A compiler for my own programming language:

define sayX with x of type integer gives back void as
  say x stop
stop

let a of type integer be 10 plus 5 times 20 minus 2 stop

call sayX with a stop

• Variables
• Functions
• Pointers
• Expression parsing
• Loops

First, all the tokens are split based on a list of delimeters. Once they're split, each token is assigned a TokenType from token.h. All of these lexed tokens are then passed onto the next step, parsing.

With each token given a TokenType, I start constructing the abstract syntax tree (AST). The AST for the following variable statement is shown below:

let a of type integer be 5 plus 10 divide 2 stop

Variable Statement
|
|__ Identifier - "a"
|
|__ Variable type - Integer
|
|__ Value - Binary Expression
    |
    |__ Operator - Plus
    |
    |__ Left - Integer literal
        |
        |___ Value - 5
    |
    |__ Right - Binary Expression
        |
        |__ Operator - Divide
        |
        |__ Left - Integer Literal
            |
            |__ Value - 10
        |
        |__ Right - Integer Literal
            |
            |__ Value - 2

As you can see, this strucutre is fairly recursive as a BinaryExpression can contain other binary expressions inside of it. This same process is applied to all the code and various types of nodes are created which are found in node.h. The implementions of the functions for creating each of these nodes is found in ast.cpp.

With the AST created all we have to do is just loop through each node and call the generateCode method attached to it. Since every node is a child class of the abstract class ASTNode (shown below) we can call generateCode on all of them without worrying about the type:

struct ASTNode {
  virtual ~ASTNode() = default;
  virtual std::string generateCode() = 0;
};

All of this code is then writen into a compiled.cpp file and then a command is run in the terminal to build and run this code.

Feel free to reach out to me via any of the contact methods below:

• Email
• Linkedin