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package com.feilong.lib.ognl.internal;

import java.util.Arrays;

import com.feilong.lib.ognl.ClassCacheInspector;

/**
 * Implementation of {@link ClassCache}.
 */
public class ClassCacheImpl implements ClassCache{

    /* this MUST be a power of 2 */
    private static final int    TABLE_SIZE      = 512;

    /* ...and now you see why. The table size is used as a mask for generating hashes */
    private static final int    TABLE_SIZE_MASK = TABLE_SIZE - 1;

    private final Entry[]       _table;

    private ClassCacheInspector _classInspector;

    private int                 _size           = 0;

    public ClassCacheImpl(){
        _table = new Entry[TABLE_SIZE];
    }

    @Override
    public void setClassInspector(ClassCacheInspector inspector){
        _classInspector = inspector;
    }

    @Override
    public void clear(){
        for (int i = 0; i < _table.length; i++){
            _table[i] = null;
        }

        _size = 0;
    }

    @Override
    public int getSize(){
        return _size;
    }

    @Override
    public final Object get(Class key){
        Object result = null;
        int i = key.hashCode() & TABLE_SIZE_MASK;

        for (Entry entry = _table[i]; entry != null; entry = entry.next){
            if (entry.key == key){
                result = entry.value;
                break;
            }
        }

        return result;
    }

    @Override
    public final Object put(Class key,Object value){
        if (_classInspector != null && !_classInspector.shouldCache(key)){
            return value;
        }

        Object result = null;
        int i = key.hashCode() & TABLE_SIZE_MASK;
        Entry entry = _table[i];

        if (entry == null){
            _table[i] = new Entry(key, value);
            _size++;
        }else{
            if (entry.key == key){
                result = entry.value;
                entry.value = value;
            }else{
                while (true){
                    if (entry.key == key){
                        /* replace value */
                        result = entry.value;
                        entry.value = value;
                        break;
                    }else{
                        if (entry.next == null){
                            /* add value */
                            entry.next = new Entry(key, value);
                            break;
                        }
                    }
                    entry = entry.next;
                }
            }
        }

        return result;
    }

    @Override
    public String toString(){
        return "ClassCacheImpl[" + "_table=" + (_table == null ? null : Arrays.asList(_table)) + '\n' + ", _classInspector="
                        + _classInspector + '\n' + ", _size=" + _size + '\n' + ']';
    }
}