flex VS Lark

I am using Flex++, which is Flex for C++ and I am having trouble setting the input file. Flex++ uses the FlexLexer class provided in FlexLexer.h to create the lexer object(https://github.com/westes/flex/blob/master/src/FlexLexer.h). In my main function I have

Further applications of DFA and NFA: lex or flex, yacc or bison, and POE :-)

How about writing a programming language using Flex and Bison? There are lots of good tutorials and examples out there.

Some lexer generators (notably Flex) take input from a file handle by default. While you can always read a file into a string before passing it to the generated lexer, this is not seen as "the best" since you have to read in all the data into memory, which can be a lot.

Ages ago, I loved writing domain-specific toy languages, and almost always used flex to generate lexers and GNU bison to generate the parser. I've begun a new toy project and I don't think those two will cut it this time, so I'm looking for other tools that integrate well with C++.

I don't understand :c don't lexers like Flex work off of regex rules? Isn't this the correct first step to parse it?

I wrote a C compiler using flex [1] and bison [2]. The glue between them is a bit hacky.

At some point ANTLR [3] looked promising, but these days I'd probably write a lexer and recursive descent parser by hand, then generate LLVM IR.

[1] https://github.com/westes/flex

github.com/westes/flex/releases

Un commento in flex, uno storico software, tanto per mostrare che anche i migliori fanno le cose alla buona.

Lark supports, and recommends, writing and storing the grammar in a .lark file. We have syntax highlighting support in all major IDEs, and even in github itself. For example, here is Lark's built-in grammar for Python: https://github.com/lark-parser/lark/blob/master/lark/grammar...

You can also test grammars "live" in our online IDE: https://www.lark-parser.org/ide/

The rationale is that it's more terse and has less visual clutter than a DSL over Python, which makes it easier to read and write.

First, let me introduce myself. My name is Erez. You may know some of the Python libraries I wrote in the past: Lark, Preql and Data-diff.

It's not super maintained but you might enjoy building something with ppci, Pure Python Compiler Infrastructure. It has some front-ends and some back-ends. There's also PeachPy for an assembler. People like using Lark for parsing, I hear.

lark, a parsing library where I am somewhat involved has a really nice solution to this: Rules starting with _ are inlined in a post processing step.

Lark is a good library to assist with this.

If I may ask, did you consider Lark, and if so, why wasn't it fit for your purposes?

A grammar provides the high level constructs you need to define the "shape" of your data, and it largely takes care of the rest. Grammar libraries exist in other language (eg. lark or Parsimonius in Python) and they weren't created just to make XML parsing easier.

I made a solid attempt at an Earley parser framework of my own, but apparently to get the most reliable performance from Earley parsing you need to implement Joop Leo's improvement for right-recursive grammars, which nobody has been able to adequately explain to me. I've read Kegler's open letter to Vaillant, I've tried to read other implementations, I've even tried to beat my head against the original academic paper, but I don't have the background knowledge to make sense of it all.