This program will consist 3 out of the 5 phases of the traditional language compilers, lexical, syntax, and semantic analysis. These phases will produce and display the tokens, produciton rules used, symbol table, and a fictitious assembly code instruction listing.

The source code will be a simplified language without reals and function definition productions. The program must also consider that Boolean variables must not be able to perform arithmetic operations and no conversion of data type in operations are allowed.

• Python 2.7

1. Open terminal
2. Change directory to …/Programming_Lang_Compiler
3. Type command: python compiler_driver.py

The program produces “Tokens.txt” from input file “src.txt”. Tokens.txt will contain tokens and lexemes with their corresponding line number. The program will output tokens, lexemes, line number first then outputs the corresponding production rules used. Lastly, prints out the symbol table and the assembly code listings.

The program utilizes the previous two phases: lexical analyzer and syntax analyzer and performs a semantic analysis while performing the syntax analyzer. This method is call Syntax-direct translation. The semantic actions will be performed as the syntax analyzer traverses through the tokens. The program will keep track of variables declared and instructions generated in an array. It also uses a stack to allow a back patching of missing addresses of resulting control structures such as loops and if statements. When the program ends, it will print out the content of its symbol table and its generated instructions.

The program generates assembly instructions defined by a fictitious assembly language following: PUSHI, PUSHM, POPM, STDOUT, STDIN, ADD, SUB, MUL, DIV, GRT, LES, EQU, NEQ, GEQ, LEQ, JUMPZ, JUMP, and LABEL.

Input Source code:

%% integer i, max, sum;

sum := 0;
i := 1;
read ( max);
while (i <  max)  {
      sum := sum + i;
      i  := i + 1; 
 }
 write (sum+max);

Output:

Identifier Mem_Address Type

i 10000 integer

max 10001 integer

sum 10002 integer

Instr_id Operator Operand

1 PUSHI 0

2 POPM 10002

3 PUSHI 1

4 POPM 10000

5 STDIN

6 POPM 10001

7 LABEL

8 PUSHM 10000

9 PUSHM 10001

10 LES

11 JUMPZ 21

12 PUSHM 10002

13 PUSHM 10000

14 ADD

15 POPM 10002

16 PUSHM 10000

17 PUSHI 1

18 ADD

19 POPM 10000

20 JUMP 7

21 PUSHM 10002

22 PUSHM 10001

23 ADD

24 STDOUT