feat: diff-lcs 2.0.0 beta 1

.github/workflows/ci.yml

@@ -37,19 +37,14 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: '3.4'
           rubygems: latest
           bundler: 2
-          bundler-cache: false
+          bundler-cache: true
 
-      - name: Run standardrb
-        run: |
-          bundle install --jobs 4 --retry 3
-          bundle exec standardrb
-        env:
-          MAINTENANCE: true
+      - run: bundle exec standardrb
 
   coverage:
     name: Generate Coverage Report
@@ -76,18 +71,14 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: '3.4'
           rubygems: latest
           bundler: 2
-          bundler-cache: false
+          bundler-cache: true
 
-      - run: |
-          bundle install --jobs 4 --retry 3
-          bundle exec ruby -S rake coverage --trace
-        env:
-          COVERAGE: true
+      - run: bundle exec ruby -S rake coverage --trace
 
       - uses: coverallsapp/github-action@648a8eb78e6d50909eff900e4ec85cab4524a45b #v2.3.6
 
@@ -104,12 +95,10 @@ jobs:
           - ubuntu-22.04
           - ubuntu-24.04
         ruby:
-          - '2.6'
-          - '2.7'
-          - '3.1'
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
           - truffleruby
 
     runs-on: ${{ matrix.os }}
@@ -131,7 +120,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: ${{ matrix.ruby }}
           rubygems: latest
@@ -154,12 +143,10 @@ jobs:
           - macos-15
           - macos-26
         ruby:
-          - '2.6'
-          - '2.7'
-          - '3.1'
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
 
     runs-on: ${{ matrix.os }}
 
@@ -180,7 +167,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: ${{ matrix.ruby }}
           rubygems: latest
@@ -202,13 +189,10 @@ jobs:
           - windows-2022
           - windows-2025
         ruby:
-          - '2.6'
-          - '2.7'
-          - '3.0'
-          - '3.1'
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
           - mingw
           - mswin
           - ucrt
@@ -232,7 +216,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: ${{ matrix.ruby }}
           rubygems: latest
@@ -278,7 +262,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: ${{ matrix.ruby }}
           rubygems: latest
@@ -324,7 +308,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           ruby-version: ${{ matrix.ruby }}
           rubygems: latest

.github/workflows/dco-check.yml

@@ -27,4 +27,4 @@ jobs:
             api.github.com:443
             github.com:443
 
-      - uses: KineticCafe/actions-dco@cd9508e5ae82413fbd74b20af21551db0ea3eb78 # v2.0.0
+      - uses: KineticCafe/actions-dco@76b7fc30ff5988e68d01ea07deeaf7e71256598f # v2.1.0

.github/workflows/publish-docs.yml

@@ -38,7 +38,7 @@ jobs:
             'print "version=", Gem::Specification.load(ARGV[0]).rubygems_version, "\n"' \
             diff-lcs.gemspec >>"${GITHUB_OUTPUT}"
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           bundler-cache: false
           ruby-version: ruby

.github/workflows/publish-gem.yml

@@ -65,7 +65,7 @@ jobs:
             'print "version=", Gem::Specification.load(ARGV[0]).rubygems_version, "\n"' \
             diff-lcs.gemspec >>"${GITHUB_OUTPUT}"
 
-      - uses: ruby/setup-ruby@d354de180d0c9e813cfddfcbdc079945d4be589b # v1.275.0
+      - uses: ruby/setup-ruby@8a836efbcebe5de0fe86b48a775b7a31b5c70c93 # v1.277.0
         with:
           bundler-cache: false
           ruby-version: ruby

.mise.toml

@@ -1,6 +1,2 @@
 [tools]
 ruby = "3.4"
-
-[env]
-MAINTENANCE = "true"
-COVERAGE = "true"

.standard.yml

@@ -1,15 +1,11 @@
 ---
 parallel: true
-ruby_version: 2.0
+ruby_version: 3.2
 
 ignore:
   - '*.gemspec'
   - research/**/*
   - pkg/**/*
-  - Gemfile:
-      - Style/HashSyntax
-  - Rakefile:
-      - Layout/HeredocIndentation
 
