First off, parser theory was always one of my weak points. I mostly work on semantic analyzers. Second, all the C# parsers I’ve ever worked on have been hand-generated recursive descent parsers. One of my former colleagues who does have a strong background in parser theory did build his own parser generator and fed the … Read more
GLR is great if you want a parse tree/forest and don’t mind black boxes. It lets you type in whatever CFG you want at the cost of checking for ambiguities at parse time via exhaustive testing, instead of resolving LR/LALR conflicts statically. Some say that’s a good trade-off. Ira Baxter’s DMS tool or Elkhound, which … Read more
At a high level, the difference between LR(0), LALR(1), and LR(1) is the following: An LALR(1) parser is an “upgraded” version of an LR(0) parser that keeps track of more precise information to disambiguate the grammar. An LR(1) parser is a significantly more powerful parser that keeps track of even more precise information than an … Read more
Examples from wikipedia LL(1) grammar S -> F S -> ( S + F ) F -> a input ( a + a ) parsing steps S -> “(” S “+” F “)” -> ( “F” + F ) -> ( “a” + F ) -> ( a + “a” ) LR(0) grammar (1) E … Read more