//
// VinilString.java  
// 

package vinil;

// Imports here

/**
 * class VinilString
 * Stores a String type for Vinil
 */
public class VinilString extends VinilElement
{
  public VinilString()
  {
    setValue("");
  }

  public VinilString(String s)
  {
    setValue(s);
  }

  /** get/set access functions */
  public String getValue()
  {
    return value;
  }
  
  public void setValue(String newValue)
  {
    value = newValue;
  }
  
  protected String value;
  
  /** Return the string equivalent of this element */
  public String toString()
  {
    return "\"" + value + "\"";
  }
  
  /** Produces a hashcode for the object */
  public int hashCode()
  {
    return value.hashCode();
  }
  
  /** Determines if two objects are equal */
  public boolean equals(Object obj)
  {
    return (obj != null) && (obj.getClass().equals(getClass())) && (((VinilString)obj).value.equals(value));
  }
  
  /** Parser helper functions */
  /** Determine if the token can denote this object */
  boolean isTokenValid(VinilToken token)
  {
    return token.tokenType == VinilToken.VT_STRING;
  }
  
  /** Parse the given token stream and store the result in the active object */
  void parse(VinilTokenizer tokenizer) throws VinilException
  {
    VinilToken token = tokenizer.nextToken();
    //		if (!isTokenValid(token))
    //			throw new VinilException("internal error: string");
    
    value = token.token.substring(1, token.token.length() - 1);
  }
  
  /** Interpreter helper functions */
  /** Evaluate the current element */
  VinilElement evaluate(VinilEnvironment env, VinilElement parameters) throws VinilException
  {
    if (parameters == null)
      return this;
    else
      {
	try
	  {
	    if (!parameters.getClass().equals(Class.forName("vinil.VinilNumber")))
	      throw new VinilException("string dereferencements must be numbers");
	  }
	catch (VinilException e)
	  {
	    throw e;
	  }
	catch (Exception e)
	  {
	    throw new VinilException("internal error: VinilNumber class missing");
	  }
	
	VinilString str = new VinilString();
	VinilNumber num = (VinilNumber)parameters;
	int i = num.getValue().intValue();
	
	try
	  {
	    str.setValue(String.valueOf(value.charAt(i)));
	  }
	catch (Exception e)
	  {
	    throw new VinilException("string dereferencement out of range");
	  }
	
	return str;
      }
  }
}