MAmattrighetti·Feb 12, 2026Submission
Srgn – A grep-like tool which understands source code syntax
3 points · Open discussionalexpovel
srgn
Rust2023–2026
alexpovel / srgn
srgn
A grep-like tool which understands source code syntax and allows for manipulation in addition to search
2Distinct people
8Mentions
0Explicit recommenders
915GitHub stars
What to know before exploring
What it is
A grep-like tool which understands source code syntax and allows for manipulation in addition to search
GitHub
Where it is used
No documented product use has been verified yet.
What people are saying
No recommendation phrase was found in the indexed comments.
No classified warning is attached to this page. Read the discussions before treating silence as approval.
Also in these discussions
No other repository is repeatedly linked in the same discussions.
This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by month8 dated mentions
Observed mentions: 2023-12-10 13:36:47 UTC to 2026-02-12 19:14:53 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| Dec 2023 | 2023-12-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 3 | 0 | 3 |
| Jan 2024 | 2024-01-01 00:00:00 UTC | 2024-02-01 00:00:00 UTC | 1 | 1 | 0 |
| Feb 2024 | 2024-02-01 00:00:00 UTC | 2024-03-01 00:00:00 UTC | 0 | 0 | 0 |
| Mar 2024 | 2024-03-01 00:00:00 UTC | 2024-04-01 00:00:00 UTC | 0 | 0 | 0 |
| Apr 2024 | 2024-04-01 00:00:00 UTC | 2024-05-01 00:00:00 UTC | 0 | 0 | 0 |
| May 2024 | 2024-05-01 00:00:00 UTC | 2024-06-01 00:00:00 UTC | 1 | 0 | 1 |
| Jun 2024 | 2024-06-01 00:00:00 UTC | 2024-07-01 00:00:00 UTC | 0 | 0 | 0 |
| Jul 2024 | 2024-07-01 00:00:00 UTC | 2024-08-01 00:00:00 UTC | 0 | 0 | 0 |
| Aug 2024 | 2024-08-01 00:00:00 UTC | 2024-09-01 00:00:00 UTC | 0 | 0 | 0 |
| Sep 2024 | 2024-09-01 00:00:00 UTC | 2024-10-01 00:00:00 UTC | 2 | 0 | 2 |
| Oct 2024 | 2024-10-01 00:00:00 UTC | 2024-11-01 00:00:00 UTC | 0 | 0 | 0 |
| Nov 2024 | 2024-11-01 00:00:00 UTC | 2024-12-01 00:00:00 UTC | 0 | 0 | 0 |
| Dec 2024 | 2024-12-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 0 | 0 | 0 |
| Jan 2025 | 2025-01-01 00:00:00 UTC | 2025-02-01 00:00:00 UTC | 0 | 0 | 0 |
| Feb 2025 | 2025-02-01 00:00:00 UTC | 2025-03-01 00:00:00 UTC | 0 | 0 | 0 |
| Mar 2025 | 2025-03-01 00:00:00 UTC | 2025-04-01 00:00:00 UTC | 0 | 0 | 0 |
| Apr 2025 | 2025-04-01 00:00:00 UTC | 2025-05-01 00:00:00 UTC | 0 | 0 | 0 |
| May 2025 | 2025-05-01 00:00:00 UTC | 2025-06-01 00:00:00 UTC | 0 | 0 | 0 |
| Jun 2025 | 2025-06-01 00:00:00 UTC | 2025-07-01 00:00:00 UTC | 0 | 0 | 0 |
| Jul 2025 | 2025-07-01 00:00:00 UTC | 2025-08-01 00:00:00 UTC | 0 | 0 | 0 |
| Aug 2025 | 2025-08-01 00:00:00 UTC | 2025-09-01 00:00:00 UTC | 0 | 0 | 0 |
| Sep 2025 | 2025-09-01 00:00:00 UTC | 2025-10-01 00:00:00 UTC | 0 | 0 | 0 |
| Oct 2025 | 2025-10-01 00:00:00 UTC | 2025-11-01 00:00:00 UTC | 0 | 0 | 0 |
| Nov 2025 | 2025-11-01 00:00:00 UTC | 2025-12-01 00:00:00 UTC | 0 | 0 | 0 |
| Dec 2025 | 2025-12-01 00:00:00 UTC | 2026-01-01 00:00:00 UTC | 0 | 0 | 0 |
| Jan 2026 | 2026-01-01 00:00:00 UTC | 2026-02-01 00:00:00 UTC | 0 | 0 | 0 |
| Feb 2026 | 2026-02-01 00:00:00 UTC | 2026-03-01 00:00:00 UTC | 1 | 1 | 0 |
What Hacker News says
8 sourcesThese sorts of cases are why I wrote srgn [0]. It's based on tree-sitter too. Calling it as
cat file.py | srgn --py def --py identifiers 'database' 'db'
will replace all mentions of `database` inside identifiers inside (only!) function definitions (`def`) with `db`.
