org.extendj.ast.Option Maven / Gradle / Ivy

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package org.extendj.ast;

import java.util.ArrayList;
import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.IOException;
import java.util.Set;
import beaver.*;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.LinkedHashSet;
import java.util.*;
import org.jastadd.util.PrettyPrintable;
import org.jastadd.util.PrettyPrinter;
import java.util.zip.*;
import java.io.*;
import org.jastadd.util.*;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
/**
 * @ast class
 * @aspect OptionType
 * @declaredat /home/jesper/git/extendj/java8/frontend/Option.jadd:41
 */
public abstract class Option extends java.lang.Object {
  
    protected static final Option NONE = new Option() {
      @Override public Object get() {
        throw new NullPointerException();
      }

      @Override public Object getOrElse(Object v) {
        return v;
      }

      @Override public boolean hasValue() {
        return false;
      }
    };

  

    protected static class OptionSome extends Option {
      private final V value;

      public OptionSome(V value) {
        assert (value != null);
        this.value = value;
      }

      @Override public V get() {
        return value;
      }

      @Override public V getOrElse(V v) {
        return value;
      }

      @Override public boolean hasValue() {
        return true;
      }
    }

  

    protected Option() { }

  

    /**
     * Get the contained value.
     * Throws an error if there is no object.
     */
    public abstract T get();

  

    /**
     * Get the contained value.
     * If there is no value, the argument is returned.
     */
    public abstract T getOrElse(T v);

  

    /** Test if there is a value in this option object. */
    public abstract boolean hasValue();

  

    /**
     * Convert a nullable object to an option.
     */
    public static  Option maybe(U u) {
      if (u != null) {
        return new OptionSome(u);
      } else {
        return (Option) NONE;
      }
    }

  

    /**
     * Convert a nullable object to an option.
     */
    public static  Option some(U u) {
      if (u == null) {
        throw new Error("Can't create an option containing null using Option.some(). "
            + "Use Option.none() or Option.maybe() instead.");
      }
      return new OptionSome(u);
    }

  

    /**
     * Returns the empty option object.
     */
    public static  Option none() {
      return (Option) NONE;
    }


}