Swift

Regular Expression with Multiple Matches and Named Capture Groups

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Demonstrates regular expressions with named capture groups and multiple matches. Swift

func chilkatTest() {
    var success: Bool = false

    let sb = CkoStringBuilder()!
    var crlf: Bool = true
    sb.appendLine(str: "Name: John Smith", crlf: crlf)
    sb.appendLine(str: "Name: Jack Johnson", crlf: crlf)
    sb.appendLine(str: "Name: Mary Adams", crlf: crlf)

    print("\(sb.getAsString()!)")

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

    var pattern: String? = "Name:\\s+(?<first>\\w+)\\s+(?<last>\\w+)"
    let json = CkoJsonObject()!
    json.emitCompact = false

    var timeoutMs: Int = 2000
    var numMatches: Int = sb.regexMatch(pattern: pattern, json: json, timeoutMs: timeoutMs).intValue
    if numMatches < 0 {
        // Probably an error in the regular expression.
        // Suggestion: Use AI to help create and/or diagnose regular expressions.
        print("\(sb.lastErrorText!)")
        return
    }

    // Examine the matches:
    print("\(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: Int = json.int(of: "named.first").intValue
    var idx_last: Int = json.int(of: "named.last").intValue

    var i: Int = 0
    var matchCount: Int = json.size(ofArray: "match").intValue
    while i < matchCount {
        print("Match \(i + 1):")
        json.i = i

        json.j = idx_first
        print("first: \(json.string(of: "match[i].group[j].cap")!)")

        json.j = idx_last
        print("first: \(json.string(of: "match[i].group[j].cap")!)")

        print("")
        i = i + 1
    }

    // Output is: 

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

}