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:
“A poet’s object is not to tell what actually happened but what could or would happen either probably or inevitably.... For this reason poetry is something more scientific and serious than history, because poetry tends to give general truths while history gives particular facts.”
—Aristotle (384–323 B.C.)
“Every member of the family of the future will be a producer of some kind and in some degree. The only one who will have the right of exemption will be the mother ...”
—Ruth C. D. Havens, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 4, ch. 13, by Susan B. Anthony and Ida Husted Harper (1902)
“So in accepting the leading of the sentiments, it is not what we believe concerning the immortality of the soul, or the like, but the universal impulse to believe, that is the material circumstance, and is the principal fact in this history of the globe.”
—Ralph Waldo Emerson (1803–1882)