I'm using a regular expression to validate a certain format in a string. This string will become a rule for a game.
Example: "DX 3" is OK according to the rule, but "DX 14" could be OK too... I know how to look at the string and find one or more "numbers", so the problem is that the regex will match 34 too, and this number is out of "range" for the rule...
Am I missing something about the regex to do this? Or is this not possible at all?
Unfortunately there's no easy way to define ranges in regex. If you are to use the range 1-23 you'll end up with a regex like this:
([1-9]|1[0-9]|2[0-3])
Explanation:
It is not that short, and not flexible.
If you search for 1 to 19, you can search for "DX 1?[0-9]", for example, but if it doesn't end at a number boundary, it get's ugly pretty soon, and changing the rules is not flexible.
Splitting the String at the blank, and then using x > 0 and x < 24 is better to understand and more flexible.
You can use following format for writing a regular expression solving your problem. Suppose your range is 0-15.
"^DX [0-9]|1[0-5]$"
You can even make it dynamic depending on your range by appending strings.
package dev.dump;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.Collections;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Created by IntelliJ IDEA. User: User Date: 28.09.2007 Time: 9:46:47 To change this template use
* File | Settings | File Templates.
*/
class NumberDiapasone2RegExp {
private static final String invalidArgumentEmpty="Invalid argument \"{0}\" was found! {1}";
private static final Pattern pattern=Pattern.compile("^(\\d+)-(\\d+)?$");
private String src;
private String result="";
private Long left;
private Long right;
private boolean transform09ToD;
public NumberDiapasone2RegExp(final String src) {
this(src, false);
}
public NumberDiapasone2RegExp(final String src, final boolean transform09ToD) {
this.transform09ToD=transform09ToD;
if (src==null || src.trim().length()==0)
throw new IllegalArgumentException(MessageFormat.format(invalidArgumentEmpty,
src,
"It cannot be empty."));
if (src.indexOf("-")<0)
throw new IllegalArgumentException(MessageFormat.format(invalidArgumentEmpty,
src,
"It is supposed to have \"-\"."));
if (src.indexOf("-")!=src.lastIndexOf("-"))
throw new IllegalArgumentException(MessageFormat.format(invalidArgumentEmpty,
src,
"It is supposed to have only one \"-\"."));
Matcher syntaxChecker=pattern.matcher(src);
if (!syntaxChecker.find()){
throw new IllegalArgumentException(MessageFormat.format(invalidArgumentEmpty,
src,
"It is supposed to be in format \"##-##\"."));
}
this.src=src;
parseAndCheck();
String theSameDigits="";
//the same digit goes towards result
if (left.toString().length()==right.toString().length()){
for (int i=0; i<left.toString().length(); i++){
if (i<right.toString().length() &&
left.toString().charAt(i)==right.toString().charAt(i)){
theSameDigits+=left.toString().charAt(i);
}
}
if (theSameDigits.length()>0){
this.src=this.src.replaceFirst(Pattern.quote(theSameDigits),"");
this.src=this.src.replaceFirst(Pattern.quote("-"+theSameDigits),"-");
parseAndCheck();
}
}
result=glueParts(compact(transform09ToD, toParts()));
Matcher m=secondCompact.matcher(result);
while (m.find()){
result=m.group(1).replace("(","").replace(")","")+"["+m.group(2).replaceAll("[\\[\\]]","")+m.group(3).replaceAll("[\\[\\]]","")+"][0-9]";
m.reset(result);
