That's much more important than knowing the particular syntax for any language.

Finite State Machines, adding a lexer that follows them automatically,

Look at these two intersecting lines.

These grammars that we've been introducing describe something new context free languages.

It turns out that interprocedural data flow analysis is the same problem as, in a theoretical sense, context free language reachability, which is the same problem as could I generate a string in a context free grammar.

It relates grammars to parsing, which is one of the concepts in this class.

You might think, Boy, is there a context expensive grammar out there? What's the opposite of free?

All right. Now that you've gone to the hard work of defining all of those procedures,

This concept is not particularly tricky, but it does require a context free grammar.

like HTML or SQL, the language of database queries.

They specify sets of strings, and they can be implemented under the hood with finite state machines.

You might use the Let's Begin section to set context for interpreting the video or to define a learning objective for your students.

unparsed entity reference in wrong context

Well, because, sentences are more interesting.

That line above it is the context.

Here I've written down four claims.

We're going to design together formal grammars that exactly capture HTML and JavaScript or at least interesting subsets of them.

And that gives us the entire expression is 0.229.

It depends on the context.

This branch of the family is all about representation.

I am just gonna pause for a moment to let you think about that.

The set of languages that can be described by re write rules or grammers like this are called context free languages.

This is called being lazy, and it's a phenomenal virtue when you're writing programs.

In fact, just as we saw that regular languages and regular expressions weren't powerful enough to do everything we needed they couldn't handle balanced parentheses, so we couldn't use them for parsing it's going to turn out that context free languages and context free grammars will only take us so far, and we're going to use additional techniques like interpretation or keeping track of local variables in order to find other things out.

We need to know where we came from in order to know where we're going.

So in lecture, we spent a lot of time learning about context free grammars and languages.

But that's an example of an application that also uses this sort of linguistic analysis perhaps a little less related to context free grammars but still in the same vein.

All of that is going to matter for figuring out the true interpretations of programs.

These are just the ESPN SportsCenter version of the game.

We much prefer grammatical sentences.

All right. So, it's another one of these puzzle like questions.

I can do that, just wait. (ding!)

I'm afraid of losing this place.

To do this, we use 2 key techniques lexical analysis, which broke the string down into a stream of tokens, and syntactic analysis or parsing, which takes a string of tokens and checks to see if they adhere to, if they conform to a context free grammar.

Y has the value of 2.

But if right above it I've written X 0, then we'd get a different answer.

It handles LL. It handles LR. It handles LALR.

I have to understand the meaning of this sentence.

I need to understand the meaning of this sentence.

These days I think your time, the human's time, is more important than the computers.

If you want to go try Oink out later on, it accepts this same sort of context free grammar format that we're used to.

We can combine context free grammars and, potentially, memoization together to get parsing, which is the process of determining if a list of tokens is in the language of a context free grammar.

That's an excellent question.

Reading literary criticism is very helpful to understanding literature.

He couldn't understand the sentence.