org.basex.query.xpath.locpath
Class Preds

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.xpath.locpath.Preds

public final class Preds
extends ExprInfo

Location Steps.

Author:

Workgroup DBIS, University of Konstanz 2005-08, ISC License, Christian Gruen

Constructor Summary

Preds()

Method Summary

void	add(Expr expr) Adds an expression as predicate.
void	add(Pred pred) Adds a predicate.
java.lang.String	color() Returns a string description of the expression.
boolean	compile(XPContext ctx) Optimizes the predicates.
void	eval(XPContext ctx, NodeBuilder nodes, NodeBuilder result) Evaluates the predicates.
Pred	get(int i) Returns a predicate.
void	plan(Serializer ser) Recursively sends the abstract syntax of this expression to the specified serializer.
void	remove(int s) Removes the specified step.
boolean	sameAs(Preds cmp) Returns the predicates for equality.
int	size() Returns the number of location steps.
java.lang.String	toString()
boolean	usesPos() Checks whether the predicates make use of the position parameter.
boolean	usesSetSize() Checks whether the predicates make use of the size parameter.

Methods inherited from class org.basex.query.ExprInfo

info, name

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Preds

public Preds()

Method Detail

size

public int size()

Returns the number of location steps.

Returns:

number of steps

get

public Pred get(int i)

Returns a predicate.

Parameters:

i - predicate offset

Returns:

predicate

add

public void add(Pred pred)

Adds a predicate.

Parameters:

pred - predicate to be added

remove

public void remove(int s)

Removes the specified step.

Parameters:

s - step index

add

public void add(Expr expr)

Adds an expression as predicate.

Parameters:

expr - expression to be added

eval

public void eval(XPContext ctx,
                 NodeBuilder nodes,
                 NodeBuilder result)
          throws QueryException

Evaluates the predicates.

Parameters:

ctx - query context

nodes - nodes to be evaluated

result - result nodes

Throws:

QueryException - evaluation exception

compile

public boolean compile(XPContext ctx)
                throws QueryException

Optimizes the predicates.

Parameters:

ctx - query context

Returns:

false if predicate always yields false

Throws:

QueryException - evaluation exception

usesPos

public boolean usesPos()

Checks whether the predicates make use of the position parameter.

Returns:

whether position is used

usesSetSize

public boolean usesSetSize()

Checks whether the predicates make use of the size parameter.

Returns:

whether node set size is used

sameAs

public boolean sameAs(Preds cmp)

Returns the predicates for equality.

Parameters:

cmp - predicates to be compared

Returns:

result of check

plan

public void plan(Serializer ser)
          throws java.io.IOException

Description copied from class: ExprInfo

Recursively sends the abstract syntax of this expression to the specified serializer.

Specified by:

plan in class ExprInfo

Parameters:

ser - serializer

Throws:

java.io.IOException - exception

color

public java.lang.String color()

Description copied from class: ExprInfo

Returns a string description of the expression. Contrary to the ExprInfo.toString() method, the current expressions aren't included in the output.

Overrides:

color in class ExprInfo

Returns:

result of check

toString

public java.lang.String toString()

Specified by:

toString in class ExprInfo