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#pyparsing

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Public
Paul McGuire

Well, I had a minor stumble releasing #pyparsing 3.2.2 this past weekend, with a bug (Issue #600) that snuck past several thousand unit tests. So I added 1 new test with several hundred new cases that caught that bug, then fixed it (and a sibling bug 10 lines of code away from the first one). Great immediate notice of failing CI pipelines from diligent users, I was able to get 3.2.3 out with the fix Monday evening. And all's right with the world again (the #Python world, anyway).

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Paul McGuire

Pyparsing 3.2.2 cleans up a formerly internal-only utility method make_compressed_re(), and makes it part of the public API. Given a list of strings, it generates a regex to match those strings and only those (so no cheating like ".*").

Here are before/after expressions for matching chemical symbols.

A regular expression for matching chemical symbols: Ac|Ag|Al|Am|Ar|As|At|Au|Ba|Be|Bh|Bi|Bk|Br|B|Ca|Cd|Ce|Cf|Cl|Cm|Cn| Co|Cr|Cs|Cu|C|Db|Ds|Dy|Er|Es|Eu|Fe|Fl|Fm|Fr|F|Ga|Gd|Ge|He|Hf|Hg| Ho|Hs|H|In|Ir|I|Kr|K|La|Li|Lr|Lu|Lv|Mc|Md|Mg|Mn|Mo|Mt|Na|Nb|Nd|Ne |Nh|Ni|No|Np|N|Og|Os|O|Pa|Pb|Pd|Pm|Po|Pr|Pt|Pu|P|Ra|Rb|Re|Rf|Rg| Rh|Rn|Ru|Sb|Sc|Se|Sg|Si|Sm|Sn|Sr|S|Ta|Tb|Tc|Te|Th|Ti|Tl|Tm|Ts|U|V| W|Xe|Yb|Y|Zn|Zr An optimized regular expression for matching chemical symbols: A[cglmrstu]|B[aehikr]?|C[adeflmnorsu]?|D[bsy]|E[rsu]|F[elmr]?|G[ade] |H[efgos]?|I[nr]?|Kr?|L[airuv]|M[cdgnot]|N[abdehiop]?|O[gs]?|P[abdmo rtu]?|R[abefghnu]|S[bcegimnr]?|T[abcehilms]|U|V|W|Xe|Yb?|Z[nr]
#python#pyparsing#regex
Public
Paul McGuire

#Pyparsing API going back to version 1.0.0 (2003) has used a camelCase name scheme for its methods and argument names. In versions 3.0-3.1 (Oct 2021-Jun 2023), I added PEP8-compliant snake_case names, while maintaining synonym definitions for the legacy names for backward compatibility.

Soon, pyparsing will begin emitting DeprecationWarnings for the legacy names. To ease this transition, the next release 3.2.2 will include a utility to convert in place scripts that use the legacy names. #python

Public
Paul McGuire

Pyparsing sightings - recent posts/pages using pyparsing (2/2):

- ciscoconfparse parses configuration files for various network devices using pyparsing
pypi.org/project/ciscoconfpars

- moto is a mocking package for AWS boto API, using pyparsing for an internal infix notation parser
github.com/getmoto/moto

- Pegasus SaaS application builder uses pyparsing internally
docs.saaspegasus.com/

- EasyABC is an editor for the ABC music notation language
github.com/jwdj/EasyABC

#pyparsing#python
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Paul McGuire

Pyparsing sightings - some recent posts/pages using pyparsing (1/2):

- Pyparsing is embedded as a parsing engine for Juniper Networks Junos PyEZ automation environment for smart devices.
juniper.net/documentation/us/e

- Pyparsing included in the examples for the Python Packaging User Guide.
packaging.python.org/en/latest

- Papercrawler uses pyparsing to extract metadata from published papers, journals, and conference proceedings.
github.com/sucv/paperCrawler

#pyparsing#python#parsing
Replied in thread
Public
Paul McGuire

@jshaffstall I'm glad to hear pyparsing worked so well for you! Check out the pyparsing spinoff project plusminus, which wraps pyparsing's 𝚒𝚗𝚏𝚒𝚡_𝚗𝚘𝚝𝚊𝚝𝚒𝚘𝚗 function in an API. plusminus includes a dice roller in its examples (though it does not include trig functions - that is one crazy dice roll expression!). github.com/pyparsing/plusminus #pyparsing

GitHubGitHub - pyparsing/plusminusContribute to pyparsing/plusminus development by creating an account on GitHub.
Public
Paul McGuire

