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RegExExtractAll

Function RegExExtractAll( const aExpression, aInput : String; var aStrings : TStringArray): Boolean

Example​

procedure ScriptEvent(var Value: variant);
var
  Parts: TStringArray;
begin
  if RegExExtractAll('([A-Z]{2})-([0-9]{4})', 'NZ-2048; AU-1001', Parts) then
    Value := Parts[2]; // 2048
end;

Usage​

RegExExtractAll returns the complete first regular-expression match and all of that match's capture groups in an output array.

Parameters

ParameterMeaning
aExpressionVelox/PCRE pattern, including any desired capture groups.
aInputText searched for the first non-empty match.
aStringsOutput array. It is reset to length zero before matching. On success it is resized to the first match's Groups.Count.

Important behavior and quirks

  • NZ-2048; AU-1001 in the example produces groups for NZ-2048 only. AU-1001 is not represented.
  • A pattern without explicit capture groups still returns a one-element array containing the complete match.
  • The input is not changed, but the caller's output array is always cleared before pattern evaluation.
  • Matching is unanchored and case-sensitive unless the expression changes those rules.

Additional Technical Info​

RegExExtractAll writes the complete first match and each capture group belonging to that match into aStrings. The name is misleading: it does not return all matches in the input.

The example is fictional and source-reviewed only.

Return value and output layout

The function returns True when the first TRegEx.Match succeeds. On success:

  • aStrings[0] is the complete matched text;
  • aStrings[1] is capture group 1;
  • subsequent elements follow capture-group order; and
  • an optional group that did not participate normally contributes an empty value.

On a normal False result, aStrings remains an empty array.

How it works

Velox clears the output, calls TRegEx.Match(aInput, aExpression), then copies Match.Groups[i].Value for i = 0 through Groups.Count - 1. It never calls Matches or advances to another match. Delphi's default roNotEmpty option prevents a solely empty match from succeeding.

Errors, performance and concurrency

Invalid patterns and regex engine errors propagate as exceptions. If evaluation raises, aStrings has already been cleared. Each call constructs a new regex object and then allocates/copies the group array. Pathological expressions can consume excessive CPU or memory; do not apply untrusted expressions to large untrusted input without independent limits.

Related entries

External references

Created 2026-07-15