Kotlin Symbol Processing

Introducció

How Annotation Processors Work

Annotation processing is a powerful technique used in software development to generate code, validate code elements, and reduce boilerplate code. In Kotlin, annotation processors play a vital role in analyzing annotated elements in the source code and generating new source files or classes at compile time. This process helps automate repetitive tasks, streamlining the development process by minimizing manual coding.

Basic Concepts of Annotation Processing in Kotlin

Annotation processing involves using annotations defined in your code to trigger specific actions. Annotations are markers attached to code elements like classes, methods, and fields. When the Kotlin compiler processes these annotations, it invokes an annotation processor to perform predefined tasks such as code generation, validation, and analysis.

Key Components of a KSP Processor

Understanding the core components of a KSP processor is crucial for writing effective annotation processors. KSP introduces a set of APIs that enable developers to work directly with Kotlin’s syntax and semantics, providing greater control over how annotations are processed and how code is generated.

• Symbols: In KSP, symbols represent various elements of the Kotlin source code, such as classes, functions, properties, and annotations. A symbol is an abstraction of a code element, allowing the processor to inspect and interact with the code’s structure without directly modifying the source code.

• **Resolvers^^: A resolver in KSP is responsible for providing information about symbols and their relationships. It acts as an intermediary between the processor and the codebase, enabling the annotation processor to query for specific symbols, resolve types, and gather information necessary for code generation.

• Visitors: Visitors in KSP are used to traverse symbols in a structured way. They allow the annotation processor to visit each symbol, perform actions based on specific conditions, and generate code accordingly. Visitors provide a flexible mechanism for analyzing and transforming the source code during the annotation processing phase.

Writing Your First Symbol Processor Class

To create an annotation processor with KSP, you need to implement a symbol processor class that extends SymbolProcessor. This class defines the logic for processing annotations, resolving symbols, and generating new code. Below is a basic example of a symbol processor that processes a custom annotation and generates code based on it:

With the addition of AutoService, you no longer need to explicitly register your processor. The service loader will discover and register it for you.

TODO

• API
• Code generation with KSP or how to teach Kotlin to write code
• So, how do I write a Kotlin Symbol Processor (KSP)?
• https://github.com/Morfly/ksp-sample
• How To Build Your First Kotlin Annotation Processor With KSP
• Unveiling the Magic of Kotlin Symbol Processing (KSP) for Beginners