Denoで簡易的なCLIツールを作る

Table of Contents

Introduction

DenoでCLIツールを試験的に作ったのでメモしておく。

方針

cliffy で作成
cat と grep をSub Commandで簡易的に作成

ディレクトリ構造

$ nix run nixpkgs#tree .
.
├── deno.json
├── deno.lock
└── src
    ├── commands
    │   ├── cat.ts
    │   └── grep.ts
    ├── deps.ts
    └── main.ts

3 directories, 6 files

作業手順

1. 依存関係をインストール

$ deno install で入れて使い易いように src/deps.ts を用意する

deno.json:

{
  "imports": {
    "@cliffy/command": "jsr:@cliffy/command@^1.0.0-rc.7"
  }
}

src/deps.ts:

export { Command } from '@cliffy/command';

2. Command作成

import { Command } from './deps.ts';
import { catCommand } from './commands/cat.ts';
import { grepCommand } from './commands/grep.ts';

await new Command()
  .name('mycli')
  .version('0.1.0')
  .description('My CLI tool')
  .command('cat', catCommand)
  .command('grep', grepCommand)
  .parse(Deno.args);

3. Sub Command

3.1 cat

import { Command } from '../deps.ts';

const displayFiles = async (files: string[]): Promise<void> => {
  for (const file of files) {
    try {
      const content = await Deno.readTextFile(file);
      console.log(`--- ${file} ---`);
      console.log(content);
    } catch (err) {
      if (err instanceof Error) {
        console.error(`Error reading ${file}: ${err.message}`);
      } else {
        console.error(`Unknown error:`, err);
      }
    }
  }
};

export const catCommand = new Command()
  .name('cat')
  .description('Display content of files')
  .arguments('<files...>')
  .action(async (_, ...files: string[]) => await displayFiles(files));

3.2 grep

import { Command } from '../deps.ts';

const grepFiles = async (pattern: string, files: string[]): Promise<void> => {
  const regex = new RegExp(pattern, 'g');

  for (const file of files) {
    try {
      const content = await Deno.readTextFile(file);
      const lines = content.split('\n');
      let matchFound = false;

      for (let i = 0; i < lines.length; i++) {
        if (regex.test(lines[i])) {
          if (!matchFound) {
            console.log(`\n--- ${file} ---`);
            matchFound = true;
          }
          console.log(`${i + 1}: ${lines[i]}`);
          regex.lastIndex = 0; // Reset regex for next test
        }
      }
    } catch (err) {
      if (err instanceof Error) {
        console.error(`Error reading ${file}: ${err.message}`);
      } else {
        console.error(`Unknown error:`, err);
      }
    }
  }
};

export const grepCommand = new Command()
  .name('grep')
  .description('Search for pattern in files')
  .arguments('<pattern> <files...>')
  .action(async (_, pattern: string, ...files: string[]) =>
    await grepFiles(pattern, files)
  );

4. Command実行

4.1 cat

$ deno run --allow-read src/main.ts cat deno.json src/deps.ts
--- deno.json ---
{
  "imports": {
    "@cliffy/command": "jsr:@cliffy/command@^1.0.0-rc.7"
  }
}

--- src/deps.ts ---
export { Command } from '@cliffy/command';

4.2 grep

$ deno run --allow-read src/main.ts grep "command" deno.json src/main.ts

--- deno.json ---
3:     "@cliffy/command": "jsr:@cliffy/command@^1.0.0-rc.7"

--- src/main.ts ---
2: import { catCommand } from './commands/cat.ts';
3: import { grepCommand } from './commands/grep.ts';
9:   .command('cat', catCommand)
10:   .command('grep', grepCommand)

終わりに

TypeScriptで記述できるのはnpmの資産が使えて便利だし、cliffyも使い勝手が非常によい。