Package ch.njol.skript.lang.util

Source Code of ch.njol.skript.lang.util.SimpleExpression

/*
*   This file is part of Skript.
*
*  Skript is free software: you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation, either version 3 of the License, or
*  (at your option) any later version.
*
*  Skript is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with Skript.  If not, see <http://www.gnu.org/licenses/>.
*
*
* Copyright 2011-2014 Peter Güttinger
*
*/

package ch.njol.skript.lang.util;

import java.lang.reflect.Array;
import java.util.Iterator;

import org.bukkit.event.Event;
import org.eclipse.jdt.annotation.Nullable;

import ch.njol.skript.ScriptLoader;
import ch.njol.skript.Skript;
import ch.njol.skript.SkriptAPIException;
import ch.njol.skript.classes.Changer;
import ch.njol.skript.classes.Changer.ChangeMode;
import ch.njol.skript.classes.ClassInfo;
import ch.njol.skript.classes.Converter;
import ch.njol.skript.lang.Expression;
import ch.njol.skript.lang.ExpressionType;
import ch.njol.skript.registrations.Classes;
import ch.njol.skript.util.Utils;
import ch.njol.util.Checker;
import ch.njol.util.Kleenean;
import ch.njol.util.coll.CollectionUtils;
import ch.njol.util.coll.iterator.ArrayIterator;

/**
* An implementation of the {@link Expression} interface. You should usually extend this class to make a new expression.
*
* @see Skript#registerExpression(Class, Class, ExpressionType, String...)
* @author Peter Güttinger
*/
public abstract class SimpleExpression<T> implements Expression<T> {
 
  private int time = 0;
 
  protected SimpleExpression() {}
 
  @Override
  @Nullable
  public final T getSingle(final Event e) {
    final T[] all = getArray(e);
    if (all.length == 0)
      return null;
    if (all.length > 1)
      throw new SkriptAPIException("Call to getSingle() on a non-single expression");
    return all[0];
  }
 
  /**
   * {@inheritDoc}
   * <p>
   * Unlike {@link #get(Event)} you have to make sure that the this method's returned array is neither null nor contains null elements.
   */
  @Override
  public T[] getAll(final Event e) {
    final T[] all = get(e);
    if (all == null) {
      final T[] r = (T[]) Array.newInstance(getReturnType(), 0);
      assert r != null;
      return r;
    }
    if (all.length == 0)
      return all;
    int numNonNull = 0;
    for (final T t : all)
      if (t != null)
        numNonNull++;
    if (numNonNull == all.length)
      return all;
    final T[] r = (T[]) Array.newInstance(getReturnType(), numNonNull);
    assert r != null;
    int i = 0;
    for (final T t : all)
      if (t != null)
        r[i++] = t;
    return r;
  }
 
  @Override
  public final T[] getArray(final Event e) {
    final T[] all = get(e);
    if (all == null) {
      final T[] r = (T[]) Array.newInstance(getReturnType(), 0);
      assert r != null;
      return r;
    }
    if (all.length == 0)
      return all;
   
    int numNonNull = 0;
    for (final T t : all)
      if (t != null)
        numNonNull++;
   
    if (!getAnd()) {
      if (all.length == 1 && all[0] != null)
        return all;
      int rand = Utils.random(0, numNonNull);
      final T[] one = (T[]) Array.newInstance(getReturnType(), 1);
      for (final T t : all) {
        if (t != null) {
          if (rand == 0) {
            one[0] = t;
            return one;
          }
          rand--;
        }
      }
      assert false;
    }
   
    if (numNonNull == all.length)
      return all;
    final T[] r = (T[]) Array.newInstance(getReturnType(), numNonNull);
    assert r != null;
    int i = 0;
    for (final T t : all)
      if (t != null)
        r[i++] = t;
    return r;
  }
 
  /**
   * This is the internal method to get an expression's values.<br>
   * To get the expression's value from the outside use {@link #getSingle(Event)} or {@link #getArray(Event)}.
   *
   * @param e The event
   * @return An array of values for this event. May not contain nulls.
   */
  @Nullable
  protected abstract T[] get(Event e);
 
  @Override
  public final boolean check(final Event e, final Checker<? super T> c) {
    return check(e, c, false);
  }
 
  @Override
  public final boolean check(final Event e, final Checker<? super T> c, final boolean negated) {
    return check(get(e), c, negated, getAnd());
  }
 
