标题： 面向解析表达式的自动错误恢复 显示英文标题

标题： Towards Automatic Error Recovery in Parsing Expression

摘要： 错误恢复是解析器的一个关键功能，应嵌入集成开发环境（IDEs），这些环境必须即使对于语法无效的程序也要构建抽象语法树（ASTs），以提供诸如自动重构和代码补全等功能。解析表达式文法（PEGs）是一种形式化方法，它使用一种限制性的回溯形式自然地描述递归的自顶向下解析器。标记失败是对PEGs的保守扩展，它为PEG解析器添加了一个错误报告机制，这些标签也可以与恢复表达式相关联，从而也成为一种错误恢复机制。这些表达式可以利用PEGs的全部表达能力来从语法错误中恢复。手动为大型语法添加标签和恢复表达式可能很困难。在本工作中，我们提出了一种算法，该算法可以自动为PEG添加标签，并构建其对应的恢复表达式。我们通过将错误恢复添加到Titan编程语言的解析器来评估该算法。结果表明，通过少量的人工干预，我们的算法可以用于生成错误恢复解析器，其中大部分替代项是不相交的。 显示英文摘要

摘要： Error recovery is an essential feature for a parser that should be plugged in Integrated Development Environments (IDEs), which must build Abstract Syntax Trees (ASTs) even for syntactically invalid programs in order to offer features such as automated refactoring and code completion. Parsing Expressions Grammars (PEGs) are a formalism that naturally describes recursive top-down parsers using a restricted form of backtracking. Labeled failures are a conservative extension of PEGs that adds an error reporting mechanism for PEG parsers, and these labels can also be associated with recovery expressions to also be an error recovery mechanism. These expressions can use the full expressivity of PEGs to recover from syntactic errors. Manually annotating a large grammar with labels and recovery expressions can be difficult. In this work, we present an algorithm that automatically annotates a PEG with labels, and builds their corresponding recovery expressions. We evaluate this algorithm by adding error recovery to the parser of the Titan programming language. The results shown that with a small amount of manual intervention our algorithm can be used to produce error recovering parsers for PEGs where most of the alternatives are disjoint.