package edu.princeton.toy.lang;

/**
 * TDefaultExceptionHandler is the simplest mutable implementation of TExceptionHandler.
 *
 * @author btsang
 * @version 7.1
 */

public class TDefaultExceptionHandler implements TExceptionHandler
{
    private boolean willThrow[];

    /**
     * Instantiates a new TDefaultExceptionHandler in an exceptionless state.
     */
    public TDefaultExceptionHandler()
    {
        willThrow = new boolean[TExceptionType.TYPES.length];
    }

    /**
     * Throws a TException with the specified type iff the specified exception was not set to be
     * ignored.  The Virtual Machine should raise all exceptional conditions and let the handler
     * decide wheter or not that exception should be propagated through the rest of the machine.
     * 
     * @param type The type of exceptional condition that was raised in the Virtual Machine.
     */
    public void raise(TExceptionType type) throws TException
    {
        if (willThrow[type.hashCode()])
            throw new TException(type);
    }

    /**
     * Gets wheter or not the handler should throw a raised exception of the specified type.
     *
     * @param index The index of type (in the TExceptionType.TYPES array) in question.  An invalid
     * value will result in an ArrayIndexOutOfBoundsException.
     * @return True iff the handler will throw exceptions of this type.
     * @see edu.princeton.toy.lang.TExceptionType#TYPES
     */
    public boolean getWillThrow(int index)
    {
        return willThrow[index];
    }

    /**
     * Gets wheter or not the handler should throw a raised exception of the specified type.
     *
     * @param type The type in question.  A null value will result in a NullPointerException.
     * @return True iff the handler will throw exceptions of this type.
     * @see edu.princeton.toy.lang.TExceptionType#TYPES
     */
    public boolean getWillThrow(TExceptionType type)
    {
        return willThrow[type.hashCode()];
    }

    /**
     * Sets wheter or not the handler should throw a raised exception of the specified type.
     *
     * @param type The type in question.  A null value will result in a NullPointerException.
     * @param willThrow Wheter or not the handler should throw exceptions of this type.
     * @see edu.princeton.toy.lang.TExceptionType#TYPES
     */
    public void setWillThrow(TExceptionType type, boolean willThrow)
    {
        this.willThrow[type.hashCode()] = willThrow;
    }

    /**
     * Sets wheter or not the handler should throw a raised exception of the specified type.
     *
     * @param index The index of type (in the TExceptionType.TYPES array) in question.  An invalid
     * value will result in an ArrayIndexOutOfBoundsException.
     * @param willThrow Wheter or not the handler should throw exceptions of this type.
     * @see edu.princeton.toy.lang.TExceptionType#TYPES
     */
    public void setWillThrow(int index, boolean willThrow)
    {
        this.willThrow[index] = willThrow;
    }
}