multikeymap.java

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        int index = map.hashIndex(hashCode, map.data.length);
        AbstractHashedMap.HashEntry entry = map.data[index];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3)) {
                Object oldValue = entry.getValue();
                map.updateEntry(entry, value);
                return oldValue;
            }
            entry = entry.next;
        }
        
        map.addMapping(index, hashCode, new MultiKey(key1, key2, key3), value);
        return null;
    }

    /**
     * Removes the specified multi-key from this map.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @return the value mapped to the removed key, null if key not in map
     */
    public Object remove(Object key1, Object key2, Object key3) {
        int hashCode = hash(key1, key2, key3);
        int index = map.hashIndex(hashCode, map.data.length);
        AbstractHashedMap.HashEntry entry = map.data[index];
        AbstractHashedMap.HashEntry previous = null;
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3)) {
                Object oldValue = entry.getValue();
                map.removeMapping(entry, index, previous);
                return oldValue;
            }
            previous = entry;
            entry = entry.next;
        }
        return null;
    }

    /**
     * Gets the hash code for the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @return the hash code
     */
    protected int hash(Object key1, Object key2, Object key3) {
        int h = 0;
        if (key1 != null) {
            h ^= key1.hashCode();
        }
        if (key2 != null) {
            h ^= key2.hashCode();
        }
        if (key3 != null) {
            h ^= key3.hashCode();
        }
        h += ~(h << 9);
        h ^=  (h >>> 14);
        h +=  (h << 4);
        h ^=  (h >>> 10);
        return h;
    }

    /**
     * Is the key equal to the combined key.
     * 
     * @param entry  the entry to compare to
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @return true if the key matches
     */
    protected boolean isEqualKey(AbstractHashedMap.HashEntry entry, Object key1, Object key2, Object key3) {
        MultiKey multi = (MultiKey) entry.getKey();
        return
            multi.size() == 3 &&
            (key1 == null ? multi.getKey(0) == null : key1.equals(multi.getKey(0))) &&
            (key2 == null ? multi.getKey(1) == null : key2.equals(multi.getKey(1))) &&
            (key3 == null ? multi.getKey(2) == null : key3.equals(multi.getKey(2)));
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the value mapped to the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @return the mapped value, null if no match
     */
    public Object get(Object key1, Object key2, Object key3, Object key4) {
        int hashCode = hash(key1, key2, key3, key4);
        AbstractHashedMap.HashEntry entry = map.data[map.hashIndex(hashCode, map.data.length)];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4)) {
                return entry.getValue();
            }
            entry = entry.next;
        }
        return null;
    }

    /**
     * Checks whether the map contains the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @return true if the map contains the key
     */
    public boolean containsKey(Object key1, Object key2, Object key3, Object key4) {
        int hashCode = hash(key1, key2, key3, key4);
        AbstractHashedMap.HashEntry entry = map.data[map.hashIndex(hashCode, map.data.length)];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4)) {
                return true;
            }
            entry = entry.next;
        }
        return false;
    }

    /**
     * Stores the value against the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @param value  the value to store
     * @return the value previously mapped to this combined key, null if none
     */
    public Object put(Object key1, Object key2, Object key3, Object key4, Object value) {
        int hashCode = hash(key1, key2, key3, key4);
        int index = map.hashIndex(hashCode, map.data.length);
        AbstractHashedMap.HashEntry entry = map.data[index];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4)) {
                Object oldValue = entry.getValue();
                map.updateEntry(entry, value);
                return oldValue;
            }
            entry = entry.next;
        }
        
        map.addMapping(index, hashCode, new MultiKey(key1, key2, key3, key4), value);
        return null;
    }

    /**
     * Removes the specified multi-key from this map.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @return the value mapped to the removed key, null if key not in map
     */
    public Object remove(Object key1, Object key2, Object key3, Object key4) {
        int hashCode = hash(key1, key2, key3, key4);
        int index = map.hashIndex(hashCode, map.data.length);
        AbstractHashedMap.HashEntry entry = map.data[index];
        AbstractHashedMap.HashEntry previous = null;
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4)) {
                Object oldValue = entry.getValue();
                map.removeMapping(entry, index, previous);
                return oldValue;
            }
            previous = entry;
            entry = entry.next;
        }
        return null;
    }

    /**
     * Gets the hash code for the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @return the hash code
     */
    protected int hash(Object key1, Object key2, Object key3, Object key4) {
        int h = 0;
        if (key1 != null) {
            h ^= key1.hashCode();
        }
        if (key2 != null) {
            h ^= key2.hashCode();
        }
        if (key3 != null) {
            h ^= key3.hashCode();
        }
        if (key4 != null) {
            h ^= key4.hashCode();
        }
        h += ~(h << 9);
        h ^=  (h >>> 14);
        h +=  (h << 4);
        h ^=  (h >>> 10);
        return h;
    }

    /**
     * Is the key equal to the combined key.
     * 
     * @param entry  the entry to compare to
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @return true if the key matches
     */
    protected boolean isEqualKey(AbstractHashedMap.HashEntry entry, Object key1, Object key2, Object key3, Object key4) {
        MultiKey multi = (MultiKey) entry.getKey();
        return
            multi.size() == 4 &&
            (key1 == null ? multi.getKey(0) == null : key1.equals(multi.getKey(0))) &&
            (key2 == null ? multi.getKey(1) == null : key2.equals(multi.getKey(1))) &&
            (key3 == null ? multi.getKey(2) == null : key3.equals(multi.getKey(2))) &&
            (key4 == null ? multi.getKey(3) == null : key4.equals(multi.getKey(3)));
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the value mapped to the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @param key5  the fifth key
     * @return the mapped value, null if no match
     */
    public Object get(Object key1, Object key2, Object key3, Object key4, Object key5) {
        int hashCode = hash(key1, key2, key3, key4, key5);
        AbstractHashedMap.HashEntry entry = map.data[map.hashIndex(hashCode, map.data.length)];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4, key5)) {
                return entry.getValue();
            }
            entry = entry.next;
        }
        return null;
    }

    /**
     * Checks whether the map contains the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @param key5  the fifth key
     * @return true if the map contains the key
     */
    public boolean containsKey(Object key1, Object key2, Object key3, Object key4, Object key5) {
        int hashCode = hash(key1, key2, key3, key4, key5);
        AbstractHashedMap.HashEntry entry = map.data[map.hashIndex(hashCode, map.data.length)];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4, key5)) {
                return true;
            }
            entry = entry.next;
        }
        return false;
    }

    /**
     * Stores the value against the specified multi-key.
     * 
     * @param key1  the first key
     * @param key2  the second key
     * @param key3  the third key
     * @param key4  the fourth key
     * @param key5  the fifth key
     * @param value  the value to store
     * @return the value previously mapped to this combined key, null if none
     */
    public Object put(Object key1, Object key2, Object key3, Object key4, Object key5, Object value) {
        int hashCode = hash(key1, key2, key3, key4, key5);
        int index = map.hashIndex(hashCode, map.data.length);
        AbstractHashedMap.HashEntry entry = map.data[index];
        while (entry != null) {
            if (entry.hashCode == hashCode && isEqualKey(entry, key1, key2, key3, key4, key5)) {
                Object oldValue = entry.getValue();
                map.updateEntry(entry, value);
                return oldValue;
            }
            entry = entry.next;
        }
        
        map.addMapping(index, hashCode, new MultiKey(key1, key2, key3, key4, key5), value);
        return null;
    }

    /**
     * Removes the specified multi-key from this map.