# nathansobo/treetop

A Ruby-based parsing DSL based on parsing expression grammars.

Repository: https://github.com/nathansobo/treetop
Canonical: https://ross.abutalabs.com/products/treetop
Homepage: http://treetop.rubyforge.org
Language: Ruby
License: MIT
License Family: permissive
Last push: 2018-05-09T12:50:21+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 6760, "days_push": 3038, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1010, forks 110 (observed 2026-08-28T04:03:12.910974+00:00)

## What it is
Treetop is a Ruby DSL for building parsers based on parsing expression grammars (PEGs). This original repository is unmaintained and development has moved to the cjheath/treetop fork.

## Use cases
- write a parser for a custom DSL in Ruby
- define grammars using parsing expression grammars
- parse structured text files in Ruby
- build a small programming language interpreter
- generate parsers from grammar definitions

## When to choose
- you need a PEG-based parser library in Ruby
- you prefer defining grammars as readable Ruby DSL code

## When to avoid
- you want an actively maintained project - use the cjheath/treetop fork instead
- you need parser performance or features beyond what PEGs offer

## Facets
- artifact type: library
- maturity: abandoned
- function: parser, programming-language
- domain: parsers, programming-languages, developer-tools
- platform: ruby, cross-platform
- tags: parsing-expression-grammars, peg, parser-generator, ruby-dsl

## Member repositories
- nathansobo/treetop (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:12.910974+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:11:57.630408+00:00, confidence not recorded.
  - readme: https://github.com/nathansobo/treetop (fetched 2026-08-28T04:03:12.910974+00:00, sha ffc78a718081)
- Data as of 2026-08-30T08:39:29.467469+00:00.