[all-commits] [llvm/llvm-project] e30a5d: [libc++][NFC] Simplify string a bit (#127135)

[Peng Liu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e30a5d657034c1cf7081be4601a39888c0c1f2a6
      https://github.com/llvm/llvm-project/commit/e30a5d657034c1cf7081be4601a39888c0c1f2a6
  Author: Peng Liu <winner245 at hotmail.com>
  Date:   2025-03-15 (Sat, 15 Mar 2025)

  Changed paths:
    M libcxx/include/string

  Log Message:
  -----------
  [libc++][NFC] Simplify string a bit (#127135)

This PR refactors `basic_string` a bit to simplify its implementation in
the following ways:
- Instead of manually checking whether a string is short or long,
followed by calling the specific functions (e.g., `__get_short_size()`,
`__get_long_size()`), we call the general functions (`size()`) to hide
the conditional checks and make the code more concise.
- Once a string is determined to be short or long, we directly call the
specific functions instead of the general versions to get rid of
unnecessary internal conditional checks. For example, for a long string,
we would directly call `{__set, __get}_long_pointer` instead of `{__set,
__get}_pointer()`.
- Variables that are defined in both the `if` and `else` branches are
now declared in a common scope to reduce redundancy.
- When the string size is calculated multiple times using
`traits_type::length(__s)`, a variable is introduced to store its
length. While modern compilers can optimize this with constant folding,
explicitly storing the length improves code readability and makes the
logic clearer.
- Fixed synopsis with missing default arguments.



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