11 items tagged “parsing”
2023
Lark parsing library JSON tutorial (via) A very convincing tutorial for a new-to-me parsing library for Python called Lark.
The tutorial covers building a full JSON parser from scratch, which ends up being just 19 lines of grammar definition code and 15 lines for the transformer to turn that tree into the final JSON.
It then gets into the details of optimization—the default Earley algorithm is quite slow, but swapping that out for a LALR parser (a one-line change) provides a 5x speedup for this particular example. # 13th August 2023, 9:50 pm
Building Search DSLs with Django (via) Neat tutorial by Dan Lamanna: how to build a GitHub-style search feature—supporting modifiers like “is:open author:danlamanna”—using PyParsing and the Django ORM. # 19th June 2023, 8:30 am
2022
Comby (via) Describes itself as “Structural search and replace for any language”. Lets you execute search and replace patterns that look a little bit like simplified regular expressions, but with some deep OCaml-powered magic that makes them aware of comment, string and nested parenthesis rules for different languages. This means you can use it to construct scripts that automate common refactoring or code upgrade tasks. # 18th May 2022, 5:47 am
2020
pup. This is a great idea: a command-line tool for parsing HTML on stdin using CSS selectors. It’s like jq but for HTML. Supports a sensible collection of selectors and has a number of output options for the selected nodes, including plain text and JSON. It also works as a simple pretty-printer for HTML. # 14th February 2020, 4:25 pm
2018
Parsing CSV using ANTLR and Python 3. I’ve been trying to figure out how to use ANTLR grammars from Python—this is the first example I’ve found that really clicked for me. # 6th April 2018, 2:33 pm
2017
Parse shell one-liners with pyparsing. Neat introduction to the pyparsing library, both for parsing tokens into labeled sections and constructing an AST from them. # 22nd October 2017, 1:35 pm
2009
Every time you attempt to parse HTML with regular expressions, the unholy child weeps the blood of virgins, and Russian hackers pwn your webapp. Parsing HTML with regex summons tainted souls into the realm of the living. HTML and regex go together like love, marriage, and ritual infanticide.
— Andrew Clover # 16th November 2009, 10:32 am
HTML 5 Parsing. Firefox nightlies include a new parser that implements the HTML5 parsing algorithm (disabled by default), which uses C++ code automatically generated from Henri Sivonen’s Java parser first used in the HTML5 validator. # 11th July 2009, 11:36 pm
South’s Design. Andrew Godwin explains why South resorts to parsing your models.py file in order to construct information about for creating automatic migrations. # 13th May 2009, 12:30 pm
2008
Simple Top-Down Parsing in Python. Eye-opening tutorial on building a recursive descent parser for Python, in Python that uses top-down operator precedence. # 19th July 2008, 11:37 pm
python4ply tutorial. python4ply is a parser for Python written in Python using the PLY toolkit, which compiles to Python bytecode using the built-in compiler module. The tutorial shows how to use it to add support for Perl-style 1_000_000 readable numbers. # 11th March 2008, 5:49 am