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25 
26 package com.sun.tools.javac.comp;
27 
28 import com.sun.tools.javac.tree.*;
29 import java.util.Iterator;
30 import 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  */
44 public 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      */
Env(JCTree tree, A info)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      */
dup(JCTree tree, A info)94     public Env<A> dup(JCTree tree, A info) {
95         return dupto(new Env<A>(tree, info));
96     }
97 
98     /** Duplicate this environment into a given Environment,
99      *  using its tree and info, and copying all other fields.
100      */
dupto(Env<A> that)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      */
dup(JCTree tree)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      */
enclosing(JCTree.Tag tag)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
toString()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 
iterator()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