org.basex.query.path
Class AxisPath

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.expr.Expr
          org.basex.query.path.Path
              org.basex.query.path.AxisPath

Direct Known Subclasses:

IterPath

public class AxisPath
extends Path

Axis Path expression.

Author:

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

Nested Class Summary

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

Expr.Use

Field Summary

Step[]

step Expression list.

Fields inherited from class org.basex.query.path.Path

root

Method Summary

AxisPath	addPred(Expr pred) Adds a predicate to the last step.
Expr	addText(QueryContext ctx) Optionally adds a text node to an expression for potential index rewriting.
Expr	comp(QueryContext ctx) Optimizes and compiles the expression.
static AxisPath	get(Expr r, Step... st) Constructor.
AxisPath	invertPath(Expr r, Step curr) Inverts a location path.
Iter	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.
boolean	removable(Var v, QueryContext ctx) Checks if the specified variable is removable.
Expr	remove(Var v) Removes the specified variable in a sub expression.
Return	returned(QueryContext ctx) Indicates the return type of an expression.
boolean	sameAs(Expr cmp) Checks the current and specified expression for equality.
long	size(QueryContext ctx) Returns the sequence size or 1.
String	toString()
boolean	uses(Expr.Use u, QueryContext ctx) Indicates if an expression uses the specified type.

Methods inherited from class org.basex.query.path.Path

color, toString

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

atomic, checkCtx, checkDbl, checkItr, duplicates, e, ebv, i, indexAccessible, indexEquivalent, 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

step

public Step[] step

Expression list.

Method Detail

get

public static final AxisPath get(Expr r,
                                 Step... st)

Constructor.

Parameters:

r - root expression; can be null

st - location steps; will at least have one entry

Returns:

class instance

comp

public final Expr comp(QueryContext ctx)
                throws QueryException

Description copied from class: Expr

Optimizes and compiles the expression.

Overrides:

comp in class Path

Parameters:

ctx - query context

Returns:

optimized Expression

Throws:

QueryException - query exception

iter

public Iter 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

size

public final long size(QueryContext ctx)

Description copied from class: Expr

Returns the sequence size or 1.

Overrides:

size in class Expr

Parameters:

ctx - query context

Returns:

result of check

invertPath

public final AxisPath invertPath(Expr r,
                                 Step curr)

Inverts a location path.

Parameters:

r - new root node

curr - current location step

Returns:

inverted path

addPred

public final AxisPath addPred(Expr pred)

Adds a predicate to the last step.

Parameters:

pred - predicate to be added

Returns:

resulting path instance

addText

public final Expr addText(QueryContext ctx)
                   throws QueryException

Description copied from class: Expr

Optionally adds a text node to an expression for potential index rewriting.

Overrides:

addText in class Expr

Parameters:

ctx - query context

Returns:

expression

Throws:

QueryException - query exception

uses

public final boolean uses(Expr.Use u,
                          QueryContext ctx)

Description copied from class: Expr

Indicates if an expression uses the specified type. Called by the compiler to perform certain optimizations. true is returned by default and thus assumed as "worst-case".

Specified by:

uses in class Expr

Parameters:

u - use type to be checked

ctx - query context

Returns:

result of check

removable

public final boolean removable(Var v,
                               QueryContext ctx)

Description copied from class: Expr

Checks if the specified variable is removable.

Overrides:

removable in class Expr

Parameters:

v - variable to be removed

ctx - query context

Returns:

result of check

remove

public final Expr remove(Var v)

Description copied from class: Expr

Removes the specified variable in a sub expression.

Overrides:

remove in class Path

Parameters:

v - variable to be removed

Returns:

expression with removed variable

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

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

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.

Specified by:

plan in class ExprInfo

Parameters:

ser - serializer

Throws:

IOException - I/O exception

toString

public final String toString()

Specified by:

toString in class ExprInfo