DataFlex

Regular Expression Replace Capture Groups

See more Regular Expressions Examples

Demonstrates replacing capture groups for a regular expression.

Note: Chilkat uses PCRE2. See PCRE2 Regular Expressions
Also see: PCRE2 Performance

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    String sSubject
    String sPattern
    Handle hoSb
    Variant vJson
    Handle hoJson
    Integer iTimeoutMs
    Integer iNumMatches
    Integer iFirstNameIdx
    Integer iLastNameIdx
    Variant vSbTemp
    Handle hoSbTemp
    Integer i
    String sTemp1

    Move False To iSuccess

    Move "John Anders, +_+_+ Mary Robins $$$$" To sSubject
    Move "(?<first>\w+)\s+(?<last>\w+)" To sPattern

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSb
    If (Not(IsComObjectCreated(hoSb))) Begin
        Send CreateComObject of hoSb
    End
    Get ComAppend Of hoSb sSubject To iSuccess

    Get Create (RefClass(cComChilkatJsonObject)) To hoJson
    If (Not(IsComObjectCreated(hoJson))) Begin
        Send CreateComObject of hoJson
    End
    Set ComEmitCompact Of hoJson To False

    Move 2000 To iTimeoutMs
    Get pvComObject of hoJson to vJson
    Get ComRegexMatch Of hoSb sPattern vJson iTimeoutMs To iNumMatches
    If (iNumMatches < 0) Begin
        // Probably an error in the regular expression.
        // Suggestion: Use AI to help create and/or diagnose regular expressions.
        Get ComLastErrorText Of hoSb To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Examine the matches:
    Get ComEmit Of hoJson To sTemp1
    Showln sTemp1

    // There are 2 matches:

    // {
    //   "named": {
    //     "first": 1,
    //     "last": 2
    //   },
    //   "match": [
    //     {
    //       "group": [
    //         {
    //           "cap": "John Anders",
    //           "idx": 0,
    //           "len": 11
    //         },
    //         {
    //           "cap": "John",
    //           "idx": 0,
    //           "len": 4
    //         },
    //         {
    //           "cap": "Anders",
    //           "idx": 5,
    //           "len": 6
    //         }
    //       ]
    //     },
    //     {
    //       "group": [
    //         {
    //           "cap": "Mary Robins",
    //           "idx": 19,
    //           "len": 11
    //         },
    //         {
    //           "cap": "Mary",
    //           "idx": 19,
    //           "len": 4
    //         },
    //         {
    //           "cap": "Robins",
    //           "idx": 24,
    //           "len": 6
    //         }
    //       ]
    //     }
    //   ]
    // }

    // To replace capture groups, write code to examine each capture group within
    // each match, and provide a replacement string.
    // Then call RegexReplace.

    // For example, let's capitalize the first names, and add append "on" to the last name.
    // After doing replacements, we should get:  JOHN Anderson, +_+_+ MARY Robinson $$$$

    Get ComIntOf Of hoJson "named.first" To iFirstNameIdx
    Get ComIntOf Of hoJson "named.last" To iLastNameIdx

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbTemp
    If (Not(IsComObjectCreated(hoSbTemp))) Begin
        Send CreateComObject of hoSbTemp
    End

    Move 0 To i
    Get ComSizeOfArray Of hoJson "match" To iNumMatches
    While (i < iNumMatches)

        Set ComI Of hoJson To i

        // The replacement string for the first name will be all uppercase.
        Set ComJ Of hoJson To iFirstNameIdx
        Send ComClear To hoSbTemp
        Get pvComObject of hoSbTemp to vSbTemp
        Get ComStringOfSb Of hoJson "match[i].group[j].cap" vSbTemp To iSuccess
        Get ComToUppercase Of hoSbTemp To iSuccess
        Get pvComObject of hoSbTemp to vSbTemp
        Get ComUpdateSb Of hoJson "match[i].group[j].rep" vSbTemp To iSuccess

        // Append "on" to the last name.
        Set ComJ Of hoJson To iLastNameIdx
        Send ComClear To hoSbTemp
        Get pvComObject of hoSbTemp to vSbTemp
        Get ComStringOfSb Of hoJson "match[i].group[j].cap" vSbTemp To iSuccess
        Get ComAppend Of hoSbTemp "on" To iSuccess
        Get pvComObject of hoSbTemp to vSbTemp
        Get ComUpdateSb Of hoJson "match[i].group[j].rep" vSbTemp To iSuccess

        Move (i + 1) To i
    Loop

    // The JSON now has replacement strings:
    Get ComEmit Of hoJson To sTemp1
    Showln sTemp1

    // {
    //   "named": {
    //     "first": 1,
    //     "last": 2
    //   },
    //   "match": [
    //     {
    //       "group": [
    //         {
    //           "cap": "John Anders",
    //           "idx": 0,
    //           "len": 11
    //         },
    //         {
    //           "cap": "John",
    //           "idx": 0,
    //           "len": 4,
    //           "rep": "JOHN"
    //         },
    //         {
    //           "cap": "Anders",
    //           "idx": 5,
    //           "len": 6,
    //           "rep": "Anderson"
    //         }
    //       ]
    //     },
    //     {
    //       "group": [
    //         {
    //           "cap": "Mary Robins",
    //           "idx": 19,
    //           "len": 11
    //         },
    //         {
    //           "cap": "Mary",
    //           "idx": 19,
    //           "len": 4,
    //           "rep": "MARY"
    //         },
    //         {
    //           "cap": "Robins",
    //           "idx": 24,
    //           "len": 6,
    //           "rep": "Robinson"
    //         }
    //       ]
    //     }
    //   ]
    // }

    // Call RegexReplace to update the StringBuilder with the replacements.
    Get pvComObject of hoJson to vJson
    Get ComRegexReplace Of hoSb vJson To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSb To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Result after doing replacements:"
    Get ComGetAsString Of hoSb To sTemp1
    Showln sTemp1

    // Result after doing replacements:
    // JOHN Anderson, +_+_+ MARY Robinson $$$$


End_Procedure