formatter

🎨 BIRD Config Formatter (@birdcc/formatter)

⚠️ Alpha Stage: This package is in early development. APIs may change frequently, and unexpected issues may occur. Please evaluate carefully before deploying in production environments.

Overview · Features · Installation · Usage · Configuration · API Reference · Architecture

Overview

@birdcc/formatter is the formatting component in the BIRD-LSP toolchain, purpose-built for BIRD Internet Routing Daemon configuration files. It employs a dual-engine architecture combining dprint performance with builtin reliability.

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Features

Feature	Description
⚡ dprint Engine	Rust/WASM-based for lightning-fast formatting
🛡️ Builtin Fallback	Automatic fallback when dprint is unavailable
🔒 Safe Mode	AST semantic verification before/after formatting
🔄 Async API	Promise-based interface for modern architectures
🧩 Zero Dependencies	Builtin engine requires no external deps

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Installation

# Using pnpm (recommended)
pnpm add @birdcc/formatter

# Using npm
npm install @birdcc/formatter

# Using yarn
yarn add @birdcc/formatter

Prerequisites

• Node.js >= 18
• TypeScript >= 5.0 (if using TypeScript)

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Usage

Basic Formatting

import { formatBirdConfig } from "@birdcc/formatter";

const source = `
protocol bgp bgp_peer {
local as 65001;
neighbor 192.0.2.1 as 65002;
}
`;

const formatted = await formatBirdConfig(source, {
  engine: "dprint",
  safeMode: true,
});

console.log(formatted.text);
console.log(`Changed: ${formatted.changed}`);
console.log(`Engine: ${formatted.engine}`);

Format Checking

import { checkBirdConfigFormat } from "@birdcc/formatter";

const result = await checkBirdConfigFormat(source);
console.log(`Needs formatting: ${result.changed}`);

Using Builtin Engine

const formatted = await formatBirdConfig(source, {
  engine: "builtin",
  indentSize: 4,
  safeMode: true,
});

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Configuration

Options

Option	Type	Default	Description
engine	'dprint' | 'builtin'	'dprint'	Formatter engine selection
safeMode	boolean	true	Enable semantic equivalence check
indentSize	number	2	Number of spaces for indentation
lineWidth	number	80	Maximum line width

Configuration Details

• engine: dprint uses Rust/WASM; builtin uses TypeScript as fallback
• safeMode: Compares AST fingerprints to ensure semantic equivalence
• indentSize: Indentation spaces (positive integer)
• lineWidth: Target line width (positive integer)

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API Reference

formatBirdConfig(text, options?)

Format BIRD2 configuration file content.

import { formatBirdConfig } from "@birdcc/formatter";

const result = await formatBirdConfig(text, options);
// result.text    → Formatted content
// result.changed → Whether changes were made
// result.engine  → Engine used

Parameters:

• text: string — The configuration file content to format
• options?: FormatBirdConfigOptions — Formatting options

Returns: Promise<BirdFormatResult>

checkBirdConfigFormat(text, options?)

Check if the configuration file needs formatting (without actually formatting).

import { checkBirdConfigFormat } from "@birdcc/formatter";

const result = await checkBirdConfigFormat(text, options);
// result.changed → Whether formatting is needed

Type Definitions

interface FormatBirdConfigOptions {
  engine?: "dprint" | "builtin";
  safeMode?: boolean;
  indentSize?: number;
  lineWidth?: number;
}

interface BirdFormatResult {
  text: string;
  changed: boolean;
  engine: "dprint" | "builtin";
}

interface BirdFormatCheckResult {
  changed: boolean;
}

type FormatterEngine = "dprint" | "builtin";

