AkankshCaimi/CS202-Compiler-Design

Compiler Design for B--

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Table of Contents

• About
• Variables
• Precedence of Operators
  • Arithmetic Operators
  • Relational Operators
  • Logical Operators
• Statements
• Compile and Run Instructions
• Authors

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About

B-- is a toy programming language based on BASIC programming language. It is made using lex and bison.

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Variables

1. Variable Names: Single Upper-Case Letter (A – Z) followed by an optional single digit (0 – 9). Example: A, F, H, A0, Z9
2. Data Types: Numeric – Integer (%), Single Precision (!), Double Precision (#) & Strings ($).
3. Type declaration uses special characters along with variable names as given above. Example: P1# (double precision), N$ (string), A9 (integer), M! (single precision)

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Precedence of Operators

Arithematic Operators:

Operator	Operation	Example
()	Parenthesis	(X + Y)
^	Exponentiation	X ^ Y
-	Negation	-X
*, /	Multiplication / Division	X * Y, X / Y
+, -	Addition / Subtraction	X + Y, X - Y

Relational Operators:

Operator	Operation	Example
=	Equality	X = Y
<>	Inequality	X <> Y
<	Less Than	X < Y
>	Greater Than	X > Y
<=	Less than or equal to	X <= Y
>=	Greater than or equal to	X >= Y

Logical Operators:

NOT, AND, OR, XOR

NOTE: In case of equal precedence evaluation for operators is done from left-to-right.

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Statements

1. The DATA statement is used to contain values that will be later used by the READ statement. Example:

   DATA 3.14159, “PI”

2. The DEF statement is used to define a user-defined function of one numeric variable or a pseudo-constant. Example:

   DEF FNF(X) = X^4 – 1

   DEF FNP = 3.14159

3. The DIM statement is used to specify non-default sizes of numeric arrays. Example:

   DIM A(6), B(10,20)

4. The END statement is used to specify the end of the source program.

   END

5. The FOR statement is used for coding pre-test loops that use an index numeric variable. Example:

   10 FOR X=1 TO 9 STEP 4
   
   20 PRINT X
   
   30 NEXT X
   
   40 PRINT "AFTER LOOP X IS"; X
   
   50 END
   

6. The GOSUB statement is used to call a subroutine.

7. The IF statement is used to branch conditionally to a new statement. Example:

   IF F<>1 THEN 260

   IF A$="Y" THEN 170

8. The LET statement is used to assign a value to a variable. Examples:

   LET A(X,3) = X*Y – 1

   LET A$ = “ABC”

9. The INPUT statement is used to read data into one or more variables from the keyboard. Example:

   INPUT X

10. The PRINT statement is used to send output to the terminal. Example:

    PRINT “X = ”, 10

11. The REM statement is used to add a comment to the source code of the program.

12. The RETURN statement is used to exit a subroutine that was entered with GOSUB and continue execution on the line immediately following the GOSUB that invoked the subroutine.

13. The STOP statement will halt execution of the program immediately.

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How to Compile and Run the Program

1. Clone the repository and extract the zipped files.

2. Open terminal and navigate to the extracted folder using cd command.

3. Install Lex and Yacc on your device.

4. To compile the lex and yacc file run the following command:

        $lex BMM_Scanner.l
        $yacc -d BMM_Parser.y
   

   This will create a new file lex.yy.c, then run the following command to compile it:

        $gcc lex.yy.c y.tab.c -o b--
   

5. To run this file run the following command:

        $./b--
   

6. You will get the desired output in the output.txt file.

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Authors

Ajaybeer Singh (2021CSB1063)

Akanksh Caimi (2021CSB1064)