com.wormsim.utils.Context.java Source code

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Here is the source code for com.wormsim.utils.Context.java

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package com.wormsim.utils;

import java.util.HashMap;
import org.apache.commons.math3.util.FastMath;

/**
 *
 * TODO: Replace with the version worked on at home.
 *
 * @author ah810
 */
public abstract class Context implements Cloneable {

    public static final BasicContext GLOBAL_CONTEXT = new BasicContext();

    static {
        GLOBAL_CONTEXT.addVariable("e", FastMath.E);
        GLOBAL_CONTEXT.addVariable("pi", FastMath.PI);
        GLOBAL_CONTEXT.addVariable("true", 1.0);
        GLOBAL_CONTEXT.addVariable("false", 0.0);

        GLOBAL_CONTEXT.addMethod("ln", (p) -> FastMath.log(p[0]));
        GLOBAL_CONTEXT.addMethod("log", (p) -> FastMath.log(p[0], p[1]));
        GLOBAL_CONTEXT.addMethod("log10", (p) -> FastMath.log10(p[0]));
        GLOBAL_CONTEXT.addMethod("exp", (p) -> FastMath.exp(p[0]));
        GLOBAL_CONTEXT.addMethod("logit", (p) -> Utils.logit(p[0]));
        GLOBAL_CONTEXT.addMethod("logistic", (p) -> Utils.logistic(p[0]));
        GLOBAL_CONTEXT.addMethod("e", (p) -> FastMath.E);
        GLOBAL_CONTEXT.addMethod("pi", (p) -> FastMath.PI);
    }

    public abstract double get(String ref);

    public abstract Method getMethod(String ref);

    public static interface Method {
        public double evaluate(double... params);

        public static final Method ZERO = (p) -> 0.0;
    }

    public final static class BasicContext extends Context {
        public BasicContext() {
            this(null);
        }

        public BasicContext(Context parent) {
            this.parent = parent;
            this.variables = new HashMap<>();
            this.methods = new HashMap<>();
        }

        private final HashMap<String, Method> methods;
        private final Context parent;
        private final HashMap<String, Double> variables;

        public void addMethod(String ref, Method method) {
            methods.put(ref, method);
        }

        public void addVariable(String ref, double param) {
            variables.put(ref, param);
        }

        @Override
        public BasicContext clone() {
            try {
                return (BasicContext) super.clone();
            } catch (CloneNotSupportedException ex) {
                throw new AssertionError("Should be able to clone BasicContext.", ex);
            }
        }

        @Override
        public double get(String ref) {
            Double val = variables.get(ref);
            if (val == null) {
                if (parent != null) {
                    return parent.get(ref);
                } else {
                    return 0.0;
                }
            } else {
                return val;
            }
        }

        @Override
        public Method getMethod(String ref) {
            Method meth = methods.get(ref);
            if (meth == null) {
                if (parent != null) {
                    return parent.getMethod(ref);
                } else {
                    return Method.ZERO;
                }
            } else {
                return meth;
            }
        }

        public BasicContext push() {
            return new BasicContext(this);
        }
    }
}