Lexer.fsl

{
//
// IDLC - Interface Definition Language Compiler
//
// Copyright (C) 2018-2019  Wael El Oraiby
//
// All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
module Lexer

open FSharp.Text.Lexing
open System
open Parser
open Ast

exception SyntaxError of string

let lexeme (lexbuf : LexBuffer<char>) = new System.String(lexbuf.Lexeme)
let newline (lexbuf:LexBuffer<_>) = lexbuf.EndPos <- lexbuf.EndPos.NextLine
let getPosition streamName (lexbuf: LexBuffer<char>) =
    { Position.streamName = streamName
      line = lexbuf.StartPos.Line + 1
      column = lexbuf.StartPos.Column
      cursor = lexbuf.StartPos.AbsoluteOffset }

}

let int = ['0'-'9']+
let digit = ['0'-'9']
let frac = '.' digit*
let exp = ['e' 'E'] ['-' '+']? digit+
let float = '-'? digit* frac? exp?
let char = '\'' ( [^'\\'] | ('\\' ( '\\' | '\'' | "\"" | 'n' | 't' | 'b' | 'r'))) '\''
let charUpper = ['A'-'Z']
let charLower = ['a'-'z']
let charAll = ['A'-'Z'] | ['a' - 'z'] | ['0'-'9']
let typeName = charUpper charAll*
let identName = charLower charAll*
let white = [' ' '\t']+
let newline = '\r' | '\n' | "\r\n"

rule read streamName =
    parse
    | white         { read streamName lexbuf }
    | newline       { newline lexbuf; read streamName lexbuf }
    | int           { INT (int (lexeme lexbuf)) }
    | float         { FLOAT (float (lexeme lexbuf)) }
    | "Unit"        { UNIT }
    | "Bool"        { BOOL }
    | "Char"        { CHAR }
    | "U8"          { U8 }
    | "U16"         { U16 }
    | "U32"         { U32 }
    | "U64"         { U64 }
    | "S8"          { S8 }
    | "S16"         { S16 }
    | "S32"         { S32 }
    | "S64"         { S64 }
    | "F32"         { F32 }
    | "F64"         { F64 }
    | typeName      { let pos = getPosition streamName lexbuf in TYPENAME (lexeme lexbuf, pos) }
    | "interface"   { INTERFACE }
    | "object"      { OBJECT }
    | "import"      { IMPORT }
    | "fn"          { FN }
    | "struct"      { STRUCT }
    | "enum"        { ENUM }
    | "union"       { UNION }
    | "{"           { LBRACE }
    | "}"           { RBRACE }
    | "["           { LSQB }
    | "]"           { RSQB }
    | "("           { LPAREN }
    | ")"           { RPAREN }
    | "->"          { RARROW }
    | ","           { COMMA }
    | ";"           { SC }
    | ":"           { COL }
    | "*"           { MUL }
    | "="           { EQ }
    | "."           { DOT }
    | "-"           { MINUS }
    | eof           { EOF }
    | "//"          { readComment streamName lexbuf }
    | identName     { let pos = getPosition streamName lexbuf in IDENTIFIER (lexeme lexbuf, pos) }
    | _ { raise (Exception (sprintf "SyntaxError: Unexpected char: '%s' Line: %d Column: %d" (lexeme lexbuf) (lexbuf.StartPos.Line+1) lexbuf.StartPos.Column)) }

and readComment streamName =
    parse
    | newline { newline lexbuf; read streamName lexbuf }
    | _ { readComment streamName lexbuf }