feat: Add ArrowArray and ArrowArrayStream C++ iterators

[bkietz]

All of this should be c++11

-  auto arrow_array = ImportArray(&array, large_utf8());
-  ARROW_EXPECT_OK(arrow_array);
-
-  auto builder = LargeStringBuilder();
-  ARROW_EXPECT_OK(builder.Append("1234"));
-  ARROW_EXPECT_OK(builder.AppendNulls(2));
-  ARROW_EXPECT_OK(builder.Append("56789"));
-  ARROW_EXPECT_OK(builder.AppendEmptyValue());
-  auto expected_array = builder.Finish();
-
-  EXPECT_TRUE(arrow_array.ValueUnsafe()->Equals(expected_array.ValueUnsafe()));
+  EXPECT_THAT(nanoarrow::ViewAsBytes<64>(&array),
+              ElementsAre("1234"_v, kNull, kNull, "56789"_v, ""_v));

fixes #403

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.78%. Comparing base (dc50114) to head (89e73bc).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #404      +/-   ##
==========================================
+ Coverage   88.74%   88.78%   +0.03%     
==========================================
  Files          81       81              
  Lines       14398    14486      +88     
==========================================
+ Hits        12778    12861      +83     
- Misses       1620     1625       +5     

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[paleolimbot]

I know you're still working on this...just a few early comments!

[paleolimbot]

In file included from /home/runner/work/arrow-nanoarrow/arrow-nanoarrow/dev/benchmarks/c/array_benchmark.cc:22:
  /home/runner/work/arrow-nanoarrow/arrow-nanoarrow/dev/benchmarks/c/util.h:25:2: error: #error "Zip cannot be supported without C++17 features"
     25 | #error "Zip cannot be supported without C++17 features"
        |  ^~~~~

...might be fixed by set(CMAKE_CXX_STANDARD 17) in the dev/benchmarks/CMakeLists.txt (unless you were checking that it failed on purpose, in which case ignore me 🙂 ).

[paleolimbot]

Thank you for working on this!

Just small comments from me...the big one is that I'd prefer to put the ViewArrayAs helper in nanoarrow_testing.hpp if we don't have the bandwidth to dedicate test coverage for it right now.

[paleolimbot]

(Pushes to the branch at Ben's invitation 🙂 )

Thank you for bearing with me on this PR and thank you for the tests! I made a few changes to satisfy the constraints enforced by CI here:

• Because we test against the bundled version (as defined by cmake . -NANOARROW_BUNDLE=ON && cmake --install .), the extra file had to be bundled in the same way as all the others.
• The benchmarks are specifically designed to build against previous versions (so that they can be run by downstream users to determine if they should upgrade their version pin). This means that ViewArrayAs would have to be guarded with an #ifdef, but then different versions would be benchmarking different code. It seems as though the use of Zip is mostly useful alongside ViewArrayAs, so I removed that particular change from this PR (but saved those changes and pushed them to chore(dev/benchmarks): Benchmark ViewArrayAs for versions that contain the helper #443). I'm sorry for not catching that at an earlier stage in the review 😬

Before this merges I think the new helpers need at least a cursory documentation section since this is a user-facing change (I'm happy to circle back and add this and will definitely do so before the next release).

[paleolimbot]

Thank you!