lexer.x

{
module Lexer where

import System.IO
import System.IO.Unsafe
}

%wrapper "posn"

$digit = 0-9      -- digits
$alpha = [a-zA-Z] -- alphabetic characters

tokens :-

  "//".*                                ;
  :                                     { \p s -> Colon (getLC p)}
  ";"                                   { \p s -> SemiColon (getLC p)}
  int                                   { \p s -> Type s (getLC p)}
  if                                    { \p s -> If (getLC p)}
  "else"                                { \p s -> Else (getLC p)}
  "loop"                                { \p s -> Loop (getLC p)}
  then                                  { \p s -> Then (getLC p)}
  write                                 { \p s -> Write (getLC p)}
  >                                     { \p s -> Greater (getLC p)}
  "<"                                   { \p s -> Less (getLC p)}
  $digit+                               { \p s -> Int (read s)  (getLC p)}
  "("                                   { \p s -> OpenPar  (getLC p)}  
  ")"                                   { \p s -> ClosePar (getLC p)}
  Float                                 { \p s -> Float s (getLC p)}
  Char                                  { \p s -> Char s (getLC p)}  
  types                                 { \p s -> TypesBlock (getLC p)}
  vars                                  { \p s -> VarsBlock (getLC p)}
  subprograms                           { \p s -> SubprogramsBlock (getLC p)}
  process                               { \p s -> ProcessBlock (getLC p)}
  fields                                { \p s -> FieldsBlock (getLC p)}
  operations                            { \p s -> OperationsBlock (getLC p)}
  "{"                                   { \p s -> OpenCurlyBrackets (getLC p)}
  "}"                                   { \p s -> CloseCurlyBrackets (getLC p)}
  =                                     { \p s -> Equals (getLC p)}
  num                                   { \p s -> Num s (getLC p)}
  tempTemp                              { \p s -> NumWithSpecification (getLC p)}
  return                                { \p s -> Return (getLC p)}
  ","                                   { \p s -> Comma (getLC p)}
  "+"                                   { \p s -> Add (getLC p)}
  "*"                                   { \p s -> Mult (getLC p)}
  "-"                                   { \p s -> Sub (getLC p)}
  "^"                                   { \p s -> Pow (getLC p)}
  "/"                                   { \p s -> Div (getLC p)}
  "%"                                   { \p s -> Mod (getLC p)}
  "=="                                  { \p s -> Equiv (getLC p)}
  "!="                                  { \p s -> Diff (getLC p)}
  print                                 { \p s -> Print (getLC p)}
  input                                 { \p s -> Input (getLC p)}
  "."                                   { \p s -> Dot (getLC p)}
  \" .* \"                              { \p s -> StringLit s (getLC p)}
  $alpha [$alpha $digit \_ \']*         { \p s -> Id s  (getLC p)}
  '"'                                   { \p s -> Quote (getLC p)}
  $white+                               ;


{
-- Each action has type :: AlexPosn -> String -> Token

-- The token type:
data Token =
  Colon                (Int, Int) |
  SemiColon            (Int, Int) |
  Type     String      (Int, Int) |
  If                   (Int, Int) |
  Else                 (Int, Int) |
  Loop                 (Int, Int) |
  Then                 (Int, Int) |
  Write                (Int, Int) |
  Greater              (Int, Int) |
  Less                 (Int, Int) |
  Id       String      (Int, Int) |
  Int      Int         (Int, Int) |
  StringLit   String   (Int, Int) |
  OpenPar              (Int, Int) |
  ClosePar             (Int, Int) |
  Float    String      (Int, Int) |
  Char     String      (Int, Int) |
  TypesBlock           (Int, Int) |
  VarsBlock            (Int, Int) |
  SubprogramsBlock     (Int, Int) |
  ProcessBlock         (Int, Int) |
  FieldsBlock          (Int, Int) |
  OperationsBlock      (Int, Int) |
  OpenCurlyBrackets    (Int, Int) |
  CloseCurlyBrackets   (Int, Int) |
  Equals               (Int, Int) |
  Num      String      (Int, Int) |
  NumWithSpecification (Int, Int) |
  Comma                (Int, Int) |
  Add                  (Int, Int) |
  Sub                  (Int, Int) |
  Mult                 (Int, Int) |
  Pow                  (Int, Int) |
  Div                  (Int, Int) |
  Mod                  (Int, Int) |
  Equiv                (Int, Int) |
  Diff                 (Int, Int) |
  Print                (Int, Int) |
  Input                (Int, Int) |
  Dot                  (Int, Int) |
  Quote                (Int, Int) |
  Return               (Int, Int)
  deriving (Eq,Show)   

getLC (AlexPn _ l c) = (l, c) 

getTokens fn = unsafePerformIO (getTokensAux fn)

getTokensAux fn = do {fh <- openFile fn ReadMode;
                      s <- hGetContents fh;
                      return (alexScanTokens s)}
}