nearley
Lark
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nearley | Lark | |
---|---|---|
3 | 35 | |
3,548 | 4,481 | |
- | 2.7% | |
0.0 | 7.5 | |
8 months ago | 10 days ago | |
JavaScript | Python | |
MIT License | MIT License |
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nearley
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Writing a C compiler in 500 lines of Python
While I suspect I would learn more writing a tokenizer and parsing logic myself I find grammars much easier to read and maintain.
ANTLR is pretty good and is supported across several languages and something I had previously used for some quick Elasticsearch query syntax munging in Python. It also means you can often start from an already existing grammar.
The JS version of ANTLR didn't seem to work for me so for the SQL/JSONPath stuff ended up using the Moo lever and Nearly parser which was rather pleasant. https://nearley.js.org
- Parser generators vs. handwritten parsers: surveying major languages in 2021
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Applicative Parsing
Parsers in nearley.js [1] are written in a very readable EBNF-like DSL; then they get desugared down to a JS file that's a lot like your snippet.
[1] https://github.com/kach/nearley
Lark
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Show HN: I wrote a RDBMS (SQLite clone) from scratch in pure Python
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.
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Oops, I wrote yet another SQLAlchemy alternative (looking for contributors!)
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.
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Hey guys, have any of you tried creating your own language using Python? I'm interested in giving it a shot and was wondering if anyone has any tips or resources to recommend. Thanks in advance!
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.
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Is it possible to propagate higher level constructs (+, *) to the generated parse tree in an LR-style parser?
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.
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can you create your own program language in python, if yes how?
Lark is a good library to assist with this.
- Lark a Python lexer/parser library
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Create your own scripting language in Python with Sly
If I may ask, did you consider Lark, and if so, why wasn't it fit for your purposes?
- Creating a language with Python.
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Not Your Grandfather’s Perl
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.
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Earley Parsing Explained
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.
What are some alternatives?
PEG.js - PEG.js: Parser generator for JavaScript
pyparsing - Python library for creating PEG parsers [Moved to: https://github.com/pyparsing/pyparsing]
Jison - Bison in JavaScript.
PLY - Python Lex-Yacc
Chevrotain - Parser Building Toolkit for JavaScript
pydantic - Data validation using Python type hints
markdown-it - Markdown parser, done right. 100% CommonMark support, extensions, syntax plugins & high speed
sqlparse - A non-validating SQL parser module for Python
xml2js - XML to JavaScript object converter.
Atoma - Atom, RSS and JSON feed parser for Python 3
parse5 - HTML parsing/serialization toolset for Node.js. WHATWG HTML Living Standard (aka HTML5)-compliant.
Construct - Construct: Declarative data structures for python that allow symmetric parsing and building