parson
PEGTL
parson | PEGTL | |
---|---|---|
1 | 12 | |
57 | 1,874 | |
- | 1.0% | |
2.0 | 7.2 | |
10 months ago | 2 days ago | |
Python | C++ | |
- | Boost Software License 1.0 |
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parson
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A complete compiler and VM in 150 lines of code
That's powerful enough to conveniently write, for example, a numerical root finding program for an arbitrary arithmetic expression.
But I think that within a complexity budget of 150 lines of code you can maybe be even more ambitious than that.
The example compiler in https://github.com/darius/parson/blob/master/eg_calc_compile... is a bit more stripped down than that, but in its 32 lines of code it compiles arithmetic assignment statements to a three-address RISC-like code (though using an unbounded number of registers). https://github.com/darius/parson/blob/master/eg_calc_to_rpn.... is a 16-line version that compiles the same language to a stack machine like your tutorial example.
In 66 lines of code in https://github.com/kragen/peg-bootstrap/blob/master/peg.md I wrote an example compiler which compiles a PEG grammar into a JavaScript parser for that grammar. Admittedly those 66 lines do not include an implementation of JavaScript to run the code on. It compiles the language it's written in.
In 132 lines of code in https://github.com/kragen/stoneknifeforth/blob/master/tinybo... I wrote an example compiler which compiles a crippled Forth dialect into i386 machine code, including an ELF header so you can run the result. It also compiles the language it's written in. It also doesn't include an i386 emulator to run it on.
In 83 lines of code in http://canonical.org/~kragen/sw/dev3/neelcompiler.ml Neel Krishnaswami wrote a compiler from the untyped λ-calculus to a simple assembly language for a register machine. It also doesn't include an implementation of the assembly language.
In 18 lines of code in http://canonical.org/~kragen/sw/dev3/meta5ix.m5, a simplification of META-II, I wrote a compiler from grammar descriptions to an assembly code for a parsing-oriented virtual machine. It compiles the language it's written in. A Python interpreter for the machine is in http://canonical.org/~kragen/sw/dev3/meta5ixrun.py (109 lines of code) and a precompiled version of the compiler-compiler for bootstrapping is in http://canonical.org/~kragen/sw/dev3/meta5ix.generated.m5asm.
A slightly incompatible variant of Meta5ix which instead compiles itself to C is in http://canonical.org/~kragen/sw/dev3/meta5ix2c.m5 (133 lines of code, depending on how you count). (No C compiler is included.) The precompiled C output for bootstrapping is in http://canonical.org/~kragen/sw/dev3/meta5ix2c.c.
Meta5ix is extremely weak and limited, really only enough for a compiler front-end; it can't, for example, do the kinds of RPN tricks we're talking about above.
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.
https://github.com/taocpp/PEGTL
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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.
What are some alternatives?
proofs - My personal repository of formally verified mathematics.
lexy - C++ parsing DSL
peg-bootstrap - A PEG that compiles itself.
cpp-peglib - A single file C++ header-only PEG (Parsing Expression Grammars) library
pyparsing - Python library for creating PEG parsers
spirit - Boost.org spirit module
stoneknifeforth - a tiny self-hosted Forth implementation
C++ B-tree - Git mirror of the official (mercurial) repository of cpp-btree
kefir - 🥛turkic morphology project
pybind11 - Seamless operability between C++11 and Python
konbini - Parser library for Kotlin
sparsepp - A fast, memory efficient hash map for C++