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.ApplyExpr;
24  import org.millscript.millscript.expr.Expr;
25  
26  /**
27   * This class implements parenthesis syntax. The open parenthesis character can
28   * be both prefix and postfix. In the postfix form, you are applying a function,
29   * while in prefix form you are writing a simple expression.
30   *
31   * <dl>
32   * <dt>Postfix: Function application</dt>
33   * <dd><code>E( E' )</code></dd>
34   * <dt>Prefix: Simple expression</dt>
35   * <dd><code>( E )</code></dd>
36   * </dl>
37   *
38   * @see ApplyExpr
39   */
40  public final class ParenSyntax extends BothfixSyntax {
41  
42      /**
43       * The matching close parenthesis character.
44       */
45      static final String CLOSE = ")".intern();
46  
47      /**
48       * @see org.millscript.millscript.syntax.PostfixSyntaxInterface#postfix(java.lang.String, int, org.millscript.millscript.expr.Expr, org.millscript.millscript.syntax.Parser)
49       */
50      @Override
51      public ApplyExpr postfix( final String sym, final int prec, final Expr lhs, final Parser parser ) {
52          // The lhs is an expression that represents a function, so we read
53          // statements to the close parenthesis and apply the function to the
54          // arguments
55          return new ApplyExpr( lhs, parser.readStmntsTo( ")" ) );
56      }
57  
58      /**
59       * @see org.millscript.millscript.syntax.PrefixSyntaxInterface#prefix(java.lang.String, org.millscript.millscript.syntax.Parser)
60       */
61      @Override
62      public Expr prefix( final String sym, final Parser parser ) {
63          // Simply read the statements to the closing parenthesis character
64          return parser.readStmntsTo( ")" );
65      }
66  
67  }