{
  open Expression_parser
  module Expression = ImportExpression.T

  exception UnclosedQuote of { content: string ; line : int}
}


let spaces = [ ' ' '\t' ]
let letters = [^ '"' '\'' '(' ')' '[' ']' ':' '.' ',' '^' ' ' '\t' '\n' '\r' ]
let digit = [ '0'-'9' ]
let eol = [ '\r' '\n' ]

let escaped = [ '\'' '\\']

rule token = parse
| eol            { Lexing.new_line lexbuf; token lexbuf }
| spaces         { token lexbuf }
| '\''           { 
    try read_quoted_string (Buffer.create 17) lexbuf 
    with Failure _ ->
        let line = lexbuf.Lexing.lex_curr_p.pos_lnum
        and content = Bytes.to_string lexbuf.Lexing.lex_buffer in
        raise (UnclosedQuote {line; content})
}
| '"'            { read_dquoted_string (Buffer.create 17) lexbuf }
| '#'            { skip_comment lexbuf }
| '('            { L_PAREN }
| ')'            { R_PAREN }
| '['            { L_BRACKET }
| ']'            { R_BRACKET }
| ':'            { COLUMN }
| '.'            { DOT }
| ','            { COMA }
| '^'            { CONCAT_OPERATOR }
| '+'            { BINARY_OPERATOR (Expression.Add) }
| '-'            { BINARY_OPERATOR (Expression.Minus) }
| '/'            { BINARY_OPERATOR (Expression.Division) }
| "and"          { BOOL_OPERATOR (Expression.And) }
| "or"           { BOOL_OPERATOR (Expression.Or) }
| '<'            { INEQUALITY_OPERATOR (Expression.LT) }
| '>'            { INEQUALITY_OPERATOR (Expression.GT) }
| "<>"           { EQUALITY_OPERATOR (Expression.Different) }
| '='            { EQUALITY_OPERATOR (Expression.Equal) }
| digit+ as l    { INTEGER l}
| '-' digit+ as l { INTEGER l}
| letters+ as l  { IDENT l}
| eof            { EOF }

and skip_comment = parse
  | [^  '\r' '\n' ] 
    { skip_comment lexbuf }
  | eol
    { token lexbuf }

(* Read the content until we got another one quote *)
and read_quoted_string buf = parse
  | [^ '\'' '\\' ]+
    { Buffer.add_string buf (Lexing.lexeme lexbuf);
      read_quoted_string buf lexbuf
    }
  | "\\\'"
    { Buffer.add_char buf '\'';
      read_quoted_string buf lexbuf
    }
  | '\\'
    { Buffer.add_char buf '\\';
      read_quoted_string buf lexbuf
    }
  | '\''
    { LITERAL (Buffer.contents buf)
    }

(* Read the content until we got another one quote *)
and read_dquoted_string buf = parse
  | [^ '"' '\\' ]+
    { Buffer.add_string buf (Lexing.lexeme lexbuf);
      read_dquoted_string buf lexbuf
    }
  | "\\\""
    { Buffer.add_char buf '"';
      read_dquoted_string buf lexbuf
    }
  | '\\'
    { Buffer.add_char buf '\\';
      read_dquoted_string buf lexbuf
    }
  | '"'
    {
        LITERAL (Buffer.contents buf)
    }