View Javadoc

1   ////////////////////////////////////////////////////////////////////////////////
2   // MillScript: an Open Spice interpreter and batch website creation tool
3   // Copyright (C) 2001-2004 Open World Ltd
4   //
5   // This file is part of MillScript.
6   //
7   // MillScript is free software; you can redistribute it and/or modify it under
8   // the terms of the GNU General Public License as published by the Free
9   // Software Foundation; either version 2 of the License, or (at your option)
10  // any later version.
11  //
12  // MillScript is distributed in the hope that it will be useful, but WITHOUT
13  // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
15  // more details.
16  //
17  // You should have received a copy of the GNU General Public License along with
18  // MillScript; if not, write to the Free Software Foundation, Inc., 59 Temple
19  // Place, Suite 330, Boston, MA  02111-1307  USA
20  ////////////////////////////////////////////////////////////////////////////////
21  package org.millscript.millscript.syntax;
22  
23  import org.millscript.millscript.expr.Expr;
24  
25  /**
26   * This class represents simple postfix syntax. This is a convenience class to
27   * reduce the work required to implement a piece of simple postfix syntax. The
28   * 'simple' refers to the fact that the syntax follows the form
29   *
30   * <p>
31   * <code>&lt;expr&gt; S &lt;expr&gt;</code>
32   * </p>
33   *
34   * <p>
35   * and as such is rather simple. In these situations, the syntax doesn't involve
36   * other functions
37   * </p>
38   *
39   * <p>
40   * e.g. <code>&lt;expr&gt; &#38;&#38; &lt;expr&gt;</code>
41   * </p>
42   */
43  public abstract class SimplePostfixSyntax extends PostfixSyntax {
44  
45      /**
46       * Returns the expression for this simple postfix syntax, which is made by
47       * combining the left and right hand side expressions.
48       *
49       * @param   lhs the expression on the left hand side of this syntax
50       * @param   rhs the expression on the right hand side of this syntax
51       * @return  the expression for this syntax
52       */
53      abstract Expr simple( final Expr lhs, final Expr rhs );
54  
55      /**
56       * @see org.millscript.millscript.syntax.PostfixSyntaxInterface#postfix(java.lang.String, int, org.millscript.millscript.expr.Expr, org.millscript.millscript.syntax.Parser)
57       */
58      @Override
59      public Expr postfix( final String sym, final int prec, final Expr lhs, final Parser parser ) {
60          // Read the RHS expression at the current precedence
61          Expr rhs = parser.readExprPrec( prec );
62          // Return the expression resulting from the combination of the lhs and
63          // rhs expressions
64          return simple( lhs, rhs );
65      }
66  
67  }