HAREL

Rust implementation of Harel Statecharts parser.

What is Harel • Features • How To Use • Documentation • License

📌 Table of Contents

🤔 What is Harel

harel is a Rust library that provides a parser for Harel Statecharts, a powerful extension of finite state machines that supports hierarchical (nested) states, concurrent states, and complex state transitions. Harel Statecharts were introduced by David Harel in 1987 as a visual formalism for describing the behavior of complex reactive systems.

Use Cases

• Embedded Systems: Model complex device behaviors and state machines
• Game Development: Implement AI behaviors and game state management
• Protocol Implementation: Design and validate communication protocols
• Workflow Systems: Model business processes and workflow logic
• Reactive Systems: Handle event-driven system behaviors

Architecture

The library provides:

1. Parser: Converts textual statechart descriptions into structured data
2. AST Representation: Abstract syntax tree for statechart elements
3. Validation: Ensures statechart correctness and well-formedness
4. Traversal: Navigate and analyze statechart structures

📷 Features

Core Parsing

• Hierarchical States: Support for nested state structures
• Concurrent States: Parallel state execution modeling
• Transitions: State-to-state transitions with guards and actions
• Events: Event-driven state machine behavior

Statechart Elements

• States: Simple states, composite states, and concurrent regions
• Transitions: Internal and external transitions with conditions
• Guards: Boolean conditions for transition enablement
• Actions: Entry, exit, and transition actions

Validation & Analysis

• Syntax Validation: Ensures proper statechart syntax
• Semantic Checks: Validates statechart semantics and consistency
• Structure Analysis: Analyzes state hierarchy and relationships

🚙 How to Use

Installation

Add to your Cargo.toml:

[dependencies]
harel = "0.1"

Or install with cargo:

cargo add harel

Example

use harel::*;

// Parse a simple statechart
let statechart_text = r#"
statechart TrafficLight {
    state Red {
        on timer -> Green
    }
    state Green {
        on timer -> Yellow
    }
    state Yellow {
        on timer -> Red
    }
}
"#;

// Parse the statechart
let parser = HarelParser::new();
let statechart = parser.parse(statechart_text)?;

// Analyze the parsed statechart
println!("Statechart name: {}", statechart.name());
println!("Number of states: {}", statechart.states().len());

📚 Documentation

Comprehensive documentation is available at docs.rs/harel, including:

• API reference for all public types and functions
• Tutorial on parsing statecharts
• Examples of different statechart patterns
• Best practices for statechart design

🖊 Author

CryptoPatrick

Keybase Verification:
https://keybase.io/cryptopatrick/sigs/8epNh5h2FtIX1UNNmf8YQ-k33M8J-Md4LnAN

🐣 Support

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🗄 License

This project is licensed under MIT. See LICENSE for details.