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/*
 * Copyright (C) 2003-2007 Jost Boekemeier
 *
 * 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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 io.soluble.pjb.bridge;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/**
 * Cache [Entry(object, method, parameters) - Method].  No
 * synchronization, so use this class per thread or per request
 * only.
 */
public final class MethodCache {
    Map map;
    static final Entry noCache = new NoCache();

    private void init() {
        map = new HashMap();
    }

    /**
     * Create a new method cache.
     */
    public MethodCache() {
        init();
    }

    private static class CachedMethod {
        private Method method;
        private Class[] typeCache;

        public CachedMethod(Method method) {
            this.method = method;
        }

        public Method get() {
            return method;
        }

        public Class[] getParameterTypes() {
            if (typeCache != null) return typeCache;
            return typeCache = method.getParameterTypes();
        }
    }

    /**
     * A cache entry.
     */
    public static class Entry {
        boolean isStatic;
        String name;
        Class clazz;
        Class params[];

        protected Entry() {
        }

        protected Entry(String name, Object obj, Class params[]) {
            this.name = name; // intern() is ~10% slower than lazy string comparison
            boolean isStatic = obj instanceof Class;
            this.clazz = isStatic ? (Class) obj : obj.getClass();
            this.isStatic = isStatic;
            this.params = params;
        }

        private boolean hasResult = false;
        private int result = 1;

        @Override
        public int hashCode() {
            if (hasResult) return result;
            for (Class param : params) {
                result = result * 31 + (param == null ? 0 : param.hashCode());
            }
            result = result * 31 + clazz.hashCode();
            result = result * 31 + name.hashCode();
            result = result * 31 + (isStatic ? 1231 : 1237);
            hasResult = true;
            return result;
        }

        @Override
        public boolean equals(Object o) {
            Entry that = (Entry) o;
            if (clazz != that.clazz) return false;
            if (isStatic != that.isStatic) return false;
            if (params.length != that.params.length) return false;
            if (!name.equals(that.name)) return false;
            for (int i = 0; i < params.length; i++) {
                if (params[i] != that.params[i]) return false;
            }
            return true;
        }

        private CachedMethod cache;

        public void setMethod(CachedMethod cache) {
            this.cache = cache;
        }

        public Class[] getParameterTypes(Method method) {
            return cache.getParameterTypes();
        }
    }

    private static final class NoCache extends Entry {
        @Override
        public Class[] getParameterTypes(Method method) {
            return method.getParameterTypes();
        }
    }

    /**
     * Get the method for the entry
     *
     * @param entry The entry
     * @return The method
     */
    public Method get(Entry entry) {
        if (entry == noCache) return null;
        CachedMethod cache = (CachedMethod) map.get(entry);
        if (cache == null) return null;
        entry.setMethod(cache);
        return cache.get();
    }

    /**
     * Store a constructor with an entry
     *
     * @param entry  The cache entry
     * @param method The method
     */
    public void put(Entry entry, Method method) {
        if (entry != noCache) {
            CachedMethod cache = new CachedMethod(method);
            entry.setMethod(cache);
            map.put(entry, cache);
        }
    }

    /**
     * Get a cache entry from a name, class and arguments.
     *
     * @param name The method name
     * @param obj  The object or class
     * @param args The arguments
     * @return A cache entry.
     */
    public Entry getEntry(String name, Object obj, Object args[]) {
        Class params[] = new Class[args.length];
        for (int i = 0; i < args.length; i++) {
            Class c = args[i] == null ? null : args[i].getClass();
            if (c == PhpArray.class) return noCache;
            params[i] = c;
        }
        return new Entry(name, obj, params);
    }

    /**
     * Removes all mappings from this cache.
     */
    public void clear() {
        init();
    }
}