setPrimaryAxis
in interface Expression
- Overrides:
setPrimaryAxis
in class Step
Copyright (C) Wolfgang Meier. All rights reserved.