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Functional types (Core)
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/*
 * Copyright © 2014  http://io7m.com
 * 
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
 * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package com.io7m.jfunctional;

import com.io7m.jequality.annotations.EqualityStructural;
import com.io7m.jnull.NullCheck;
import com.io7m.jnull.Nullable;

/**
 *  A value. 
 *
 * @param  The type of values.
 *
 * @see OptionType
 */

@EqualityStructural public final class Some implements OptionType
{
  private static final long serialVersionUID = 9158960385113454019L;
  private final T x;

  private Some(
    final T in_x)
  {
    this.x = NullCheck.notNull(in_x, "Some value");
  }

  static  Some some(
    final T x)
  {
    return new Some(x);
  }

  @Override public void map_(final ProcedureType p)
  {
    NullCheck.notNull(p, "Procedure");
    p.call(this.x);
  }

  @Override public  void mapPartial_(
    final PartialProcedureType p)
    throws E
  {
    NullCheck.notNull(p, "Procedure");
    p.call(this.x);
  }

  @Override public  U accept(
    final OptionVisitorType v)
  {
    NullCheck.notNull(v, "Visitor");
    return v.some(this);
  }

  @Override public  U acceptPartial(
    final OptionPartialVisitorType v)
    throws E
  {
    NullCheck.notNull(v, "Visitor");
    return v.some(this);
  }

  @Override public boolean equals(
    final @Nullable Object obj)
  {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (this.getClass() != obj.getClass()) {
      return false;
    }
    final Some other = (Some) obj;
    return this.x.equals(other.x);
  }

  /**
   * @return The value contained within.
   */

  public T get()
  {
    return this.x;
  }

  @Override public int hashCode()
  {
    return this.x.hashCode();
  }

  @Override public  OptionType map(
    final FunctionType f)
  {
    NullCheck.notNull(f, "Function");
    return Option.of(f.call(this.x));
  }

  @Override public  OptionType mapPartial(
    final PartialFunctionType f)
    throws E
  {
    NullCheck.notNull(f, "Function");
    return Option.of(f.call(this.x));
  }

  @Override public String toString()
  {
    final StringBuilder builder = new StringBuilder();
    builder.append("[Some ");
    builder.append(this.x);
    builder.append("]");
    final String s = builder.toString();
    assert s != null;
    return s;
  }

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

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