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org.sablecc.sablecc
Class LR0ItemSet  view LR0ItemSet download LR0ItemSet.java

java.lang.Object
  extended byorg.sablecc.sablecc.LR0ItemSet
All Implemented Interfaces:
java.lang.Cloneable, java.lang.Comparable

final class LR0ItemSet
extends java.lang.Object
implements java.lang.Cloneable, java.lang.Comparable


Field Summary
private  int hashCode
           
private  java.util.TreeMap items
           
(package private)  LR0Item[] items_
           
(package private)  boolean modified_
           
 
Constructor Summary
(package private) LR0ItemSet()
           
private LR0ItemSet(LR0ItemSet set)
           
 
Method Summary
 java.lang.Object clone()
          This method may be called to create a new copy of the Object.
 int compareTo(java.lang.Object object)
          Compares this object with another, and returns a numerical result based on the comparison.
private  void computeArray()
           
 boolean equals(java.lang.Object obj)
          Determine whether this Object is semantically equal to another Object.
(package private)  boolean get(LR0Item item)
           
 int hashCode()
          Get a value that represents this Object, as uniquely as possible within the confines of an int.
(package private)  LR0Item[] items()
           
(package private)  void set(LR0Item item)
           
 java.lang.String toString()
          Convert this Object to a human-readable String.
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

items

private final java.util.TreeMap items

hashCode

private int hashCode

items_

LR0Item[] items_

modified_

boolean modified_
Constructor Detail

LR0ItemSet

LR0ItemSet()

LR0ItemSet

private LR0ItemSet(LR0ItemSet set)
Method Detail

set

void set(LR0Item item)

get

boolean get(LR0Item item)

computeArray

private void computeArray()

items

LR0Item[] items()

toString

public java.lang.String toString()
Description copied from class: java.lang.Object
Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() 55 and such.

It is typical, but not required, to ensure that this method never completes abruptly with a java.lang.RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).


clone

public java.lang.Object clone()
Description copied from class: java.lang.Object
This method may be called to create a new copy of the Object. The typical behavior is as follows:
  • o == o.clone() is false
  • o.getClass() == o.clone().getClass() is true
  • o.equals(o) is true

However, these are not strict requirements, and may be violated if necessary. Of the three requirements, the last is the most commonly violated, particularly if the subclass does not override Object.equals(Object)>Object.equals(Object) 55 .

If the Object you call clone() on does not implement java.lang.Cloneable (which is a placeholder interface), then a CloneNotSupportedException is thrown. Notice that Object does not implement Cloneable; this method exists as a convenience for subclasses that do.

Object's implementation of clone allocates space for the new Object using the correct class, without calling any constructors, and then fills in all of the new field values with the old field values. Thus, it is a shallow copy. However, subclasses are permitted to make a deep copy.

All array types implement Cloneable, and override this method as follows (it should never fail):

 public Object clone()
 {
   try
     {
       super.clone();
     }
   catch (CloneNotSupportedException e)
     {
       throw new InternalError(e.getMessage());
     }
 }
 


equals

public boolean equals(java.lang.Object obj)
Description copied from class: java.lang.Object
Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

  • It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
  • It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
  • It must be reflexive. a.equals(a) must always be true.
  • It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
  • a.equals(null) must be false.
  • It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a java.lang.ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a java.lang.NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, java.util.IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.


hashCode

public int hashCode()
Description copied from class: java.lang.Object
Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

  • Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
  • It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)


compareTo

public int compareTo(java.lang.Object object)
Description copied from interface: java.lang.Comparable
Compares this object with another, and returns a numerical result based on the comparison. If the result is negative, this object sorts less than the other; if 0, the two are equal, and if positive, this object sorts greater than the other. To translate this into boolean, simply perform o1.compareTo(o2) <op> 0, where op is one of <, <=, =, !=, >, or >=.

You must make sure that the comparison is mutual, ie. sgn(x.compareTo(y)) == -sgn(y.compareTo(x)) (where sgn() is defined as -1, 0, or 1 based on the sign). This includes throwing an exception in either direction if the two are not comparable; hence, compareTo(null) should always throw an Exception.

You should also ensure transitivity, in two forms: x.compareTo(y) > 0 && y.compareTo(z) > 0 implies x.compareTo(z) > 0; and x.compareTo(y) == 0 implies x.compareTo(z) == y.compareTo(z).

Specified by:
compareTo in interface java.lang.Comparable