/*
	* Copyright (C) 2007-2019 Sebastiano Vigna
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	*     http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
package it.unimi.dsi.fastutil.ints;
import java.util.Map;
import java.util.NoSuchElementException;
import it.unimi.dsi.fastutil.objects.AbstractObjectSet;
import it.unimi.dsi.fastutil.objects.ObjectIterator;
import it.unimi.dsi.fastutil.objects.ObjectCollection;
import it.unimi.dsi.fastutil.objects.AbstractObjectCollection;
import it.unimi.dsi.fastutil.objects.ObjectArrays;
A simple, brute-force implementation of a map based on two parallel backing
arrays.

The main purpose of this implementation is that of wrapping cleanly the
brute-force approach to the storage of a very small number of pairs: just put
them into two parallel arrays and scan linearly to find an item.
/**
 * A simple, brute-force implementation of a map based on two parallel backing
 * arrays.
 *
 * <p>
 * The main purpose of this implementation is that of wrapping cleanly the
 * brute-force approach to the storage of a very small number of pairs: just put
 * them into two parallel arrays and scan linearly to find an item.
 */
public class Int2ObjectArrayMap<V> extends AbstractInt2ObjectMap<V> implements java.io.Serializable, Cloneable {
	private static final long serialVersionUID = 1L;
	
The keys (valid up to Int2ObjectArrayMap<V>.size, excluded). /** The keys (valid up to {@link #size}, excluded). */
	private transient int[] key;
	
The values (parallel to Int2ObjectArrayMap<V>.key). /** The values (parallel to {@link #key}). */
	private transient Object[] value;
	
The number of valid entries in Int2ObjectArrayMap<V>.key and Int2ObjectArrayMap<V>.value. /** The number of valid entries in {@link #key} and {@link #value}. */
	private int size;
	
Creates a new empty array map with given key and value backing arrays. The
resulting map will have as many entries as the given arrays.
 It is responsibility of the caller that the elements of key are distinct. 
Params:
key – 
           the key array.
value – 
           the value array (it must have the same length as key)./**
	 * Creates a new empty array map with given key and value backing arrays. The
	 * resulting map will have as many entries as the given arrays.
	 *
	 * <p>
	 * It is responsibility of the caller that the elements of {@code key} are
	 * distinct.
	 *
	 * @param key
	 *            the key array.
	 * @param value
	 *            the value array (it <em>must</em> have the same length as
	 *            {@code key}).
	 */
	public Int2ObjectArrayMap(final int[] key, final Object[] value) {
		this.key = key;
		this.value = value;
		size = key.length;
		if (key.length != value.length)
			throw new IllegalArgumentException(
					"Keys and values have different lengths (" + key.length + ", " + value.length + ")");
	}
	
Creates a new empty array map.
/**
	 * Creates a new empty array map.
	 */
	public Int2ObjectArrayMap() {
		this.key = IntArrays.EMPTY_ARRAY;
		this.value = ObjectArrays.EMPTY_ARRAY;
	}
	
Creates a new empty array map of given capacity.
Params:
capacity – 
           the initial capacity./**
	 * Creates a new empty array map of given capacity.
	 *
	 * @param capacity
	 *            the initial capacity.
	 */
	public Int2ObjectArrayMap(final int capacity) {
		this.key = new int[capacity];
		this.value = new Object[capacity];
	}
	
Creates a new empty array map copying the entries of a given map.
Params:
m – 
           a map./**
	 * Creates a new empty array map copying the entries of a given map.
	 *
	 * @param m
	 *            a map.
	 */
	public Int2ObjectArrayMap(final Int2ObjectMap<V> m) {
		this(m.size());
		putAll(m);
	}
	
Creates a new empty array map copying the entries of a given map.
Params:
m – 
           a map./**
	 * Creates a new empty array map copying the entries of a given map.
	 *
	 * @param m
	 *            a map.
	 */
	public Int2ObjectArrayMap(final Map<? extends Integer, ? extends V> m) {
		this(m.size());
		putAll(m);
	}
	