}
//compact squares again
StringBuffer sb=new StringBuffer();
Pattern squresP=Pattern.compile("(\\[(\\d|-)+\\])");
m=squresP.matcher(result);
while (m.find()) {
m.appendReplacement(sb, Matcher.quoteReplacement(compactSquares(m.group(1))));
}
m.appendTail(sb);
result=sb.toString();
result=result.replaceAll("\\[(\\d)-\\1\\]","$1");
result=result.replaceAll("\\[(\\d)\\]","$1");
result=result.replace("{1}","").replace("{0,1}","?");
if (result.indexOf("|")>=0) result=theSameDigits+"("+result+")";
else result=theSameDigits+result;
if (result.startsWith("(") && result.endsWith(")")) result=result.substring(1, result.length()-1);
}
private static Pattern secondCompact=Pattern.compile("(.*)(\\[\\d-?\\d\\]|\\d)\\[0-9\\]\\|(\\[\\d-?\\d\\]|\\d)\\[0-9\\]");
static List<String> compact(boolean transform09ToD, String... parts) {
Set<String> unique=new HashSet<String>();
List<String> result=new ArrayList<String>();
for (String part : parts){
if (part==null || part.length()==0) continue;
part=compactSquares(part);
part=part.replaceAll("\\[(\\d)\\]","$1");
if (part.indexOf("[0-9]")>=0){
if (transform09ToD) part=part.replace("[0-9]","\\d");
}
//[0-3][0-9]|4[0-9]=>[0-34][0-9]
//[023][0-9]|4[0-9]=>[0234][0-9]
//[02345789]=>[02-57-9]
Matcher m=secondCompact.matcher(part);
if (m.find()){
part=m.group(1).replace("(","").replace(")","")+"["+m.group(2).replaceAll("[\\[\\]]","")+m.group(3).replaceAll("[\\[\\]]","")+"][0-9]";
}
part=part.replaceAll("\\[(\\d)-\\1\\]","$1");
if (unique.add(part)) result.add(part);
}
return result;
}
static String compactSquares(String src){
boolean inSquares=false;
if (src.startsWith("[") && src.endsWith("]")){
inSquares=true;
src=src.substring(1,src.length()-1);
}
StringBuffer sb=new StringBuffer();
if (!src.contains("-")) {
List<Integer> digits=new ArrayList<Integer>();
for (int i=0; i<src.length();i++){
digits.add(Integer.parseInt(""+src.charAt(i)));
}
Collections.sort(digits);
for (Integer s : digits){
sb.append(s);
}
src=sb.toString();
sb.setLength(0);
}
int firstChar = -2;
int lastChar = -2;
int currentChar;
for (int i=0; i<src.length(); i++) {
currentChar=src.charAt(i);
if (currentChar == lastChar + 1) {
lastChar = currentChar;
continue;
}
if (currentChar == '-' && i+1 < src.length()) {
lastChar = src.charAt(i + 1) - 1;
continue;
}
flush(sb, firstChar, lastChar);
firstChar = currentChar;
lastChar = currentChar;
}
flush(sb, firstChar, lastChar);
return (inSquares?"[":"")+sb.toString()+(inSquares?"]":"");
}
private static void flush(StringBuffer sb, int firstChar, int lastChar) {
if (lastChar<=0) return;
if (firstChar==lastChar) {
sb.append((char)firstChar);
return;
}
if (firstChar+1==lastChar){
sb.append((char)firstChar);
sb.append((char)lastChar);
return;
}
sb.append((char)firstChar);
sb.append('-');
sb.append((char)lastChar);
}
static String glueParts(List<String> parts) {
if (parts==null || parts.isEmpty()) return "";
if (parts.size()==1) return parts.get(0);
StringBuilder result=new StringBuilder(128);
for (String part : parts){
result.append(part);
result.append("|");
}
result.deleteCharAt(result.length()-1);
return result.toString();
}
private String[] toParts() {
List<String> result=new ArrayList<String>();
if (getNumberOfDigits(left)>2 || getNumberOfDigits(right)>2) {
result.add(startPart(left));
}
long leftPart=left;
long rightPart=right;
if (!String.valueOf(left).matches("10*")) leftPart=toPower(left);
