This repository explains how to write a compiler from scratch by Go. The compiler has some constraints

• Can compile only arithmetic operations.
• Runs only on Linux
• Outputs X86-64 assembly (GAS)

First you need to run a docker container and get in it.

./docker-run

And then you can use the compiler.

echo '30 + 12' | go run main.go

This program receives source code from stdin, and emit compiled code to stdout.

If you want to compile and run it immediately, you can use asrun script.

echo '30 + 12' | go run main.go | ./asrun

asrun takes assembly code from stdin, execute it and shows the code with the resulting status code.

$ echo  '30 + 12' | go run main.go | ./asrun
-------- a.s ----------------
  .global main
main:
  movq $30, %rax # intliteral
  movq $12, %rbx # intliteral
  addq %rbx, %rax
  ret
-------- result -------------
42

There are 3 phases in this compiler.

Source Code -> [Tokenizer] -> Tokens -> [Parser] -> AST -> [Code Generator] -> Assembly

Source Code -> [Tokenizer] -> Tokens

Tokenizer analyzes byte stream of source code, and break it down into a list of tokens.

In this compiler, tokenize() does this task.

Tokens -> [Parser] -> AST

Parser analyzes stream of tokens, and composer a tree of nested structs , which represents sytanx structure of source code.

This tree is called a AST (Abstract Syntax Tree).

parser() does this task.

AST -> [Code Generator] -> Assembly

Code generator converts ASTs into code of the target language.

In this compiler, the target language is GAS(GNU Assembly) for X86-64 linux.

generateCode() does this task.

$ ./test.sh