org.basex.query.path
Class Step

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

Direct Known Subclasses:

IterStep, SimpleIterStep

public class Step
extends Preds

Location Step expression.

Author:

Workgroup DBIS, University of Konstanz 2005-10, ISC License, Christian Gruen

Nested Class Summary

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

Expr.Use

Field Summary

Axis	axis Axis.
Test	test Node test.

Fields inherited from class org.basex.query.expr.Preds

pred

Method Summary

Expr	comp(QueryContext ctx) Optimizes and compiles the expression.
static Step	get(Axis a, Test t, Expr... p) This method creates a step instance.
NodeIter	iter(QueryContext 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.
Return	returned(QueryContext ctx) Indicates the return type of an expression.
boolean	sameAs(Expr cmp) Checks the current and specified expression for equality.
boolean	simple(Axis ax, boolean name) Checks if this is a simple axis without predicates.
String	toString()

Methods inherited from class org.basex.query.expr.Preds

color, removable, remove, uses

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

addText, atomic, checkCtx, checkDbl, checkItr, duplicates, e, ebv, i, indexAccessible, indexEquivalent, size, test, v

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

Field Detail

axis

public Axis axis

Axis.

test

public Test test

Node test.

Method Detail

get

public static Step get(Axis a,
                       Test t,
                       Expr... p)

This method creates a step instance.

Parameters:

a - axis

t - node test

p - predicates

Returns:

step

comp

public Expr comp(QueryContext ctx)
          throws QueryException

Description copied from class: Expr

Optimizes and compiles the expression.

Overrides:

comp in class Preds

Parameters:

ctx - query context

Returns:

optimized Expression

Throws:

QueryException - query exception

iter

public NodeIter iter(QueryContext ctx)
              throws QueryException

Description copied from class: Expr

Evaluates the expression and returns an iterator on the resulting items. If this method is not overwritten, Expr.atomic(org.basex.query.QueryContext) must be implemented.

Overrides:

iter in class Expr

Parameters:

ctx - query context

Returns:

resulting item

Throws:

QueryException - query exception

simple

public final boolean simple(Axis ax,
                            boolean name)

Checks if this is a simple axis without predicates.

Parameters:

ax - axis to be checked

name - name/node test

Returns:

result of check

sameAs

public final boolean sameAs(Expr cmp)

Description copied from class: Expr

Checks the current and specified expression for equality.

Overrides:

sameAs in class Expr

Parameters:

cmp - expression to be compared

Returns:

result of check

returned

public final Return returned(QueryContext ctx)

Description copied from class: Expr

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

Overrides:

returned in class Expr

Parameters:

ctx - query context

Returns:

result of check

plan

public final void plan(Serializer ser)
                throws IOException

Description copied from class: ExprInfo

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

Overrides:

plan in class Preds

Parameters:

ser - serializer

Throws:

IOException - I/O exception

toString

public final String toString()

Overrides:

toString in class Preds