org.exist.xquery
Class PathExpr

java.lang.Object
  org.exist.xquery.AbstractExpression
      org.exist.xquery.PathExpr

All Implemented Interfaces:

CompiledXQuery, Expression, RewritableExpression, org.xmldb.api.base.CompiledExpression

Direct Known Subclasses:

BinaryOp, EnclosedExpr, Function, Predicate, RangeExpression, SequenceConstructor, UnaryExpr, XSLPathExpr

public class PathExpr
extends AbstractExpression
implements CompiledXQuery, org.xmldb.api.base.CompiledExpression, RewritableExpression

PathExpr is just a sequence of XQuery/XPath expressions, which will be called step by step.

Field Summary

protected boolean	inPredicate
protected boolean	keepVirtual
protected static org.apache.log4j.Logger	LOG
protected Expression	parent
protected boolean	staticContext
protected java.util.List<Expression>	steps

Fields inherited from class org.exist.xquery.AbstractExpression

column, context, contextDocSet, contextId, line, unordered

Fields inherited from interface org.exist.xquery.Expression

DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_NODE_CONSTRUCTOR, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NEED_INDEX_INFO, NO_CONTEXT_ID, NON_STREAMABLE, POSITIONAL_PREDICATE, SINGLE_STEP_EXECUTION, UNORDERED, USE_TREE_TRAVERSAL

Constructor Summary

PathExpr(XQueryContext context)

Method Summary

void	accept(ExpressionVisitor visitor) Start traversing the expression tree using the specified ExpressionVisitor.
void	add(Expression s) Add an arbitrary expression to this object's list of child-expressions.
void	add(PathExpr path) Add all the child-expressions from another PathExpr to this object's child-expressions.
void	addPath(PathExpr path) Add another PathExpr to this object's expression list.
void	addPredicate(Predicate pred) Add a predicate expression to the list of expressions.
boolean	allowMixNodesInReturn()
void	analyze(AnalyzeContextInfo contextInfo) Statically analyze the expression and its subexpressions.
void	dump(ExpressionDumper dumper) Write a diagnostic dump of the expression to the passed ExpressionDumper.
void	dump(java.io.Writer writer) Writes a diagnostic dump of the expression structure to the specified writer.
Sequence	eval(Sequence contextSequence, Item contextItem) Evaluate the expression represented by this object.
int	getCardinality() The default cardinality is Cardinality.EXACTLY_ONE.
int	getColumn()
XQueryContext	getContext()
int	getDependencies() Returns Dependency.DEFAULT_DEPENDENCIES.
DocumentSet	getDocumentSet()
Expression	getExpression(int pos)
Expression	getLastExpression()
int	getLength()
int	getLine()
java.lang.String	getLiteralValue()
Expression	getParent()
int	getPrimaryAxis()
Expression	getSubExpression(int pos)
int	getSubExpressionCount()
boolean	isValid() Is the compiled expression still valid? Returns false if, for example, the source code of one of the imported modules has changed.
void	replaceExpression(Expression oldExpr, Expression newExpr) Replace the given expression by a new expression.
void	replaceLastExpression(Expression s)
void	reset() Reset the compiled expression tree.
void	resetState(boolean postOptimization) Called to inform an expression that it should reset to its initial state.
int	returnsType() The static return type of the expression.
void	setContext(XQueryContext context)
void	setPrimaryAxis(int axis)
void	setUseStaticContext(boolean staticContext)
Expression	simplify()
java.lang.String	toString()

Methods inherited from class org.exist.xquery.AbstractExpression

eval, getContextDocSet, getContextId, getExpressionId, getSource, match, needsReset, setASTNode, setContextDocSet, setContextId, setLocation

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.exist.xquery.CompiledXQuery

eval, getSource

Field Detail

LOG

protected static final org.apache.log4j.Logger LOG

keepVirtual

protected boolean keepVirtual

steps

protected java.util.List<Expression> steps

staticContext

protected boolean staticContext

inPredicate

protected boolean inPredicate

parent

protected Expression parent

Constructor Detail

PathExpr

public PathExpr(XQueryContext context)

Method Detail

add

public void add(Expression s)

Add an arbitrary expression to this object's list of child-expressions.

Parameters:

s -

add

public void add(PathExpr path)

Add all the child-expressions from another PathExpr to this object's child-expressions.

Parameters:

path -

addPath

public void addPath(PathExpr path)

Add another PathExpr to this object's expression list.

Parameters:

path -

addPredicate

public void addPredicate(Predicate pred)

Add a predicate expression to the list of expressions. The predicate is added to the last expression in the list.

Parameters:

pred -

replaceExpression

public void replaceExpression(Expression oldExpr,
                              Expression newExpr)

Replace the given expression by a new expression.

