javatools.parsers

Class RegularExpression

java.lang.Object

javatools.parsers.RegularExpression

All Implemented Interfaces:

Iterable<List<String>>

public class RegularExpression
extends Object
implements Iterable<List<String>>

Copyright 2016 Fabian M. Suchanek Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. 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

Nested Classes

Modifier and Type	Class and Description
static class	RegularExpression.RegExState Represents one position in a regular expression

Field Summary

Fields

Modifier and Type	Field and Description
List<RegularExpression.RegExState>	entries RegExStates with which the RegularExpression starts
List<RegularExpression.RegExState>	exits Valid exit states of this RegularExpression
String	original Holds the original regex

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RegularExpression() Internal constructor
protected	RegularExpression(String token) Internal constructor

Method Summary

Modifier and Type	Method and Description
static RegularExpression	compile(String regex) Returns a RegularExpression for a string
String	describe() returns a nice String description
List<RegularExpression.RegExState>	getEntries() Returns the entry states of this RegularExpression
String	getOrginal() returns the original
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<List<String>>	iterator() Returns an iterator over incarnations of the expression
static void	main(String[] args) Test routine
static RegularExpression	parseSimple(StringTokenizer regex) Parses a regex from a StringTokenizer
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

entries

public List<RegularExpression.RegExState> entries

RegExStates with which the RegularExpression starts

exits

public List<RegularExpression.RegExState> exits

Valid exit states of this RegularExpression

original

public String original

Holds the original regex

Constructor Detail

RegularExpression

protected RegularExpression(String token)

Internal constructor

RegularExpression

protected RegularExpression()

Internal constructor

Method Detail

getOrginal

public String getOrginal()

returns the original

compile

public static RegularExpression compile(String regex)

Returns a RegularExpression for a string

toString

public String toString()

Overrides:

toString in class Object

isExit

public boolean isExit(RegularExpression.RegExState e)

Tells whether this RegExState is a valid exit

getEntries

public List<RegularExpression.RegExState> getEntries()

Returns the entry states of this RegularExpression

parseSimple

public static RegularExpression parseSimple(StringTokenizer regex)

Parses a regex from a StringTokenizer

describe

public String describe()

returns a nice String description

getStates

public 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<List<String>> iterator()

Returns an iterator over incarnations of the expression

Specified by:

iterator in interface Iterable<List<String>>

main

public static void main(String[] args)

Test routine