ktsu.Coder

A flexible and extensible .NET library for representing code as Abstract Syntax Trees (AST), serializing to YAML, and generating code in multiple programming languages.

Overview

ktsu.Coder provides a language-agnostic way to represent code structures using Abstract Syntax Trees. The library allows you to:

• Build AST structures programmatically
• Serialize AST to human-readable YAML format
• Generate code in supported programming languages
• Perform round-trip serialization/deserialization

This makes it ideal for code generation tools, transpilers, and any application that needs to work with code structures in a language-independent way.

Features

• Language-Agnostic AST: Represent code structures without being tied to a specific programming language
• YAML Serialization: Human-readable serialization format that's perfect for version control and diffs
• Extensible Language Support: Plugin-based architecture for adding new target languages
• Deep Cloning: Full support for cloning AST structures
• Type Safety: Strongly-typed AST nodes with compile-time safety
• Metadata Support: Attach custom metadata to any AST node

Supported AST Node Types

• FunctionDeclaration: Represents function/method declarations with parameters and body
• Parameter: Function parameters with optional default values
• ReturnStatement: Return statements with optional expressions
• AstLeafNode: Generic leaf nodes for literals (strings, numbers, booleans)

Supported Target Languages

• Python: Full support for function generation with type hints and proper indentation

Installation

Add the NuGet package:

dotnet add package ktsu.Coder

Quick Start

Creating an AST

using ktsu.Coder.Core.Ast;
using ktsu.Coder.Core.Languages;
using ktsu.Coder.Core.Serialization;

// Create a function declaration
var function = new FunctionDeclaration("calculate_sum")
{
    ReturnType = "int"
};

// Add parameters
function.Parameters.Add(new Parameter("a", "int"));
function.Parameters.Add(new Parameter("b", "int"));
function.Parameters.Add(new Parameter("debug", "bool")
{
    IsOptional = true,
    DefaultValue = "False"
});

// Add function body
function.Body.Add(new ReturnStatement(new AstLeafNode<string>("a + b")));

Serializing to YAML

var serializer = new YamlSerializer();
string yamlContent = serializer.Serialize(function);
Console.WriteLine(yamlContent);

Output:

functionDeclaration:
    name: calculate_sum
    returnType: int
    parameters:
        - name: a
          type: int
        - name: b
          type: int
        - name: debug
          type: bool
          isOptional: true
          defaultValue: False
    body:
        - returnStatement:
              expression:
                  Leaf<String>: a + b

Generating Code

var pythonGenerator = new PythonGenerator();
string pythonCode = pythonGenerator.Generate(function);
Console.WriteLine(pythonCode);

Output:

def calculate_sum(a: int, b: int, debug: bool = False) -> int:
    return "a + b"

Round-trip Serialization

// Deserialize from YAML
var deserializer = new YamlDeserializer();
AstNode deserializedAst = deserializer.Deserialize(yamlContent);

// Generate code from deserialized AST
string regeneratedCode = pythonGenerator.Generate(deserializedAst);

Architecture

The library follows SOLID principles with a clean separation of concerns:

• AST Layer: Language-agnostic representation of code structures
• Serialization Layer: YAML serialization/deserialization
• Language Layer: Pluggable code generators for specific languages

Extending with New Languages

To add support for a new language, implement the ILanguageGenerator interface:

public class JavaScriptGenerator : LanguageGeneratorBase
{
    public override string LanguageId => "javascript";
    public override string DisplayName => "JavaScript";
    public override string FileExtension => "js";

    protected override void GenerateInternal(AstNode node, StringBuilder builder, int indentLevel)
    {
        // Implementation for JavaScript code generation
    }
}

Examples

The repository includes two example applications:

• Coder.CLI: Command-line tool demonstrating basic functionality
• Coder.App: Console application with more complex examples

Run them to see the library in action:

dotnet run --project Coder.CLI
dotnet run --project Coder.App

Contributing

Contributions are welcome! Please feel free to submit pull requests or open issues for:

• New language generators
• Additional AST node types
• Bug fixes and improvements
• Documentation enhancements

License

MIT License. Copyright (c) ktsu.dev