freenode ##c caze K&R C exercise 1.24 example from https://ideone.com/94U6aJ

k-and-r-1.24.c

#include <stdio.h>
#include <stdlib.h>

typedef void effector(int);
typedef struct transition transition;
struct transition {
  int state;
  effector *effect;
};

enum sigil { Letter, Slash, Star, EndOfFile, Squote, Dquote, Bslash };
typedef enum sigil sigil;

sigil sigilify(int c) {
  switch (c) {
    case '/':  return Slash;
    case '*':  return Star;
    case EOF:  return EndOfFile;
    case '\'': return Squote;
    case '"':  return Dquote;
    case '\\': return Bslash;
    default:   return Letter;
  }
}

void emit    (int c) { putchar(c); }
void slash   (int c) { putchar('/'); putchar(c); }
void nothing (int c) { }
void halt    (int c) { exit(EXIT_SUCCESS); }

#define T(state, sigil) (((state) << 4) | sigil)

int main() {
  transition state = { 0, emit };
  transition table[] = {

    [T(0, Slash)] =     { 1, nothing },
    [T(0, Letter)] =    { 0, emit },
    [T(0, Star)] =      { 0, emit },
    [T(0, EndOfFile)] = { 0, halt },
    [T(0, Squote)] =    { 6, emit },
    [T(0, Dquote)] =    { 4, emit },
    [T(0, Bslash)] =    { 0, emit  },

    [T(1, Slash)] =     { 0, slash },
    [T(1, Letter)] =    { 0, slash },
    [T(1, Star)] =      { 2, nothing },
    [T(1, EndOfFile)] = { 0, halt },
    [T(1, Squote)] =    { 0, slash },
    [T(1, Dquote)] =    { 0, slash },
    [T(1, Bslash)] =    { 0, slash },

    [T(2, Slash)] =     { 2, nothing },
    [T(2, Letter)] =    { 2, nothing},
    [T(2, Star)] =      { 3, nothing },
    [T(2, EndOfFile)] = { 0, halt },
    [T(2, Squote)] =    { 2, nothing },
    [T(2, Dquote)] =    { 2, nothing },
    [T(2, Bslash)] =    { 2, nothing },

    [T(3, Slash)] =     { 0, nothing },
    [T(3, Letter)] =    { 2, nothing },
    [T(3, Star)] =      { 2, nothing },
    [T(3, EndOfFile)] = { 0, halt },
    [T(3, Squote)] =    { 2, nothing },
    [T(3, Dquote)] =    { 2, nothing },
    [T(3, Bslash)] =    { 2, nothing },

    [T(4, Slash)] =     { 4, emit },
    [T(4, Letter)] =    { 4, emit },
    [T(4, Star)] =      { 4, emit },
    [T(4, EndOfFile)] = { 0, halt },
    [T(4, Squote)] =    { 4, emit },
    [T(4, Dquote)] =    { 0, emit },
    [T(4, Bslash)] =    { 5, emit },

    [T(5, Slash)] =     { 4, emit },
    [T(5, Letter)] =    { 4, emit },
    [T(5, Star)] =      { 4, emit },
    [T(5, EndOfFile)] = { 0, halt },
    [T(5, Squote)] =    { 4, emit },
    [T(5, Dquote)] =    { 4, emit },
    [T(5, Bslash)] =    { 4, emit},

    [T(6, Slash)] =     { 8, emit },
    [T(6, Letter)] =    { 8, emit },
    [T(6, Star)] =      { 8, emit },
    [T(6, EndOfFile)] = { 0, halt },
    [T(6, Squote)] =    { 8, emit },
    [T(6, Dquote)] =    { 8, emit },
    [T(6, Bslash)] =    { 7, emit },

    [T(7, Slash)] =     { 8, emit },
    [T(7, Letter)] =    { 8, emit },
    [T(7, Star)] =      { 8, emit },
    [T(7, EndOfFile)] = { 8, emit },
    [T(7, Squote)] =    { 8, emit },
    [T(7, Dquote)] =    { 8, emit },
    [T(7, Bslash)] =    { 8, emit },

    [T(8, Slash)] =     { 0, emit },
    [T(8, Letter)] =    { 0, emit },
    [T(8, Star)] =      { 0, emit },
    [T(8, EndOfFile)] = { 0, halt },
    [T(8, Squote)] =    { 0, emit },
    [T(8, Dquote)] =    { 0, emit },
    [T(8, Bslash)] =    { 0, emit },
  };

  for (;;) {
    int c = getchar();
    (state = table[T(state.state, sigilify(c))]).effect(c);
  }
}