libjava/gnu/java/beans/decoder/Context.java

   1 /* gnu.java.beans.decoder.Context
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package gnu.java.beans.decoder;
  39
  40 /** A Context is the environment for an object which is being assembler. If there
  41  * are no errors each handler creates one Context.
  42  * <p>Depending on the result of isStatement() a Context can be statement or an
  43  * expression. An expression returns a value to the Context of its parent handler,
  44  * a statement does not. Whenever a Context is a statement the parent handler's
  45  * Context is informed about that through the {@link notifyStatement}-method.</p>
  46  *
  47  * @author Robert Schuster
  48  */
  49 interface Context
  50 {
  51   /** Adds a parameter object to the context. This method is used when
  52    * sub-Contexts return their result.
  53    *
  54    * Some Contexts do not accept more than a certain amount of objects
  55    * and throw an AssemblerException if the amount is exceeded.
  56    *
  57    * @param o The object added to this context.
  58    */
  59   void addParameterObject(Object o) throws AssemblyException;
  60
  61   /** Notifies that the next element is a statement. This can mean
  62    * that an argument list is complete to be called.
  63    *
  64    */
  65   void notifyStatement(Context outerContext) throws AssemblyException;
  66
  67   /** Notifies that the context ends and the returns the appropriate result
  68    * object.
  69    *
  70    * @param outerContext
  71    * @return
  72    */
  73   Object endContext(Context outerContext) throws AssemblyException;
  74
  75   /** Notifies that the assembly of a subcontext failed and returns
  76    * whether this Context is affected in a way that it fails too.
  77    *
  78    * @return Whether the failure of a subcontext lets this context fail, too.
  79    */
  80   boolean subContextFailed();
  81
  82   /** Calls an appropriate indexed set method if it is available or
  83    * throws an AssemblerException if that is not allowed on this Context.
  84    *
  85    * The behaviour of this method is equal to List.set(int, Object).
  86    *
  87    * @param index Index position to be set.
  88    * @param o Object to be set at the given index position.
  89    * @throws AssemblerException Indexed set is not allowed or otherwise failed.
  90    */
  91   void set(int index, Object o) throws AssemblyException;
  92
  93   /** Calls an appropriate indexed get method if it is available or
  94    * throws an AssemblerException if that is not allowed on this Context.
  95    *
  96    * The behaviour of this method is equal to List.get(int).
  97    *
  98    * @param index Index position of the object return.
  99    * @throws AssemblerException Indexed get is not allowed or otherwise failed.
 100    */
 101   Object get(int index) throws AssemblyException;
 102
 103   /** Returns the result which was calculated by calling endContext() or reportStatement().
 104    * Its the handler's responsibility to care that any of these two methods was called.
 105    *
 106    * This is used by sub-Contexts to access this Context's result.
 107    *
 108    * @return
 109    */
 110   Object getResult();
 111
 112   /** Gives this Context a unique id. For convenience the id may be null which means
 113    * that no id exists at all.
 114    *
 115    * @param id
 116    */
 117   void setId(String id);
 118
 119   /** Returns this Context's unique id or null if does not have such an id.
 120    *
 121    * @return This Context's id or null.
 122    */
 123   String getId();
 124
 125   /** Returns whether this Context is a statement (not returning result back
 126    * to parent handler's Context) or not (= expression).
 127    *
 128    * @return
 129    */
 130   boolean isStatement();
 131
 132   /** Sets whether this Context is a statement or not.
 133    *
 134    * @param b
 135    */
 136   void setStatement(boolean b);
 137 }