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regex puzzle

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  regex puzzle Roedy Green <see_website@mindprod.com.invalid> - 2014-04-09 15:57 -0700
    Re: regex puzzle Knute Johnson <eternal@knutejohnson.com> - 2014-04-09 16:11 -0700
      Re: regex puzzle Roedy Green <see_website@mindprod.com.invalid> - 2014-04-09 16:14 -0700
        Re: regex puzzle Roedy Green <see_website@mindprod.com.invalid> - 2014-04-09 16:24 -0700
          Re: regex puzzle Knute Johnson <eternal@knutejohnson.com> - 2014-04-09 18:24 -0700
          Re: regex puzzle Arne Vajhøj <arne@vajhoej.dk> - 2014-04-11 21:06 -0400
      Re: regex puzzle markspace <markspace@nospam.nospam> - 2014-04-09 19:07 -0700
        Re: regex puzzle Robert Klemme <shortcutter@googlemail.com> - 2014-04-11 01:56 -0700

#28005 — regex puzzle

Is there a way within a regex to find strings of the from: 

1 .. 20?

For reasons hard to explain I don't want to capture then check outside
the regex.
-- 
Roedy Green Canadian Mind Products http://mindprod.com
"Don't worry about people stealing an idea; if it's original, you'll
 have to shove it down their throats." 
~ Howard Aiken (born: 1900-03-08 died: 1973-03-14 at age: 73)

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#28006

On 4/9/2014 15:57, Roedy Green wrote:
> Is there a way within a regex to find strings of the from:
>
> 1 .. 20?
>
> For reasons hard to explain I don't want to capture then check outside
> the regex.
>

So does 1 .. 20 mean 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 
or 1 .. 20?

1 .. 20  ^\d+ \.\. \d+$

-- 

Knute Johnson

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#28007

On Wed, 09 Apr 2014 16:11:04 -0700, Knute Johnson
<eternal@knutejohnson.com> wrote, quoted or indirectly quoted someone
who said :

>
>So does 1 .. 20 mean 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 
>or 1 .. 20?

nope  1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20

hopefully a little more terse.

and would not match  2099

-- 
Roedy Green Canadian Mind Products http://mindprod.com
"Don't worry about people stealing an idea; if it's original, you'll
 have to shove it down their throats." 
~ Howard Aiken (born: 1900-03-08 died: 1973-03-14 at age: 73)

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#28008

On Wed, 09 Apr 2014 16:14:45 -0700, Roedy Green
<see_website@mindprod.com.invalid> wrote, quoted or indirectly quoted
someone who said :

>nope  1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20
>
>hopefully a little more terse.
>
>and would not match  2099

I think you need a new regex operator that collects characters 0-9,
0-9\. etc then parses a number, then compares it with low and high
bound in the regex operator.

It seems like such a simple problem.

Regex gets foiled so easily, like parsing HTML tags when they don't
appear in canonical order.
-- 
Roedy Green Canadian Mind Products http://mindprod.com
"Don't worry about people stealing an idea; if it's original, you'll
 have to shove it down their throats." 
~ Howard Aiken (born: 1900-03-08 died: 1973-03-14 at age: 73)

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#28011

On 4/9/2014 16:24, Roedy Green wrote:
> On Wed, 09 Apr 2014 16:14:45 -0700, Roedy Green
> <see_website@mindprod.com.invalid> wrote, quoted or indirectly quoted
> someone who said :
>
>> nope  1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20
>>
>> hopefully a little more terse.
>>
>> and would not match  2099
>
> I think you need a new regex operator that collects characters 0-9,
> 0-9\. etc then parses a number, then compares it with low and high
> bound in the regex operator.
>
> It seems like such a simple problem.
>
> Regex gets foiled so easily, like parsing HTML tags when they don't
> appear in canonical order.
>

import java.util.regex.*;

public class test5 {
     public static void main(String[] args) {
         String sequence = "1..20";
         String subject = "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 
19 20";

         System.out.println(matchSeq(sequence,subject) ? "matches" : "no 
match");
     }

     public static boolean matchSeq(String seq, String subject) {
         Pattern p1 = Pattern.compile("(\\d+)\\.\\.(\\d+)");
         Matcher m1 = p1.matcher(seq);
         if (m1.matches()) {
             int from = Integer.parseInt(m1.group(1));
             int to = Integer.parseInt(m1.group(2));
             String s2 = Integer.toString(from);
             for (int i=from+1; i<=to; i++)
                 s2 = s2.concat(String.format(" %d",i));
             Pattern p2 = Pattern.compile(s2);
             Matcher m2 = p2.matcher(subject);
             return m2.matches();
         } else {
             throw new IllegalArgumentException("bad sequence");
         }
     }
}



-- 

Knute Johnson

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#28039

On 4/9/2014 7:24 PM, Roedy Green wrote:
> On Wed, 09 Apr 2014 16:14:45 -0700, Roedy Green
> <see_website@mindprod.com.invalid> wrote, quoted or indirectly quoted
> someone who said :
>
>> nope  1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20
>>
>> hopefully a little more terse.
>>
>> and would not match  2099
>
> I think you need a new regex operator that collects characters 0-9,
> 0-9\. etc then parses a number, then compares it with low and high
> bound in the regex operator.
>
> It seems like such a simple problem.

Sure but it is not a regex problem.

Arne

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#28012

On 4/9/2014 5:52 PM, Stefan Ram wrote:

>    { final java.lang.String r = "[1-9]|1[0-9]|20";


This is the type of solution I'm used to seeing for problems of this 
type.  Roedy said he didn't want to match substrings (so "2009" should 
not be matched.  I think you just have to add some "not digit" to the 
outside of that.

  "\\D([1-9]|1[0-9]|20)\\D"

Not tested.

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#28025

On Thursday, April 10, 2014 4:07:30 AM UTC+2, markspace wrote:

> This is the type of solution I'm used to seeing for problems of this 
> type.  Roedy said he didn't want to match substrings (so "2009" should 
> not be matched.  I think you just have to add some "not digit" to the 
> outside of that.
> 
>   "\\D([1-9]|1[0-9]|20)\\D"

But better use lookaround for that:

package regexp;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RoedyNumberMatch {

    private static final String[] P_FIXES = { "", "foo", "bar ", "20" };

    private static final Pattern PAT = Pattern
	    .compile("(?<!\\d)(?:20|1\\d|[1-9])(?!\\d)");

    public static void main(String[] args) {
	final Matcher m = PAT.matcher("");

	for (int i = 0; i < 30; ++i) {
	    System.out.println("i = " + i);

	    for (final String pre : P_FIXES) {
		for (final String post : P_FIXES) {
		    final String s = pre + i + post;
		    System.out.println("s = '" + s + "'");

		    if (m.reset(s).matches()) {
			System.out.println("Matches: '" + m.group() + "'");
		    }

		    if (m.reset(s).find()) {
			System.out.println("Finds: '" + m.group() + "'");
		    }
		}
	    }

	    System.out.println();
	}
    }

}

Also here: https://gist.github.com/rklemme/10451386

Cheers

robert

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