LALR Parser

In computer science, an LALR parser or Look-Ahead LR parser is a simplified version of a Canonical LR parser. It was invented by Frank DeRemer for his 1969 PhD. dissertation "Practical Translators for LR(k) languages" in order to address the practical difficulties of that time of implementing Canonical LR parsers. The simplification that takes place results in a parser with significantly reduced memory requirements but decreased language recognition power. However, this power is enough for many real computer languages including Java. Usually this happens with the addition of some hand-written code that extends the power of the parser.

LALR parsers are automatically generated by compiler compilers such as Yacc and GNU Bison.