History
In 1965 Donald Knuth invented the LR(k) parser (Left to right, Rightmost derivation parser) a type of shift-reduce parser, as a generalization of existing precendence parsers. This parser has the potential of recognizing all deterministic context-free languages and can produce both left and right derivations of grammar rules. Knuth proved that it reaches its maximum language recognition power for k=1 and provided a method for transforming LR(k), k > 1 grammars into a LR(1) grammar.
Unfortunately, the LR(1) parser has the practical disadvantage of having enormous memory requirements for its internal grammar representation. The first attempt to solve this problem were the memory optimizations introduced in 1977 by D. Pager but still the LR parser required significantly more memory than other parsing methods. Earlier, in 1969, Frank DeRemer had suggested two simplified version of the LR Parser called LALR and SLR which greatly reduced memory requirements at the cost of less language recognition power. These two parsers (especially LALR) have since been and still are by far the most common implementations of the LR Parser.
Read more about this topic: Canonical LR Parser
Famous quotes containing the word history:
“It takes a great deal of history to produce a little literature.”
—Henry James (1843–1916)
“Three million of such stones would be needed before the work was done. Three million stones of an average weight of 5,000 pounds, every stone cut precisely to fit into its destined place in the great pyramid. From the quarries they pulled the stones across the desert to the banks of the Nile. Never in the history of the world had so great a task been performed. Their faith gave them strength, and their joy gave them song.”
—William Faulkner (1897–1962)
“When we of the so-called better classes are scared as men were never scared in history at material ugliness and hardship; when we put off marriage until our house can be artistic, and quake at the thought of having a child without a bank-account and doomed to manual labor, it is time for thinking men to protest against so unmanly and irreligious a state of opinion.”
—William James (1842–1910)