Description

Programming Assignment #2

DUE:  10/25/2019

This is a group assignment

TASK:  in this assignment you will write  a  Java program to implement a lexical analyzer (scanner) and a syntax analyzer(recursive descent parser)  for the following language, which similar to the syntax of Ada:

*******   GRAMMAR    for  the parser  **********************

<program> à procedure name begin <stmt_list> end ;

<stmt_list> à  <stmt> ;{ <stmt_list}*

<stmt>à  <assign> | <if>

<if> à  if ( <bool>  )  then <stmt_list> [ else  <stmt_list>]   endif;

   !!! NOTE items that are bold are PART of the construct, and thus terminal symbols

<assign> à <var>: = <expr>;                      // assignment is := in Ada

<expr> à  <term> { ( + | - | * | / ) <term> }

<term> à <var> | <int>

<bool> à  <var>(= | !=) <int>  

** NOTE THE name on the procedure and end statement must match, and must be a valid identifier

********* description of identifiers, and  integer literals for the scanner *****

<letter> à  a  |  b  |  c  |  d  |  e  | … |  z  |  A  |  … |  Z

<digit>  à  0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

<letterdigit>  à  <letter> | <digit>

<var> à  <letter><letterdigit>*

<int>  à  <digit><digit>*

A valid sample program #1 in this language:

procedure calculate

begin

   x := 10;

   y := 3;

  val1:= x - 6 + y;

end;

An invalid sample program would be:

procedure sum

begin

                x := 10;

                y := x - 3

                sum :=  x + y;

end ;

<<<< NOTE the missing semicolon in the second expression. >>>>>>

****  These samples can be saved into a file of type txt  and used as input to your lexical analyzer ***