An input like
import database
import pytest
@pytest.fixture()
def test_a(database):
return database
def test_b(database):
return database
database = "database"
class database:
pass
is turned into
import database
import pytest
@pytest.fixture()
def test_a(db):
return db
def test_b(db):
return db
database = "database"
class database:
pass
which seems roughly like what the author is after. Mentions of "database" outside function definitions are not mod
Read the rest
ified. That sort of logic I always found hard to replicate in basic GNU-like tools. If run without stdin, the above command runs recursively, in-place (careful with that one!).
Note: I just wrote this, and version 0.13.2 is required for the above to work.
[0]: https://github.com/alexpovel/srgn
Regarding your third point, I put together a tool capable of that to some degree.
It allows you to grep inside source code, but limit the search to e.g. “only docstrings inside class definitions”, among other things. That is, it allows nesting and is syntax aware. That example is for Python, but the tool speaks more languages (thanks to treesitter).
https://github.com/alexpovel/srgn/blob/main/README.md#multip...
In Greppability is an underrated code metricThe tool you are describing is what I am trying to build at https://github.com/alexpovel/srgn . The idea is a compromise between regex (think ripgrep) and grammar awareness (through tree-sitter).
In Amber: A code search and replace toolShow HN: Srgn, AST-aware text manipulation
srgn is a niche source code (or just text) manipulation tool. It's written in Rust, with performance in mind. I used it to learn the language a while back, in order to work towards something resembling "useful in the real world".
Think of srgn as a blend of rip-grep, tree-sitter and GNU `tr`/`sed`. At its core, it most closely resembles `tr`, but expands on it in two important ways.
First, srgn provides scoping, used to specify what part of an input to work on. This can be literal text, regular expressions, or tree-sitter queries. The latter is the most interesting one. As tree-sitter queries can be tough to construct (although the tool is excellent, with an online playground for testing and more), srgn has pre-defined queries and makes an effort to unify these across languages. For example, across TypeScript, C#, Go, Rust and Python, you
Read the rest
can specify to scope all "comments", and it (hopefully) just works as expected, despite these languages having different ideas of how comments work and look like (C# has multi-line and inline, for example, while Python only has a single type, all of which is also reflected in what tree-sitter calls those corresponding nodes).
Secondly, there's actions, which simply perform text manipulation on whatever is in scope from the previous step. One could delete certain parts of all comments, for example, or rewrite all import statements across an entire code base (https://github.com/alexpovel/srgn#mass-import-module-renamin...).
I had looked around a bunch for similar tools (https://github.com/alexpovel/srgn#similar-tools), but couldn't find any that quite did what srgn does.
The CLI is a rather thin wrapper around the Rust library, which is usable in the usual way.
By the way, the name srgn stands for surgeon, in the sense of a code surgeon: precise manipulation of text. Regular expressions and tree-sitter queries can be combined, which turns out to be much more powerful than either of these by itself, and also fills a different niche than LSP-powered Rename all-like features. It can also be used in CI, as a simple custom linter ("fail if you find any 'TODO' strings in comments").
A lot of the use cases can be covered by just regex, and then fixing mistakes manually; srgn mainly inches the precision of these operations closer to 100%, for when it's needed (like large refactors, where srgn offers full parallelization as well).
It's currently whitelist-based [0]. The downside is larger (code) size. The upside is simplicity. I imagine a blacklist could also work well, at smaller size but with more preprocessing needed.
[0]: https://github.com/alexpovel/srgn/blob/0008cce1c71f0d83f6a31...
In Ask HN: What apps have you created for your own use?https://github.com/alexpovel/srgn
It grew out of a niche, almost historical need: using a QWERTY keyboard, but needing access to German Umlauts (ä, ö, ü, as well as ß). Switching keyboard layouts is possible but exhausting (it's much more pleasant sticking to one); using modifier keys is similarly tedious, and custom setups break and aren't portable.
So this tool can do:
$ echo 'Gruess Gott, Poeten und Abenteuergruetze!' | srgn --german
Grüß Gott, Poeten und Abenteuergrütze!
meaning it not only replaces Umlauts and Eszett, it also knows when not to (Poeten), and handles arbitrary compound words. Write your text, slap it all into the tool, it spits out results instantly. The original text can use alternative spellings (ou, ae, ue, ss), which is ergonomic. Combined with tools like AutohotKey, GUI integration through a single keyboa
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rd shortcut is possible. See [0] for a similar example.
A niche need I haven't yet come across someone else having as well! (just the amount of text explaining what it's all about is saying a lot in terms of specificity...)
The tool now grew into a tree-sitter based (== language grammar-aware) text manipulation thing, mostly for fun. The bizarre German core is still there however.
[0]: https://github.com/alexpovel/betterletter/blob/c19245bf90589...
Wow! What a coincidence. Just the other day I finished "v1" of a similar tool: https://github.com/alexpovel/srgn , calling it a combination of tr/sed, ripgrep and tree-sitter. It's more about editing code in-place, not finding matches.
I've spent a lot of time trying to find similar tools, and even list them in the README, but `AST-grep` did not come up! I was a bit confused, as I was sure such a thing must exist already. AST-grep looks much more capable and dynamic, great work, especially around the variable syntax.
In AST-grep(sg) is a CLI tool for code structural search, lint, and rewriting