org.blockartistry.DynSurround.registry.Evaluator.java Source code

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Here is the source code for org.blockartistry.DynSurround.registry.Evaluator.java

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/* This file is part of Dynamic Surroundings, licensed under the MIT License (MIT).
 *
 * Copyright (c) OreCruncher
 *
 * 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.blockartistry.DynSurround.registry;

import java.util.ArrayList;
import java.util.IdentityHashMap;
import java.util.List;
import javax.annotation.Nonnull;

import org.apache.commons.lang3.StringUtils;
import org.blockartistry.DynSurround.DSurround;
import org.blockartistry.DynSurround.client.event.ExpressionEvent;
import org.blockartistry.lib.script.Expression;
import org.blockartistry.lib.script.Variant;

import net.minecraftforge.common.MinecraftForge;

public final class Evaluator {

    private static final IdentityHashMap<String, Expression> cache = new IdentityHashMap<String, Expression>();
    private static final List<String> naughtyList = new ArrayList<String>();

    @Nonnull
    public static List<String> getNaughtyList() {
        return naughtyList;
    }

    // This forces a compile and validation of the expression
    // that is passed in. This will make use of any supplied
    // built-in references. Custom instance variables, functions,
    // or operators will cause this to fail since they cannot
    // be set unless there is an Expression instance. Symbols
    // in the built-in tables will work, however.
    //
    // Expressions are cached. If multiple requests come in for
    // the same expression the cached version is reused.
    @Nonnull
    private static Expression compile(final String expression) {
        Expression exp = null;

        try {
            exp = cache.get(expression);
            if (exp == null) {
                exp = new Expression(expression);
                final ExpressionEvent.Create event = new ExpressionEvent.Create(exp);
                MinecraftForge.EVENT_BUS.post(event);
                exp.getRPN();
                cache.put(expression, exp);
            }
        } catch (final Throwable t) {
            naughtyList.add(expression);
            exp = new Expression("'" + t.getMessage() + "'");
            cache.put(expression, exp);
            DSurround.log().warn("Unable to compile [%s]: %s", expression, t.getMessage());
        }
        return exp;
    }

    @Nonnull
    public static Variant eval(@Nonnull final String script) {
        return compile(script.intern()).eval();
    }

    public static boolean check(@Nonnull final String conditions) {
        // If the string is empty return true.  They are always
        // true.
        if (StringUtils.isEmpty(conditions))
            return true;

        return eval(conditions).asBoolean();
    }
}