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/*******************************************************************************
 * Copyright (c) 2009 Luaj.org. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ******************************************************************************/
package org.luaj.vm2;

import java.util.Vector;

public class LuaTable extends LuaValue {
	private static final int      MIN_HASH_CAPACITY = 2;
	private static final LuaString N = valueOf("n");
	
	protected LuaValue[] array;
	protected LuaValue[] hashKeys;
	protected LuaValue[] hashValues;
	protected int hashEntries;
	protected LuaValue m_metatable;
	
	public LuaTable() {
		array = NOVALS;
		hashKeys = NOVALS;
		hashValues = NOVALS;
	}
	
	public LuaTable(int narray, int nhash) {
		presize(narray, nhash);
	}
	
	public LuaTable(LuaValue[] named, LuaValue[] unnamed, Varargs lastarg) {
		int nn = (named!=null? named.length: 0);
		int nu = (unnamed!=null? unnamed.length: 0);
		int nl = (lastarg!=null? lastarg.narg(): 0);
		presize(nu+nl, nn-(nn>>1));
		for ( int i=0; i array.length )
			array = resize( array, narray );
	}

	public void presize(int narray, int nhash) {
		if ( nhash > 0 && nhash < MIN_HASH_CAPACITY )
			nhash = MIN_HASH_CAPACITY;
		array = (narray>0? new LuaValue[narray]: NOVALS);
		hashKeys = (nhash>0? new LuaValue[nhash]: NOVALS);
		hashValues = (nhash>0? new LuaValue[nhash]: NOVALS);
		hashEntries = 0;
	}

	private static LuaValue[] resize( LuaValue[] old, int n ) {
		LuaValue[] v = new LuaValue[n];
		System.arraycopy(old, 0, v, 0, old.length);
		return v;
	}
	
	protected int getArrayLength() {
		return array.length;
	}

	protected int getHashLength() {
		return hashValues.length;
	}
	
	public LuaValue getmetatable() {
		return m_metatable;
	}
	
	public LuaValue setmetatable(LuaValue metatable) {
		m_metatable = metatable;
		LuaValue mode;
		if ( m_metatable!=null && (mode=m_metatable.rawget(MODE)).isstring() ) {
			String m = mode.tojstring();
			boolean k = m.indexOf('k')>=0;
			boolean v = m.indexOf('v')>=0;
			return changemode(k,v);
		}
		return this;
	}
	
	protected LuaTable changemode(boolean weakkeys, boolean weakvalues) {
		if ( weakkeys || weakvalues )
			return new WeakTable(weakkeys, weakvalues, this);
		return this;
	}
	
	public LuaValue get( int key ) {
		LuaValue v = rawget(key);
		return v.isnil() && m_metatable!=null? gettable(this,valueOf(key)): v;
	}
	
	public LuaValue get( LuaValue key ) {
		LuaValue v = rawget(key);
		return v.isnil() && m_metatable!=null? gettable(this,key): v;
	}

	public LuaValue rawget( int key ) {
		if ( key>0 && key<=array.length ) 
			return array[key-1]!=null? array[key-1]: NIL;
		return hashget( LuaInteger.valueOf(key) );
	}
	
	public LuaValue rawget( LuaValue key ) {
		if ( key.isinttype() ) {
			int ikey = key.toint();
			if ( ikey>0 && ikey<=array.length ) 
				return array[ikey-1]!=null? array[ikey-1]: NIL;
		}
		return hashget( key );
	}
		
	protected LuaValue hashget(LuaValue key) {
		if ( hashEntries > 0 ) {
			LuaValue v = hashValues[hashFindSlot(key)];
			return v!=null? v: NIL;
		}
		return NIL;
	}

	public void set( int key, LuaValue value ) {
		if ( m_metatable==null || ! rawget(key).isnil() || ! settable(this,LuaInteger.valueOf(key),value) )
			rawset(key, value);
	}

	/** caller must ensure key is not nil */
	public void set( LuaValue key, LuaValue value ) {
		key.checkvalidkey();
		if ( m_metatable==null || ! rawget(key).isnil() ||  ! settable(this,key,value) )
			rawset(key, value);
	}

	public void rawset( int key, LuaValue value ) {
		if ( ! arrayset(key, value) )
			hashset( LuaInteger.valueOf(key), value );
	}

	/** caller must ensure key is not nil */
	public void rawset( LuaValue key, LuaValue value ) {
		if ( !key.isinttype() || !arrayset(key.toint(), value) )
			hashset( key, value );
	}

	private boolean arrayset( int key, LuaValue value ) {
		if ( key>0 && key<=array.length ) {
			array[key-1] = (value.isnil()? null: value);
			return true;
		} else if ( key==array.length+1 && !value.isnil() ) {
			expandarray();
			array[key-1] = value;
			return true;
		}
		return false;
	}
	
	private void expandarray() {
		int n = array.length;
		int m = Math.max(2,n*2);
		array = resize(array, m);
		for ( int i=n; i0; --n )
			if ( !rawget(n).isnil() )
				return LuaInteger.valueOf(n);
		return ZERO;
	}

	/**
	 * Get the length of this table, as lua defines it.
	 */
	public int length() {
		int a = getArrayLength();
		int n = a+1,m=0;
		while ( !rawget(n).isnil() ) {
			m = n;
			n += a+getHashLength()+1;
		}
		while ( n > m+1 ) {
			int k = (n+m) / 2;
			if ( !rawget(k).isnil() )
				m = k;
			else
				n = k;
		}
		return m;
	}
	
	public LuaValue len()  { 
		return LuaInteger.valueOf(length());
	}
	
	public int maxn() {
		int n = 0;
		for ( int i=0; i n )
					n = key;
			}
		}
		return n;
	}

