%header {:
 package AST;
:};
%embed {:
  class Events extends Parser.Events {
    public void syntaxError(Symbol token) {
      StringBuffer s = new StringBuffer();
      s.append(token.getLine(token.getStart()) + ", " + token.getColumn(token.getStart()) + "\n");
      s.append("  *** Syntactic error: unexpected token " + Terminals.NAMES[token.getId()]);
      throw new Error(s.toString());
    }
    public void scannerError(Scanner.Exception e) {
      StringBuffer s = new StringBuffer();
      s.append(e.line + ", " + e.column + "\n");
      s.append("  *** Lexical error: " + e.getMessage());
      throw new Error(s.toString());
    }
  }

  { report = new Events(); } // Use error handler in parser
:};

Program goal =
  block                        {: return new Program(block); :}
  ;

Block block =
  LBRACE block_stmt_list_opt RBRACE {: return new Block(block_stmt_list_opt); :}
  ;

List block_stmt_list_opt =
                               {: return new List(); :}
  | block_stmt_list            {: return block_stmt_list; :}
  ;

List block_stmt_list =
    block_stmt                 {: return new List().add(block_stmt); :}
  | block_stmt_list block_stmt {: return block_stmt_list.add(block_stmt); :}
  ;

BlockStmt block_stmt =
    class_decl 
  | var_decl
  | stmt
  ;

Stmt stmt =
    assign_stmt
  | while_stmt
  ;

ClassDecl class_decl =
  CLASS IDENTIFIER extends_opt block {: return new ClassDecl(IDENTIFIER, extends_opt, block); :}
  ;
Opt extends_opt =
                               {: return new Opt(); :}
  | EXTENDS IDENTIFIER         {: return new Opt(new Use(IDENTIFIER)); :}
  ;

VarDecl var_decl = 
  name IDENTIFIER SEMICOLON    {: return new VarDecl(IDENTIFIER, name); :}
  ;

AssignStmt assign_stmt =
  name ASSIGN exp SEMICOLON    {: return new AssignStmt(name, exp); :}
  ;

WhileStmt while_stmt =
  WHILE LPAREN exp RPAREN stmt {: return new WhileStmt(exp, stmt); :}
  ;

Exp exp =
    name
  | boolean_literal
  ;

Access name =
    IDENTIFIER                 {: return new Use(IDENTIFIER); :}
  | name DOT IDENTIFIER        {: return new Dot(name, new Use(IDENTIFIER)); :}
  ;

Exp boolean_literal =
  BOOLEAN_LITERAL              {: return new BooleanLiteral(BOOLEAN_LITERAL); :}
  ;