org.basex.query.xquery.path
Class Step

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.xquery.expr.Expr
          org.basex.query.xquery.expr.Arr
              org.basex.query.xquery.path.Step

Direct Known Subclasses:

IterStep, SimpleIterStep

public class Step
extends Arr

Location Step expression.

Author:

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

Nested Class Summary

Nested classes/interfaces inherited from class org.basex.query.xquery.expr.Expr

Expr.Return, Expr.Using

Field Summary

Axis	axis Axis.
Test	test Node test.

Fields inherited from class org.basex.query.xquery.expr.Arr

expr

Constructor Summary

Step(Axis a, Test t, Expr[] p)
Constructor.

Method Summary

Expr	comp(XQContext ctx) Optimizes and compiles the expression.
NodeIter	iter(XQContext ctx) Evaluates the expression and returns an iterator on the resulting items.
void	plan(Serializer ser) Recursively sends the abstract syntax of this expression to the specified serializer.
Type	returned() Indicates if an expression returns the specified type.
boolean	simple(Axis ax) Checks if this is a simple axis (node test, no predicates).
java.lang.String	toString()
boolean	uses(Expr.Using u) Indicates if an expression uses the specified type.

Methods inherited from class org.basex.query.xquery.expr.Expr

e, i

Methods inherited from class org.basex.query.ExprInfo

color, info, name

Methods inherited from class java.lang.Object

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

Field Detail

axis

public Axis axis

Axis.

test

public Test test

Node test.

Constructor Detail

Step

public Step(Axis a,
            Test t,
            Expr[] p)

Constructor.

Parameters:

a - axis

t - node test

p - predicates

Method Detail

comp

public Expr comp(XQContext ctx)
          throws XQException

Description copied from class: Expr

Optimizes and compiles the expression.

Overrides:

comp in class Arr

Parameters:

ctx - query context

Returns:

optimized Expression

Throws:

XQException - evaluation exception

iter

public NodeIter iter(XQContext ctx)
              throws XQException

Description copied from class: Expr

Evaluates the expression and returns an iterator on the resulting items.

Specified by:

iter in class Expr

Parameters:

ctx - query context

Returns:

resulting item

Throws:

XQException - evaluation exception

simple

public boolean simple(Axis ax)

Checks if this is a simple axis (node test, no predicates).

Parameters:

ax - axis to be checked

Returns:

result of check

uses

public boolean uses(Expr.Using u)

Description copied from class: Expr

Indicates if an expression uses the specified type. Called by the compiler to check if expressions can be reformulated. true is returned by default.

Overrides:

uses in class Arr

Parameters:

u - using flag

Returns:

result of check

returned

public Type returned()

Description copied from class: Expr

Indicates if an expression returns the specified type. Called by the compiler to check if expressions can be reformulated. null is returned by default.

Overrides:

returned in class Arr

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.

Overrides:

plan in class Arr

Parameters:

ser - serializer

Throws:

java.io.IOException - exception

toString

public java.lang.String toString()

Specified by:

toString in class ExprInfo