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package com.sun.tools.javac.comp;

import com.sun.tools.javac.tree.*;
import java.util.Iterator;
import java.util.NoSuchElementException;

A class for environments, instances of which are passed as
 arguments to tree visitors.  Environments refer to important ancestors
 of the subtree that's currently visited, such as the enclosing method,
 the enclosing class, or the enclosing toplevel node. They also contain
 a generic component, represented as a type parameter, to carry further
 information specific to individual passes.
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/** A class for environments, instances of which are passed as
 *  arguments to tree visitors.  Environments refer to important ancestors
 *  of the subtree that's currently visited, such as the enclosing method,
 *  the enclosing class, or the enclosing toplevel node. They also contain
 *  a generic component, represented as a type parameter, to carry further
 *  information specific to individual passes.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public class Env<A> implements Iterable<Env<A>> {

    
The next enclosing environment.
/** The next enclosing environment.
     */
    public Env<A> next;

    
The environment enclosing the current class.
/** The environment enclosing the current class.
     */
    public Env<A> outer;

    
The tree with which this environment is associated.
/** The tree with which this environment is associated.
     */
    public JCTree tree;

    
The enclosing toplevel tree.
/** The enclosing toplevel tree.
     */
    public JCTree.JCCompilationUnit toplevel;

    
The next enclosing class definition.
/** The next enclosing class definition.
     */
    public JCTree.JCClassDecl enclClass;

    
The next enclosing method definition.
/** The next enclosing method definition.
     */
    public JCTree.JCMethodDecl enclMethod;

    
A generic field for further information.
/** A generic field for further information.
     */
    public A info;

    
Is this an environment for evaluating a base clause?
/** Is this an environment for evaluating a base clause?
     */
    public boolean baseClause = false;

    
Create an outermost environment for a given (toplevel)tree,
 with a given info field.
/** Create an outermost environment for a given (toplevel)tree,
     *  with a given info field.
     */
    public Env(JCTree tree, A info) {
        this.next = null;
        this.outer = null;
        this.tree = tree;
        this.toplevel = null;
        this.enclClass = null;
        this.enclMethod = null;
        this.info = info;
    }

    
Duplicate this environment, updating with given tree and info,
 and copying all other fields.
/** Duplicate this environment, updating with given tree and info,
     *  and copying all other fields.
     */
    public Env<A> dup(JCTree tree, A info) {
        return dupto(new Env<>(tree, info));
    }

    
Duplicate this environment into a given Environment,
 using its tree and info, and copying all other fields.
/** Duplicate this environment into a given Environment,
     *  using its tree and info, and copying all other fields.
     */
    public Env<A> dupto(Env<A> that) {
        that.next = this;
        that.outer = this.outer;
        that.toplevel = this.toplevel;
        that.enclClass = this.enclClass;
        that.enclMethod = this.enclMethod;
        return that;
    }

    
Duplicate this environment, updating with given tree,
 and copying all other fields.
/** Duplicate this environment, updating with given tree,
     *  and copying all other fields.
     */
    public Env<A> dup(JCTree tree) {
        return dup(tree, this.info);
    }

    
Return closest enclosing environment which points to a tree with given tag.
/** Return closest enclosing environment which points to a tree with given tag.
     */
    public Env<A> enclosing(JCTree.Tag tag) {
        Env<A> env1 = this;
        while (env1 != null && !env1.tree.hasTag(tag)) env1 = env1.next;
        return env1;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Env[").append(info);
        if (outer != null)
            sb.append(",outer=").append(outer);
        sb.append("]");
        return sb.toString();
    }

    public Iterator<Env<A>> iterator() {
        return new Iterator<Env<A>>() {
            Env<A> next = Env.this;
            public boolean hasNext() {
                return next.outer != null;
            }
            public Env<A> next() {
                if (hasNext()) {
                    Env<A> current = next;
                    next = current.outer;
                    return current;
                }
                throw new NoSuchElementException();
            }
            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }
}