javatools.parsers
Class RegularExpression

java.lang.Object
  javatools.parsers.RegularExpression

All Implemented Interfaces:

java.lang.Iterable<java.util.List<java.lang.String>>

public class RegularExpression
extends java.lang.Object
implements java.lang.Iterable<java.util.List<java.lang.String>>

This class is part of the Java Tools (see http://mpii.de/yago-naga/javatools). It is licensed under the Creative Commons Attribution License (see http://creativecommons.org/licenses/by/3.0) by the YAGO-NAGA team (see http://mpii.de/yago-naga). The class represents a regular expression. You can walk through the regular expression by RegExStates. Each RegExState represents one position in the regular expression. Each RegExState knows which other RegExStates are valid sucessors. The regular expression itself knows which RegExStates are valid exit points. The regular expression can also be inverted.
Example:

         D.p(RegularExpression.compile("a|(b c+)+").describe());
         -->
            1(a) -> []             // From a, we're done
            2(b) -> [3(c)]         // From b, go to c
            3(c) -> [3(c), 2(b)]   // From c, go either to c or to b
            Valid exits: 1(a), 3(c),  
         D.p(RegularExpression.compile("a|(b c+)+").inverse().describe());            
         -->
            4(a) -> []
            6(c) -> [5(b), 6(c)]
            5(b) -> [6(c)]    
            Valid exits: 4(a), 5(b),       
   

Nested Class Summary

static class

RegularExpression.RegExState Represents one position in a regular expression

Field Summary

java.util.List<RegularExpression.RegExState>	entries RegExStates with which the RegularExpression starts
java.util.List<RegularExpression.RegExState>	exits Valid exit states of this RegularExpression
java.lang.String	original Holds the original regex

Method Summary

static RegularExpression	compile(java.lang.String regex) Returns a RegularExpression for a string
java.lang.String	describe() returns a nice String description
java.util.List<RegularExpression.RegExState>	getEntries() Returns the entry states of this RegularExpression
java.lang.String	getOrginal() returns the original
java.util.List<RegularExpression.RegExState>	getStates() Returns the set of States (expensive)
RegularExpression	inverse() Returns the inverse of this Regular Expression (expensive)
boolean	isExit(RegularExpression.RegExState e) Tells whether this RegExState is a valid exit
PeekIterator<java.util.List<java.lang.String>>	iterator() Returns an iterator over incarnations of the expression
static void	main(java.lang.String[] args) Test routine
static RegularExpression	parseSimple(java.util.StringTokenizer regex) Parses a regex from a StringTokenizer
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

entries

public java.util.List<RegularExpression.RegExState> entries

RegExStates with which the RegularExpression starts

exits

public java.util.List<RegularExpression.RegExState> exits

Valid exit states of this RegularExpression

original

public java.lang.String original

Holds the original regex

Method Detail

getOrginal

public java.lang.String getOrginal()

returns the original

compile

public static RegularExpression compile(java.lang.String regex)

Returns a RegularExpression for a string

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

isExit

public boolean isExit(RegularExpression.RegExState e)

Tells whether this RegExState is a valid exit

getEntries

public java.util.List<RegularExpression.RegExState> getEntries()

Returns the entry states of this RegularExpression

parseSimple

public static RegularExpression parseSimple(java.util.StringTokenizer regex)

Parses a regex from a StringTokenizer

describe

public java.lang.String describe()

returns a nice String description

getStates

public java.util.List<RegularExpression.RegExState> getStates()

Returns the set of States (expensive)

inverse

public RegularExpression inverse()

Returns the inverse of this Regular Expression (expensive)

iterator

public PeekIterator<java.util.List<java.lang.String>> iterator()

Returns an iterator over incarnations of the expression

Specified by:

iterator in interface java.lang.Iterable<java.util.List<java.lang.String>>

main

public static void main(java.lang.String[] args)

Test routine