onetomanymap.java

jena2.5.4推理机系统的一种最基本实现 HP实验室出品

     * @param key The key object
     * @param value The value object
     * @return Null.
     */
    public Object put( Object key, Object value ) {
        ArrayList entries = (ArrayList) m_table.get( key );
        entries = entries == null ? new ArrayList() : entries;

        // add the new value to the list of values held against this key
        entries.add( value );
        m_table.put( key, entries );

        return null;
    }


    /**
     * <p>Put all entries from one map into this map. Tests for m being a 
     * OneToManyMap, and, if so, copies all of the entries for each key.</p>
     * @param m The map whose contents are to be copied into this map
     */
    public void putAll( Map m ) {
        boolean many = (m instanceof OneToManyMap);
        
        for (Iterator i = m.keySet().iterator(); i.hasNext(); ) {
            Object key = i.next();
            if (many) {
                for (Iterator j = ((OneToManyMap) m).getAll( key ); j.hasNext(); ) {
                    put( key, j.next() );
                }
            }
            else {
                put( key, m.get( key ) );
            }
        }
    }


    /**
     * Remove all of the associations for the given key.  If only a specific
     * association is to be removed, use {@link #remove( java.lang.Object, java.lang.Object )}
     * instead.  Has no effect if the key is not present in the map.  Since no
     * single specific association with the key is defined, this method always
     * returns null.
     *
     * @param key All associations with this key will be removed
     * @return null
     */
    public Object remove( Object key ) {
        m_table.remove( key );
        return null;
    }


    /**
     * <p>Remove the specific association between the given key and value. Has
     * no effect if the association is not present in the map. If all values
     * for a particular key have been removed post removing this particular
     * association, the key will no longer appear as a key in the map.</p>
     *
     * @param key The key object
     * @param value The value object
     */
    public void remove( Object key, Object value ) {
        List entries = (List) m_table.get( key );

        if (entries != null) {
            entries.remove( value );
            
            if (entries.isEmpty()) {
                m_table.remove( key );
            }
        }
    }


    /**
     * <p>Answer the number of key-value mappings in the map</p>
     * @return The number of key-value pairs.
     */
    public int size() {
        int size = 0;

        for (Iterator i = m_table.keySet().iterator();  i.hasNext();  ) {
            size += ((List) m_table.get( i.next() )).size();
        }

        return size;
    }


    /**
     * <p>Returns a collection view of the values contained in this map.
     * Specifically, this will be a set, so duplicate values that appear
     * for multiple keys are suppressed.</p>
     * @return A set of the values contained in this map.
     */
    public Collection values() {
        Set s = CollectionFactory.createHashedSet();

        for (Iterator e = m_table.keySet().iterator();  e.hasNext();  ) {
            s.addAll( (List) m_table.get(e.next()) );
        }

        return s;
    }

    /**
     * <p>Answer a string representation of this map. This can be quite a long string for
     * large maps.<p>
     */
    public String toString() {
        StringBuffer buf = new StringBuffer( "OneToManyMap{" );
        String sep = "";
        
        for (Iterator i = keySet().iterator(); i.hasNext(); ) {
            Object key = i.next();
            buf.append( sep );
            buf.append( key );
            buf.append( "={" );
            
            String sep1 = "";
            for (Iterator j = getAll(key); j.hasNext(); ) {
                buf.append( sep1 );
                buf.append( j.next() );
                sep1=",";
            }
            buf.append("}");
            sep=",";
        }
        buf.append("}");
        return buf.toString();
    }

    // Internal implementation methods
    //////////////////////////////////////
    
    
    // Inner classes 
    //////////////////////////////////////
    
    
    //////////////////////////////////


    //==============================================================================
    // Inner class definitions
    //==============================================================================

    /**
     * Helper class to implement the Map.Entry interface to enumerate entries in the map
     */
    public static class Entry
        implements Map.Entry
    {
        /** My key object */
        private Object m_key = null;

        /** My value object */
        private Object m_value = null;


        /**
         * Constructor - save the key and value
         */
        private Entry( Object key, Object value ) {
            m_key = key;
            m_value = value;
        }


        /**
         * Compares the specified object with this entry for equality. Returns true if the given
         * object is also a map entry and the two entries represent the same mapping.
         * More formally, two entries e1 and e2 represent the same mapping if
         * <code><pre>
         *      (e1.getKey()==null ?
         *                         e2.getKey()==null : e1.getKey().equals(e2.getKey()))  &&
         *      (e1.getValue()==null ?
         *                         e2.getValue()==null : e1.getValue().equals(e2.getValue()))
         * </pre></code>
         *
         * This ensures that the equals method works properly across different implementations of the Map.Entry interface.
         *
         * @param x The object to compare against
         * @return True if the given object is equal to this Map.Entry object.
         */
        public boolean equals( Object x ) {
            if (x instanceof java.util.Map.Entry) {
                Map.Entry e1 = (Map.Entry) x;

                return (e1.getKey()==null ?
                                          m_key==null : e1.getKey().equals(m_key))  &&
                       (e1.getValue()==null ?
                                            m_value == null : e1.getValue().equals(m_value));
            }
            else
                return false;
        }


        /**
         * Answer the key for the entry
         *
         * @return The key object
         */
        public Object getKey() {
            return m_key;
        }


        /**
         * Answer the value for the entry
         *
         * @return The value object
         */
        public Object getValue() {
            return m_value;
        }


        /**
         * Set the value, which writes through to the map. Not implemented.
         */
        public Object setValue( Object value )
            throws  UnsupportedOperationException
        {
            throw new UnsupportedOperationException( "not implemented" );
        }


        /**
         * Returns the hash code value for this map entry.
         * The hash code of a map entry e is defined to be:
         *     (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
         *     (e.getValue()==null ? 0 : e.getValue().hashCode())
         *
         * This ensures that e1.equals(e2) implies that e1.hashCode()==e2.hashCode() for any two
         * Entries e1 and e2, as required by the general contract of Object.hashCode.
         */
        public int hashCode() {
            return (getKey()==null   ? 0 : getKey().hashCode()) ^
                   (getValue()==null ? 0 : getValue().hashCode());
        }


    }

}

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