if (!String.valueOf(right).matches("10*")) rightPart=toPower(right)/10;
if (rightPart/leftPart>=10) {
result.add(speedUpPart(left, right));
}
//for 1-2 digit process
if (getNumberOfDigits(left)==1 && getNumberOfDigits(right)==1){
result.add("["+left+"-"+right+"]");
}
else if (getNumberOfDigits(left)==1 && getNumberOfDigits(right)==2){
if (0==Integer.parseInt(getMajorDigit(right))) {
result.add(getMajorDigit(left)+
"["+
getMajorDigit(getNumberWithoutMajorDigit(left))+
"-"+
getMajorDigit(getNumberWithoutMajorDigit(right))+
"]");
}
else if (1==Integer.parseInt(getMajorDigit(right))) {
result.add("["+
getMajorDigit(getNumberWithoutMajorDigit(left))+
"-9]");
result.add(getMajorDigit(right)+
"[0-"+
getMajorDigit(getNumberWithoutMajorDigit(right))+
"]");
}
else if (2<=Integer.parseInt(getMajorDigit(right))) {
result.add("["+
getMajorDigit(left)+
"-9]");
result.add("[1-"+
(Integer.parseInt(getMajorDigit(right))-1)+
"][0-9]");
result.add(getMajorDigit(right)+
"[0-"+
getMajorDigit(getNumberWithoutMajorDigit(right))+
"]");
}
else throw new IllegalStateException();
}
else if (getNumberOfDigits(left)==2 && getNumberOfDigits(right)==2){
if (Integer.parseInt(getMajorDigit(left))==Integer.parseInt(getMajorDigit(right))) {
result.add(getMajorDigit(left)+
"["+
getMajorDigit(getNumberWithoutMajorDigit(left))+
"-"+
getMajorDigit(getNumberWithoutMajorDigit(right))+
"]");
}
else if (Integer.parseInt(getMajorDigit(left))+1==Integer.parseInt(getMajorDigit(right))) {
result.add(getMajorDigit(left)+
"["+
getMajorDigit(getNumberWithoutMajorDigit(left))+
"-9]");
result.add(getMajorDigit(right)+
"[0-"+
getMajorDigit(getNumberWithoutMajorDigit(right))+
"]");
}
else if (Integer.parseInt(getMajorDigit(left))+2<=Integer.parseInt(getMajorDigit(right))) {
result.add(getMajorDigit(left)+
"["+
getMajorDigit(getNumberWithoutMajorDigit(left))+
"-9]");
result.add("["+(Integer.parseInt(getMajorDigit(left))+1)+
"-"+(Integer.parseInt(getMajorDigit(right))-1)+
"][0-9]");
result.add(getMajorDigit(right)+
"[0-"+
getMajorDigit(getNumberWithoutMajorDigit(right))+
"]");
}
else throw new IllegalStateException();
}
else result.add(staticPart(right));
result.add(breakPart(right));
return result.toArray(new String[0]);
}
static String breakPart(final Long number) {
if (getNumberOfDigits(number)<=2) {
return "";
}
StringBuilder result=new StringBuilder(256);
StringBuilder staticSection=new StringBuilder(32);
staticSection.append(getMajorDigit(number));
for (int i=1; i<getNumberOfDigits(number)-1; i++){
if (i!=1) result.append("|");
result.append(staticSection.toString());
staticSection.append(String.valueOf(number).charAt(i));
final long nextDigit=Long.parseLong(""+String.valueOf(number).charAt(i))-1;
if (nextDigit<0) {
result.setLength(0);
result.append("|");
continue;
}
if (nextDigit==0) result.append("0");
else if (nextDigit==1) result.append("[01]");
else result.append("[0-"+(nextDigit)+"]");
final int numberOfRepeats=(getNumberOfDigits(number)-i-1);
if (numberOfRepeats==1) result.append("[0-9]");
else result.append("[0-9]{"+numberOfRepeats+"}");
}
//остаток - 2 последние цифры числа
if (result.length()>0) {
result.append("|");
result.append(staticSection.toString());
//последнюю цифру от 0 до нее
result.append("[0-"+Long.parseLong(number.toString().replaceFirst("\\d+(\\d)","$1"))+"]");
}
if (result.length()>0) return result.toString().replace("||","|").replaceAll("^\\|","");