	/**
	 * Get the next element after a particular key in the table 
	 * @return key,value or nil
	 */
	/**
	 * Get the next element after a particular key in the table 
	 * @return key,value or nil
	 */
	public Varargs next( LuaValue key ) {
		int i = 0;
		do {
			// find current key index
			if ( ! key.isnil() ) {
				if ( key.isinttype() ) { 
					i = key.toint();
					if ( i>0 && i<=array.length ) {
						if ( array[i-1] == null )
							error( "invalid key to 'next'" );
						break;
					}
				}
				if ( hashKeys.length == 0 )
					error( "invalid key to 'next'" );
				i = hashFindSlot(key);
				if ( hashKeys[i] == null )
					error( "invalid key to 'next'" );
				i += 1+array.length;
			}
		} while ( false );
		
		// check array part
		for ( ; i 0 ) {
			int slot = hashFindSlot( key );
			hashClearSlot( slot );
		}
	}
	
	protected void hashClearSlot( int i ) {
		if ( hashKeys[ i ] != null ) {
			
			int j = i;
			int n = hashKeys.length; 
			while ( hashKeys[ j = ( ( j + 1 ) % n ) ] != null ) {
				final int k = ( ( hashKeys[ j ].hashCode() )& 0x7FFFFFFF ) % n;
				if ( ( j > i && ( k <= i || k > j ) ) ||
					 ( j < i && ( k <= i && k > j ) ) ) {
					hashKeys[ i ] = hashKeys[ j ];
					hashValues[ i ] = hashValues[ j ];
					i = j;
				}
			}
			
			--hashEntries;
			hashKeys[ i ] = null;
			hashValues[ i ] = null;
			
			if ( hashEntries == 0 ) {
				hashKeys = NOVALS;
				hashValues = NOVALS;
			}
		}
	}

	private boolean checkLoadFactor() {
		// Using a load factor of (n+1) >= 7/8 because that is easy to compute without
		// overflow or division.
		final int hashCapacity = hashKeys.length;
		return hashEntries >= (hashCapacity - (hashCapacity>>3));
	}

	private void rehash() {
		final int oldCapacity = hashKeys.length;
		final int newCapacity = oldCapacity+(oldCapacity>>2)+MIN_HASH_CAPACITY;
		
		final LuaValue[] oldKeys = hashKeys;
		final LuaValue[] oldValues = hashValues;
		
		hashKeys = new LuaValue[ newCapacity ];
		hashValues = new LuaValue[ newCapacity ];
		
		for ( int i = 0; i < oldCapacity; ++i ) {
			final LuaValue k = oldKeys[i];
			if ( k != null ) {
				final LuaValue v = oldValues[i];
				final int slot = hashFindSlot( k );
				hashKeys[slot] = k;
				hashValues[slot] = v;
			}
		}
	}
	
	// ----------------- sort support -----------------------------
	//
	// implemented heap sort from wikipedia
	//
	// Only sorts the contiguous array part. 
	//
	public void sort(LuaValue comparator) {
		int n = array.length;
		while ( n > 0 && array[n-1] == null )
			--n;
		if ( n > 1 ) 
			heapSort(n, comparator);
	}

	private void heapSort(int count, LuaValue cmpfunc) {
		heapify(count, cmpfunc);
		for ( int end=count-1; end>0; ) {
			swap(end, 0);
			siftDown(0, --end, cmpfunc);
		}
	}

	private void heapify(int count, LuaValue cmpfunc) {
		for ( int start=count/2-1; start>=0; --start )
			siftDown(start, count - 1, cmpfunc);
	}

	private void siftDown(int start, int end, LuaValue cmpfunc) {
		for ( int root=start; root*2+1 <= end; ) { 
			int child = root*2+1; 
			if (child < end && compare(child, child + 1, cmpfunc))
				++child; 
			if (compare(root, child, cmpfunc)) {
				swap(root, child);
				root = child;
			} else
				return;
		}
	}

	private boolean compare(int i, int j, LuaValue cmpfunc) {
		LuaValue a = array[i];
		LuaValue b = array[j];
		if ( a == null || b == null )
			return false;
		if ( ! cmpfunc.isnil() ) {
			return cmpfunc.call(a,b).toboolean();
		} else {
			return a.lt_b(b);
		}
	}
	
	private void swap(int i, int j) {
		LuaValue a = array[i];
		array[i] = array[j];
		array[j] = a;
	}
	
	/** This may be deprecated in a future release.  
	 * It is recommended to count via iteration over next() instead */
	public int keyCount() {
		LuaValue k = LuaValue.NIL;
		for ( int i=0; true; i++ ) {
			Varargs n = next(k);
			if ( (k = n.arg1()).isnil() )
				return i;
		}
	}
	
	/** This may be deprecated in a future release.  
	 * It is recommended to use next() instead */
	public LuaValue[] keys() {
		Vector l = new Vector();
		LuaValue k = LuaValue.NIL;
		while ( true ) {
			Varargs n = next(k);
			if ( (k = n.arg1()).isnil() )
				break;
			l.addElement( k );
		}
		LuaValue[] a = new LuaValue[l.size()];
		l.copyInto(a);
		return a;
	}
	
	// equality w/ metatable processing
	public LuaValue eq( LuaValue val ) {  return eq_b(val)? TRUE: FALSE; }
	public boolean eq_b( LuaValue val )  {
		if ( this == val ) return true;
		if ( m_metatable == null || !val.istable() ) return false;
		LuaValue valmt = val.getmetatable();
		return valmt!=null && LuaValue.eqmtcall(this, m_metatable, val, valmt); 
	}
}




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