Import test and README

README.md

@@ -1 +1,103 @@
-# How to write a compiler from scratch
+# How to write a compiler from scratch in 30 minutes
+
+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)
+
+# Usage
+
+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 emits assembly code to stdout.
+
+If you want to compile and run at once, `asrun` script helps you.
+
+```
+$ echo '30 + 12' | go run main.go | ./asrun
+```
+
+`asrun` takes assembly code from stdin and executes it while displaying the code and the resulting status code.
+
+```
+$ echo  '30 + 12' | go run main.go | ./asrun
+-------- a.s ----------------
+  .global main
+main:
+  movq  $30, %rax
+  movq  $12, %rcx
+  addq %rcx, %rax
+  ret
+-------- result -------------
+42
+```
+
+# Design
+
+The compiler has 3 phases.
+
+Source Code -> [Tokenizer] -> Tokens -> [Parser] -> AST -> [Code Generator] -> Assembly
+
+## Tokenizer
+
+Source Code -> [Tokenizer] -> Tokens
+
+Tokenizer analyzes the byte stream of source code, and breaks it down into a list of tokens.
+
+In this compiler, the function `tokenize()` does this task.
+
+## Parser
+
+Tokens -> [Parser] -> AST
+
+Parser analyzes stream of tokens, and composes a tree of nested structs , which represents sytanx structure of source code.
+
+This tree is called AST (Abstract Syntax Tree).
+
+The function `parser()` does this task.
+
+## Code Generator
+
+AST -> [Code Generator] -> Assembly
+
+Code generator converts AST into target language code.
+
+In this compiler, the target language is GAS(GNU Assembly) for X86-64 linux.
+
+The function `generateCode()` does this task.
+
+# How to run unit tests
+
+```
+$ ./test.sh
+```
+
+# SEE ALSO
+
+This project is based on the history of my Go compiler.
+
+https://github.com/DQNEO/minigo
+
+Actually, [the first 7 commits](https://github.com/DQNEO/minigo/commit/454fc2f4ad6669fc45c56e988599293e3f530976) of `minigo` are equivalent to the whole history of this repo.
+
+# License
+
+MIT License
+
+# Author
+
+@DQNEO

test.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+function unit_test() {
+    local input=$1
+    local expected=$2
+    echo "$input" | go run main.go > a.s
+    gcc a.s
+    ./a.out
+    local actual=$?
+    if [[ $expected -eq $actual ]];then
+        echo "ok"
+    else
+        echo "not ok : $expected != $actual"
+        exit 1
+    fi
+}
+
+unit_test '42' '42'
+unit_test '+7' '7'
+unit_test ' 7' '7'
+unit_test '7;' '7'
+unit_test ' 7 ;' '7'
+unit_test '-1' '255'
+unit_test '30+12' '42'
+unit_test '6 * 7' '42'
+unit_test '42 / 2' '21'
+