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:
“... in a history of spiritual rupture, a social compact built on fantasy and collective secrets, poetry becomes more necessary than ever: it keeps the underground aquifers flowing; it is the liquid voice that can wear through stone.”
—Adrienne Rich (b. 1929)
“A man acquainted with history may, in some respect, be said to have lived from the beginning of the world, and to have been making continual additions to his stock of knowledge in every century.”
—David Hume (1711–1776)
“I believe my ardour for invention springs from his loins. I can’t say that the brassiere will ever take as great a place in history as the steamboat, but I did invent it.”
—Caresse Crosby (1892–1970)