Go

Regular Expression with Multiple Matches and Named Capture Groups

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

    success := false

    sb := chilkat.NewStringBuilder()
    crlf := true
    sb.AppendLine("Name: John Smith",crlf)
    sb.AppendLine("Name: Jack Johnson",crlf)
    sb.AppendLine("Name: Mary Adams",crlf)

    fmt.Println(*sb.GetAsString())

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

    pattern := "Name:\\s+(?<first>\\w+)\\s+(?<last>\\w+)"
    json := chilkat.NewJsonObject()
    json.SetEmitCompact(false)

    timeoutMs := 2000
    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.
        fmt.Println(sb.LastErrorText())
        sb.DisposeStringBuilder()
        json.DisposeJsonObject()
        return
    }

    // Examine the matches:
    fmt.Println(*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:

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

    i := 0
    matchCount := json.SizeOfArray("match")
    for i < matchCount {
        fmt.Println("Match ", i + 1, ":")
        json.SetI(i)

        json.SetJ(idx_first)
        fmt.Println("first: ", *json.StringOf("match[i].group[j].cap"))

        json.SetJ(idx_last)
        fmt.Println("first: ", *json.StringOf("match[i].group[j].cap"))

        fmt.Println("")
        i = i + 1
    }

    // Output is: 

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

    sb.DisposeStringBuilder()
    json.DisposeJsonObject()