reworked comment.

git-svn-id: https://svn.code.sf.net/p/jode/code/trunk@1251 379699f6-c40d-0410-875b-85095c16579e

jode/jode/decompiler/OuterValues.java

@@ -30,44 +30,69 @@ import java.util.Vector;
 import java.util.Enumeration;
 
 /**
- * OuterValues are used in method scoped classes: If a method
+ * A list of local variables that a method scoped class inherits
- * scoped class uses a local of the surrounding method, the java
+ * from its declaring method.
- * compiler adds the locals to the param list of each constructor
- * of the method scoped class.  Each invocation of the constructor
- * must give the correct values for these locals.
  *
- * These extra parameters are the outerValues.
+ * A method scoped class is a class that is declared in a method and
+ * it can access other (final) local variables declared earlier.  To
+ * realize this the java compiler adds hidden parameters to the
+ * constructor of the method scoped class, where it passes the values
+ * of the local varaiables.  If a method scoped class has more than
+ * one constructor, each gets this hidden parameters.  These hidden
+ * parameters are the outerValues, because they are used to transport
+ * a value of a local variable from an outer method.
  *
- * The main problem here is, that we don't know immediately if a
+ * Unfortunately there is no definite way to distinguish this outer
- * parameter is a standard parameter or a local of the outer
+ * value parameters from the real parameters, so jode has to do a
- * method.  We may shrink this array if we notice a problem later.
+ * guess: It first assumes that everything is an outer value parameter
+ * added by the compiler and if this leads to contradiction shrinks
+ * the count of these parameters.  A contradiction can occur, because
+ * the constructor is called two times with different values.
  *
- * Every class interested in outer values, may register itself
+ * On the other hand the TransformConstructor class assumes at some
- * as OuterValueListener.  It will then be notified every time the
+ * point that some parameters are outer values.  If later a
- * outer values shrink.
+ * contradiction occurs, jode has to give up and complain loudly.
  *
- * The outer instance of a non static _class_ scoped class is not
+ * Every class interested in outer values, may register itself as
- * considered as outer value, mainly because it can be changed.  With
+ * OuterValueListener.  It will then be notified every time the outer
- * jikes method scoped classes also have an outer class instance, but
+ * values shrink.  Sometimes there are real listener queues: if
- * that is considered as outer value.
+ * another method scoped class creates instances of the first in its
+ * constructor by passing some of its own outer value parameter, it
+ * may first seem that all parameters of the first class's constructor
+ * are outer values.  Because we can't be sure that the parameter from
+ * the second class's constructor is really an outer value, we have to
+ * add a listener.  If later a constructor invokation for the second
+ * class is found, where a parameter does not have the right outer
+ * value, the listener will also shrink the outer values list of the 
+ * first class.
  *
- * Under jikes anonymous classes that extends class or method scoped
+ * A non static _class_ scoped class (i.e. a normal inner class) also
- * classes have as last parameter the outer instance of the parent
+ * has a hidden parameter, namely the instance of its outer class.
- * class.  This should really be the first parameter (just after the
+ * This hidden parameter is not considered as outer value though.
- * outerValues), like it is under javac.  We mark such classes as
+ * Note that you can even explicitly invoke the constructor with a
- * jikesAnonymousInner. This is done in the initialize() pass.
+ * different outer class instance, by using the
+ * <code>outerInstance.new InnerClass()</code> construct.  This
+ * exception doesn't apply to method scoped classes, though.
  *
- * Under javac the outer class paramter for anonymous classes that
+ * Anonymous classes can of course also extend class or method scoped
- * extends class scoped classes is at the right position, just before
+ * classes.  If they are compiled by jikes the constructor takes as
- * the other parameters. 
+ * last parameter the outer instance of its super class.  This should
+ * really be the first parameter just after the outerValues, as it
+ * is under javac.  We mark such classes as jikesAnonymousInner.  This
+ * is done in the initialize() pass.
  *
  * @see #shrinkOuterValues
  * @see #addOuterValueListener
- * @since 1.0.93 */
+ * @since 1.0.93 
+ */
 public class OuterValues 
 {
     private ClassAnalyzer clazzAnalyzer;
 
+    /**
+     * The outer values.  An outer value is either a
+     * LocalLoadOperator, a ThisOperator, or a OuterLocalOperator.
+     */
     private Expression[] head;
     private Vector ovListeners;
     private boolean jikesAnonymousInner;