groovy2kotlin

An utility converting Groovy sources to Kotlin language.

Started Nov 2019 by zencd in order to convert a project of mine because I've not found any existing tools (and it's easy to write one by myself). The result of translation isn't 100% Kotlin-correct usually and user is required to review the result, but a significant amount of work can be saved for free.

The policy:

• Don't loose any piece of code;
• Produced code could be partially invalid in syntax/linking;
• But it is acceptable since an operator can easily review such errors;
• Silent behavioural changes are highly undesirable;
• But they are still possible because Groovy can do unpredictable things in runtime;
• Nevertheless do the best to emit valid, readable code;
• Prefer val over var when possible;
• Prefer emitting non-optionals;
• Prefer emitting non-mutables;
• No runtime dependencies.

The current implementation's passes:

• One or multiple modules are parsed into AST by the Groovy itself;
• All types (including dependent libs) gets resolved as strictly as possible;
• AST traversed to resolve types of locals and expressions;
• Inferring optionals;
• Kotlin source code generated finally.

Feel free to submit a bug, ticket and do all the github things.

Requirements

• JDK 1.8 (for running the tool)
• Groovy 2.5.8 (for running the tool + input language level)
• Kotlin 1.3.60 (produced code level)

Others may be supported but was not tested.

Usage

See here

Structure

• Gtk.toKotlinAsSingleString() - converts a Groovy script text into Kotlin
• BulkProcessor - converts a directory recursively
• GroovyToKotlin - the translator engine
• test-data/input-output-tests/ - a set of input/output tests showing how the things gets translated

Example

Todo

See here