Regex issue - Matching API name

Question

I am currently working with a large code base, in which recently one of the API's signature changed. So I need to modify thousands of files to get the new feature. So developed a java program to get take all *.java files and look for old API pattern. If found replace it with new pattern.

Old API

API(3,Utils.FIFTY,key1,key4)

New API

API(key1,key4)

So I created a regex pattern to match the old API as API\([\d,\s\.\w]*(key[\.\w\s,]*)\) If it matches it will replace it with

replaceString = matcher.group(1) + "(" + matcher.group(2) + ")";

So with the current code instead of expected API(key1,key4), I am getting API(key4). I've analyzed the issue and my inference is that the \w caught the first key pattern. If we need to match, we need to do a negative look ahead.

Can any one share the best consistent way to resolve the regex issue ?

Why not @deprecate the API(3,Utils.FIFTY,key1,key4) form, call the new form internally, and recompile? — Andrew Thompson
– Andrew Thompson, Commented Feb 20, 2013 at 18:54
The API is developed by another team and we don't have access to it. The API still exists for backward compatibility. Since we need the new feature, we need to call the new method — RahulRP
– RahulRP, Commented Feb 20, 2013 at 18:58

Aubin · Accepted Answer · 2013-02-20 20:21:29Z

2

The F.J's answer doesn't match this test case:

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

public class APIUpdater {
   public static void main( String[] args ) {
      String source = "\n" +
        "API( key.getValue( 18 ),call( key1 ).mth(),key1,key4);\n" +
        "API(\n" +
        "\t3,\n" +
        "\tUtils.FIFTY,\n" +
        "\tkey1,\n" +
        "\tkey4 );\n" +
        "API(3,Utils.FIFTY,key1,key4);\n";
      Pattern p =
         Pattern.compile( "API\\([.\\w\\s,]*?,\\s*(key[\\.\\w\\s,]*)\\)" );
      Matcher m = p.matcher( source );
      while( m.find())
      {
         System.err.println( m.replaceAll( "API(key1,key4)" ));
      }
   }
}

Output is:

API( key.getValue( 18 ),call( key1 ).mth(),key1,key4);
API(key1,key4);
API(key1,key4);

A call on several lines doesn't match but spaces are correctly handled.

A true parser with a grammar is required to parse Java, a regular expressions can't do this complex job because they works at lexical level (the words, not the sentences).

edited Feb 20, 2013 at 20:21

answered Feb 20, 2013 at 19:22

Aubin

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1 Comment

RahulRP Over a year ago

I don't have complex scenarios like the first example you mentioned. But the second and third samples are valid for me, means the API can be broken in to multiple lines due to code formatting. Such cases the the reluctant quantifier approach(*?) works fine. We have already incorporated \s for the whitespace chanracters.

Andrew Clark · Accepted Answer · 2013-02-20 19:37:47Z

1

Something like the following should work:

API\([\.\w \t,]*?,\s*(key[\.\w \t,]*)\)

The main change here was to change the repetition on the first character class from * to *?, this means it will now match as few characters as possible instead of as many as possible, so you all of your key arguments will be included in your matching group.

edited Feb 20, 2013 at 19:37

answered Feb 20, 2013 at 19:00

Andrew Clark

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2 Comments

Aubin Over a year ago

What about line feed between ( and )?

Andrew Clark Over a year ago

@Aubin I replaced the \s so the character classes will match spaces and tabs but not line feeds, good suggestion.

Javier · Accepted Answer · 2013-02-20 19:43:26Z

1

You may want to try Recoder, which allows you to apply source code transformations.

answered Feb 20, 2013 at 19:43

Javier

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2 Comments

Aubin Over a year ago

+1: this solution tackle the problem at correct abstraction level

RahulRP Over a year ago

I liked the Recorder pattern and will have try.

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