return "";
}
static String staticPart(final Long number) {
final long majorDigitMinus1=(Long.parseLong(getMajorDigit(number))-1);
if (majorDigitMinus1<=0) return "";
if (majorDigitMinus1==2) return "[1"+majorDigitMinus1+"][0-9]{"+(getNumberOfDigits(number)-1)+"}";
else if (majorDigitMinus1==1) return "1[0-9]{"+(getNumberOfDigits(number)-1)+"}";
return "[1-"+majorDigitMinus1+"][0-9]{"+(getNumberOfDigits(number)-1)+"}";
}
/**
* [1-9][0-9]{<X-1>,<Y-1>}, where X-number of digits of less number, Y-number of digits of greater number
*/
static String speedUpPart(Long left, Long right) {
//найти ближайшее до 0 то есть для 23 найти 100 для 777 найти 1000
//округленные до ближайшего 0
if (!String.valueOf(left).matches("10*")) left=toPower(left);
if (!String.valueOf(right).matches("10*")) right=toPower(right)/10;
final int leftPartRepeat=getNumberOfDigits(left)+(String.valueOf(left).matches("10*")?0:1)-1;
final int rightPartRepeat=getNumberOfDigits(right)+(String.valueOf(right).matches("10*")?0:1)-2;
if (getNumberOfDigits(left)==1 && getNumberOfDigits(right)==2)
return "[1-9]";
else if (leftPartRepeat>=rightPartRepeat)
return "[1-9][0-9]{"+rightPartRepeat+"}";
else
return "[1-9][0-9]{"+leftPartRepeat+","+rightPartRepeat+"}";
}
private static long toPower(final Long number) {
final double dValue=Math.pow(10, getNumberOfDigits(number));
final String value=String.format(Locale.US,"%24.0f",dValue);
return Long.parseLong(value.replaceFirst("\\s*(\\d+)(\\D\\d+)?","$1"));
}
private static int getNumberOfDigits(long number){
return (String.valueOf(number).length());
}
private static String getMajorDigit(long number){
return (String.valueOf(number).substring(0,1));
}
private static long getNumberWithoutMajorDigit(long number){
return Long.parseLong(String.valueOf(number).replaceFirst("\\d(\\d+)","$1"));
}
/**
* f(<n>>2)=<major digit>(f(<n-1>)|[<major digit+1>-9][0-9]{<n-1>})
*/
static String startPart(long number) {
int i=getNumberOfDigits(number);
if (i==1) {
if (number==9) return "9";
else if (number==8) return "[89]";
return "["+number+"-9]";
}
final long majorPlusOne=Long.parseLong(getMajorDigit(number))+1;
final int numberOfDigitsMinusOne=getNumberOfDigits(number)-1;
String result = (majorPlusOne < 10 ? "(" : "");
result+=getMajorDigit(number);
result+=startPart(getNumberWithoutMajorDigit(number));
result+=result.indexOf("|")<0 && majorPlusOne<10 && majorPlusOne!=numberOfDigitsMinusOne && numberOfDigitsMinusOne>1?"{"+numberOfDigitsMinusOne+"}":"";
result+=(majorPlusOne < 10
? "|[" + majorPlusOne + "-9][0-9]"+(numberOfDigitsMinusOne > 1 ? "{" + numberOfDigitsMinusOne + "}" : "")
: "");
result+=(majorPlusOne < 10 ? ")" : "");
return result;
}
private void parseAndCheck() {
Matcher matcher=pattern.matcher(src);
matcher.find();
try{
left=Long.parseLong(matcher.group(1));
right=Long.parseLong(matcher.group(2));
}
catch(Exception ex){
left=right+1;
}
if (left>right){
throw new IllegalArgumentException(MessageFormat.format(invalidArgumentEmpty,
src,
"Left part must be less than right one."));
}
}
public String getPattern() {
return result;
}
public static void main(String[] args) {
System.err.println(new NumberDiapasone2RegExp(args[0]).getPattern());
}
}
I was also trying to find a range of valid range for minutes [0-60] worked for me.
I am using jdk 1.8 though
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