Delphi ActiveX

Regular Expression with Multiple Matches and Named Capture Groups

See more Regular Expressions Examples

Demonstrates regular expressions with named capture groups and multiple matches. Delphi ActiveX

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
sb: TChilkatStringBuilder;
crlf: Integer;
pattern: WideString;
json: TChilkatJsonObject;
timeoutMs: Integer;
numMatches: Integer;
idx_first: Integer;
idx_last: Integer;
i: Integer;
matchCount: Integer;

begin
success := 0;

sb := TChilkatStringBuilder.Create(Self);
crlf := 1;
sb.AppendLine('Name: John Smith',crlf);
sb.AppendLine('Name: Jack Johnson',crlf);
sb.AppendLine('Name: Mary Adams',crlf);

Memo1.Lines.Add(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 := TChilkatJsonObject.Create(Self);
json.EmitCompact := 0;

timeoutMs := 2000;
numMatches := sb.RegexMatch(pattern,json.ControlInterface,timeoutMs);
if (numMatches < 0) then
  begin
    // Probably an error in the regular expression.
    // Suggestion: Use AI to help create and/or diagnose regular expressions.
    Memo1.Lines.Add(sb.LastErrorText);
    Exit;
  end;

// Examine the matches:
Memo1.Lines.Add(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');
while i < matchCount do
  begin
    Memo1.Lines.Add('Match ' + IntToStr(i + 1) + ':');
    json.I := i;

    json.J := idx_first;
    Memo1.Lines.Add('first: ' + json.StringOf('match[i].group[j].cap'));

    json.J := idx_last;
    Memo1.Lines.Add('first: ' + json.StringOf('match[i].group[j].cap'));

    Memo1.Lines.Add('');
    i := i + 1;
  end;

// Output is: 

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