☯️ Toml::Merge

if ci_badges.map(&:color).detect { it != "green"} ☝️ let me know, as I may have missed the discord notification.

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toml-merge provides intelligent merging of TOML files by parsing them into tree-sitter AST nodes and comparing structural elements. It supports:

• Smart key matching - Keys and tables are matched by their structural signatures
• Table matching - Tables are matched using a multi-factor scoring algorithm that considers key similarity, value overlap, and position
• Freeze blocks - Mark sections with comments to preserve them during merges
• Configurable merge strategies - Choose whether template or destination wins for conflicts, or use a Hash for per-node-type preferences with node_splitter (see ast-merge docs)
• Full TOML support - Works with all TOML 1.0 features including inline tables, arrays of tables, and dotted keys

This gem is part of a family of gems that provide intelligent merging for various file formats:

Example implementations for the gem templating use case:

Tokens to Remember
Works with JRuby
Works with Truffle Ruby
Works with MRI Ruby 3
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... 💖	🧊 🐙 🛖 🧪

Compatible with MRI Ruby 3.2.0+, and concordant releases of JRuby, and TruffleRuby.

Federated DVCS Repository	Status	Issues	PRs	Wiki	CI	Discussions
🧪 kettle-rb/toml-merge on GitLab	The Truth	💚	💚	💚	🐭 Tiny Matrix	➖
🧊 kettle-rb/toml-merge on CodeBerg	An Ethical Mirror (Donate)	💚	💚	➖	⭕️ No Matrix	➖
🐙 kettle-rb/toml-merge on GitHub	Another Mirror	💚	💚	💚	💯 Full Matrix	💚
🎮️ Discord Server		Let's	talk	about	this	library!

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Alternatively:

Install the gem and add to the application's Gemfile by executing:

bundle add toml-merge

If bundler is not being used to manage dependencies, install the gem by executing:

gem install toml-merge

This gem is cryptographically signed, and has verifiable SHA-256 and SHA-512 checksums by stone_checksums. Be sure the gem you install hasn’t been tampered with by following the instructions below.

Add my public key (if you haven’t already, expires 2045-04-29) as a trusted certificate:

gem cert --add <(curl -Ls https://raw.github.com/galtzo-floss/certs/main/pboling.pem)

You only need to do that once. Then proceed to install with:

gem install toml-merge -P HighSecurity

The HighSecurity trust profile will verify signed gems, and not allow the installation of unsigned dependencies.

If you want to up your security game full-time:

bundle config set --global trust-policy MediumSecurity

MediumSecurity instead of HighSecurity is necessary if not all the gems you use are signed.

NOTE: Be prepared to track down certs for signed gems and add them the same way you added mine.

toml-merge uses tree_haver for parsing, which supports multiple backends:

Tree-sitter backend (default, requires native library):

• Set the TREE_SITTER_TOML_PATH environment variable to point to your compiled libtree-sitter-toml.so (or .dylib on macOS):

export TREE_SITTER_TOML_PATH=/path/to/libtree-sitter-toml.so

Citrus backend (pure Ruby, no native dependencies):

• Alternative option using the citrus and toml-rb gems
• No compilation or system dependencies required
• Ideal for environments where native extensions are problematic
• Configure via tree_haver's backend selection

For more details on backend configuration, see the tree_haver documentation.

merger = Toml::Merge::SmartMerger.new(
  template_content,
  dest_content,
  # Which version to prefer when nodes match
  # :destination (default) - keep destination values
  # :template - use template values
  preference: :destination,

  # Whether to add template-only nodes to the result
  # false (default) - only include keys that exist in destination
  # true - include all template keys and tables
  add_template_only_nodes: false,

  # Token for freeze block markers
  # Default: "toml-merge"
  # Looks for: # toml-merge:freeze / # toml-merge:unfreeze
  freeze_token: "toml-merge",

  # Custom signature generator (optional)
  # Receives a node, returns a signature array or nil
  signature_generator: ->(node) { [:table, node.name] if node.type == :table },
)

require "toml/merge"

# Template defines the structure
template = <<~TOML
  [package]
  name = "my-app"
  version = "1.0.0"
  
  [dependencies]
  serde = "1.0"
  tokio = "1.0"
TOML

# Destination has customizations
destination = <<~TOML
  [package]
  name = "my-app"
  version = "2.0.0"
  authors = ["Custom Author"]
  
  [dev-dependencies]
  criterion = "0.5"
TOML

merger = Toml::Merge::SmartMerger.new(template, destination)
result = merger.merge
puts result.content

