Increased accuracy in wildcard regexp usage

Question

Increased accuracy in wildcard regexp usage

I wrote a script that uses wildcards to filter filenames. For example, using `*.js` will give me all the JavaScript files in a directory.

However, I encountered an issue where it also includes `.json` files in the results, which is not what I intended.

To create the RegExp pattern, I used the `wildcardStringToRegexp` function that I found on a website because regex isn't my strong suit:

function wildcardStringToRegexp( s ) 
{
    if( isValidString( s ))
     { return false; }

    function preg_quote(str, delimiter) 
    {
        return (str + '').replace(new RegExp('[.\\\\+*?\\[\\^\\]$(){}=!<>|:\\' + (delimiter || '') + '-]', 'g'), '\\$&');
    }


    return new RegExp(preg_quote(s).replace(/\\\*/g, '.*').replace(/\\\?/g, '.'), 'g');
}

function fnmatch( sMask, sMatch, bReturnMatches )
{
    if( !isValidString( sMatch ))
     { return false; }

    var aMatches = sMatch.match( wildcardStringToRegexp( sMask ) );

    if( bReturnMatches )
     { return isValidArray( aMatches )?aMatches:[]; }

    return isValidArray( aMatches )?aMatches.length:0;
}

For instance:

fnmatch( '*.js', 'myfile.js' )   returns 1
fnmatch( '*.js', 'myfile.json' ) returns 1 , but this is not desired

How can I modify the wildcardStringToRegexp() function or make other changes so that fnmatch( '*.js', 'myfile.json' ) is no longer valid and the filtering becomes more accurate?

javascript regex string pattern-matching match

Answer 1

Answer №1

In my opinion, it seems like the function you are utilizing may be a bit excessive. Instead of that, all you really need to do is substitute all instances of wildcards with their regex equivalents and ensure that you match both the beginning and end of the input. The modified code should look something like this:

const fnmatch = (glob, input) => {

  const matcher = glob
                  .replace(/\*/g, '.*')
                  .replace(/\?/g, '.'); // Converting wildcards to regex values
  const r = new RegExp(`^${ matcher }$`); // Matching beginning and end of input using ^ and $
  
  return r.test(input);
 }

console.log(fnmatch('*.js', 'myfile.js')); // true
console.log(fnmatch('*.js', 'myfile.json')); // false
console.log(fnmatch('?yfile.js', 'myfile.js')); //true

Answer 2

In my opinion, it seems like the function you are utilizing may be a bit excessive. Instead of that, all you really need to do is substitute all instances of wildcards with their regex equivalents and ensure that you match both the beginning and end of the input. The modified code should look something like this:

const fnmatch = (glob, input) => {

  const matcher = glob
                  .replace(/\*/g, '.*')
                  .replace(/\?/g, '.'); // Converting wildcards to regex values
  const r = new RegExp(`^${ matcher }$`); // Matching beginning and end of input using ^ and $
  
  return r.test(input);
 }

console.log(fnmatch('*.js', 'myfile.js')); // true
console.log(fnmatch('*.js', 'myfile.json')); // false
console.log(fnmatch('?yfile.js', 'myfile.js')); //true

Increased accuracy in wildcard regexp usage

Answer №1

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