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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3.  
  4. typedef void effector(int);
  5. typedef struct transition transition;
  6. struct transition {
  7.   int state;
  8.   effector *effect;
  9. };
  10.  
  11. enum sigil { Letter, Slash, Star, EndOfFile, Squote, Dquote, Bslash, Newline };
  12. typedef enum sigil sigil;
  13.  
  14. sigil sigilify(int c) {
  15.   switch (c) {
  16.     case '/':  return Slash;
  17.     case '*':  return Star;
  18.     case EOF:  return EndOfFile;
  19.     case '\'': return Squote;
  20.     case '"':  return Dquote;
  21.     case '\\': return Bslash;
  22.     case '\n': return Newline;
  23.     default:   return Letter;
  24.   }
  25. }
  26.  
  27. void emit    (int c) { putchar(c); }
  28. void slash   (int c) { putchar('/'); putchar(c); }
  29. void nothing (int c) { }
  30. void halt    (int c) { exit(EXIT_SUCCESS); }
  31.  
  32. #define T(state, sigil) (((state) << 4) | sigil)
  33.  
  34. int main() {
  35.   transition state = { 0, emit };
  36.   transition table[] = {
  37.  
  38.     [T(0, Slash)] =     { 1, nothing },
  39.     [T(0, Letter)] =    { 0, emit },
  40.     [T(0, Star)] =      { 0, emit },
  41.     [T(0, EndOfFile)] = { 0, halt },
  42.     [T(0, Squote)] =    { 6, emit },
  43.     [T(0, Dquote)] =    { 4, emit },
  44.     [T(0, Bslash)] =    { 0, emit },
  45.     [T(0, Newline)] =   { 0, emit }, // Handle newline in state 0
  46.  
  47.     [T(1, Slash)] =     { 9, nothing },    // Transition to line comment state
  48.     [T(1, Star)] =      { 2, nothing },    // Start of block comment
  49.     [T(1, Letter)] =    { 0, slash },      // Not a comment, emit '/'
  50.     [T(1, EndOfFile)] = { 0, halt },
  51.     [T(1, Squote)] =    { 0, slash },
  52.     [T(1, Dquote)] =    { 0, slash },
  53.     [T(1, Bslash)] =    { 0, slash },
  54.     [T(1, Newline)] =   { 0, slash },      // Not a comment, emit '/'
  55.  
  56.     [T(2, Slash)] =     { 2, nothing },
  57.     [T(2, Letter)] =    { 2, nothing },
  58.     [T(2, Star)] =      { 3, nothing },
  59.     [T(2, EndOfFile)] = { 0, halt },
  60.     [T(2, Squote)] =    { 2, nothing },
  61.     [T(2, Dquote)] =    { 2, nothing },
  62.     [T(2, Bslash)] =    { 2, nothing },
  63.     [T(2, Newline)] =   { 2, nothing },    // Newlines inside block comments are ignored
  64.  
  65.     [T(3, Slash)] =     { 0, nothing },
  66.     [T(3, Letter)] =    { 2, nothing },
  67.     [T(3, Star)] =      { 2, nothing },
  68.     [T(3, EndOfFile)] = { 0, halt },
  69.     [T(3, Squote)] =    { 2, nothing },
  70.     [T(3, Dquote)] =    { 2, nothing },
  71.     [T(3, Bslash)] =    { 2, nothing },
  72.     [T(3, Newline)] =   { 2, nothing },
  73.  
  74.     [T(4, Slash)] =     { 4, emit },
  75.     [T(4, Letter)] =    { 4, emit },
  76.     [T(4, Star)] =      { 4, emit },
  77.     [T(4, EndOfFile)] = { 0, halt },
  78.     [T(4, Squote)] =    { 4, emit },
  79.     [T(4, Dquote)] =    { 0, emit },
  80.     [T(4, Bslash)] =    { 5, emit },
  81.     [T(4, Newline)] =   { 4, emit },
  82.  
  83.     [T(5, Slash)] =     { 4, emit },
  84.     [T(5, Letter)] =    { 4, emit },
  85.     [T(5, Star)] =      { 4, emit },
  86.     [T(5, EndOfFile)] = { 0, halt },
  87.     [T(5, Squote)] =    { 4, emit },
  88.     [T(5, Dquote)] =    { 4, emit },
  89.     [T(5, Bslash)] =    { 4, emit },
  90.     [T(5, Newline)] =   { 4, emit },
  91.  
  92.     [T(6, Slash)] =     { 8, emit },
  93.     [T(6, Letter)] =    { 8, emit },
  94.     [T(6, Star)] =      { 8, emit },
  95.     [T(6, EndOfFile)] = { 0, halt },
  96.     [T(6, Squote)] =    { 8, emit },
  97.     [T(6, Dquote)] =    { 8, emit },
  98.     [T(6, Bslash)] =    { 7, emit },
  99.     [T(6, Newline)] =   { 8, emit },
  100.  
  101.     [T(7, Slash)] =     { 8, emit },
  102.     [T(7, Letter)] =    { 8, emit },
  103.     [T(7, Star)] =      { 8, emit },
  104.     [T(7, EndOfFile)] = { 8, emit },
  105.     [T(7, Squote)] =    { 8, emit },
  106.     [T(7, Dquote)] =    { 8, emit },
  107.     [T(7, Bslash)] =    { 8, emit },
  108.     [T(7, Newline)] =   { 8, emit },
  109.  
  110.     [T(8, Slash)] =     { 0, emit },
  111.     [T(8, Letter)] =    { 0, emit },
  112.     [T(8, Star)] =      { 0, emit },
  113.     [T(8, EndOfFile)] = { 0, halt },
  114.     [T(8, Squote)] =    { 0, emit },
  115.     [T(8, Dquote)] =    { 0, emit },
  116.     [T(8, Bslash)] =    { 0, emit },
  117.     [T(8, Newline)] =   { 0, emit },
  118.  
  119.     // New State 9: Inside Line Comment
  120.     [T(9, Slash)] =     { 9, nothing },
  121.     [T(9, Star)] =      { 9, nothing },
  122.     [T(9, Letter)] =    { 9, nothing },
  123.     [T(9, Squote)] =    { 9, nothing },
  124.     [T(9, Dquote)] =    { 9, nothing },
  125.     [T(9, Bslash)] =    { 9, nothing },
  126.     [T(9, Newline)] =   { 0, emit },       // End of line comment
  127.     [T(9, EndOfFile)] = { 0, halt },       // End of file while in line comment
  128.   };
  129.  
  130.   for (;;) {
  131.     int c = getchar();
  132.     state = table[T(state.state, sigilify(c))];
  133.     state.effect(c);
  134.   }
  135. }
Success #stdin #stdout 0s 5284KB
comments (?)
stdin
copy 
abc/*comment/*still comment*/def
" /*not a comment "
'/* broken syntax, but not a comment
abcd //test comment
//test comment
stdout
copy 
abcdef
" /*not a comment "
'/* broken syntax, but not a comment
abcd
https://ideone.com/bUu6tj
language:
C99 (gcc 8.3)
created:
5 days ago
visibility:
public

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