Code summarization aims to generate brief natural language descriptions for source codes. The state-of-the-art approaches follow a transformer-based encoder-decoder architecture. As the source code is highly structured and follows strict grammars, its Abstract Syntax Tree (AST) is widely used for encoding structural information. However, ASTs are much longer than the corresponding source code. Existing approaches ignore the size constraint and simply feed the whole linearized AST into the encoders. We argue that such a simple process makes it difficult to extract the truly useful dependency relations from the overlong input sequence. It also incurs significant computational overhead since each node needs to apply self-attention to all other nodes in the AST. To encode the AST more effectively and efficiently, we propose AST-Trans in this paper which exploits two types of node relationships in the AST: ancestor-descendant and sibling relationships. It applies the tree-structured attention to dynamically allocate weights for relevant nodes and exclude irrelevant nodes based on these two relationships. We further propose an efficient implementation to support fast parallel computation for tree-structure attention. On the two code summarization datasets, experimental results show that AST-Trans significantly outperforms the state-of-the-arts while being times more efficient than standard transformers1.

As User Reviews (URs) of mobile Apps are proven to provide valuable feedback for maintaining and evolving applications, how to make full use of URs more efficiently in the release cycle of mobile Apps has become a widely concerned and researched topic in the Software Engineering (SE) community. In order to speed up the completion of coding work related to URs to shorten the release cycle as much as possible, the task of User Review-based code localization is proposed and studied in depth. However, due to the lack of large-scale ground truth dataset (i.e., truly related pairs), existing methods are all unsupervised learning-based. In order to light up supervised learning approaches, which are driven by large labeled datasets, for Review2Code, and to compare their performances with unsupervised learning-based methods, we first introduce a large-scale human-labeled ground truth dataset, including the annotation process and statistical analysis. Then, a benchmark consisting of two SOTA unsupervised learning-based and four supervised learning-based Review2Code methods is constructed based on this dataset. We believe that this paper can provide a basis for in-depth exploration of the supervised learning-based Review2Code solutions.

Code summarization aims to generate brief natural language descriptions for source code. As source code is highly structured and follows strict programming language grammars, its Abstract Syntax Tree (AST) is often leveraged to inform the encoder about the structural information. However, ASTs are usually much longer than the source code. Current approaches ignore the size limit and simply feed the whole linearized AST into the encoder. To address this problem, we propose AST-Transformer to efficiently encode tree-structured ASTs. Experiments show that AST-Transformer outperforms the state-of-arts by a substantial margin while being able to reduce 90 ~ 95% of the computational complexity in the encoding process.