/** Parser for Assignment 1 */

import java.io._
import java.util._
import scala.collection.mutable.ArrayBuffer

class Parser(in: Lexer) {
  
  /** Convenience constructor that takes a Reader as input */
  
  def this(inputStream: Reader) { this(new Lexer(inputStream)) }
  
  def this(fileName: String) { this(new FileReader(fileName)) }
  
  def lexer():Lexer = in
  
  /** Parses the program text in the lexer bound to 'in' and returns the corresponding AST. 
    * @throws ParseException if a syntax error is encountered (including lexical errors). 
    */
  def parse():AST = { 
    /* YOUR CODE GOES HERE */                   
  }
  
  /** Parses:
   *   <exp> :: = if <exp> then <exp> else <exp>
   *            | let <prop-def-list> in <exp>
   *            | map <id-list> to <exp>
   *            | <term> { <biop> <exp> } 
   */
  private def parseExp():AST = {
    /* YOUR CODE GOES HERE */
  }

  /* CODE HERE FOR PARSE METHODS FOR OTHER SYNTACTIC CATEGORIES (E.G., TERM)
}