DB<170> x / ( (['"]) [^\g\-1]*? \g-1 ) /gx
0  '\'abc\''
1  '\''
2  '"def"'
3  '"'
  DB<171> x / ( (['"]) [^\g{\-1}]*? \g-1 ) /gx
0  '\'abc\''
1  '\''
2  '"def"'
3  '"'
  DB<172> x / ( (['"]) [^\g2]*? \g-1 ) /gx
0  '\'abc\''
1  '\''
2  '"def"'
3  '"'
  DB<173>