Env.java revision 2628:8df25ec8c930 
1/*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.tools.javac.comp;
27
28import com.sun.tools.javac.tree.*;
29import java.util.Iterator;
30import java.util.NoSuchElementException;
31
32/** A class for environments, instances of which are passed as
33 *  arguments to tree visitors.  Environments refer to important ancestors
34 *  of the subtree that's currently visited, such as the enclosing method,
35 *  the enclosing class, or the enclosing toplevel node. They also contain
36 *  a generic component, represented as a type parameter, to carry further
37 *  information specific to individual passes.
38 *
39 *  <p><b>This is NOT part of any supported API.
40 *  If you write code that depends on this, you do so at your own risk.
41 *  This code and its internal interfaces are subject to change or
42 *  deletion without notice.</b>
43 */
44public class Env<A> implements Iterable<Env<A>> {
45
46    /** The next enclosing environment.
47     */
48    public Env<A> next;
49
50    /** The environment enclosing the current class.
51     */
52    public Env<A> outer;
53
54    /** The tree with which this environment is associated.
55     */
56    public JCTree tree;
57
58    /** The enclosing toplevel tree.
59     */
60    public JCTree.JCCompilationUnit toplevel;
61
62    /** The next enclosing class definition.
63     */
64    public JCTree.JCClassDecl enclClass;
65
66    /** The next enclosing method definition.
67     */
68    public JCTree.JCMethodDecl enclMethod;
69
70    /** A generic field for further information.
71     */
72    public A info;
73
74    /** Is this an environment for evaluating a base clause?
75     */
76    public boolean baseClause = false;
77
78    /** Create an outermost environment for a given (toplevel)tree,
79     *  with a given info field.
80     */
81    public Env(JCTree tree, A info) {
82        this.next = null;
83        this.outer = null;
84        this.tree = tree;
85        this.toplevel = null;
86        this.enclClass = null;
87        this.enclMethod = null;
88        this.info = info;
89    }
90
91    /** Duplicate this environment, updating with given tree and info,
92     *  and copying all other fields.
93     */
94    public Env<A> dup(JCTree tree, A info) {
95        return dupto(new Env<>(tree, info));
96    }
97
98    /** Duplicate this environment into a given Environment,
99     *  using its tree and info, and copying all other fields.
100     */
101    public Env<A> dupto(Env<A> that) {
102        that.next = this;
103        that.outer = this.outer;
104        that.toplevel = this.toplevel;
105        that.enclClass = this.enclClass;
106        that.enclMethod = this.enclMethod;
107        return that;
108    }
109
110    /** Duplicate this environment, updating with given tree,
111     *  and copying all other fields.
112     */
113    public Env<A> dup(JCTree tree) {
114        return dup(tree, this.info);
115    }
116
117    /** Return closest enclosing environment which points to a tree with given tag.
118     */
119    public Env<A> enclosing(JCTree.Tag tag) {
120        Env<A> env1 = this;
121        while (env1 != null && !env1.tree.hasTag(tag)) env1 = env1.next;
122        return env1;
123    }
124
125    @Override
126    public String toString() {
127        StringBuilder sb = new StringBuilder();
128        sb.append("Env[").append(info);
129//        if (enclMethod != null)
130//            sb.append(",enclMethod=").append(Pretty.toSimpleString(enclMethod));
131//        if (enclClass != null)
132//            sb.append(",enclClass=").append(Pretty.toSimpleString(enclClass));
133        if (outer != null)
134            sb.append(",outer=").append(outer);
135        sb.append("]");
136        return sb.toString();
137    }
138
139    public Iterator<Env<A>> iterator() {
140        return new Iterator<Env<A>>() {
141            Env<A> next = Env.this;
142            public boolean hasNext() {
143                return next.outer != null;
144            }
145            public Env<A> next() {
146                if (hasNext()) {
147                    Env<A> current = next;
148                    next = current.outer;
149                    return current;
150                }
151                throw new NoSuchElementException();
152
153            }
154            public void remove() {
155                throw new UnsupportedOperationException();
156            }
157        };
158    }
159}
160