com.izforge.izpack.util

Class OsConstraintHelper

java.lang.Object

com.izforge.izpack.util.OsConstraintHelper

public class OsConstraintHelper
extends Object

Encapsulates OS constraints specified on creation time and allows to check them against the current OS.

For example, this is used for <executable>s to check whether the executable is suitable for the current OS.

Author:

Olexij Tkatchenko

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	OsConstraintHelper.UnsatisfiableOsConstraintsException

Constructor Summary

Constructors

Constructor and Description
OsConstraintHelper()

Method Summary

Modifier and Type	Method and Description
static List<OsModel>	commonOsList(List<OsModel> osList, List<OsModel> otherOsList) Computes a list of constraints which satisfies both osList and otherOsList.
static List<OsModel>	getOsList(IXMLElement element) Extract a list of OS constraints from given element.
static String	toOsContraintsString(List<OsModel> osList) Converts list of OS constraints to a string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OsConstraintHelper

public OsConstraintHelper()

Method Detail

getOsList

public static List<OsModel> getOsList(IXMLElement element)

Extract a list of OS constraints from given element.

Parameters:

element - parent IXMLElement

Returns:

List of OsModel (or empty List if no constraints found)

commonOsList

public static List<OsModel> commonOsList(List<OsModel> osList,
                                         List<OsModel> otherOsList)
                                  throws OsConstraintHelper.UnsatisfiableOsConstraintsException

Computes a list of constraints which satisfies both osList and otherOsList. If the combination of osList and otherOsList is unsatisfiable, a respective exception is thrown.

The ideas of the algoritm are as follows:

• Each OsModel is treated as a logic formula containing only logical and operators, i.e., OS = (x64 && windows).
• Each list of OsModel-s is treated as a logic formula of OsModel formulas joined by logical or operator, i.e., F = OS-1 || OS-2.
• When combining two lists of -s, their combined formula is created as F = F-1 && F-2 = (OS-11 || ... OS-1n) && (OS-21 || ... OS-2m).
• The distributivity of logical and is used to combine the OS formulas directly (they contain only and-s). Thus, a list of new OS formulas is obtained that are only joined by logical or-s.

Parameters:

osList - list of OS constraints

otherOsList - other list of OS constraints

Returns:

list of OsModel-s which satisfies both osList and otherOsList

Throws:

OsConstraintHelper.UnsatisfiableOsConstraintsException - when both osList and otherOsList cannot be satisfied

toOsContraintsString

public static String toOsContraintsString(List<OsModel> osList)

Converts list of OS constraints to a string.

Parameters:

osList - list of OS constraints

Returns:

string representing osList