001/*
002 * PlotSquared, a land and world management plugin for Minecraft.
003 * Copyright (C) IntellectualSites <https://intellectualsites.com>
004 * Copyright (C) IntellectualSites team and contributors
005 *
006 * This program is free software: you can redistribute it and/or modify
007 * it under the terms of the GNU General Public License as published by
008 * the Free Software Foundation, either version 3 of the License, or
009 * (at your option) any later version.
010 *
011 * This program is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
014 * GNU General Public License for more details.
015 *
016 * You should have received a copy of the GNU General Public License
017 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
018 */
019package com.plotsquared.core.util;
020
021import com.sk89q.worldedit.internal.expression.Expression;
022import org.checkerframework.checker.nullness.qual.NonNull;
023
024/**
025 * An expression that can be evaluated.
026 * Evaluation is thread-safe.
027 * This is a wrapper for {@link Expression}.
028 */
029public class PlotExpression {
030
031    private final Expression expression;
032    private final Object lock = new Object();
033
034    private PlotExpression(final @NonNull String rawExpression, final @NonNull String @NonNull [] variableNames) {
035        this.expression = Expression.compile(rawExpression, variableNames);
036    }
037
038    /**
039     * Compiles an expression from a string.
040     *
041     * @param expression    the expression to compile.
042     * @param variableNames the variables that can be set in {@link #evaluate(double...)}.
043     * @return the compiled expression.
044     */
045    public static @NonNull PlotExpression compile(
046            final @NonNull String expression,
047            final @NonNull String @NonNull ... variableNames
048    ) {
049        return new PlotExpression(expression, variableNames);
050    }
051
052    /**
053     * Evaluates the expression with the given variable values.
054     *
055     * @param values the values to set the variables to.
056     * @return the result of the evaluation.
057     */
058    public double evaluate(double... values) {
059        double evaluate;
060        // synchronization is likely the best option in terms of memory and cpu consumption
061        synchronized (this.lock) {
062            evaluate = this.expression.evaluate(values);
063        }
064        return evaluate;
065    }
066
067}