org.exist.xquery
Class PathExpr

java.lang.Object
  extended byorg.exist.xquery.AbstractExpression
      extended byorg.exist.xquery.PathExpr
All Implemented Interfaces:
CompiledExpression, CompiledXQuery, Expression
Direct Known Subclasses:
BinaryOp, EnclosedExpr, Function, Predicate, SequenceConstructor, UnaryExpr

public class PathExpr
extends AbstractExpression
implements CompiledXQuery, CompiledExpression

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

Author:
Wolfgang Meier (wolfgang@exist-db.org)

Field Summary
 
Fields inherited from interface org.exist.xquery.Expression
DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NO_CONTEXT_ID, SINGLE_STEP_EXECUTION
 
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.
 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.
 XQueryAST getASTNode()
          Returns the XQueryAST node from which this expression has been constructed by the parser.
 int getCardinality()
          The default cardinality is Cardinality.EXACTLY_ONE.
 XQueryContext getContext()
           
 int getDependencies()
          Returns Dependency.DEFAULT_DEPENDENCIES.
 DocumentSet getDocumentSet()
           
 Expression getExpression(int pos)
           
 Expression getLastExpression()
           
 int getLength()
           
 java.lang.String getLiteralValue()
           
 XACMLSource getSource()
          Gets the source of this query.
 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 replaceLastExpression(Expression s)
           
 void reset()
          Reset the compiled expression tree.
 void resetState()
          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 setSource(XACMLSource source)
          Sets the source of this query.
 java.lang.String toString()
           
 
Methods inherited from class org.exist.xquery.AbstractExpression
eval, getContextDocSet, getContextId, getExpressionId, setASTNode, setContextDocSet
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.exist.xquery.CompiledXQuery
eval
 

Constructor Detail

PathExpr

public PathExpr(XQueryContext context)
Method Detail

setSource

public void setSource(XACMLSource source)
Description copied from interface: CompiledXQuery
Sets the source of this query.

Specified by:
setSource in interface CompiledXQuery
Parameters:
source - This query's source

getSource

public XACMLSource getSource()
Description copied from interface: CompiledXQuery
Gets the source of this query.

Specified by:
getSource in interface CompiledXQuery
Returns:
This query's source

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 -

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
Throws:
XPathException

getContext

public XQueryContext getContext()
Specified by:
getContext in interface CompiledXQuery
Returns:
the XQueryContext used to create this query

getDocumentSet

public DocumentSet getDocumentSet()

getExpression

public Expression getExpression(int pos)

getLastExpression

public Expression getLastExpression()

getLength

public int getLength()

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()

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
See Also:
Expression.getDependencies()

replaceLastExpression

public void replaceLastExpression(Expression s)

getLiteralValue

public java.lang.String getLiteralValue()

getASTNode

public XQueryAST getASTNode()
Description copied from interface: Expression
Returns the XQueryAST node from which this expression has been constructed by the parser. This node contains location information (line number and column) important for error reports.

Specified by:
getASTNode in interface Expression
Overrides:
getASTNode in class AbstractExpression

setPrimaryAxis

public void setPrimaryAxis(int axis)
Specified by:
setPrimaryAxis in interface Expression
Overrides:
setPrimaryAxis in class AbstractExpression

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 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

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


Copyright (C) Wolfgang Meier. All rights reserved.