C言語コンパイラ

これは何？

Ruiさんのテキストを見ながらCコンパイラを実装している。

VSCode環境について

VSCodeでC言語をステップ実行するための設定。
Microsoft製のC/C++拡張はインストール済み
launch.jsonにF5で実行(launch)する内容を記述し、tasks.jsonに依存するタスク（コンパイルやmake clean）を記述している。

デバッグ時の引数は.vscode/launch.jsonのargsに指定する。

.vscode/launch.json

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "name": "make and test 9cc",
      "type": "cppdbg",
      "request": "launch",
      "program": "${workspaceFolder}/9cc",
      "args": [
        "foo=1+(1>10); bar=foo+1; return bar; return foo;"
      ],
      "stopAtEntry": false,
      "cwd": "${workspaceFolder}",
      "environment": [],
      "externalConsole": false,
      "MIMode": "gdb",
      "setupCommands": [
        {
          "description": "Enable pretty-printing for gdb",
          "text": "-enable-pretty-printing",
          "ignoreFailures": true
        }
      ],
      "preLaunchTask": "make 9cc",
      "miDebuggerPath": "/usr/bin/gdb"
    },
  ]
}

.vscode/tasks.json

{
  "tasks": [
    {
      "type": "shell",
      "label": "make 9cc",
      "command": "make",
      "args": [
        "9cc"
      ],
      "group": "build",
      // "dependsOn": [
      //   "make clean",
      // ]
    },
    {
      "type": "shell",
      "label": "make clean",
      "command": "make",
      "args": [
        "clean"
      ]
    }
  ],
  "version": "2.0.0"
}

生成規則、文法

program    = stmt*
stmt       = expr ";"
            | "{" stmt* "}"
            | "if" "(" expr ")" stmt ("else" stmt)?
            | "while" "(" expr ")" stmt
            | "for" "(" expr? ";" expr? ";" expr? ")" stmt
            | "return" expr ";"
expr       = assign
assign     = equality ("=" assign)?
equality   = relational ("==" relational | "!=" relational)*
relational = add ("<" add | "<=" add | ">" add | ">=" add)*
add        = mul ("+" mul | "-" mul)*
mul        = unary ("*" unary | "/" unary)*
unary      = ("+" | "-")? primary
primary    = num
           | ident ("(" ")")?
           | ident ("(" ")" "{" "}")?
           | "(" expr ")"