Pest grammar example for match nested parn

input.txt

(hello(world) 你好 (var))

(hello2(world))

paren_match.pest

grammar = { SOI ~ expression | newline ~ EOI }
expression = _{ paren }
paren = { opening_paren ~ paren* ~ closing_paren | inner_paren }
inner_paren = { (!(newline | opening_paren | closing_paren) ~ ANY)+ } 
opening_paren = { "(" }
closing_paren = { ")" }
newline    = _{ "\n" | "\r\n" }

result.ast

- grammar > paren
  - opening_paren: "("
  - paren > inner_paren: "hello"
  - paren
    - opening_paren: "("
    - paren > inner_paren: "world"
    - closing_paren: ")"
  - paren > inner_paren: " 你好 "
  - paren
    - opening_paren: "("
    - paren > inner_paren: "var"
    - closing_paren: ")"
  - closing_paren: ")"