PEGTL
parser-demo
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PEGTL | parser-demo | |
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12 | 13 | |
1,859 | 18 | |
1.3% | - | |
7.2 | 0.0 | |
about 1 month ago | over 2 years ago | |
C++ | Lex | |
Boost Software License 1.0 | - |
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PEGTL
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Show HN: Matcheroni, a tiny C++20 header library for building lexers/parsers
Very cool, and I like the name!
I'd be interested in reading about how Matcheroni compares with PEGTL and Lexy.
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Use PEGTL to remove my clunky homemade parser
I found a library I wanted to test: Pegtl
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What are some cool modern libraries you enjoy using?
I like PEGTL
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Are C/C++ developers allowed to import libraries to make coding easier or are they expected to build every functions and methods from scratch (without importing anything like String.h)?
Sure - libraries that are expected to be entirely self-contained. The one that comes to mind is PEGTL, a parser combinator library that is intended to be embedded inside a larger program. Making it import more dependencies would break this philosophy. Similarly, in the Rust world, there are a variety of "no-std" crates that should be able to be imported even if the standard library is not available on the target platform.
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TIL: Visual Studio has quantum state values 🤨
The program in the post was just an example meant to illustrate the problem. Originally, this (new) behavior of MSVC broke my code in the PEGTL, see [this commit](https://github.com/taocpp/PEGTL/commit/e3c8cb499dc3d1d76d23f2d5d79469dcb15550c5) that I needed to apply to fix it.
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We Built a C++ Rendering Engine for the Web
As a professional C++ programmer I feel a lot of the reasons C++ gets this response is because it's simply not "batteries included" like Go or Rust.
C++ is a very powerful, unopinionated language, that gives you a lot of freedom to attack your problem domain the way you best see fit.
If you're writing a networked application, don't use POSIX sockets, go and find a higher level library. If you're parsing complex text formats, don't iterate over buffers with char*'s, go pick up PEGTL[0]. If you're working on graphs, or need to properly index in-memory data, go pick up Boost[1][2]. If you need a GUI, go pick up Qt.
It's extremely common in C++, due to the lack of a universal package management solution, for people to try and "muddle through" and do shit themselves when it's far outside their core competency.
At one of my last employers, the core product was parsing JSON with std::regex, simply because they couldn't be bothered to integrate a JSON library.
[0] https://github.com/taocpp/PEGTL
[1] https://www.boost.org/doc/libs/1_76_0/libs/graph/
[2] https://www.boost.org/doc/libs/1_76_0/libs/multi_index/doc/i...
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Is there anything like sly for C++?
You are looking for Boost.Spirit (https://www.boost.org/doc/libs/1_76_0/libs/spirit/doc/x3/html/index.html) or PEGTL (https://github.com/taocpp/PEGTL)
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Why no more Lex/Yakk/ANTLR/whatever?
I personally prefer to use parsing combinator libraries in C++, where the "grammar" is just part of normal C++ and directly integrate. Examples are Boost.Spirit, pegtl, or (my own) lexy.
- Rust's Most Unrecognized Contributor
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Wondered if anyone is interested in a c++ parser combinators library?
While I'm not quite sure how this might transfer to your approach, with your Haskell-inspired style being quite different from our C++ templates, in the PEGTL our equivalent to your Char, which is called one, is variadic (true to the T in PEGTL a variadic template) and takes a list of possible matches.
parser-demo
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Flex scanner memory leak help
I have a demo project that fixes a lot of the default insanities.
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Advice for a first-time designer of my own original programming language? Presently writing the interpreter!
I have an old demo project that demonstrates most of that for flex/bison, but this is C/C++ oriented so might not be super applicable for you.
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Should there be many hardcoded enums for terminals, non terminals, DFA, productions or a txt/csv file processing for compiler initialization? Is it bad to use global variables in the C code for compiler?
It's just unfortunate that flex and bison have bad defaults due to historical compatibility with lex and yacc. If you're using them I have a demo project that tweaks the defaults toward sanity, though I haven't updated it for recent warnings.
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Doubt on building a tree using LEX and YACC
I made a demo project that ties them together. I'm pretty sure at least one of the fixes was due to header cycle problems, but I haven't touched it for a while. (note also that the demo was fully warning-clean at the time, but there may be new warnings since)
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Simple question on compiler and syntax rules
I made a demo project that avoids several historical annoyances with Flex and Bison - in particular, I made it warnings-clean (though I haven't updated it recently), and I avoid global state.
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Getting Lex + Yacc to recognize keywords
I have a demo project that enables all of the non-default options that you really should be using in all new projects. Note that the demo doesn't demonstrate meaningful grammars, just shows how to arrange the surrounding code and makefile.
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Declaring yylex() and yyerror() in 2022
I have a demo project that twiddles most of the important knobs.
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How to create an AST from bash in c?
Bash is a really complicated language. Redirections and such are simple; they are just tokenization, and any lexer/parser tutorial should get you there (I have a demo project using flex/bison).
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what would you use to write a parser in 2021?
Bison can be configured to avoid every single one of those problems. I use reentrant versions (both with and without push parsing) in my demo project. I admit I didn't bother with named references or cleaning up after errors.
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Practical parsing with Flex and Bison
a lot of the things that people hate about flex/bison is actually just their defaults for compatibility with lex/yacc, which can be changed. I have a demo project that does some of the things: https://github.com/o11c/parser-demo
What are some alternatives?
lexy - C++ parsing DSL
re2c - Lexer generator for C, C++, Go and Rust.
cpp-peglib - A single file C++ header-only PEG (Parsing Expression Grammars) library
spirit - Boost.org spirit module
arcsecond - ✨Zero Dependency Parser Combinator Library for JS Based on Haskell's Parsec
C++ B-tree - Git mirror of the official (mercurial) repository of cpp-btree
oil - Oils is our upgrade path from bash to a better language and runtime. It's also for Python and JavaScript users who avoid shell!
pybind11 - Seamless operability between C++11 and Python
pcomb - parser combinators in PostScript and C
sparsepp - A fast, memory efficient hash map for C++
mal - mal - Make a Lisp