Exn.java

package de.unisiegen.tpml.core.expressions ;


import de.unisiegen.tpml.core.exceptions.NotOnlyFreeVariableException ;
import de.unisiegen.tpml.core.latex.DefaultLatexCommand ;
import de.unisiegen.tpml.core.latex.LatexCommandList ;
import de.unisiegen.tpml.core.latex.LatexStringBuilder ;
import de.unisiegen.tpml.core.latex.LatexStringBuilderFactory ;
import de.unisiegen.tpml.core.prettyprinter.PrettyStringBuilder ;
import de.unisiegen.tpml.core.prettyprinter.PrettyStringBuilderFactory ;


/**
 * Instances of this class represent exceptions in the expression hierarchy.
 * 
 * @author Benedikt Meurer
 * @author Christian Fehler
 * @version $Rev:1053 $
 * @see Expression
 * @see Expression#isException()
 */
public final class Exn extends Expression
{
  /**
   * The unused string.
   */
  private static final String UNUSED = "unused" ; //$NON-NLS-1$


  /**
   * The string for the <b>(EMPTY-LIST)</b> exception.
   */
  private static final String EMPTY_LIST = "empty_list" ; //$NON-NLS-1$


  /**
   * The string for the <b>(DIVIDE-BY-ZERO)</b> exception.
   */
  private static final String DIVIDE_BY_ZERO = "divide_by_zero" ; //$NON-NLS-1$


  /**
   * String for the case that the name is null.
   */
  private static final String NAME_NULL = "name is null" ; //$NON-NLS-1$


  /**
   * The caption of this {@link Expression}.
   */
  private static final String CAPTION = Expression.getCaption ( Exn.class ) ;


  /**
   * Returns a set of needed latex commands for this latex printable object.
   * 
   * @return A set of needed latex commands for this latex printable object.
   */
  public static LatexCommandList getLatexCommandsStatic ( )
  {
    LatexCommandList commands = new LatexCommandList ( ) ;
    commands.add ( new DefaultLatexCommand ( LATEX_EXN , 1 , "\\mbox{\\color{" //$NON-NLS-1$
        + LATEX_COLOR_EXPRESSION + "}{$\\uparrow$\\ #1}}" , "name" ) ) ; //$NON-NLS-1$//$NON-NLS-2$
    return commands ;
  }


  /**
   * The <b>(DIVIDE-BY-ZERO)</b> exception.
   * 
   * @return A new <b>(DIVIDE-BY-ZERO)</b> exception.
   */
  public static final Exn newDivideByZero ( )
  {
    return new Exn ( DIVIDE_BY_ZERO ) ;
  }


  /**
   * The <b>(EMPTY-LIST)</b> exception.
   * 
   * @return A new <b>(EMPTY-LIST)</b> exception.
   */
  public static final Exn newEmptyList ( )
  {
    return new Exn ( EMPTY_LIST ) ;
  }


  /**
   * The name of the exception.
   * 
   * @see #toString()
   */
  private String name ;


  /**
   * Allocates a new <code>Exn</code> instance with the specified
   * <code>name</code>.
   * 
   * @param pName the name of the exception.
   * @throws NullPointerException if <code>name</code> is <code>null</code>.
   */
  private Exn ( String pName )
  {
    if ( pName == null )
    {
      throw new NullPointerException ( NAME_NULL ) ;
    }
    this.name = pName ;
  }


  /**
   * {@inheritDoc} Cloning is not necessary for exceptions and as such, we just
   * return a reference to <code>this</code> here.
   * 
   * @see Expression#clone()
   */
  @ Override
  public Exn clone ( )
  {
    return this ;
  }


  /**
   * {@inheritDoc}
   * 
   * @see Expression#equals(Object)
   */
  @ Override
  public boolean equals ( Object pObject )
  {
    if ( pObject instanceof Exn )
    {
      Exn other = ( Exn ) pObject ;
      return this.name.equals ( other.name ) ;
    }
    return false ;
  }


  /**
   * {@inheritDoc}
   */
  @ Override
  public String getCaption ( )
  {
    return CAPTION ;
  }


  /**
   * Returns a set of needed latex commands for this latex printable object.
   * 
   * @return A set of needed latex commands for this latex printable object.
   */
  @ Override
  public LatexCommandList getLatexCommands ( )
  {
    LatexCommandList commands = super.getLatexCommands ( ) ;
    commands.add ( getLatexCommandsStatic ( ) ) ;
    return commands ;
  }


  /**
   * Returns the name of the exception.
   * 
   * @return the name of the exception.
   */
  public String getName ( )
  {
    return this.name ;
  }


  /**
   * Returns the prefix of this {@link Expression}.
   * 
   * @return The prefix of this {@link Expression}.
   * @see #prefix
   */
  @ Override
  public String getPrefix ( )
  {
    if ( this.prefix == null )
    {
      this.prefix = PREFIX_EXN ;
    }
    return this.prefix ;
  }


  /**
   * {@inheritDoc}
   * 
   * @see Expression#hashCode()
   */
  @ Override
  public int hashCode ( )
  {
    return this.name.hashCode ( ) ;
  }


  /**
   * {@inheritDoc}
   * 
   * @see Expression#isException()
   */
  @ Override
  public boolean isException ( )
  {
    return true ;
  }


  /**
   * {@inheritDoc} Substitution below exceptions is not possible, so for the
   * <code>Exn</code> class, this method always returns a reference to the
   * exception itself.
   * 
   * @see Expression#substitute(Identifier, Expression)
   */
  @ Override
  public Exn substitute ( @ SuppressWarnings ( UNUSED )
  Identifier pId , Expression pExpression )
  {
    if ( pExpression.getIdentifierFreeNotOnlyVariable ( ) )
    {
      throw new NotOnlyFreeVariableException ( ) ;
    }
    return this ;
  }


  /**
   * {@inheritDoc}
   * 
   * @see Expression#toLatexStringBuilder(LatexStringBuilderFactory,int)
   */
  @ Override
  public final LatexStringBuilder toLatexStringBuilder (
      LatexStringBuilderFactory pLatexStringBuilderFactory , int pIndent )
  {
    LatexStringBuilder builder = pLatexStringBuilderFactory.newBuilder (
        PRIO_EXN , LATEX_EXN , pIndent , this.toPrettyString ( ).toString ( ) ) ;
    builder.addText ( "{" //$NON-NLS-1$
        + this.name.replaceAll ( "_" , "\\\\_" ) + "}" ) ; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
    return builder ;
  }


  /**
   * {@inheritDoc}
   * 
   * @see Expression#toPrettyStringBuilder(PrettyStringBuilderFactory)
   */
  @ Override
  public PrettyStringBuilder toPrettyStringBuilder (
      PrettyStringBuilderFactory pPrettyStringBuilderFactory )
  {
    if ( this.prettyStringBuilder == null )
    {
      this.prettyStringBuilder = pPrettyStringBuilderFactory.newBuilder ( this ,
          PRIO_EXN ) ;
      this.prettyStringBuilder.addText ( PRETTY_EXCEPTION ) ;
      this.prettyStringBuilder.addText ( PRETTY_SPACE ) ;
      this.prettyStringBuilder.addText ( this.name ) ;
    }
    return this.prettyStringBuilder ;
  }
}