属性文法的研究与应用

本文详细讨论了有关属性文法的基本概念,属性文法的两种分类方法,两种分类之间的关系及属性文法的判定问题。本文还讨论了如何用属性文法定义编译程序的遍体制说明及与指称语义的关系。最后讨论了属性文法在编译程序中的应用与属性计算器的程序处理。     

前后义无关属性文法

本文定义了一种新的属性文法类——前后义无关属性文法。提出了一种适合该属性文法类的属性计算方法——局部多遍属性计算法。 文中证明了,在保证属性计算与具体应用无关的前提下,前后义无关属性文法具有最强的表达能力,而局部多遍属性计算法则具有最佳的实现效率。 基于上述理论,作者构造了编译程序生成系统BSX。     

自动生成前端编译程序的一种方法*

本文构造的XYZ/NGAE系统是建立在属性文法基础上的前端编译程序自动生成系统．本文在概述了属性文法及其描述语言之后，简要地介绍该系统的体结构以及为减少空间开销而采用的优化措施．     

自动生成前端编译程序的一种方法

本文构造的ＸＹＺ／ＮＧＡＥ系统是建立在属性文法基础上的前端编译程序自动生成系统。本文在概念了属性文法及其描述语言之后，简要地介绍该系统的体结构以及为减少空间开销而采用的优化措施。     

基于属性文法和语义网络的综合知识表示模型

本文提出了一个属性文法计算模型与语义网络表示模型相结合的综合知识表示模型.根据形式化的语义网络表示模型和属性文法的特点,该模型使用属性文法的符号建立了一些适合于语义网络表示模型的语法和语义规则模式,并且可通过扩充的属性文法的解释器来实现推理.     

利用多重依赖关系的增量属性计值方法

本文利用属性文法中各个属性之间的多重依赖关系,针对某一类属性文法提出了一种新的增量属性计值算法。它不仅空间开销少,而且在时间上可以被证明是最优的。更进一步,我们还将该算法推广到能适用于一般的属性文法。同时保持了时间最优性与空间复杂性的价不变。     

概念形成学习系统中数值属性的表示与聚类

本文在对ＣＯＢＷＥＢ、ＣＬＡＳＳＩＴ等概念聚类系统研究的基础上，提出了一种用数值属性的聚类分划来表示数值属性的方法．这种表示的核心是基于数值属性的取值分布．对于在这种表示下数值属性聚类的相关问题及性质，本文进行了较为详细的讨论．在此基础上，本文给出了一个能统一处理数值属性和符号属性的聚类评价函数．一个基于聚类分划表示方法的概念形成学习系统ＣＦＬＳ（ｃｏｎｃｅｐｔｆｏｒｍａｔｉｏｎｌｅａｒｎｉｎｇｓｙｓｔｅｍ）已在微机上实现，并被应用于地质学领域的三叶虫分类问题．本文对ＣＦＬＳ的设计和实现进行了介绍.     

ConcurrentC语言在分布式系统上的一种高效实现

本文介绍了ＣｏｎｃｕｒｒｅｎｔＣ语言在一分布式系统上的实现。该实现使用了不同于预编译法的编译器的构造方法，同时将Ｃｏｎｃｕｒｒｅｎｔ Ｃ语言中的进程实现为ＵＮＩＸ进程中的用户级线索，是ＣｏｎｃｕｒｒｅｎｔＣ语言在分布式系统上的一种高效实现。     

采用属性文法实现语法制导协议开发环境

近年来协议工程支撑环境的研究得到了迅速的发展，正逐渐趋于工程化，规范化、形式化、属性文法是描述程序设计语言语义特性的工具，本文介绍了采用属性文法及增量式语法分析法构造ＡＳＮ．１语法制导编辑环境的方法，本系统采用面向对象的语言ＪＡＶＡ实现。     

综合知识表示模型MAS的属性文法推理机制

根据文献［２］中提出了的基于属性文法和语义网络的综合知识表示模型ＭＡＳ，本文提出了关于实现该ＭＡＳ推理机制的基本算法，并且通过实例对该算法进行了说明，最后，证明了基于ＭＡＳ模板的属性文法是Ｌ－ＡＧ和ＩＭＡＳ的解是完全的结论。     

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.     

