theory

Could someone please explain to me why recursive-descent parsers can't work with a grammar containing left recursion? consider: A ::= A B the equivalent code is boolean A() { if (A()) { return B(); } return false; } see the infinite recursion? For whoever is interested A ::= A B | A C | D | E can be rewritten as: A ::= (D | E) (B | C)* The general form of the transformation is: any one of the non left recursive disjuncts followed by any number of the left recursive disjuncts without the first element. Reforming the action code is a bit trickery but I thing that can be plug-n-chug as well. 来源：

I want to learn the theory behind garbage collection. How do i go about it? The obvious answer is - a compiler textbook... The question is, is it necessary to learn lexical analysis, parsing and other stuff that usually precedes garbage collection in a text? In short, what are the prerequisites to learning about Garbage collection theory? P.S - I do know what is the purpose of parsing, lexical analysis etc. Just not how they are implemented. Sam Harwell Read these papers in order. They are in progressive subject matter/difficulty order (not chronological). List taken directly from Prof.

As I'm always dissatisfied with existing editors, a project I always wanted to start is my own text editor. However doing text editing is serious business. Besides analyzing the source code of existing text editors, is there any book or other resource (like academic work) about this topic? I'm interested especially in something that teaches how to handle memory and how to manage text insertion (if you have a 100 MB file and want to add a char at x position, you can't just memmove the huge text block...). Take a look at Rob Pike's description of his Sam text editor . Be sure to browse past the

I do not have any experience with programming fractals. Of course I've seen the famous Mandelbrot images and such. Can you provide me with simple algorithms for fractals. Programming language doesn't matter really, but I'm most familiar with actionscript, C#, Java. I know that if I google fractals, I get a lot of (complicated) information but I would like to start with a simple algorithm and play with it. Suggestions to improve on the basic algorithm are also welcome, like how to make them in those lovely colors and such. Programming the Mandelbrot is easy. My quick-n-dirty code is below (not

What is an NP-complete problem? Why is it such an important topic in computer science? Sam Hoice NP stands for Non-deterministic Polynomial time. This means that the problem can be solved in Polynomial time using a Non-deterministic Turing machine (like a regular Turing machine but also including a non-deterministic "choice" function). Basically, a solution has to be testable in poly time. If that's the case, and a known NP problem can be solved using the given problem with modified input (an NP problem can be reduced to the given problem) then the problem is NP complete. The main thing to

This is the DFA i have drawn- Is it correct? I am confused because q4 state has 2 different transitions for same input symbol which violates the rule of DFA , but I can't think of any other solution. Your DFA is not correct. your DFA is completely wrong so I don't comment DFA for RE: 0(1 + 0)*0 + 1(1 + 0)*1 Language Description : if string start with 0 it should end with 0 or if string start with 1 it should end with 1 . hence two final states (state-5, state-4). state-4 : accepts 1(1 + 0)*1 state-5 : accepts 0(1 + 0)*0 state-1 : start state. DFA : EDIT : + Operator in Regular Expression (0 +

Let's say that our script is included in a web-page, and a prior script (that already executed) did this: String.prototype.split = function () { return 'U MAD BRO?'; }; So, the split string method has been overwritten. We would like to use this method, so we need to recover it somehow. Of course, we could just define our own implementation of this method and use that instead. However, for the sake of this question, let's just say that we really wanted to recover the browser's implementation of that method. So, the browser has an implementation of the split method (in native code, I believe),