tiger/src/lib/tiger/tiger_lexer.mll

   1 {
   2   open Tiger_parser.Token
   3
   4   let comment_level = ref 0
   5   let string_buf    = Buffer.create 100
   6 }
   7
   8 let alpha = ['a'-'z' 'A'-'Z']
   9 let num = ['0'-'9']
  10 let newline = '\n' | '\r' | "\n\r"
  11
  12 rule token = parse
  13   | eof {
  14       EOF
  15   }
  16
  17   (* Track line number *)
  18   | newline {
  19       Lexing.new_line lexbuf;
  20       token lexbuf
  21   }
  22
  23   (* Comment *)
  24   | "/*" {
  25       incr comment_level;
  26       comment lexbuf
  27   }
  28
  29   | ":=" {ASSIGN}
  30   | "<=" {LE}
  31   | ">=" {GE}
  32   | "<>" {NEQ}
  33   | '&'  {AND}
  34   | '('  {LPAREN}
  35   | ')'  {RPAREN}
  36   | '*'  {TIMES}
  37   | '+'  {PLUS}
  38   | '-'  {MINUS}
  39   | '/'  {DIVIDE}
  40   | ','  {COMMA}
  41   | '.'  {DOT}
  42   | ':'  {COLON}
  43   | ';'  {SEMICOLON}
  44   | '>'  {GT}
  45   | '<'  {LT}
  46   | '='  {EQ}
  47   | '['  {LBRACK}
  48   | ']'  {RBRACK}
  49   | '{'  {LBRACE}
  50   | '}'  {RBRACE}
  51   | '|'  {OR}
  52
  53   (* String literal *)
  54   | '"' {
  55       string_literal lexbuf
  56   }
  57
  58   (* Drop whitespace *)
  59   | [' ' '\t'] {
  60       token lexbuf
  61   }
  62
  63   | (num+ as int) {
  64     INT (int_of_string int)
  65   }
  66
  67   | (alpha (alpha | num | '_')* as id) {
  68       match id with
  69       | "array"    -> ARRAY
  70       | "break"    -> BREAK
  71       | "do"       -> DO
  72       | "else"     -> ELSE
  73       | "end"      -> END
  74       | "for"      -> FOR
  75       | "function" -> FUNCTION
  76       | "if"       -> IF
  77       | "in"       -> IN
  78       | "let"      -> LET
  79       | "nil"      -> NIL
  80       | "of"       -> OF
  81       | "then"     -> THEN
  82       | "to"       -> TO
  83       | "type"     -> TYPE
  84       | "var"      -> VAR
  85       | "while"    -> WHILE
  86       | _          -> ID id
  87   }
  88
  89   (* Eat unimplemented. FIXME: stop indiscriminate eating *)
  90   | _ {
  91       token lexbuf
  92   }
  93 and string_literal = parse
  94   (* Keep escaped quote marks as part of the string literal *)
  95   | '\\' '"' {
  96       Buffer.add_char string_buf '"';
  97       string_literal lexbuf
  98   }
  99
 100   | '"' {
 101       let string = Buffer.contents string_buf in
 102       Buffer.reset string_buf;
 103       STRING string
 104   }
 105
 106
 107   | (_ as c) {
 108       Buffer.add_char string_buf c;
 109       string_literal lexbuf
 110   }
 111 and comment = parse
 112   | eof {
 113       (* TODO: Error: unterminated comment? or we don't care? *)
 114       EOF
 115   }
 116
 117   (* Track line number *)
 118   | newline {
 119       Lexing.new_line lexbuf;
 120       comment lexbuf
 121   }
 122
 123   | "/*" {
 124       incr comment_level;
 125       comment lexbuf
 126   }
 127
 128   | "*/" {
 129       decr comment_level;
 130       match !comment_level with
 131       | 0            -> token lexbuf
 132       | n when n > 0 -> comment lexbuf
 133       | _            -> assert false
 134   }
 135
 136   (* Drop comment contents *)
 137   | _ {
 138       comment lexbuf
 139   }