Specified by:

replaceExpression in interface RewritableExpression

Parameters:

oldExpr - the old expression

newExpr - the new expression to replace the old

getParent

public Expression getParent()

Specified by:

getParent in interface Expression

Overrides:

getParent in class AbstractExpression

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

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 AbstractExpression

Parameters:

contextSequence - the current context sequence.

contextItem - a single item, taken from context. This defines the item, the expression should work on.

Throws:

XPathException

getContext

public XQueryContext getContext()

Specified by:

getContext in interface CompiledXQuery

Specified by:

getContext in interface Expression

Overrides:

getContext in class AbstractExpression

Returns:

the XQueryContext used to create this query

getDocumentSet

public DocumentSet getDocumentSet()

getExpression

public Expression getExpression(int pos)

getSubExpression

public Expression getSubExpression(int pos)

Specified by:

getSubExpression in interface Expression

Overrides:

getSubExpression in class AbstractExpression

getLastExpression

public Expression getLastExpression()

getLength

public int getLength()

getSubExpressionCount

public int getSubExpressionCount()

Specified by:

getSubExpressionCount in interface Expression

Overrides:

getSubExpressionCount in class AbstractExpression

allowMixNodesInReturn

public boolean allowMixNodesInReturn()

Specified by:

allowMixNodesInReturn in interface Expression

Overrides:

allowMixNodesInReturn in class AbstractExpression

setUseStaticContext

public void setUseStaticContext(boolean staticContext)

accept

public void accept(ExpressionVisitor visitor)

Description copied from interface: Expression

Start traversing the expression tree using the specified ExpressionVisitor.

Specified by:

accept in interface Expression

Overrides:

accept in class AbstractExpression

dump

public void dump(ExpressionDumper dumper)

Description copied from interface: Expression

Write a diagnostic dump of the expression to the passed ExpressionDumper.

Specified by:

dump in interface Expression

Parameters:

dumper - the expression dumper to write to

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

returnsType

public int returnsType()

Description copied from interface: Expression

The static return type of the expression. This method should return one of the type constants defined in class Type. If the return type cannot be determined statically, return Type.ITEM.

Specified by:

returnsType in interface Expression

Specified by:

returnsType in class AbstractExpression

getCardinality

public int getCardinality()

Description copied from class: AbstractExpression

The default cardinality is Cardinality.EXACTLY_ONE.

Specified by:

getCardinality in interface Expression

Overrides:

getCardinality in class AbstractExpression

getDependencies

public int getDependencies()

Description copied from class: AbstractExpression

Returns Dependency.DEFAULT_DEPENDENCIES.

Specified by:

getDependencies in interface Expression

Overrides:

getDependencies in class AbstractExpression

Returns:

set of bit-flags

See Also:

Expression.getDependencies()

replaceLastExpression

public void replaceLastExpression(Expression s)

getLiteralValue

public java.lang.String getLiteralValue()

getLine

public int getLine()

Specified by:

getLine in interface Expression

Overrides:

getLine in class AbstractExpression

getColumn

public int getColumn()

Specified by:

getColumn in interface Expression

Overrides:

getColumn in class AbstractExpression

setPrimaryAxis

public void setPrimaryAxis(int axis)

Specified by:

setPrimaryAxis in interface Expression

Overrides:

setPrimaryAxis in class AbstractExpression

getPrimaryAxis

public int getPrimaryAxis()

Specified by:

getPrimaryAxis in interface Expression

Overrides:

getPrimaryAxis in class AbstractExpression

resetState

public void resetState(boolean postOptimization)

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 xmldb:document() function calls this method whenever the input document set has changed.

Specified by:

resetState in interface Expression

Overrides:

resetState in class AbstractExpression

reset

public void reset()

Description copied from interface: CompiledXQuery

Reset the compiled expression tree. Discard all temporary expression results.

Specified by:

reset in interface CompiledXQuery

Specified by:

reset in interface org.xmldb.api.base.CompiledExpression

isValid

public boolean isValid()

Description copied from interface: CompiledXQuery

Is the compiled expression still valid? Returns false if, for example, the source code of one of the imported modules has changed.

Specified by:

isValid in interface CompiledXQuery

dump

public void dump(java.io.Writer writer)

Description copied from interface: CompiledXQuery

Writes a diagnostic dump of the expression structure to the specified writer.

Specified by:

dump in interface CompiledXQuery

setContext

public void setContext(XQueryContext context)

Specified by:

setContext in interface CompiledXQuery

simplify

public Expression simplify()

Specified by:

simplify in interface Expression

Overrides:

simplify in class AbstractExpression