Creates a new array map with given key and value backing arrays, using the
given number of elements.
 It is responsibility of the caller that the first size elements of key are distinct. 
Params:
key – 
           the key array.
value – 
           the value array (it must have the same length as key).
size –  the number of valid elements in key and value./**
	 * Creates a new array map with given key and value backing arrays, using the
	 * given number of elements.
	 *
	 * <p>
	 * It is responsibility of the caller that the first {@code size} elements of
	 * {@code key} are distinct.
	 *
	 * @param key
	 *            the key array.
	 * @param value
	 *            the value array (it <em>must</em> have the same length as
	 *            {@code key}).
	 * @param size
	 *            the number of valid elements in {@code key} and {@code value}.
	 */
	public Int2ObjectArrayMap(final int[] key, final Object[] value, final int size) {
		this.key = key;
		this.value = value;
		this.size = size;
		if (key.length != value.length)
			throw new IllegalArgumentException(
					"Keys and values have different lengths (" + key.length + ", " + value.length + ")");
		if (size > key.length)
			throw new IllegalArgumentException("The provided size (" + size
					+ ") is larger than or equal to the backing-arrays size (" + key.length + ")");
	}
	private final class EntrySet extends AbstractObjectSet<Int2ObjectMap.Entry<V>> implements FastEntrySet<V> {
		@Override
		public ObjectIterator<Int2ObjectMap.Entry<V>> iterator() {
			return new ObjectIterator<Int2ObjectMap.Entry<V>>() {
				int curr = -1, next = 0;
				@Override
				public boolean hasNext() {
					return next < size;
				}
				@Override
				@SuppressWarnings("unchecked")
				public Entry<V> next() {
					if (!hasNext())
						throw new NoSuchElementException();
					return new AbstractInt2ObjectMap.BasicEntry<>(key[curr = next], (V) value[next++]);
				}
				@Override
				public void remove() {
					if (curr == -1)
						throw new IllegalStateException();
					curr = -1;
					final int tail = size-- - next--;
					System.arraycopy(key, next + 1, key, next, tail);
					System.arraycopy(value, next + 1, value, next, tail);
					value[size] = null;
				}
			};
		}
		@Override
		public ObjectIterator<Int2ObjectMap.Entry<V>> fastIterator() {
			return new ObjectIterator<Int2ObjectMap.Entry<V>>() {
				int next = 0, curr = -1;
				final BasicEntry<V> entry = new BasicEntry<>();
				@Override
				public boolean hasNext() {
					return next < size;
				}
				@Override
				@SuppressWarnings("unchecked")
				public Entry<V> next() {
					if (!hasNext())
						throw new NoSuchElementException();
					entry.key = key[curr = next];
					entry.value = (V) value[next++];
					return entry;
				}
				@Override
				public void remove() {
					if (curr == -1)
						throw new IllegalStateException();
					curr = -1;
					final int tail = size-- - next--;
					System.arraycopy(key, next + 1, key, next, tail);
					System.arraycopy(value, next + 1, value, next, tail);
					value[size] = null;
				}
			};
		}
		@Override
		public int size() {
			return size;
		}
		@Override

		public boolean contains(Object o) {
			if (!(o instanceof Map.Entry))
				return false;
			final Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
			if (e.getKey() == null || !(e.getKey() instanceof Integer))
				return false;
			final int k = ((Integer) (e.getKey())).intValue();
			return Int2ObjectArrayMap.this.containsKey(k)
					&& java.util.Objects.equals(Int2ObjectArrayMap.this.get(k), (e.getValue()));
		}
		@Override
		@SuppressWarnings("unchecked")
		public boolean remove(final Object o) {
			if (!(o instanceof Map.Entry))
				return false;
			final Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
			if (e.getKey() == null || !(e.getKey() instanceof Integer))
				return false;
			final int k = ((Integer) (e.getKey())).intValue();
			final V v = ((V) e.getValue());
			final int oldPos = Int2ObjectArrayMap.this.findKey(k);
			if (oldPos == -1 || !java.util.Objects.equals(v, Int2ObjectArrayMap.this.value[oldPos]))
				return false;
			final int tail = size - oldPos - 1;
			System.arraycopy(Int2ObjectArrayMap.this.key, oldPos + 1, Int2ObjectArrayMap.this.key, oldPos, tail);
			System.arraycopy(Int2ObjectArrayMap.this.value, oldPos + 1, Int2ObjectArrayMap.this.value, oldPos, tail);
			Int2ObjectArrayMap.this.size--;
			Int2ObjectArrayMap.this.value[size] = null;
			return true;
		}
	}
	@Override
	public FastEntrySet<V> int2ObjectEntrySet() {
		return new EntrySet();
	}
	private int findKey(final int k) {
		final int[] key = this.key;
		for (int i = size; i-- != 0;)
			if (((key[i]) == (k)))
				return i;
		return -1;
	}
	@Override
	@SuppressWarnings("unchecked")
	public V get(final int k) {
		final int[] key = this.key;
		for (int i = size; i-- != 0;)
			if (((key[i]) == (k)))
				return (V) value[i];
		return defRetValue;
	}
	@Override
	public int size() {
		return size;
	}
	@Override
	public void clear() {
		for (int i = size; i-- != 0;) {
			value[i] = null;
		}
		size = 0;
	}
	@Override
	public boolean containsKey(final int k) {
		return findKey(k) != -1;
	}
	@Override
	public boolean containsValue(Object v) {
		for (int i = size; i-- != 0;)
			if (java.util.Objects.equals(value[i], v))
				return true;
		return false;
	}
	@Override
	public boolean isEmpty() {
		return size == 0;
	}
	@Override
	@SuppressWarnings("unchecked")
	public V put(int k, V v) {
		final int oldKey = findKey(k);
		if (oldKey != -1) {
			final V oldValue = (V) value[oldKey];
			value[oldKey] = v;
			return oldValue;
		}
		if (size == key.length) {
			final int[] newKey = new int[size == 0 ? 2 : size * 2];
			final Object[] newValue = new Object[size == 0 ? 2 : size * 2];
			for (int i = size; i-- != 0;) {
				newKey[i] = key[i];
				newValue[i] = value[i];
			}
			key = newKey;
			value = newValue;
		}
		key[size] = k;
		value[size] = v;
		size++;
		return defRetValue;
	}
	@Override
	@SuppressWarnings("unchecked")
	public V remove(final int k) {
		final int oldPos = findKey(k);
		if (oldPos == -1)
			return defRetValue;
		final V oldValue = (V) value[oldPos];
		final int tail = size - oldPos - 1;
		System.arraycopy(key, oldPos + 1, key, oldPos, tail);
		System.arraycopy(value, oldPos + 1, value, oldPos, tail);
		size--;
		value[size] = null;
		return oldValue;
	}
	@Override
	public IntSet keySet() {
		return new AbstractIntSet() {
			@Override
			public boolean contains(final int k) {
				return findKey(k) != -1;
			}
			@Override
			public boolean remove(final int k) {
				final int oldPos = findKey(k);
				if (oldPos == -1)
					return false;
				final int tail = size - oldPos - 1;
				System.arraycopy(key, oldPos + 1, key, oldPos, tail);
				System.arraycopy(value, oldPos + 1, value, oldPos, tail);
				size--;
				return true;
			}
			@Override
			public IntIterator iterator() {
				return new IntIterator() {
					int pos = 0;
					@Override
					public boolean hasNext() {
						return pos < size;
					}
					@Override

