RAMBO: Enhancing RAG-based Repository-Level Method Body Completion

TL;DR

RAMBO is a novel retrieval-augmented approach that significantly improves method body completion accuracy in large code repositories by incorporating repository-specific elements and usages, outperforming existing methods.

Contribution

Introduces RAMBO, a RAG-based method that enhances repository-level method body completion by focusing on repository-specific elements and their usages, setting new performance benchmarks.

Findings

Up to 46% improvement in BLEU score

Up to 57% improvement in CodeBLEU

Up to 3X increase in Exact Match rate

Abstract

Code completion is essential in software development, helping developers by predicting code snippets based on context. Among completion tasks, Method Body Completion (MBC) is particularly challenging as it involves generating complete method bodies based on their signatures and context. This task becomes significantly harder in large repositories, where method bodies must integrate repositoryspecific elements such as custom APIs, inter-module dependencies, and project-specific conventions. In this paper, we introduce RAMBO, a novel RAG-based approach for repository-level MBC. Instead of retrieving similar method bodies, RAMBO identifies essential repository-specific elements, such as classes, methods, and variables/fields, and their relevant usages. By incorporating these elements and their relevant usages into the code generation process, RAMBO ensures more accurate and contextually relevant method bodies. Our experimental results with leading code LLMs across 40 Java projects show that RAMBO significantly outperformed the state-of-the-art repository-level MBC approaches, with the improvements of up to 46% in BLEU, 57% in CodeBLEU, 36% in Compilation Rate, and up to 3X in Exact Match. Notably, RAMBO surpassed RepoCoder Oracle method by up to 12% in Exact Match, setting a new benchmark for repository-level MBC.