Grammar Engineering Support for Precedence Rule Recovery and Compatibility Checking

A wide range of parser generators are used to generate parsers for programming languages. The grammar formalisms that come with parser generators provide different approaches for defining operator precedence. Some generators (e.g. YACC) support precedence declarations, others require the grammar to be unambiguous, thus encoding the precedence rules. Even if the grammar formalism provides precedence rules, a particular grammar might not use it. The result is grammar variants implementing the same language. For the C language, the GNU Compiler uses YACC with precedence rules, the C-Transformers uses SDF without priorities, while the SDF library does use priorities. For PHP, Zend uses YACC with precedence rules, whereas PHP-front uses SDF with priority and associativity declarations.The variance between grammars raises the question if the precedence rules of one grammar are compatible with those of another. This is usually not obvious, since some languages have complex precedence rules. Also, for some parser generators the semantics of precedence rules is defined operationally, which makes it hard to reason about their effect on the defined language. We present a method and tool for comparing the precedence rules of different grammars and parser generators. Although it is undecidable whether two grammars define the same language, this tool provides support for comparing and recovering precedence rules, which is especially useful for reliable migration of a grammar from one grammar formalism to another. We evaluate our method by the application to non-trivial mainstream programming languages, such as PHP and C.     

ArF浸没式光刻在55nm逻辑器件制造中的优势

通过比较干法和浸没光刻技术在超越焦深(DOF)提高方面的一些主要特点,举例说明了采用浸没式光刻技术的许多优势。浸没式光刻技术同干法光刻技术比较起来改善了关键尺寸一致性(CDU)又避开了必需而强硬的分辨率提高技术(RET)。因此利用浸没式光刻技术能够有效地减少光学邻近校正(OPC)的麻烦。就成像技术而言,我们研究了光刻技术对畸变的敏感性和浸没式光刻技术光源光谱带宽对强光相对曝光量对数E95波动性能的优势。去年已经见证了被认为对浸没光刻技术在批量生产中主要难题的套刻精度、缺陷控制和焦平面精度方面有效的改进。如今55nm逻辑器件的生产制造技术要求的挑战已经得到了满足。浸没光刻技术的成就包括抗蚀剂圆片内10nm套刻精度和圆片间20nm的套刻精度,每一圆片上低于10个缺陷以及在整个圆片上40nm以内的焦平面误差。我们形成了一个顶涂层抗蚀剂工艺。总之,浸没光刻技术是55nm节点逻辑器件最有希望的制造生产技术,它可提供与干法ArF光刻技术在CDU控制、套刻性能和焦平面精度方面等效的解决方案,缺陷程度没有增加。NEC电子公司今年采用浸没光刻技术完成了55nm逻辑器件"UX7LS"的开发和试生产并形成这种UX7LS的批量生产光刻技术。     

A pure embedding of attribute grammars

Attribute grammars are a powerful specification paradigm for many language processing tasks, particularly semantic analysis of programming languages. Recent attribute grammar systems use dynamic scheduling algorithms to evaluate attributes on demand. In this paper, we show how to remove the need for a generator, by embedding a dynamic approach in a modern, object-oriented and functional programming language. The result is a small, lightweight attribute grammar library that is part of our larger Kiama language processing library. Kiama’s attribute grammar library supports a range of advanced features including cached, uncached, higher order, parameterised and circular attributes. Forwarding is available to modularise higher order attributes and decorators abstract away from the details of attribute value propagation. Kiama also implements new techniques for dynamic extension and variation of attribute equations. We use the Scala programming language because of its support for domain-specific notations and emphasis on scalability. Unlike generators with specialised notation, Kiama attribute grammars use standard Scala notations such as pattern-matching functions for equations, traits and mixins for composition and implicit parameters for forwarding. A benchmarking exercise shows that our approach is practical for realistic language processing.     

Static consistency checking of web applications with WebDSL

Modern web application development frameworks provide web application developers with high-level abstractions to improve their productivity. However, their support for static verification of applications is limited. Inconsistencies in an application are often not detected statically, but appear as errors at run-time. The reports about these errors are often obscure and hard to trace back to the source of the inconsistency. A major part of this inadequate consistency checking can be traced back to the lack of linguistic integration of these frameworks. Parts of an application are defined with separate domain-specific languages, which are not checked for consistency with the rest of the application. Examples include regular expressions, query languages and XML-based languages for definition of user interfaces. We give an overview and analysis of typical problems arising in development with frameworks for web application development, with Ruby on Rails, Lift and Seam as representatives.To remedy these problems, in this paper, we argue that domain-specific languages should be designed from the ground up with static verification and cross-aspect consistency checking in mind, providing linguistic integration of domain-specific sub-languages. We show how this approach is applied in the design of WebDSL, a domain-specific language for web applications, by examining how its compiler detects inconsistencies not caught by web frameworks, providing accurate and clear error messages. Furthermore, we show how this consistency analysis can be expressed with a declarative rule-based approach using the Stratego transformation language.     

Integration of data validation and user interface concerns in a DSL for web applications

Data validation rules constitute the constraints that data input and processing must adhere to in addition to the structural constraints imposed by a data model. Web modeling tools do not make all types of data validation explicit in their models, hampering full code generation and model expressivity. Web application frameworks do not offer a consistent interface for data validation. In this paper, we present a solution for the integration of declarative data validation rules with user interface models in the domain of web applications, unifying syntax, mechanisms for error handling, and semantics of validation checks, and covering value well-formedness, data invariants, input assertions, and action assertions. We have implemented the approach in WebDSL, a domain-specific language for the definition of web applications.     

XT: A bundle of program transformation tools system description

XT bundles existing and newly developed program transformation libraries and tools into an open framework that supports component-based development of program transformations. We discuss the roles of XT's constituents in the development process of program transformation tools, as well as some experiences with building program transformation systems with XT.