defs.pas

unit defs;

interface

uses
  Classes, SysUtils;

const
  NUM_RES_WORDS = 11;           {no. of reserved words}
  ID_TABLE_LEN = 100;           {length of identifier table}
  MAX_DIGITS_IN_NUM = 10;       {max. no. of digits in numbers}
  IDENTIFIER_LEN = 10;          {length of identifiers}
  ADDR_MAX = 2047;              {maximum address}
  MAX_BLOCK_NESTING = 3;        {maximum depth of block nesting}
  CODE_ARR_SIZE = 200;          {size of code array}
  ERR_MSGS: array[1..32] of string = (
    //1
    'Use = instead of :=',
    '= must be followed by a number',
    'Identifier must be followed by =',
    'const, var, procedure must be followed by an identifier',
    'Semicolon or comma missing',
    //6
    'Incorrect symbol after procedure declaration',
    'Statement expected',
    'Incorrect symbol after statement part in block',
    'Period expected',
    'Semicolon between statements is missing',
    //11
    'Undeclared identifier',
    'Assignment to constant or procedure is not allowed',
    'Assignment operator := expected',
    'Call must be followed by an identifier',
    'Call of a constant or a variable is meaningless',
    //16
    'then expected',
    'Semicolon or end expected',
    'do expected',
    'Incorrect symbol following statement',
    'Relational operator expected',
    //21
    'Expression must not contain a procedure identifier',
    'Right parenthesis missing',
    'The preceding factor cannot be followed by this symbol',
    'An expression cannot begin with this symbol',
    '',
    //26
    'A read must be followed by an identifier',
    'A read to constant or procedure is meaningless',
    '',
    '',
    'This number is too large',
    //31
    '',
    'Block nesting too deep'
    );

type
  symbol =
    (nul, ident, number, plus, minus, times, slash, oddsym,
    eql, neq, lss, leq, gtr, geq, lparen, rparen, comma, semicolon,
    period, becomes, beginsym, endsym, ifsym, thensym,
    whilesym, dosym, callsym, constsym, varsym, procsym, writesym, readsym);
  alfa = packed array [1..IDENTIFIER_LEN] of char;
  Obj = (constant, variable, proc);
  symset = set of symbol;
  fct = (lit, opr, lod, sto, cal, int, jmp, jpc);   {functions}

  instruction = packed record
    f: fct;           {function code}
    l: 0..MAX_BLOCK_NESTING;     {level}
    a: 0..ADDR_MAX        {displacement address}
  end;

procedure exitprog;

var
  cc: integer;      {character count}
  ll: integer;      {line length}
  kk, err: integer;
  cx: integer;      {code allocation index}
  a: alfa;
  code: array [0..CODE_ARR_SIZE] of instruction;
  mnemonic: array [fct] of packed array [1..5] of char;
  declbegsys, statbegsys, facbegsys: symset;
  table: array [0..ID_TABLE_LEN] of record
    Name: alfa;
    case kind: Obj of
      constant: (val: integer);
      variable, proc: (level, adr: integer)
  end;

implementation

procedure exitprog;
begin
  Writeln;
  Halt(1);
end;

end.