Paste number 24849: Regular expression engine in 14 lines of Python

def iconcat(xs, ys): for x in xs: yield x for y in ys: yield y def nil(s): yield s def seq(l, r): return lambda s: (sr for sl in l(s) for sr in r(sl)) def alt(l, r): return lambda s: iconcat(l(s), r(s)) def star(e): return lambda s: iconcat(nil(s), seq(e, star(e))(s)) def plus(e): return seq(e, star(e)) def char(c): def match(s): if s and s[0] == c: yield s[1:] return match # c(a|d)+r e = seq(char

[kenkitii]

14行で書いた正規表現エンジン