Package org.basex.query.var

Enum VarUsage

java.lang.Object

java.lang.Enum<VarUsage>

org.basex.query.var.VarUsage

All Implemented Interfaces:

Serializable, Comparable<VarUsage>

public enum VarUsage
extends Enum<VarUsage>

A tri-state encoding the number of usages of a variable or context reference.

Author:

BaseX Team 2005-24, BSD License, Leo Woerteler

Enum Constant Summary

Enum Constants

Enum Constant	Description
MORE_THAN_ONCE	More than one usage.
NEVER	No usages.
ONCE	Exactly one usage.

Method Summary

Modifier and Type	Method	Description
VarUsage	max(VarUsage other)	Combines the usages for two alternative branches.
static VarUsage	maximum(Var var, Expr... exprs)	Checks how often a variable or context reference is used in any of the given expressions.
VarUsage	plus(VarUsage other)	Combines the usages for two expressions that are both executed.
static VarUsage	sum(Var var, Expr... exprs)	Checks how often a variable or context reference is accessed in all given expressions.
VarUsage	times(long count)	Number of usages if the code is executed count times.
static VarUsage	valueOf(String name)	Returns the enum constant of this type with the specified name.
static VarUsage[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

NEVER

public static final VarUsage NEVER

No usages.

ONCE

public static final VarUsage ONCE

Exactly one usage.

MORE_THAN_ONCE

public static final VarUsage MORE_THAN_ONCE

More than one usage.

Method Detail

values

public static VarUsage[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (VarUsage c : VarUsage.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static VarUsage valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

max

public VarUsage max(VarUsage other)

Combines the usages for two alternative branches.

Parameters:

other - usage count to be combined

Returns:

number of usages for the disjunction of both branches

plus

public VarUsage plus(VarUsage other)

Combines the usages for two expressions that are both executed.

Parameters:

other - usage count to be combined

Returns:

number of usages of both expressions combined

times

public VarUsage times(long count)

Number of usages if the code is executed count times.

Parameters:

count - number of executions (-1 if not known)

Returns:

number of usages

sum

public static VarUsage sum(Var var,
                           Expr... exprs)

Checks how often a variable or context reference is accessed in all given expressions.

Parameters:

var - variable (Var reference) or context (null) to inline

exprs - expressions

Returns:

number of accesses to the variable in all expressions combined

maximum

public static VarUsage maximum(Var var,
                               Expr... exprs)

Checks how often a variable or context reference is used in any of the given expressions.

Parameters:

var - variable (Var reference) or context (null) to inline

exprs - expressions

Returns:

maximum number of accesses in any given expression