package rebelsky.compiler.pascal;

import java.util.Vector;

/**
 * A collection of constants that define the nonterminals in Pascal.
 * (Not yet complete.)
 *
 * @author Samuel A. Rebelsky
 * @version 0.5 of October 2002
 */

public class PascalNonterminals
{
  // +---------+-----------------------------------------------------------
  // | Fields  |
  // +---------+
 
  /** The number of nonterminals. */ 
  private static int NUM_NONTERMINALS = 0;

  /** The names of the various nonterminals. */
  private static String[] names;


  // +-----------+-----------------------------------------------------------
  // | Constants |
  // +-----------+

  /** 
   * An addition operator, such as plus or minus. 
   */
  public static final int ADDING_OPERATOR	= NUM_NONTERMINALS++;

  /** 
   * An assignment statement. 
   */
  public static final int ASSIGNMENT		= NUM_NONTERMINALS++;

  /** 
   * A list of assignment statements.  Not used in the standard
   * Pascal grammar, but useful for some variant grammars that
   * I like to create.
   *
   * <assignment_list> ::= <assignment> TSEMI { <assignment> TSEMI }
   */
  public static final int ASSIGNMENT_LIST	= NUM_NONTERMINALS++;

  /**
   * A block of code.  In Pascal, lots of declarations followed by
   * a group of statements enclosed in begin and end.
   */
  public static final int BLOCK			= NUM_NONTERMINALS++;

  /**
   * A constant.
   */
  public static final int CONSTANT		= NUM_NONTERMINALS++;

  /**
   * A single constant definition.
   */
  public static final int CONSTANT_DEFINITION	= NUM_NONTERMINALS++;

  /**
   * Zero or more constant definitions.
   */
  public static final int CONSTANT_DEFINITIONS	= NUM_NONTERMINALS++;

  /**
   * The famous expression.
   */
  public static final int EXPRESSION 		= NUM_NONTERMINALS++;

  /**
   * Part of an expression.  Factors contain no unparenthesized
   * addition and multiplication symbols.
   */
  public static final int FACTOR		= NUM_NONTERMINALS++;

  /**
   * An identifier that names a file.  Used in the program heading.
   */
  public static final int FILE_IDENTIFIER 	= NUM_NONTERMINALS++;

  /**
   * A non-empty list of identifiers.
   */
  public static final int IDENTIFIER_LIST	= NUM_NONTERMINALS++;

  /**
   * A label, typically used as the destination of a (blech) goto
   * statement.
   */
  public static final int LABEL			= NUM_NONTERMINALS++;

  /**
   * The declaration of zero or more labels that are to be used
   * within a block.
   */
  public static final int LABEL_DECLARATION	= NUM_NONTERMINALS++;

  /** 
   * An operator with the precedence of multiplication, such as 
   * multiplication, division, or modulus.
   */
  public static final int MULTIPLYING_OPERATOR	= NUM_NONTERMINALS++;

  /**
   * The heading of a program.  Gives name, input, and output.
   */
  public static final int PROGRAM_HEADING	= NUM_NONTERMINALS++;

  /**
   * Part of an expression.  Terms are expression with no unparenthesized
   * additive operations.
   */
  public static final int TERM			= NUM_NONTERMINALS++;

  /**
   * The name of a type.
   */
  public static final int TYPE_IDENTIFIER	= NUM_NONTERMINALS++;

  /**
   * A non-negative number.
   */
  public static final int UNSIGNED_NUMBER	= NUM_NONTERMINALS++;

  /**
   * A variable (something that can be assigned to).
   */
  public static final int VARIABLE		= NUM_NONTERMINALS++;

  /**
   * Declare the type of one or more variables.
   */
  public static final int VARIABLE_DECLARATION	= NUM_NONTERMINALS++;

  /**
   * Zero or more variable declarations.
   */
  public static final int VARIABLE_DECLARATIONS	= NUM_NONTERMINALS++;


  // +---------+-----------------------------------------------------------
  // | Methods |
  // +---------+

  /**
   * Get the number of nonterminal symbols.
   */
  public static int numNonterminals() {
    return NUM_NONTERMINALS;
  } // numNonterminals()

  /**
   * Get the name of a nonterminal.
   *
   * Pre: 0 <= ntnum < numNonterminals
   */
  public static String getName(int ntnum) {
    return (String) names[ntnum];
  } // getName(int)

  public static void  init() {
    names = new String[NUM_NONTERMINALS];
    names[ADDING_OPERATOR] = "<adding_operator>";
    names[ASSIGNMENT] = "<assignment>";
    names[ASSIGNMENT_LIST] = "<assignment_list>";
    names[VARIABLE] = "<variable>";
    names[VARIABLE_DECLARATION] = "<variable_declaration>";
    names[VARIABLE_DECLARATIONS] = "<variable_declarations>";
  } // init()

} // class PascalNonterminals