					public int nextInt() {
						if (!hasNext())
							throw new NoSuchElementException();
						return key[pos++];
					}
					@Override
					public void remove() {
						if (pos == 0)
							throw new IllegalStateException();
						final int tail = size - pos;
						System.arraycopy(key, pos, key, pos - 1, tail);
						System.arraycopy(value, pos, value, pos - 1, tail);
						size--;
					}
				};
			}
			@Override
			public int size() {
				return size;
			}
			@Override
			public void clear() {
				Int2ObjectArrayMap.this.clear();
			}
		};
	}
	@Override
	public ObjectCollection<V> values() {
		return new AbstractObjectCollection<V>() {
			@Override
			public boolean contains(final Object v) {
				return containsValue(v);
			}
			@Override
			public it.unimi.dsi.fastutil.objects.ObjectIterator<V> iterator() {
				return new it.unimi.dsi.fastutil.objects.ObjectIterator<V>() {
					int pos = 0;
					@Override
					public boolean hasNext() {
						return pos < size;
					}
					@Override
					@SuppressWarnings("unchecked")
					public V next() {
						if (!hasNext())
							throw new NoSuchElementException();
						return (V) value[pos++];
					}
					@Override
					public void remove() {
						if (pos == 0)
							throw new IllegalStateException();
						final int tail = size - pos;
						System.arraycopy(key, pos, key, pos - 1, tail);
						System.arraycopy(value, pos, value, pos - 1, tail);
						size--;
					}
				};
			}
			@Override
			public int size() {
				return size;
			}
			@Override
			public void clear() {
				Int2ObjectArrayMap.this.clear();
			}
		};
	}
	
Returns a deep copy of this map.

This method performs a deep copy of this hash map; the data stored in the
map, however, is not cloned. Note that this makes a difference only for
object keys.
Returns:
a deep copy of this map./**
	 * Returns a deep copy of this map.
	 *
	 * <p>
	 * This method performs a deep copy of this hash map; the data stored in the
	 * map, however, is not cloned. Note that this makes a difference only for
	 * object keys.
	 *
	 * @return a deep copy of this map.
	 */
	@Override
	@SuppressWarnings("unchecked")
	public Int2ObjectArrayMap<V> clone() {
		Int2ObjectArrayMap<V> c;
		try {
			c = (Int2ObjectArrayMap<V>) super.clone();
		} catch (CloneNotSupportedException cantHappen) {
			throw new InternalError();
		}
		c.key = key.clone();
		c.value = value.clone();
		return c;
	}
	private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
		s.defaultWriteObject();
		for (int i = 0; i < size; i++) {
			s.writeInt(key[i]);
			s.writeObject(value[i]);
		}
	}
	private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
		s.defaultReadObject();
		key = new int[size];
		value = new Object[size];
		for (int i = 0; i < size; i++) {
			key[i] = s.readInt();
			value[i] = s.readObject();
		}
	}
}