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Programming-Idioms

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Idiom #369 Parse matching brackets

Generate a collection, a, of index-values, given the text, s, containing paired bracket values.

For example, "{ { } } { }" is `(0, 6) (2, 4) (8, 10)`.

https://en.wikipedia.org/wiki/Bracket_(mathematics)
https://en.wikipedia.org/wiki/Scope_(computer_science)

import java.util.ArrayList;
import java.util.List;
List<int[]> a = new ArrayList<>();
int i, x, y, n = s.length(), c;
for (i = y = 0; i < n; ++i)
    if (s.charAt(i) == '{') {
        x = i + ++y;
        while (x < n) {
            c = s.charAt(x++);
            if (c == '{') ++y;
            else if (c == '}')
                if (--y == 0) break;
        }
        a.add(new int[] { i, x - 1 });
    }
var
  i, k,B,Len: Integer;
  List: array of integer;
  c: Char;
const
  S = '{.{.}.}.{.}';
begin
  SetLength(List,Length(S));
  Len:=Length(S);
  for i:=1 to Len do begin
    if S[i]='{' then begin
      B:=0;
      for k:=i+1 to Len do begin
        c:=S[k];
        if c='{' then
          Inc(B)
        else
          if c = '}' then begin
            if (B<=0) then Break;
            Dec(B);
          end;
      end;
      List[i-1]:=k-1;
    end
    else
      List[i-1]:=-1;
  end;
end.
New implementation...
< > ⌨
reilas 
List<int[]> a = new ArrayList<>();
int i, x, y, n = s.length(), c;
for (i = y = 0; i < n; ++i)
    if (s.charAt(i) == '{') {
        x = i + ++y;
        while (x < n) {
            c = s.charAt(x++);
            if (c == '{') ++y;
            else if (c == '}')
                if (--y == 0) break;
        }
        a.add(new int[] { i, x - 1 });
    }
var
  i, k,B,Len: Integer;
  List: array of integer;
  c: Char;
const
  S = '{.{.}.}.{.}';
begin
  SetLength(List,Length(S));
  Len:=Length(S);
  for i:=1 to Len do begin
    if S[i]='{' then begin
      B:=0;
      for k:=i+1 to Len do begin
        c:=S[k];
        if c='{' then
          Inc(B)
        else
          if c = '}' then begin
            if (B<=0) then Break;
            Dec(B);
          end;
      end;
      List[i-1]:=k-1;
    end
    else
      List[i-1]:=-1;
  end;
end.