Question

The question involves two parts and is for a compiler design course. See the image below for the question. It may help if you have used a tool called ANTLR and know about grammar files. Answer part 1 and part 2 correctly and I will give a positive rating. Thank you.

Part 1: In BDL (badly designed language), the equal sign is the assignment operator. The language allows multiple assignments such as i -j k which first assigns the value of variable k to variable j, and then the variable i to variable i. The following is from the ANTLR 4 grammar BDLg4: (1) grammar BDL; (2) program: stmtist (3) stmtlist stmt stmt; (4) stmt: asgn l; (5) asgn (6) source (7) expr: var; (8) ar: ID (9) ID: a-zA-ZI][a-zA-ZO-9; (10) WS:Iltn+-> skip; Complete the right sides of the rules for asgn (line 5) and source (line 6) Part 2: In BDL, the equal sign is also the comparison operator. (Yes this is based on an actual programming language.) A comparison is surrounded by parentheses, For example, in the statement j- (j k) the value of i is set to either true or false, depending on whether j is equal or not equal to k. Modify the grammar of Part 1 to support the comparison operator. Hint. You need to replace line 7 witlh one or more new rules

Answer 1

part 1 :

asgn =>asgn = digit ++

asgn = digit + digit ++

i = j = k = digit + digit ++

  i = j = k = 1 + digit ++

  i = j = k = 1 + 1 ++

source :

antlr4 {

    source = file('src/main/antlr')

    output = file('build/generated-src/me/tomassetti/pythonast/parser')

    extraArgs = ['-package', 'me.tomassetti.pythonast.parser']

}

part 2 :

replacement of line 7 :

exp ? var1 : var 2 ;

(Now the two variables var1(j) and var2(k) will check those condition and then get assigned to the variable (i) .