CAREER: Better Systems With Extensible C

随着系统越来越多地集成到全球计算环境中，一个关键的挑战是如何管理由此产生的软件复杂性。元编程可以帮助应对这一挑战。为了调和语言/编译器工作与系统实践之间的差距，这项工作将探索以下研究问题：如何安全地扩展不安全的低级编程语言C，包括使用新的定义构造(如对象)和新类型(如类)；如何将语言和编译器扩展分解为最大限度地重用；以及管理和组合产生的细粒度扩展需要哪些支持。该项目将为C开发和构建一个宏系统，称为XTC，即可扩展C，但与C预处理器不同，XTC宏是作为程序抽象语法树(AST)上的转换指定和实现的，并保持宏的安全性。该项目还将探索支持复杂AST转换的树查询语言、支持引入新类型的可扩展类型系统等方法，并将研究如何禁用指针等选择语言功能，以及如何表示特定于域的编译器优化。使用XTC构建的软件将更加可靠和安全，随着企业和政府越来越依赖IT谋生，这一点至关重要。此外，通过开放C语言，拟议的工作使语言和编译器研究人员能够产生更大的影响，使教育工作者能够更容易地探索教授计算机科学的新方法。为了强调最后一点，该项目将在所有适当的课程中使用XTC，包括研究生级别的编译器，并将开发一门新的面向对象编程的本科课程和相应的教科书，其中不仅探索相关概念，而且探索其基本实现(作为XTC宏)。

As systems are increasingly integrated within a global computing environment, a crucial challenge is how to manage the resulting software complexity. Metaprogramming can help meet this challenge. To reconcile the gap between language/compiler efforts and systems practice, this work will explore the following research questions: how can an unsafe and low-level programming language, C, be safely extended, including with new definitional constructs, such as objects, and new kinds of types, such as classes and how can language and compiler extensions be factored to maximize reuse, and what support is necessary for managing and composing the resulting fine-grained extensions . The project will develop and build a macro system for C, called xtc for eXTensible C, but unlike the C preprocessor, xtc macros are specified and implemented as transformations on a program's abstract syntax tree (AST) and preserve macro hygiene . The project will also explore methods such as a tree querying language that supports complex AST transformations, an extensible type system, which supports the introduction of new kinds of types, and will investigate how to disable select language features, such as pointers, and how to express domain-specific compiler optimizations. Software built with xtc will be more reliable and secure, which is of critical importance as business and government increasingly depend on IT for their livelihood. Furthermore, by opening up C, the proposed work enables language and compiler researchers to have more impact and educators to more easily explore new approaches to teaching computer science. To emphasize the last point, the project will leverage xtc in all appropriate courses, including the graduate-level compilers and will also develop a new undergraduate courseon object-oriented programming and the corresponding textbook, which explore not only the relevant concepts but also their underlying implementation (as xtc macros).