 plugins:
   - rubocop-thread_safety

CHANGELOG.md

@@ -1,5 +1,40 @@
 # Changelog
 
+## 2.0.0.beta.1 / 2025-12-31
+
+This release has significant **breaking changes**.
+
+- diff-lcs 2 supports Ruby 3.2 or higher. This allowed:
+
+  - readability improvements (endless methods, pattern matching);
+
+  - support for immutable Data classes (`Diff::LCS::Block`, `Diff::LCS::Change`,
+    and `Diff::LCS::ContextChange`);
+
+  - removal of compatibility shims;
+
+  - reduction in conditional tests in loops, especially for String character
+    extraction (compare `string ? seq[i, 1] : seq[i]` to `seq[i]`); and
+
+  - optimizations to string and relying on standard encoding support present
+    since Ruby 2.1.
+
+  The primary API (methods and class methods on `Diff::LCS`) has not changed,
+  with one exception noted below. Internal APIs (including `Diff::LCS::Block`,
+  `Diff::LCS::Change`, `Diff::LCS::ContextChange`, and `Diff::LCS::Hunk`) have
+  changed for compatibility.
+
+- The `htmldiff` binary and supporting code have been removed without
+  replacement.
+
+- `ldiff` no longer supports `ed`-script output (`ed` and `reverse_ed` formats).
+  As Baptiste Courtois says in [#108][pull-108], the "implementation was broken
+  for a while and no-one reported it."
+
+- The method `Diff::LCS.LCS` has been removed as an alias for `Diff::LCS.lcs`.
+  Most callers are using `Diff::LCS.lcs` and modern Ruby did-you-mean support
+  should assist with this update.
+
 ## 1.6.2 / 2025-05-12
 
 - Handle upcoming changes to the `cgi` gem in Ruby 3.5 ([#147][pull-147])
@@ -504,6 +539,7 @@
 [pull-103]: https://github.com/halostatue/diff-lcs/pull/103
 [pull-104]: https://github.com/halostatue/diff-lcs/pull/104
 [pull-105]: https://github.com/halostatue/diff-lcs/pull/105
+[pull-108]: https://github.com/halostatue/diff-lcs/pull/108
 [pull-129]: https://github.com/halostatue/diff-lcs/pull/129
 [pull-147]: https://github.com/halostatue/diff-lcs/pull/147
 [pull-148]: https://github.com/halostatue/diff-lcs/pull/148

CONTRIBUTING.md

@@ -1,54 +1,65 @@
 # Contributing
 
 Contribution to diff-lcs is encouraged: bug reports, feature requests, or code
-contributions. There are a few DOs and DON'Ts that should be followed.
+contributions. New features should be proposed and discussed in an
+[issue][issues].
 
-## DO
+Before contributing patches, please read the [Licence](./LICENCE.md).
 
-- Keep the coding style that already exists for any updated Ruby code (support
-  or otherwise). I use [Standard Ruby][standardrb] for linting and formatting.
+diff-lcs is governed under the [Contributor Covenant Code of Conduct][cccoc].
 
-- Use thoughtfully-named topic branches for contributions. Rebase your commits
-  into logical chunks as necessary.
+## Code Guidelines
 
-- Use [quality commit messages][qcm].
+I have several guidelines to contributing code through pull requests:
 
-- Add your name or GitHub handle to `CONTRIBUTORS.md` and a record in the
-  `CHANGELOG.md` as a separate commit from your main change. (Follow the style
-  in the `CHANGELOG.md` and provide a link to your PR.)
+- All code changes require tests. In most cases, this will be added or updated
+  unit tests. I use [RSpec][rspec].
 
-- Add or update tests as appropriate for your change. The test suite is written
-  in [RSpec][rspec].
+- I use code formatters, static analysis tools, and linting to ensure consistent
+  styles and formatting. There should be no warning output from test run
+  processes. I use [Standard Ruby][standardrb].
 
-- Add or update documentation as appropriate for your change. The documentation
-  is RDoc; diff-lcs does not use extensions that may be present in alternative
-  documentation generators.
+- Proposed changes should be on a thoughtfully-named topic branch and organized
+  into logical commit chunks as appropriate.
 
-## DO NOT
+- Use [Conventional Commits][conventional] with my
+  [conventions](#commit-conventions).
 
-- Modify `VERSION` in `lib/diff/lcs/version.rb`. When your patch is accepted and
-  a release is made, the version will be updated at that point.
+- Versions must not be updated in pull requests unless otherwise directed. This
+  means that you must not:
 
-- Modify `diff-lcs.gemspec`; it is a generated file. (You _may_ use
-  `rake gemspec` to regenerate it if your change involves metadata related to
-  gem itself).
+  - Modify `VERSION` in `lib/diff/lcs/version.rb`. When your patch is accepted
+    and a release is made, the version will be updated at that point.
 
-- Modify the `Gemfile`.
+  - Modify `diff-lcs.gemspec`; it is a generated file. (You _may_ use
+    `rake gemspec` to regenerate it if your change involves metadata related to
+    gem itself).
 
-## LLM-Generated Contribution Policy
+  - Modify the `Gemfile`.
 
