[ADT] Use std::string_view inside StringRef #113775
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This patch makes minimum changes to replace Data and Length with an instance of std::string_view. Previously, I opted for public inheritance (llvm#113752), but I encountered a lot of errors from gcc stemming from ambiguity between std::string_view and StringRef. The composition approach in this patch gives us greater control at the expense of forwarder functions.
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@llvm/pr-subscribers-llvm-adt Author: Kazu Hirata (kazutakahirata) ChangesThis patch makes minimum changes to replace Data and Length with an Previously, I opted for public inheritance (#113752), but I The composition approach in this patch gives us greater control at the Full diff: https://github.com/llvm/llvm-project/pull/113775.diff 1 Files Affected:
diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h
index d5f30b88c4c6a2..f879bbf7164fd6 100644
--- a/llvm/include/llvm/ADT/StringRef.h
+++ b/llvm/include/llvm/ADT/StringRef.h
@@ -60,11 +60,7 @@ namespace llvm {
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
private:
- /// The start of the string, in an external buffer.
- const char *Data = nullptr;
-
- /// The length of the string.
- size_t Length = 0;
+ std::string_view View;
// Workaround memcmp issue with null pointers (undefined behavior)
// by providing a specialized version
@@ -86,27 +82,25 @@ namespace llvm {
/// Construct a string ref from a cstring.
/*implicit*/ constexpr StringRef(const char *Str)
- : Data(Str), Length(Str ?
+ : View(Str, Str ?
// GCC 7 doesn't have constexpr char_traits. Fall back to __builtin_strlen.
#if defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE < 8
- __builtin_strlen(Str)
+ __builtin_strlen(Str)
#else
- std::char_traits<char>::length(Str)
+ std::char_traits<char>::length(Str)
#endif
- : 0) {
+ : 0) {
}
/// Construct a string ref from a pointer and length.
/*implicit*/ constexpr StringRef(const char *data, size_t length)
- : Data(data), Length(length) {}
+ : View(data, length) {}
/// Construct a string ref from an std::string.
- /*implicit*/ StringRef(const std::string &Str)
- : Data(Str.data()), Length(Str.length()) {}
+ /*implicit*/ StringRef(const std::string &Str) : View(Str) {}
/// Construct a string ref from an std::string_view.
- /*implicit*/ constexpr StringRef(std::string_view Str)
- : Data(Str.data()), Length(Str.size()) {}
+ /*implicit*/ constexpr StringRef(std::string_view Str) : View(Str) {}
/// @}
/// @name Iterators
@@ -140,13 +134,13 @@ namespace llvm {
/// data - Get a pointer to the start of the string (which may not be null
/// terminated).
- [[nodiscard]] constexpr const char *data() const { return Data; }
+ [[nodiscard]] constexpr const char *data() const { return View.data(); }
/// empty - Check if the string is empty.
[[nodiscard]] constexpr bool empty() const { return size() == 0; }
/// size - Get the string size.
- [[nodiscard]] constexpr size_t size() const { return Length; }
+ [[nodiscard]] constexpr size_t size() const { return View.size(); }
/// front - Get the first character in the string.
[[nodiscard]] char front() const {
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kuhar
approved these changes
Oct 27, 2024
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/139/builds/5462 Here is the relevant piece of the build log for the reference |
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/52/builds/3251 Here is the relevant piece of the build log for the reference |
Collaborator
|
With inheritance I can sort of see the path forward to migration a bit (pending RFC discussion that that's the direction we're going in) - but with composition, I find it a bit harder to see the path forward. Could you clarify what this migration looks like using composition instead of (or as a precursor to) inheritance? |
kazutakahirata
added a commit
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Oct 29, 2024
This patch reverts commit 89b5d88. Some sanitizer failures have been reported, indivating that StringRef and std::string_view handle data == nulptr differently. Also, they support different values for the max size (size_t v.s. ptrdiff_t). Thanks goes to Jorge Gorbe Moya for reporting these.
kazutakahirata
added a commit
that referenced
this pull request
Oct 29, 2024
This patch reverts commit 89b5d88. Some sanitizer failures have been reported, indicating that StringRef and std::string_view handle data == nulptr differently. Also, they support different values for the max size (size_t v.s. ptrdiff_t). Thanks goes to Jorge Gorbe Moya for reporting these.
NoumanAmir657
pushed a commit
to NoumanAmir657/llvm-project
that referenced
this pull request
Nov 4, 2024
This patch makes minimum changes to replace Data and Length with an instance of std::string_view. Previously, I opted for public inheritance (llvm#113752), but I encountered a lot of errors from gcc stemming from ambiguity between std::string_view and StringRef. The composition approach in this patch gives us greater control at the expense of forwarder functions.
NoumanAmir657
pushed a commit
to NoumanAmir657/llvm-project
that referenced
this pull request
Nov 4, 2024
…lvm#114133) This patch reverts commit 89b5d88. Some sanitizer failures have been reported, indicating that StringRef and std::string_view handle data == nulptr differently. Also, they support different values for the max size (size_t v.s. ptrdiff_t). Thanks goes to Jorge Gorbe Moya for reporting these.
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This patch makes minimum changes to replace Data and Length with an
instance of std::string_view.
Previously, I opted for public inheritance (#113752), but I
encountered a lot of errors from gcc stemming from ambiguity between
std::string_view and StringRef.
The composition approach in this patch gives us greater control at the
expense of forwarder functions.