Generation of Distributed Programming Environments

This technical report consists of three related papers in the area of distributed programming environments. Incremental Attribute Evaluation in Distributed Language-Based Environments presents algorithms that extend existing technology for the generation of single-user language-based editors from attribute grammars to the cases of multiple-user concurrent and distributed environments. Multi-User Distributed Language-Based Environment, an extended abstract, provides additional information on how to apply the algorithms. Reliability in Distributed Programming Environments presents additional algorithms that extend our results to unreliable networks

Incremental Evaluation of Reference Attribute Grammars using Dynamic Dependency Tracking

Reference attribute grammars (RAGs) have proven practical for gen- erating production-quality compilers from declarative descriptions, as demonstrated by the JastAdd system. Recent results indicate their applicability also to generating semantic services in interactive editors. For use in editors, it is necessary to update the attribution after edit operations. Earlier algorithms based on statically scheduled incremental attribute evaluation are, however, not applicable to RAGs, as they do not account for the dynamic dependencies that reference attributes give rise to. In this report, we introduce a notion of consistency for RAG attributions, along with an algorithm for maintaining consistency after edit operations, based on dynamic dependency tracking. That is, we introduce a means to do incremental evaluation of RAGs using dynamic dependency tracking

Incremental Dynamic Semantics for Language-Based Programming Environments

Attribute grammars are a formal notation for expressing the static semantics of programming languages — those properties that can be derived from inspection of the program text. Attribute grammars have become popular as a mechanism for generating language-based programming environments that incrementally perform symbol resolution, type checking, code generation and derivation of other static semantic properties as the program is modified. However, attribute grammars are not suitable for expressing dynamic semantics — those properties that reflect the history of program execution and/or user interactions with the programming environment. This article presents action equations, an extension of attribute grammars suitable for specifying the static and the dynamic semantics of programming languages. It describes how action equations can be used to generate language-based programming environments that incrementally derive static and dynamic properties as the user modifies and debugs the program

Contributions to the Construction of Extensible Semantic Editors

This dissertation addresses the need for easier construction and extension of language tools. Specifically, the construction and extension of so-called semantic editors is considered, that is, editors providing semantic services for code comprehension and manipulation. Editors like these are typically found in state-of-the-art development environments, where they have been developed by hand. The list of programming languages available today is extensive and, with the lively creation of new programming languages and the evolution of old languages, it keeps growing. Many of these languages would benefit from proper tool support. Unfortunately, the development of a semantic editor can be a time-consuming and error-prone endeavor, and too large an effort for most language communities. Given the complex nature of programming, and the huge benefits of good tool support, this lack of tools is problematic. In this dissertation, an attempt is made at narrowing the gap between generative solutions and how state-of-the-art editors are constructed today. A generative alternative for construction of textual semantic editors is explored with focus on how to specify extensible semantic editor services. Specifically, this dissertation shows how semantic services can be specified using a semantic formalism called refer- ence attribute grammars (RAGs), and how these services can be made responsive enough for editing, and be provided also when the text in an editor is erroneous. Results presented in this dissertation have been found useful, both in industry and in academia, suggesting that the explored approach may help to reduce the effort of editor construction

Incremental Evaluation of Ordered Attribute Grammars for Asynchronous Subtree Replacements

Incremental algorithms for evaluating attribute grammars (AGs) have been extensively studied in recent years, primarily because of their application in language-based environments. Ordered attribute grammars are a subclass of AGs for which efficient evaluators can be constructed. Previous incremental algorithms for ordered attribute grammars only allowed one modification to the program at a time, requiring attribute evaluation due to one change to quiesce before another one due to a second change can start. This article presents new incremental evaluation algorithms for ordered attribute grammars that can handle asynchronous program modifications in an optimal manner. Support for asynchronous changes is necessary in environments for multiple users, where different programmers may be making changes to different parts of the program simultaneously. The key to the optimality of the algorithm is an ordering of the attribute evaluations so that an attribute affected by more than one change will only be evaluated once if the changes happen concurrently

AN ENVIRONMENT FOR ENGINEERING EXTENDED AFFIX GRAMMAR ENVIRONMENTS

Existing formalisms for the specification of programming environments are complex and strongly biased by the problems of environment generation. It has been investigated whether a simple two-level grammar, describing a programming language, can be used without further modification for the generation of an environment for that language. We believe that there is enough information in most language definitions - albeit implicitly - to generate most of the tools used in syntax-directed editors. This paper proposes some simple and elegant improvements in the use of place- holders and templates, and in the unparsing mechanism. Although the improvements are implemented in a completely newly designed prototype they can also be applied to existing syntax-directed editors to improve their workability

Drawing OWL 2 ontologies with Eddy the editor

In this paper we introduce Eddy, a new open-source tool for the graphical editing of OWL~2 ontologies. Eddy is specifically designed for creating ontologies in Graphol, a completely visual ontology language that is equivalent to OWL~2. Thus, in Eddy ontologies are easily drawn as diagrams, rather than written as sets of formulas, as commonly happens in popular ontology design and engineering environments. This makes Eddy particularly suited for usage by people who are more familiar with diagramatic languages for conceptual modeling rather than with typical ontology formalisms, as is often required in non-academic and industrial contexts. Eddy provides intuitive functionalities for specifying Graphol diagrams, guarantees their syntactic correctness, and allows for exporting them in standard OWL 2 syntax. A user evaluation study we conducted shows that Eddy is perceived as an easy and intuitive tool for ontology specification

A Transition-Based Directed Acyclic Graph Parser for UCCA

We present the first parser for UCCA, a cross-linguistically applicable framework for semantic representation, which builds on extensive typological work and supports rapid annotation. UCCA poses a challenge for existing parsing techniques, as it exhibits reentrancy (resulting in DAG structures), discontinuous structures and non-terminal nodes corresponding to complex semantic units. To our knowledge, the conjunction of these formal properties is not supported by any existing parser. Our transition-based parser, which uses a novel transition set and features based on bidirectional LSTMs, has value not just for UCCA parsing: its ability to handle more general graph structures can inform the development of parsers for other semantic DAG structures, and in languages that frequently use discontinuous structures.Comment: 16 pages; Accepted as long paper at ACL201

Analyzing impacts of change operations in evolving ontologies

Ontologies evolve over time to adapt to the dynamically changing knowledge in a domain. The evolution includes addition of new entities and modification or deletion of obsolete entities. These changes could have impacts on the remaining entities and dependent systems of the ontology. In this paper, we address the impacts of changes prior to their permanent implementation. To this end, we identify possible structural and semantic impacts and propose a bottom-up change impact analysis method which contains two phases. The first phase focuses on analyzing impacts of atomic change operations and the second phase focuses on analyzing impacts of composite changes which include impact cancellation, balancing and transformation due to implementation of two or more atomic changes. This method provides crucial information on the impacts and could be used for selecting evolution strategies and conducting what-if analysis before evolving the ontologies