Freeze blocks protect sections from being overwritten during merge:

[package]
name = "my-app"

# toml-merge:freeze Custom configuration
[secrets]
api_key = "my_production_api_key"
db_password = "super_secret_password"
# toml-merge:unfreeze

[dependencies]
serde = "1.0"

Content between # toml-merge:freeze and # toml-merge:unfreeze markers is preserved from the destination file, regardless of what the template contains.

merger = Toml::Merge::SmartMerger.new(
  template,
  destination,
  add_template_only_nodes: true,
)
result = merger.merge
# Result includes tables/keys from template that don't exist in destination

While kettle-rb tools are free software and will always be, the project would benefit immensely from some funding. Raising a monthly budget of... "dollars" would make the project more sustainable.

We welcome both individual and corporate sponsors! We also offer a wide array of funding channels to account for your preferences (although currently Open Collective is our preferred funding platform).

If you're working in a company that's making significant use of kettle-rb tools we'd appreciate it if you suggest to your company to become a kettle-rb sponsor.

You can support the development of kettle-rb tools via GitHub Sponsors, Liberapay, PayPal, Open Collective and Tidelift.

Support us with a monthly donation and help us continue our activities. [Become a backer]

NOTE: kettle-readme-backers updates this list every day, automatically.

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I’m driven by a passion to foster a thriving open-source community – a space where people can tackle complex problems, no matter how small. Revitalizing libraries that have fallen into disrepair, and building new libraries focused on solving real-world challenges, are my passions. I was recently affected by layoffs, and the tech jobs market is unwelcoming. I’m reaching out here because your support would significantly aid my efforts to provide for my family, and my farm (11 🐔 chickens, 2 🐶 dogs, 3 🐰 rabbits, 8 🐈‍ cats).

If you work at a company that uses my work, please encourage them to support me as a corporate sponsor. My work on gems you use might show up in bundle fund.

I’m developing a new library, floss_funding, designed to empower open-source developers like myself to get paid for the work we do, in a sustainable way. Please give it a look.

Floss-Funding.dev: 👉️ No network calls. 👉️ No tracking. 👉️ No oversight. 👉️ Minimal crypto hashing. 💡 Easily disabled nags

See SECURITY.md.

If you need some ideas of where to help, you could work on adding more code coverage, or if it is already 💯 (see below) check reek, issues, or PRs, or use the gem and think about how it could be better.

We so if you make changes, remember to update it.

See CONTRIBUTING.md for more detailed instructions.

See CONTRIBUTING.md.

Everyone interacting with this project's codebases, issue trackers, chat rooms and mailing lists agrees to follow the .

Made with contributors-img.

Also see GitLab Contributors: https://gitlab.com/kettle-rb/toml-merge/-/graphs/main

This Library adheres to . Violations of this scheme should be reported as bugs. Specifically, if a minor or patch version is released that breaks backward compatibility, a new version should be immediately released that restores compatibility. Breaking changes to the public API will only be introduced with new major versions.

dropping support for a platform is both obviously and objectively a breaking change
—Jordan Harband (@ljharb, maintainer of SemVer) in SemVer issue 716

I understand that policy doesn't work universally ("exceptions to every rule!"), but it is the policy here. As such, in many cases it is good to specify a dependency on this library using the Pessimistic Version Constraint with two digits of precision.

For example:

spec.add_dependency("toml-merge", "~> 1.0")

SemVer should, IMO, but doesn't explicitly, say that dropping support for specific Platforms is a breaking change to an API, and for that reason the bike shedding is endless.

To get a better understanding of how SemVer is intended to work over a project's lifetime, read this article from the creator of SemVer:

• "Major Version Numbers are Not Sacred"

See CHANGELOG.md for a list of releases.

The gem is available as open source under the terms of the MIT License . See LICENSE.txt for the official Copyright Notice.

• Copyright (c) 2025 Peter H. Boling, of Galtzo.com , and toml-merge contributors.

Maintainers have teeth and need to pay their dentists. After getting laid off in an RIF in March, and encountering difficulty finding a new one, I began spending most of my time building open source tools. I'm hoping to be able to pay for my kids' health insurance this month, so if you value the work I am doing, I need your support. Please consider sponsoring me or the project.

To join the community or get help 👇️ Join the Discord.

To say "thanks!" ☝️ Join the Discord or 👇️ send money.

💌 💌 💌

Thanks for RTFM. ☺️