I just released pyparsing 3.2.1 with a very cool addition to the railroad diagrams that pyparsing generates for its parsers - non-terminal diagram elements now link to their definitions elsewhere in the diagram! This is pretty handy when the diagram is for a complex parser, as in this demo of a parser/evaluator for time references like "3 weeks from today" or "0800 two days from now" or "in exactly twenty-four hours". #pyparsing #python #parser #railroaddiagram

Public
Paul McGuire

I'm seeing a number of responses from pyparsing users (or matplotlib users) that they are getting a version of pyparsing that is not compatible with their version of Python (they are running Python 3.8 or older, but the new pyparsing release requires Python 3.9 or later). After some experimenting, I found this `requirements.txt` to help in selecting the right pyparsing version:

matplotlib
pyparsing>=3.2;python_version>="3.9"
pyparsing>=3.1;python_version<"3.9"

#pyparsing#python#matplotlib
Public
Paul McGuire

Attention #pyparsing users: I just pushed release 3.2.0b3, which will be the last beta before I push out 3.2.0. This includes:

- POSSIBLE BREAKING CHANGE: Fixed bug in `transform_string()` where whitespace in the input string was not properly preserved in the output string.

- `mypy` type checking is now run as part of pyparsing's CI.

- Exception message format can now be customized, by overriding `ParseBaseException.format_message`.

Full release notes here: github.com/pyparsing/pyparsing #python

GitHubGitHub - pyparsing/pyparsing: Python library for creating PEG parsersPython library for creating PEG parsers. Contribute to pyparsing/pyparsing development by creating an account on GitHub.
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Paul McGuire

Attention pyparsing users: I just pushed release 3.2.0b1 which mostly just drops support for Python 3.6-3.8, but also changes some exception messages. Please give this release a try before I push the final release in early October.

Also includes:
- some nice enhancements to mongodb_query_expression.py
- a parser for the Lox language defined in Robert Nystrom's "Crafting Interpreters"

Full release notes here: github.com/pyparsing/pyparsing

GitHubRelease Pyparsing 3.2.0b1 · pyparsing/pyparsingDiscontinued support for Python 3.6, 3.7, and 3.8. Adopted new Python features from Python versions 3.7-3.9: Updated type annotations to use built-in container types instead of names imported from...
#python#pyparsing#mongodb
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Paul McGuire

Take 2 on the mongodb query expression transformer - I had basic scalar expression logic working before, but had a couple of bugs in working with arrays. Also added support for embedded docs and regex matching. Wrote a 25-line repl to take my human-readable queries, convert to Mongo's nested dict query and run find() against their mflix learning dataset, running in a local Docker container. #python #pyparsing #mongodb

import pymongo from mongodb_query_expression import transform_query db_connection = pymongo.MongoClient('localhost', 27017) db = db_connection.sample_mflix coll = db.movies while True: query = input('Enter query: ') if query.lower() in ('quit', 'exit'): break try: transformed = transform_query(query) except Exception as e: print(f"{type(e).__name__}: {e}") else: print(transformed) matches = coll.find(transformed) for m in matches: print(f"{m['title']} ({m['year']})") print()
Three queries converted from human-readable form to MongoDB nested dict form, and their query results found in the mflix dataset
Public
Paul McGuire

Refreshing my MongoDB skills this week, and I remember thinking it would be nice to have a converter for query expressions, to transform normal infix notation into the nested dict used by the `collection.find()` function. So here is the output of a pyparsing program to do that. See the before/after examples below. The script is included in the pyparsing examples directory at github.com/pyparsing/pyparsing #python #pyparsing #mongodb

Example code showing conversion from infix boolean statements to MongoDB nested dict notation: a = 100 {'a': 100} a = 100 and b = 200 {'a': 100, 'b': 200} a==100 and b>=200 {'$and': [{'a': 100}, {'b': {'$gte': 200}}]} 100 ≤ a < 200 {'$and': [{'a': {'$gte': 100}}, {'a': {'$lt': 200}}]} name in ["Alice", "Bob"] {'name': {'$in': ['Alice', 'Bob']}} name ∈ ["Alice", "Bob"] {'name': {'$in': ['Alice', 'Bob']}}
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Paul McGuire

A balanced testimonial from a new #pyparsing user: "I'm not gonna sugarcoat that pyparsing might need more examples on documents for dummies like me who had to search hours how to use line_end/LineEnd() from zero base - But darn, this is one very interactive and fun way to create parser! Begone, the pain of YACC and Lexer! I now will die using this for all the parser need I'll ever have in lifetime!" That's good enough for me! :D [posted as a comment on the SO answer: stackoverflow.com/a/78697404/1]

Stack Overflowpyparsing - back to basicsIn attempting to put together a very simple example to illustrate an issue I'm having with pyparsing, I have found that I can't get my simple example to work - this example is barely more complex t...
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