-diff-lcs is a library with complex interactions and subtle decisions (some of
-them possibly even wrong). It is extremely important that any issues or pull
-requests be well understood by the submitter and that, especially for pull
-requests, the developer can attest to the [Developer Certificate of Origin][dco]
-for each pull request (see [LICENCE](LICENCE.md)).
+- Documentation should be added or updated as appropriate for new or updated
+  functionality. The documentation is RDoc; diff-lcs does not use extensions
+  that may be present in alternative documentation generators.
+
+- All GitHub Actions checks marked as required must pass before a pull request
+  may be accepted and merged.
+
+- Add your name or GitHub handle to `CONTRIBUTORS.md` and a record in the
+  `CHANGELOG.md` as a separate commit from your main change. (Follow the style
+  in the `CHANGELOG.md` and provide a link to your PR.)
 
-If LLM assistance is used in writing pull requests, this must be documented in
-the commit message and pull request. If there is evidence of LLM assistance
-without such declaration, the pull request **will be declined**.
+- Include your DCO sign-off in each commit message (see [LICENCE](LICENCE.md)).
 
-Any contribution (bug, feature request, or pull request) that uses unreviewed
-LLM output will be rejected.
+## AI Contribution Policy
+
+diff-lcs is a library with complex interactions and subtle decisions (some of
+them possibly even wrong). It is extremely important that contributions of any
+sort be well understood by the submitter and that the developer can attest to
+the [Developer Certificate of Origin][dco] for each pull request (see
+[LICENCE](LICENCE.md)).
+
+Any contribution (bug, feature request, or pull request) that uses undeclared AI
+output will be rejected.
 
 ## Test Dependencies
 
@@ -58,28 +69,54 @@ tests in the same way that `rake spec` does.
 
 To assist with the installation of the development dependencies for diff-lcs, I
 have provided a Gemfile pointing to the (generated) `diff-lcs.gemspec` file.
-`minitar.gemspec` file. This will permit you to use `bundle install` to install
-the dependencies.
+This will permit you to use `bundle install` to install the dependencies.
 
 You can run tests with code coverage analysis by running `rake spec:coverage`.
 
-## Workflow
+## Commit Conventions
+
+diff-lcs has adopted a variation of the Conventional Commits format for commit
+messages. The following types are permitted:
+
+| Type    | Purpose                                               |
+| ------- | ----------------------------------------------------- |
+| `feat`  | A new feature                                         |
+| `fix`   | A bug fix                                             |
+| `chore` | A code change that is neither a bug fix nor a feature |
+| `docs`  | Documentation updates                                 |
+| `deps`  | Dependency updates, including GitHub Actions.         |
+
+I encourage the use of [Tim Pope's][tpope-qcm] or [Chris Beam's][cbeams]
+guidelines on the writing of commit messages
+
+I require the use of [git][trailers1] [trailers][trailers2] for specific
+additional metadata and strongly encourage it for others. The conditionally
+required metadata trailers are:
+
+- `Breaking-Change`: if the change is a breaking change. **Do not** use the
+  shorthand form (`feat!(scope)`) or `BREAKING CHANGE`.
+
+- `Signed-off-by`: this is required for all developers except me, as outlined in
+  the [Licence](./LICENCE.md#developer-certificate-of-origin).
 
-Here's the most direct way to get your work merged into the project:
+- `Fixes` or `Resolves`: If a change fixes one or more open [issues][issues],
+  that issue must be included in the `Fixes` or `Resolves` trailer. Multiple
+  issues should be listed comma separated in the same trailer:
+  `Fixes: #1, #5, #7`, but _may_ appear in separate trailers. While both `Fixes`
+  and `Resolves` are synonyms, only _one_ should be used in a given commit or
+  pull request.
 
-- Fork the project.
-- Clone your fork (`git clone git://github.com/<username>/diff-lcs.git`).
-- Create a topic branch to contain your change
-  (`git checkout -b my_awesome_feature`).
-- Hack away, add tests. Not necessarily in that order.
-- Make sure everything still passes by running `rake`.
-- If necessary, rebase your commits into logical chunks, without errors.
-- Push the branch up (`git push origin my_awesome_feature`).
-- Create a pull request against halostatue/diff-lcs and describe what your
-  change does and the why you think it should be merged.
+- `Related to`: If a change does not fix an issue, those issue references should
+  be included in this trailer.
 
+[cbeams]: https://cbea.ms/git-commit/
+[cccoc]: ./CODE_OF_CONDUCT.md
+[conventional]: https://www.conventionalcommits.org/en/v1.0.0/
 [dco]: licences/dco.txt
 [hoe]: https://github.com/seattlerb/hoe
-[qcm]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
+[issues]: https://github.com/halostatue/diff-lcs/issues
 [rspec]: http://rspec.info/documentation/
 [standardrb]: https://github.com/standardrb/standard
+[tpope-qcm]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
+[trailers1]: https://git-scm.com/docs/git-interpret-trailers
+[trailers2]: https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---trailerlttokengtltvaluegt