Node.js

Regular Expression with Multiple Matches and Named Capture Groups

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Demonstrates regular expressions with named capture groups and multiple matches. Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

    var sb = new chilkat.StringBuilder();
    var crlf = true;
    sb.AppendLine("Name: John Smith",crlf);
    sb.AppendLine("Name: Jack Johnson",crlf);
    sb.AppendLine("Name: Mary Adams",crlf);

    console.log(sb.GetAsString());

    //  We have the following string:
    //  Name: John Smith
    //  Name: Jack Johnson
    //  Name: Mary Adams

    var pattern = "Name:\\s+(?<first>\\w+)\\s+(?<last>\\w+)";
    var json = new chilkat.JsonObject();
    json.EmitCompact = false;

    var timeoutMs = 2000;
    var numMatches = sb.RegexMatch(pattern,json,timeoutMs);
    if (numMatches < 0) {
        //  Probably an error in the regular expression.
        //  Suggestion: Use AI to help create and/or diagnose regular expressions.
        console.log(sb.LastErrorText);
        return;
    }

    //  Examine the matches:
    console.log(json.Emit());

    //  Here is the JSON showing the matches.
    //  Important:  Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

    //  {
    //    "named": {
    //      "first": 1,
    //      "last": 2
    //    },
    //    "match": [
    //      {
    //        "group": [
    //          {
    //            "cap": "Name: John Smith",
    //            "idx": 0,
    //            "len": 16
    //          },
    //          {
    //            "cap": "John",
    //            "idx": 6,
    //            "len": 4
    //          },
    //          {
    //            "cap": "Smith",
    //            "idx": 11,
    //            "len": 5
    //          }
    //        ]
    //      },
    //      {
    //        "group": [
    //          {
    //            "cap": "Name: Jack Johnson",
    //            "idx": 18,
    //            "len": 18
    //          },
    //          {
    //            "cap": "Jack",
    //            "idx": 24,
    //            "len": 4
    //          },
    //          {
    //            "cap": "Johnson",
    //            "idx": 29,
    //            "len": 7
    //          }
    //        ]
    //      },
    //      {
    //        "group": [
    //          {
    //            "cap": "Name: Mary Adams",
    //            "idx": 38,
    //            "len": 16
    //          },
    //          {
    //            "cap": "Mary",
    //            "idx": 44,
    //            "len": 4
    //          },
    //          {
    //            "cap": "Adams",
    //            "idx": 49,
    //            "len": 5
    //          }
    //        ]
    //      }
    //    ]
    //  }

    //  The capture group index is obtained by looking up the name in the JSON result.
    //  For example:

    var idx_first = json.IntOf("named.first");
    var idx_last = json.IntOf("named.last");

    var i = 0;
    var matchCount = json.SizeOfArray("match");
    while (i < matchCount) {
        console.log("Match " + (i+1) + ":");
        json.I = i;

        json.J = idx_first;
        console.log("first: " + json.StringOf("match[i].group[j].cap"));

        json.J = idx_last;
        console.log("first: " + json.StringOf("match[i].group[j].cap"));

        console.log("");
        i = i+1;
    }

    //  Output is: 

    //  Match 1:
    //  first: John
    //  first: Smith
    //  
    //  Match 2:
    //  first: Jack
    //  first: Johnson
    //  
    //  Match 3:
    //  first: Mary
    //  first: Adams

}

chilkatExample();