How to replace string while creating variable using GREP search pattern

[nutradial]

// constraints are:

// XX T will always be first and in caps ==> ^XX T

// T will always have a value of max of 2 digits ==> {1,2}

// L may or may not be present but if present will always have a value of max of 2 digits ==> {1,2}

// the digits of L if present will always be the end of the string ==> (/\d+$/)

var testName1 = "XX T3 L22";  // viable upper case search(/^XX T\d{1,2}( L\d{1,2}$)/g)

var testName2 = "XX T44 L1";

var testName3 = "XX T5";  // viable upper case search(/^XX T\d{1,2}$/g)

var testName4 = "XX T66;

// for testName1 ==> lNumber1 = 22

if (testName1.toString().search(/^XX T\d{1,2}( L\d{1,2}$)/g) === 0) lNumber1 = testName1.toString().replace((/^XX T\d{1,2}( L\d{1,2}$)/g), testName1.toString().match(/\d+$/));

// how can I return the T value in all 4 examples?

// results:

// lNumber1 = 3

// lNumber2 = 44

// lNumber3 = 5

// lNumber4 = 66

[m1b · Accepted solution]

Hi @nutradial, I assume you are doing this via ExtendScript... see if this helps. The match method of string is great for this.

- Mark

var tests = [
    "XX T3 L22",
    "XX T44 L1",
    "XX T5",
    "XX T66"
];

// match two digits of T and two digits of L (if L exists)
var matcher = /^XX T(\d{1,2})(?: L(\d{1,2}))?/;

for (var i = 0, T, L; i < tests.length; i++) {

    // perform the regex match
    var match = tests[i].match(matcher);

    if (!match)
        // no match at all
        continue;

    T = match.length > 0 ? Number(match[1]) : undefined;
    L = match.length > 1 ? Number(match[2]) : undefined;

    $.writeln('test string "' + tests[i] + '":  T = ' + T + '  L = ' + L);

}

[nutradial]

Nice!!! Thanks. 

[m1b]

You're welcome!

[nutradial]

Can the match method as implemented above be used outside an object?

I am already iterating layer.name

[m1b]

All you need is a String and a RegExp. You can call the "match" method of any String, passing a RegExp as parameter. Documentation is here. It returns null if no match, or an array where the zeroth element is the whole string, and subsequent elements are captured from the RegExp parentheses.

[nutradial]

To me the best part of this post is how you structured the regex to return the T and L value. I appreciate it ...I learned something very useful.

var regex = /^XX T(\d{1,2})(?: L(\d{1,2}))?/;

[m1b]

Yes! Regex is the most amazing thing! Well worth taking the time to understand.

[nutradial]

This might be off topic and I'll gladly create a new thread if need be:

T = match.length > 1 ? Number(match[2]) : undefined;

When T is NaN in the match I would like to use it as follows but it fails to resolve:

if (layer.name !== "" && T == null) {    // this fails ==> while testing for NaN

if (layer.name !== "" && (!!T)) {    // this works ==> when T has value

[nutradial]

I was able to make it work using:

if ((!T) && layer.name !== "").   // for T is NaN

if ((!!T) && layer.name !== "").   // for T has value

[m1b]

You can test for NaN ...

if (isNaN(T))

Also be careful about using  !T  this will return true if T is zero. When working with numbers it might be better to use something like if (undefined == T) . Depends on your specific case, but as a general rule I don't use that when working with numbers, only objects.

[nutradial]

I added a third parameter to my search pattern and was wondering if "named capturing groups" in ExtendScript are fully supported?

XX T7 L3 D0.125 ==>  Pattern match 1 (XX T7)  Pattern match 2 (L3)  Pattern match 3 (D0.125)

/(?<t>^XX T(\d{1,2}))?(?<l> ?L(\d{1,2}))?(?<d> ?D(\d*\.?\d{1,3}))?/g

Examples of matches:

XX T7

XX T7 L3

XX T7 D0.125

XX T7 L3 D0.125

XX T7 D0.125 L3

L3

D0.125

L3 D0.125

D0.125 L3

Named capturing groups:

t = 7

l = 3

d = 0.125

If named capturing groups are viable can you please update your initial snippet of code for reference. I am using the search and match method to trigger events based on layer names. This thread has not only been of high utility but very educational. Thanks.

[m1b]

Unfortunately ExtendScript RegExp doesn't support named capture groups. The best we can do is use a non-capturing group as I did in my original code, so that only the relevant patterns are matched..

/^XX T(\d{1,2})(?:\s?L(\d{1,2}))?(?:\s?D(\d*\.?\d{1,3}))?/