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Dummy Lang

A primitive implementation of c function parser using lex, yacc and c

Description

This is the course project for Compiler Construction, Summer 2020. It uses a stack to implement control flow rather than using an AST

Getting Started

To build the program you can run the following command in terminal

make all

Then you can run the code written on a text file ( see the attached test.txt, test2.txt, test3.txt files in the root dir )

./calc < textfilename.txt

And you should see the desired output ( if the feature exists ) in the terminal

Features

  1. Supports Arithmetic Operators

    • +
    • -
    • *
    • /
    • %
    • ()
    • - negation

    Input

    // example [ don't forget the semi-colons at the end of the lines ] 
float x = 2+2-4+(-2)/4*3 ; 
display x ;

    Output

    printed 1.500

  2. Supports Conditional Operators

    • ==
    • !=
    • >
    • >=
    • <
    • <=
    • ||
    • &&
    • !

    Input

    // example [ don't forget the semi-colons at the end of the lines ] 
display 2>=2 && 4<=4 ; 
display (3==3 && 3==1 || 2==2 && !(3==3) );

    Output

    printed 1.00
printed 0.00

  3. Supports shorthand operators

    • +=
    • -=
    • *=
    • /=
    • %=
    • variableName++
    • variableName--
    • ++variableName
    • --variableName

    Input

    float x = 100 ; 

display x++;
display x;

display ++x;
display x;

float y = 100 ; 

display y--;
display y;
display --y;
display y;

    Output

    Variable x successfully updated 

printed  : 100.000000 

printed  : 101.000000 
Variable x successfully updated 

printed  : 102.000000 

printed  : 102.000000 
Variable y successfully updated 

printed  : 100.000000 

printed  : 99.000000 
Variable y successfully updated 

printed  : 98.000000 

printed  : 98.000000

  4. Supports Variable Declaration

    As of now the only types is float, however the grammar for int is recognized

    example of supported variable declarations ( uninitialized variables throw error and will result in the termination of the program )

    Input

    int v1, v2 , v3 ; // has to end line with semicolon 
int v1, v2 = 10 ; // v2 has a value of 10.0 however v1 is uninitialized
float v1=1.0, v2, v3=101.0; // v2 is uninitialized

// the action below is supported aswell 
float y = 100, z = 500; 
float x =  y + z  ; // now x will have a value of 600.0 
\\ trying to use undeclared variables will result in the termination of the program

  5. if-elseif-else and if-elseif-else nested support

    Basic Syntax Rules

    • must be in these format if(c){} or if(c){}else{} or if(c){}elseif(c){}else{} braces without semicolon in the end
    • c means conditional statement of any length

    Input

         if(2<2){
         return 1 ;
     }
     else if(3==4){
         return 2;
     }
     else{
         display 3;
         if(2==2){
             display 3.25; 
             if(3!=3){
                 display 3.5;
             }
             else if(4==2){
                 display 3.75;
             }
             else{
                 display 3.95;
             }
         }
     }

    Output

     printed  : 3.000000 
 printed  : 3.250000 
 printed  : 3.950000

  6. Supports Function Declaration

    As of now the only return types are float, void and int,

    • void types cannot return a value
    • int or float types must return a value

    Input - 1

    void foo(){}

    Input - 2

    int foo(){}

    Input - 3

    int foo()
     { 
       return 2+2;
     }

    Output

                                                 // output for input 1
   Error Function does not return any value  // output for input 2
   returned : 4                              // output for input 3

  7. Output

    The display command can be used to output results

    • as of now it only supports printing numbers

    Input

    display 2 + 2;
int x = 4;
display x+4;
display 1/2;

    Output

    4.0000
8.0000
0.5000