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Architecture

Dual-Engine Architecture

flowchart TB
    subgraph "API Layer"
        API[formatBirdConfig]
    end

    subgraph "Engine Selection"
        SEL{Engine Selection}
    end

    subgraph "dprint Engine"
        D1[@birdcc/dprint-plugin-bird<br/>Rust/WASM]
        D2[Tree-sitter Parser]
        D3[Format Logic]
    end

    subgraph "Builtin Engine"
        B1[TypeScript Implementation]
        B2[Parser Adapter]
        B3[Format Logic]
    end

    subgraph "Safety Layer"
        SAFE{Safe Mode}
        AST1[Parse Original]
        AST2[Parse Formatted]
        CMP[AST Compare]
    end

    subgraph "Output"
        OUT[Formatted Text]
    end

    API --> SEL
    SEL -->|priority| D1
    SEL -->|fallback| B1
    D1 --> D2 --> D3
    B1 --> B2 --> B3
    D3 --> SAFE
    B3 --> SAFE
    SAFE -->|enabled| AST1
    SAFE -->|enabled| AST2
    AST1 --> CMP
    AST2 --> CMP
    CMP -->|verified| OUT
    SAFE -->|disabled| OUT

    style D1 fill:#e8f5e9
    style B1 fill:#e3f2fd
    style SAFE fill:#fff3e0

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Formatting Pipeline

sequenceDiagram
    participant User as User Code
    participant API as Formatter API
    participant Engine as Format Engine
    participant Parser as @birdcc/parser
    participant Safe as Safe Mode

    User->>API: formatBirdConfig(source, options)
    API->>API: selectEngine(options)

    alt dprint Engine
        API->>Engine: dprint.format(source)
        Engine->>Engine: Rust/WASM formatting
    else builtin Engine
        API->>Engine: builtin.format(source)
        Engine->>Parser: parseBirdConfig(source)
        Parser-->>Engine: AST
        Engine->>Engine: TypeScript formatting
    end

    Engine-->>API: formattedText

    opt Safe Mode Enabled
        API->>Safe: verifySemantics(source, formattedText)
        Safe->>Parser: parseBirdConfig(source)
        Parser-->>Safe: ast1
        Safe->>Parser: parseBirdConfig(formattedText)
        Parser-->>Safe: ast2
        Safe->>Safe: compareAST(ast1, ast2)
        Safe-->>API: verification result
    end

    API-->>User: BirdFormatResult

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Engine Fallback Strategy

flowchart TD
    START[Format Request] --> CONFIG{Engine Configured?}

    CONFIG -->|explicit dprint| TRY_DPRINT[Try dprint]
    CONFIG -->|explicit builtin| USE_BUILTIN[Use builtin]
    CONFIG -->|auto| TRY_DPRINT_AUTO[Try dprint]

    TRY_DPRINT --> DPRINT_OK{dprint OK?}
    TRY_DPRINT_AUTO --> DPRINT_OK_AUTO{dprint OK?}

    DPRINT_OK -->|yes| RETURN_DPRINT[Return dprint result]
    DPRINT_OK -->|no| ERROR[Throw Error]

    DPRINT_OK_AUTO -->|yes| RETURN_DPRINT
    DPRINT_OK_AUTO -->|no| FALLBACK[Fallback to builtin]

    FALLBACK --> USE_BUILTIN
    USE_BUILTIN --> BUILTIN_OK{builtin OK?}
    BUILTIN_OK -->|yes| RETURN_BUILTIN[Return builtin result]
    BUILTIN_OK -->|no| ERROR

    RETURN_DPRINT --> SAFE{Safe Mode?}
    RETURN_BUILTIN --> SAFE

    SAFE -->|enabled| VERIFY[Verify AST]
    SAFE -->|disabled| OUTPUT[Output Result]
    VERIFY -->|pass| OUTPUT
    VERIFY -->|fail| ERROR

    style TRY_DPRINT fill:#e8f5e9
    style USE_BUILTIN fill:#e3f2fd
    style FALLBACK fill:#fff3e0

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Related Packages

Package	Description
@birdcc/parser	Tree-sitter grammar and parser
@birdcc/core	Semantic analysis engine
@birdcc/dprint-plugin-bird	dprint plugin (Rust/WASM)
@birdcc/linter	Lint rules and diagnostics
@birdcc/cli	CLI tool (birdcc fmt command)
@birdcc/lsp	LSP server implementation

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📖 Documentation

• BIRD Official Documentation
• BIRD2 User Manual
• dprint Documentation
• GitHub Project

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📝 License

This project is licensed under the GPL-3.0 License.

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_{Built with ❤️ by the BIRD Chinese Community (BIRDCC)}

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