package io.github.reggert.reb4j.charclass;
   
   import static fj.Ord.charOrd;
   import io.github.reggert.reb4j.Literal;
   
   
   import fj.data.LazyString;
   import fj.data.Set;
   
  /**
   * Character class consisting of a single character.
   */
  public final class SingleChar extends CharClass
  {
  	private static final long serialVersionUID = 1L;
  	public final char character;
  	
  	SingleChar(final char character)
  	{
  		this.character = character;
  	}
  
  	@Override
  	public Negated<SingleChar> negated()
  	{
  		return new Negated<SingleChar>(this);
  	}
  
  	@Override
  	public LazyString unitableForm()
  	{
  		return Literal.escapeChar(character);
  	}
  
  	@Override
  	public LazyString independentForm()
  	{
  		return unitableForm();
  	}
  
  	@Override
  	public int hashCode()
  	{
  		final int prime = 31;
  		int result = 1;
  		result = prime * result + character;
  		return result;
  	}
  
  	@Override
  	public boolean equals(final Object obj)
  	{
  		if (this == obj)
  			return true;
  		if (obj == null)
  			return false;
  		if (getClass() != obj.getClass())
  			return false;
  		final SingleChar other = (SingleChar) obj;
  		return character == other.character;
  	}
  	
  	/**
  	 * Overloaded version of {@link CharClass#union(CharClass)} for arguments 
  	 * of type {@link SingleChar} that simply merges the two objects into
  	 * a single instance of {@link MultiChar}.
  	 * 
  	 * @param right another instance of {@link MultiChar}; must not be <code>null</code>.
  	 * @return a new instance of {@link MultiChar}.
  	 * @throws NullPointerException
  	 * 	if the argument is <code>null</code>.
  	 */
  	public MultiChar union(final SingleChar right)
  	{
  		return new MultiChar(Set.set(charOrd, character, right.character));
  	}
  	
  	/**
  	 * Overloaded version of {@link CharClass#union(CharClass)} for arguments 
  	 * of type {@link MultiChar} that simply merges the two objects into
  	 * a single instance of {@link MultiChar}.
  	 * 
  	 * @param right another instance of {@link MultiChar}; must not be <code>null</code>.
  	 * @return a new instance of {@link MultiChar}.
  	 * @throws NullPointerException
  	 * 	if the argument is <code>null</code>.
  	 */
  	public MultiChar union(final MultiChar right)
  	{
  		return new MultiChar(right.characters.insert(character));
  	}
  }