article Free Access Share on Efficient Computation of LALR(1) Look-Ahead Sets Authors: Frank DeRemer Computer and Information Sciences, University of California, Santa Cruz, CA Computer and Information Sciences, University of California, Santa Cruz, CAView Profile , Thomas Pennello Computer and Information Sciences, University of California, Santa Cruz, CA Computer and Information Sciences, University of California, Santa Cruz, CAView Profile Authors Info & Claims ACM Transactions on Programming Languages and SystemsVolume 4Issue 4Oct. 1982 pp 615–649https://doi.org/10.1145/69622.357187Published:01 October 1982Publication History 83citation2,258DownloadsMetricsTotal Citations83Total Downloads2,258Last 12 Months471Last 6 weeks49 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

A move algorithm, and some of its formal properties, is presented for use in a practical syntactic error scheme for LR parsers. The algorithm finds fragment (comparable to a valid prefix) just to the right of a point of error detection. For expositional purposes the algorithm is presented as parsing arbitrarily far beyond the point of error detection in a parallel mode, as long as all parses agree on the read or reduce action to be taken at each parse step. In practice the forward move is achieved serially by adding recovery states to the LR machine. Based on the formal properties of the forward move we propose an error algorithm that uses the accumulated right context. The performance of the algorithm is illustrated in a specific case and discussed in general.

We distinguish the activity of writing large programs from that of writing small ones. By large programs we mean systems consisting of many small programs (modules), usually written by different people.