vec_math
Class BooleanParser

java.lang.Object
  vec_math.BooleanParser

public class BooleanParser
extends Object

A class providing arithmetics for booleans. Operators used are (sorted for precedence):

• (): Precedence shift.
• ~:boolean NOT.
• &:boolean AND.
• ^:boolean XOR.
• |:boolean OR.

Only two values of the operands are allowed, true and false. If a string obeying the above rules is passed to the class's #valueOf method, it is parsed and the reslut, true or false is returned. Parsing errors result in a ParseException to be thrown. Please note that a ParseException is not a runtime exception, therefore it must be caught in calling routines.

Nested Class Summary

static class

BooleanParser.Test Mainly test purpose.

Field Summary

private static List<Operator<String>>

valid All valid operators.

Constructor Summary

BooleanParser()

Method Summary

static Boolean	evaluateBoolean(String expression) Parses the node and returns the expression as a Boolean object.
private static String	evaluateNode(Node<String> root) Evaluates a node.
private static String	evaluateSingle(Operator<String> tie, String left, String right) Evaluates a single boolean expression.
protected static List<Operator<String>>	getValid() Returns all valid operator in this parsers context.
static String	parseBoolean(String expression) Parses the given string to obtain a single boolean value.

Methods inherited from class java.lang.Object

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

Field Detail

valid

private static final List<Operator<String>> valid

All valid operators.

Constructor Detail

BooleanParser

public BooleanParser()

Method Detail

parseBoolean

public static String parseBoolean(String expression)
                           throws ParseException

Parses the given string to obtain a single boolean value. Note that no variables are allowed within the String. Presedence of the operators follows JAVA standard rules and can be altered with parentheses.

Parameters:

expression - A String combining boolean constants

Throws:

ParseException - If the argument does not obey the specified grammar.

evaluateBoolean

public static Boolean evaluateBoolean(String expression)
                               throws ParseException

Parses the node and returns the expression as a Boolean object.

Throws:

ParseException

getValid

protected static List<Operator<String>> getValid()

Returns all valid operator in this parsers context.

evaluateNode

private static String evaluateNode(Node<String> root)
                            throws ParseException

Evaluates a node. Branches recursevely into sub-nodes until all dependencies are removed.

Throws:

ParseException

evaluateSingle

private static String evaluateSingle(Operator<String> tie,
                                     String left,
                                     String right)
                              throws ParseException

Evaluates a single boolean expression. Care must be taken to obtain a match in this routine with the static initializer.

Throws:

ParseException