Flutter String Scanner

A Rust CLI tool that scans Flutter/Dart projects to extract translatable strings, making internationalization (i18n) easier by automatically identifying all string literals in your codebase.

Overview

This is my first Rust project! It combines the power of Rust's performance and safety with Dart's analysis capabilities to help Flutter developers prepare their apps for localization. The scanner traverses your Flutter project's source code, extracts all string literals, and exports them to a structured JSON format.

Features

• Automatic Discovery: Recursively scans all .dart files in your Flutter project's lib directory
• Smart Validation: Verifies the target directory is a valid Flutter project (checks for pubspec.yaml and lib folder)
• String Extraction: Uses a Dart analyzer script to identify and extract translatable strings
• JSON Export: Outputs all extracted strings to a formatted JSON file for easy processing
• Clean Architecture: Modular design with separate concerns (scanning, analyzing, exporting, validation)

Project Structure

scanner/
├── src/
│   ├── analyzer/          # Runs Dart analyzer to extract strings
│   │   ├── mod.rs
│   │   └── dart_analyzer.rs
│   ├── scanner/           # File system traversal logic
│   │   ├── mod.rs
│   │   └── file_scanner.rs
│   ├── exporter/          # JSON export functionality
│   │   ├── mod.rs
│   │   └── json_exporter.rs
│   ├── validators/        # Path and directory validation
│   │   ├── mod.rs
│   │   └── path.rs
│   └── main.rs           # Entry point
├── extract_strings/       # Dart analyzer script
└── Cargo.toml

Prerequisites

• Rust: Install from rustup.rs
• Dart SDK: Required to run the string extraction script

Installation

1. Clone the repository:

git clone <repository-url>
cd scanner

2. Build the project:

cargo build --release

The compiled binary will be available at target/release/scanner

Usage

1. Run the scanner:

cargo run

2. When prompted, enter the path to your Flutter project:

🗂️ Please enter the path of your flutter app to scan:
/path/to/your/flutter/project

3. The tool will:
   • Validate the Flutter project structure
   • Scan all .dart files in the lib directory
   • Extract strings from each file
   • Display progress and statistics
   • Generate output.json with all extracted strings

Example Output

✅ The path is a valid Flutter app directory. Continuing...
📄 Found 45 Dart files:
 - 12 strings extracted from /path/to/project/lib/main.dart
 - 8 strings extracted from /path/to/project/lib/screens/home.dart
 - 15 strings extracted from /path/to/project/lib/widgets/button.dart
 ...

The generated output.json will contain:

{
  "welcome": "Welcome to the app",
  "login": "Login",
  "signup": "Sign Up",
  ...
}

How It Works

1. Path Validation (validators/path.rs): Checks if the provided path is a valid Flutter project by verifying the existence of pubspec.yaml and the lib directory

2. File Scanning (scanner/file_scanner.rs): Uses depth-first search (DFS) to recursively traverse the lib directory and collect all .dart files

3. String Extraction (analyzer/dart_analyzer.rs): Executes the Dart analyzer script on each file to extract string literals, filtering out:

   • Strings starting with $ (interpolated variables)
   • Single-character strings

4. JSON Export (exporter/json_exporter.rs): Aggregates all extracted strings and exports them to a formatted JSON file using the first word of each string as the key

Dependencies

• serde (1.0): Serialization framework
• serde_json (1.0): JSON support for serde

Learning Notes

As my first Rust project, I learned about:

• Rust's module system and code organization
• File I/O and path handling with std::fs and std::path
• Process spawning with Command to interact with Dart
• Error handling with Result and expect
• String manipulation and ownership
• Working with vectors and iterators
• Using external crates (serde/serde_json)

Future Improvements

• Add command-line arguments support (remove interactive prompt)
• Support custom output file paths
• Add progress bars for better UX
• Handle duplicate strings more intelligently
• Add configuration file support
• Implement parallel file processing
• Add unit tests
• Support for other file formats (CSV, YAML, etc.)

License

See LICENSE.md for details.

Contributing

This is a learning project, but suggestions and improvements are welcome! Feel free to open an issue or submit a pull request.

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Note: This project requires the extract_strings Dart script to be present in the project directory for string extraction to work properly.