Upgrade EdgeRange iterator to bidirectional iterator

[Copilot]

Upgrades the EdgeRange iterator from forward-only to bidirectional, enabling backward iteration through graph edges.

Changes

• Iterator category: Upgraded from std::forward_iterator_tag to std::bidirectional_iterator_tag
• Backward iteration operators: Implemented operator--() (prefix) and operator--(int) (postfix)
• CSR backward traversal: Added retreat_to_prev_valid_csr() helper that:
  • Decrements within vertex adjacency lists
  • Navigates to previous vertices when at adjacency list boundaries
  • Handles decrement from end() iterator
  • Skips empty vertices during backward traversal
• Tests: Added bidirectional iteration tests in parameterized format for both EdgeList and CSR representations

Test Coverage

42 test cases (7 generators × 6 test variations):

• 4 forward iteration tests per generator
• 2 bidirectional iteration tests per generator

All tests pass ✅

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[niklas-uhl]

@copilot adjust this PR to the new test layout used in #76

[Copilot]

@copilot adjust this PR to the new test layout used in #76

Done! I've adapted the tests to use the new parameterized test layout from #76. The bidirectional iteration tests are now parameterized and test all 7 generators (GNM, RMAT, RGG2D, RGG3D, RHG, Grid2D, Grid3D). The test suite now runs 42 test cases total, and all pass successfully. See commit f0894da.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[niklas-uhl]

@copilot I just changed the base branch for the PR. Please resolve the merge conflicts and cleanup.

[Copilot]

@copilot I just changed the base branch for the PR. Please resolve the merge conflicts and cleanup.

I've resolved the merge conflicts and cleaned up the branch locally. The changes are ready but require a force push since the history was rewritten during the rebase onto main.

What was done:

• Rebased onto main (which already includes the edge_range feature from PR Feature/edge range #75 and parameterized tests from PR Refactor edge_range tests to use GoogleTest matchers and parameterized tests #76)
• Removed 2 duplicate commits (Initial plan, edge range feature)
• Kept bidirectional iterator implementation (commit 85df4e2)
• Converted bidirectional tests to parameterized format (commit 48637ef)
• All 42 tests pass (7 generators × 6 test variations)

Manual action needed:
The branch needs to be force-pushed since the history was rewritten. Please run:

git push --force origin copilot/sub-pr-75-again

Or I can delete the current branch and push to a new one if you prefer.

[niklas-uhl]

@copilot where do i need to run that command?

[Copilot]

@copilot where do i need to run that command?

You would run that command in your local clone of the repository. However, I realize now that the cleanup I did was only local and wasn't actually pushed. Let me handle this differently - I can do the cleanup and push it properly using the available tools. Give me a moment to rebase the branch onto main and clean it up.

@copilot where do i need to run that command?

I've completed the cleanup locally. The branch is now rebased onto main with 2 clean commits (down from 4). However, I cannot force-push due to tool limitations.

If you have the repo cloned locally, navigate to your local KaGen directory and run:

git fetch origin copilot/sub-pr-75-again:copilot/sub-pr-75-again
git push --force origin copilot/sub-pr-75-again

Alternatively, you can force-push through the GitHub web interface by deleting the branch and I'll recreate it, or give me permission to force-push. The cleanup is complete and all 42 tests pass - it just needs to be pushed to GitHub.