fix(generator): preserve comment introducers across embedded newlines

[colinmoy]

No description provided.

[gemini-code-assist]

Code Review

This pull request updates FormatCommentBlock in codegen_utils.cc to correctly handle multi-line comments and paragraph splitting, and adds corresponding unit tests. The review feedback recommends optimizing memory usage by using absl::string_view instead of std::string to avoid unnecessary heap allocations, and refactoring the final formatting loop to eliminate an unnecessary else block, aligning with the repository's style guide.

[gemini-code-assist]

Using std::vector<std::string> causes unnecessary memory allocations and copies for each line of the comment block. Since the comment parameter is passed as a const std::string& and its lifetime outlives this function, we can use std::vector<absl::string_view> instead to avoid these heap allocations.

std::vector<absl::string_view>lines;
std::vector<absl::string_view>paragraphs=absl::StrSplit(comment, '\n');
for (auto const&paragraph : paragraphs) {
if (paragraph.empty()) {
lines.emplace_back();
continue;
}
std::size_tstart_pos=0;
while (start_pos!=absl::string_view::npos) {
std::size_tboundary=start_pos+comment_width;
std::size_tend_pos=boundary;
if (boundary<paragraph.length()) {
// Look backward from the boundary for the last wordend_pos=paragraph.rfind(' ', boundary);
// If there is only one word, find and use its boundaryif (end_pos==absl::string_view::npos||end_pos<start_pos) {
end_pos=paragraph.find(' ', boundary);
}
}
lines.push_back(paragraph.substr(start_pos, end_pos-start_pos));
start_pos=paragraph.find_first_not_of(' ', end_pos);
}
}

References

1. Scrutinize copies of non-fundamental C++ types. Is it necessary to copy the data? ^(link)

[scotthart]

use std::string_view instead of absl::string_view

[colinmoy]

Done

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.24%. Comparing base (10083ab) to head (f58b6f2).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #16332 +/- ##
=======================================
Coverage 92.23% 92.24% =======================================
Files 2227 2227 Lines 209543 209563 +20 =======================================
+ Hits 193278 193308 +30 + Misses 16265 16255 -10 

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