Base elements

• literal characters,(eg.abc)
• meta characters,(eg..)

note:all valid regex is composed by printable ascii characters

reducing rules

• position

  • anchor,(eg.$)
  • lookground,(eg.``)

• set

  • character class,(eg.[0-9])
  • shorthand,(eg.\d)
  • unicode properties,(eg.\p{L})
  • dot match,(eg..)

• escape character

  • non-printable characters,(eg.\t)
  • literal meta characters,(eg.\\)
  • non ascii characters,(eg.\uFFFF)

• logic

  • alternation,(eg.a|b)
  • repetition(greedy,lazy),(eg.[0-9]+)

• grouping and caturing

  • group,(eg.set(Value)?)
  • group without caturing,((eg.set(?:Value)?)
  • back reference,(eg.([abc])=\1)
  • named group,(eg.(?<mygroup>[abc])=\k<mygroup>)