Jean Huens

The ELL(1) parser generator and the error recovery mechanism

SummaryA syntactic error recovery technique is presented that is simple and at the same time very powerful. It has the main property that it is phrase marker oriented, where phrase markers are considered symbols delimiting language constructions, e.g., begin and end for blocks, (and) for expressions, and [and] for indices. The basic idea of this error recovery technique originates from P. Branquart and has been worked out in the Algol 68 compiler project, see [8] and [9]. Here, we are especially concerned with the generation aspects of error recovery. In particular, it is investigated how error recovery can be mechanised in an ELL(1) and LALR(1) syntax directed translation scheme and which conditions the syntax must satisfy. Both the ELL(1) and LALR(1) generators are implemented and are part of the system LILA: a Language Implementation LAboratory [28, 29, 30]. Only the ELL(1) generator is described here.

SLS/1: A Translator Writing System

The translator writing system in its didactic version is an ideal tool upon which a course on compiler construction can be based. The student can treat non-trivial examples in a flexible and modular way within a reasonable limit of time [16]. This version is implemented in PL/I on the IBM 370 model 158 under OS.