一个基于属性文法的用户界面规格说明

本文描述一种基于属性文法并结合事件模型的用户界面规格说明方法。主要强调如何在直接操作式用户界面中表示多线性对话模型。这种属性文法的规格说明可以用一个嵌套在支持通信、同步、和对话执行的运行时结构中的属性文法解释器来实现。     

Semantic equivalence of covering attribute grammars

This paper investigates some methods for proving the equivalence of different language specifications that are given in terms of attribute grammars. Different specifications of the same language may be used for different purposes, such as language definition, program verification, or language implementation. The concept of syntactic coverings is extended to the semantic part of attribute grammars. Given two attribute grammars, the paper discusses several propositions that give sufficient conditions for one attribute grammar to be semantically covered by the other one. These tools are used for a comparison of two attribute grammars that specify syntax and semantics of mixed-type expressions. This example shows a trade-off between the complexity of syntactic and semantic specifications. Another example discussed is the equivalence of different attribute grammars for the translation of the while-statement, as used in compilers for top-down and bottom-up syntax analysis.This work was in part supported by the National Research Council of Canada.     

A platform for the automatic generation of attribute evaluation hardware systems

Attribute grammars (AG) allow the addition of context-sensitive properties into context free grammars, augmenting their expressional capabilities by using syntactic and semantic notations, making them in this way a really useful tool for a considerable number of applications. AGs have extensively been utilized in applications such as artificial intelligence, structural pattern recognition, compiler construction and even text editing. Obviously, the performance of an attribute evaluation system resides in the efficiency of the syntactic and semantic subsystems. In this paper, a hardware architecture for an attribute evaluation system is presented, which is based on an efficient combinatorial implementation of Earley's parallel parsing algorithm for the syntax part of the attribute grammar. The semantic part is managed by a special purpose module that traverses the parse tree and evaluates the attributes based on a proposed stack-based approach. The entire system is described in Verilog HDL (hardware design language), in a template form that given the specification of an arbitrary attribute grammar, the HDL synthesizable source code of the system is produced on the fly by a proposed automated tool. The generated code has been simulated for validation, synthesized and tested on an Xilinx FPGA (field programmable gate arrays) board for various AGs. Our method increases the performance up to three orders of magnitude compared to previous approaches, depending on the implementation, the size of the grammar and the input string length. This makes it particularly appealing for applications where attribute evaluation is a crucial aspect, like in real-time and embedded systems. Specifically, a natural language interface is presented, based on a question-answering application from the area of airline flights.     

NEGATIVE AND POSITIVE EXPLANATIONS IN EXPERT SYSTEMS

A methodology for management of constraints in VLSI data bases is presented in this paper. The process of management is based on forma! mechanisms of attribute grammar theory. Examples of a modularized knowledge representation of a circuit at interconnection and logic levels based on attribute grammars illustrate the methodology. The ultimate goal and benefit of the proposed methodology is a well-defined development technique for VLSI design tools that will allow the user to generate a transformation system, a knowledge representation, and a system to manipulate this representation, all from a simple specification. In addition, context-dependent specifications at lower levels are automatically generated from the higher-level specifications.     

Simple multi-visit attribute grammars

An attribute grammar is simple multi-visit if each attribute of a nonterminal has a fixed visit-number associated with it such that, during attribute evaluation, the attributes of a node which have visit-number j are computed at the jth visit to the node. An attribute grammar is l-ordered if for each nonterminal a linear order of its attributes exists such that the attributes of a node can always be evaluated in that order (cf. the work of Kastens).An attribute grammar is simple multi-visit if and only if it is l-ordered. Every noncircular attribute grammar can be transformed into an equivalent simple multi-visit attribute grammar which uses the same semantic operations.For a given distribution of visit-numbers over the attributes, it can be decided in polynomial time whether the attributes can be evaluated according to these visit-numbers. The problem whether an attribute grammar is simple multi-visit is NP-complete.