  // TODO return a kleenean (UNKNOWN if 'all' is null or empty)
  public final static <T> boolean check(final @Nullable T[] all, final Checker<? super T> c, final boolean invert, final boolean and) {
    if (all == null)
      return false;
    boolean hasElement = false;
    for (final T t : all) {
      if (t == null)
        continue;
      hasElement = true;
      final boolean b = c.check(t);
      if (and && !b)
        return invert ^ false;
      if (!and && b)
        return invert ^ true;
    }
    if (!hasElement)
      return false;
    return invert ^ and;
  }
 
  /**
   * Converts this expression to another type. Unless the expression is special, the default implementation is sufficient.
   * <p>
   * This method is never called with a supertype of the return type of this expression, or the return type itself.
   *
   * @param to The desired return type of the returned expression
   * @return Expression with the desired return type or null if it can't be converted to the given type
   * @see Expression#getConvertedExpression(Class...)
   * @see ConvertedExpression#newInstance(Expression, Class...)
   * @see Converter
   */
  @Nullable
  protected <R> ConvertedExpression<T, ? extends R> getConvertedExpr(final Class<R>... to) {
    assert !CollectionUtils.containsSuperclass(to, getReturnType());
    return ConvertedExpression.newInstance(this, to);
  }
 
  @Override
  @SuppressWarnings("unchecked")
  @Nullable
  public final <R> Expression<? extends R> getConvertedExpression(final Class<R>... to) {
    if (CollectionUtils.containsSuperclass(to, getReturnType()))
      return (Expression<? extends R>) this;
    return this.getConvertedExpr(to);
  }
 
  @Nullable
  private ClassInfo<?> returnTypeInfo;
 
  @Override
  @Nullable
  public Class<?>[] acceptChange(final ChangeMode mode) {
    ClassInfo<?> rti = returnTypeInfo;
    if (rti == null)
      returnTypeInfo = rti = Classes.getSuperClassInfo(getReturnType());
    final Changer<?> c = rti.getChanger();
    if (c == null)
      return null;
    return c.acceptChange(mode);
  }
 
  @SuppressWarnings("unchecked")
  @Override
  public void change(final Event e, final @Nullable Object[] delta, final ChangeMode mode) {
    final ClassInfo<?> rti = returnTypeInfo;
    if (rti == null)
      throw new UnsupportedOperationException();
    final Changer<?> c = rti.getChanger();
    if (c == null)
      throw new UnsupportedOperationException();
    ((Changer<T>) c).change(getArray(e), delta, mode);
  }
 
  /**
   * {@inheritDoc}
   * <p>
   * This implementation sets the time but returns false.
   *
   * @see #setTime(int, Class, Expression...)
   * @see #setTime(int, Expression, Class...)
   */
  @Override
  public boolean setTime(final int time) {
    if (ScriptLoader.hasDelayBefore == Kleenean.TRUE && time != 0) {
      Skript.error("Can't use time states after the event has already passed");
      return false;
    }
    this.time = time;
    return false;
  }
 
  protected final boolean setTime(final int time, final Class<? extends Event> applicableEvent, final Expression<?>... mustbeDefaultVars) {
    if (ScriptLoader.hasDelayBefore == Kleenean.TRUE && time != 0) {
      Skript.error("Can't use time states after the event has already passed");
      return false;
    }
    if (!ScriptLoader.isCurrentEvent(applicableEvent))
      return false;
    for (final Expression<?> var : mustbeDefaultVars) {
      if (!var.isDefault()) {
        return false;
      }
    }
    this.time = time;
    return true;
  }
 
  protected final boolean setTime(final int time, final Expression<?> mustbeDefaultVar, final Class<? extends Event>... applicableEvents) {
    if (ScriptLoader.hasDelayBefore == Kleenean.TRUE && time != 0) {
      Skript.error("Can't use time states after the event has already passed");
      return false;
    }
    if (!mustbeDefaultVar.isDefault())
      return false;
    for (final Class<? extends Event> e : applicableEvents) {
      if (ScriptLoader.isCurrentEvent(e)) {
        this.time = time;
        return true;
      }
    }
    return false;
  }
 
  @Override
  public int getTime() {
    return time;
  }
 
  @Override
  public boolean isDefault() {
    return false;
  }
 
  @Override
  public boolean isLoopOf(final String s) {
    return false;
  }
 
  @Override
  @Nullable
  public Iterator<? extends T> iterator(final Event e) {
    return new ArrayIterator<T>(getArray(e));
  }
 
  @Override
  public String toString() {
    return toString(null, false);
  }
 
  @Override
  public Expression<?> getSource() {
    return this;
  }
 
  @Override
  public Expression<? extends T> simplify() {
    return this;
  }
 
  @Override
  public boolean getAnd() {
    return true;
  }
 
}
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