1 /*

     2  * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package com.sun.tools.javac.comp;

    27 

    28 import com.sun.tools.javac.util.*;

    29 import com.sun.tools.javac.tree.*;

    30 import java.util.Iterator;

    31 import java.util.NoSuchElementException;

    32 

    33 /** A class for environments, instances of which are passed as

    34  *  arguments to tree visitors.  Environments refer to important ancestors

    35  *  of the subtree that's currently visited, such as the enclosing method,

    36  *  the enclosing class, or the enclosing toplevel node. They also contain

    37  *  a generic component, represented as a type parameter, to carry further

    38  *  information specific to individual passes.

    39  *

    40  *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If

    41  *  you write code that depends on this, you do so at your own risk.

    42  *  This code and its internal interfaces are subject to change or

    43  *  deletion without notice.</b>

    44  */

    45 public class Env<A> implements Iterable<Env<A>> {

    46 

    47     /** The next enclosing environment.

    48      */

    49     public Env<A> next;

    50 

    51     /** The environment enclosing the current class.

    52      */

    53     public Env<A> outer;

    54 

    55     /** The tree with which this environment is associated.

    56      */

    57     public JCTree tree;

    58 

    59     /** The enclosing toplevel tree.

    60      */

    61     public JCTree.JCCompilationUnit toplevel;

    62 

    63     /** The next enclosing class definition.

    64      */

    65     public JCTree.JCClassDecl enclClass;

    66 

    67     /** The next enclosing method definition.

    68      */

    69     public JCTree.JCMethodDecl enclMethod;

    70 

    71     /** A generic field for further information.

    72      */

    73     public A info;

    74 

    75     /** Is this an environment for evaluating a base clause?

    76      */

    77     public boolean baseClause = false;

    78 

    79     /** Create an outermost environment for a given (toplevel)tree,

    80      *  with a given info field.

    81      */

    82     public Env(JCTree tree, A info) {

    83         this.next = null;

    84         this.outer = null;

    85         this.tree = tree;

    86         this.toplevel = null;

    87         this.enclClass = null;

    88         this.enclMethod = null;

    89         this.info = info;

    90     }

    91 

    92     /** Duplicate this environment, updating with given tree and info,

    93      *  and copying all other fields.

    94      */

    95     public Env<A> dup(JCTree tree, A info) {

    96         return dupto(new Env<A>(tree, info));

    97     }

    98 

    99     /** Duplicate this environment into a given Environment,

   100      *  using its tree and info, and copying all other fields.

   101      */

   102     public Env<A> dupto(Env<A> that) {

   103         that.next = this;

   104         that.outer = this.outer;

   105         that.toplevel = this.toplevel;

   106         that.enclClass = this.enclClass;

   107         that.enclMethod = this.enclMethod;

   108         return that;

   109     }

   110 

   111     /** Duplicate this environment, updating with given tree,

   112      *  and copying all other fields.

   113      */

   114     public Env<A> dup(JCTree tree) {

   115         return dup(tree, this.info);

   116     }

   117 

   118     /** Return closest enclosing environment which points to a tree with given tag.

   119      */

   120     public Env<A> enclosing(int tag) {

   121         Env<A> env1 = this;

   122         while (env1 != null && env1.tree.getTag() != tag) env1 = env1.next;

   123         return env1;

   124     }

   125 

   126     public String toString() {

   127         return "Env[" + info + (outer == null ? "" : ",outer=" + outer) + "]";

   128     }

   129 

   130     public Iterator<Env<A>> iterator() {

   131         return new Iterator<Env<A>>() {

   132             Env<A> next = Env.this;

   133             public boolean hasNext() {

   134                 return next.outer != null;

   135             }

   136             public Env<A> next() {

   137                 if (hasNext()) {

   138                     Env<A> current = next;

   139                     next = current.outer;

   140                     return current;

   141                 }

   142                 throw new NoSuchElementException();

   143 

   144             }

   145             public void remove() {

   146                 throw new UnsupportedOperationException();

   147             }

   148         };

   149     }

   150 }