Change strings::translate API to accept span instead of vector

[davidwendt]

Description

Changes the libcudf cudf::strings::translate to accept a span instead of a const vector.
This adds a new span overload while deprecating the vector version.
Call sites are modified to cast to span to force them to use the new API but the cast could be removed once the deprecated function is deleted in a later release.

Part of #23875 -- starting simple to prove the deprecation pattern is viable.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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📥 Commits

Reviewing files that changed from the base of the PR and between 0928c03 and 913afde.

📒 Files selected for processing (1)

• cpp/include/cudf/strings/translate.hpp

🚧 Files skipped from review as they are similar to previous changes (1)

• cpp/include/cudf/strings/translate.hpp

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📝 Summary

Summary by CodeRabbit

• New Features

  • Added support for providing string translation tables as read-only spans.
  • Existing vector-based translation support remains available but is now deprecated.
  • Updated translation API descriptions to clarify that translated strings are returned.

• Tests

  • Updated translation benchmarks and tests to use the span-based interface while preserving existing behavior and expected results.

Walkthrough

The cudf::strings::translate API now supports std::span mappings. The vector overload is deprecated and delegates through the span overload. Internal code, benchmarks, and tests use spans.

Changes

Translate span API

Layer / File(s)	Summary
Add span overload and delegation cpp/include/cudf/strings/translate.hpp, cpp/src/strings/translate.cu	The API adds a std::span overload, marks the vector overload deprecated, and forwards vector calls through a span. Internal translation accepts a read-only span.
Migrate callers and validation cpp/benchmarks/string/translate.cpp, cpp/tests/streams/strings/filter_test.cpp, cpp/tests/strings/translate_tests.cpp	The benchmark and translation tests pass mapping tables through std::span. The filter test also updates its copyright notice.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: 🔵 Low · up to 913af

The API now accepts std::span while retaining vector compatibility, but the deprecated vector path lacks direct regression coverage. The change is low risk to merge with follow-up testing.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: updating the strings::translate API to accept std::span while replacing the vector-based interface.
Description check	✅ Passed	The description accurately explains the new std::span overload, deprecation of the vector overload, updated call sites, and test coverage.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 2

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Inline comments:
In `@cpp/include/cudf/strings/translate.hpp`:
- Line 74: Update the return description for the translate API to state that it
returns a new column with translated strings, replacing the incorrect
padded-strings wording.

In `@cpp/src/strings/translate.cu`:
- Line 133: Add a direct unit test for the deprecated std::vector overload of
cudf::strings::translate, using a vector character table and verifying the
translated result; keep existing span-overload coverage unchanged.

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Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between d4eb468 and 0928c03.

📒 Files selected for processing (5)

• cpp/benchmarks/string/translate.cpp
• cpp/include/cudf/strings/translate.hpp
• cpp/src/strings/translate.cu
• cpp/tests/streams/strings/filter_test.cpp
• cpp/tests/strings/translate_tests.cpp

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