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AST Types Library

The AST Types library provides common interfaces and types used across different language implementations in the Amplication platform. It serves as the foundation for language-specific AST libraries like Java AST and C# AST.

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Key Features

• Base interfaces for AST nodes
• Common type definitions
• Shared utilities and helpers
• Type system abstractions

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Scope and Purpose

The AST Types library is not intended to cover all language functionality. It provides the core interfaces and types needed to create foundation and boilerplate code with Amplication plugins. The library focuses on essential abstractions that can be implemented by language-specific AST libraries.

The IAstNode interface is a fundamental part of this design, allowing code to be represented as structured objects while also supporting generic code blocks when needed for more specialized implementations.

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Installation

npm install @amplication/ast-types

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Usage

AST Types is typically used as a dependency by language-specific AST libraries. However, you can also use it directly in your projects if you need to access common AST interfaces and types.

import { IAstNode, IWriter } from "@amplication/ast-types";

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The IAstNode Interface

The IAstNode interface is a cornerstone of Amplication’s code generation system. It defines the common contract that all AST nodes must implement, regardless of the target language.

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Key Aspects of IAstNode

• Acts as the base interface for all language-specific AST nodes
• Enables language-agnostic code transformations
• Facilitates integration between different AST implementations
• Allows plugins to use a common type when manipulating code

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Using IAstNode in Plugins

In Amplication plugins, you’ll work extensively with the IAstNode interface:

import { IAstNode } from "@amplication/ast-types";
import { IFile } from "@amplication/code-gen-types";

// Create language-specific AST nodes that implement IAstNode
// ...

// Create a file referencing the AST node
const file: IFile<IAstNode> = {
  path: "path/to/file",
  code: astNode, // Your AST node implementing IAstNode
};

// Add the file to the context
context.files.set(file);

When developing plugins, you’ll typically follow this pattern:

1. Import IAstNode from “@amplication/ast-types”
2. Create language-specific AST nodes using a library like @amplication/java-ast or @amplication/csharp-ast
3. Create an IFile<IAstNode> that references your AST node
4. Add the file to the generation context using context.files.set()

This approach ensures your generated code integrates seamlessly with Amplication’s code generation pipeline.

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Documentation