https://github.com/kazutakahirata created
https://github.com/llvm/llvm-project/pull/156137
StringMap has four iterator classes:
- StringMapIterBase
- StringMapIterator
- StringMapConstIterator
- StringMapKeyIterator
This patch consolidates the first three into one class, namely
StringMapIterBase, adds a boolean template parameter to indicate
desired constness, and then use "using" directives to specialize the
common class:
using const_iterator = StringMapIterBase<ValueTy, true>;
using iterator = StringMapIterBase<ValueTy, false>;
just like how we simplified DenseMapIterator.
Remarks:
- This patch drops CRTP and iterator_facade_base for simplicity. For
fairly simple forward iterators, iterator_facade_base doesn't buy us
much. We just have to write a few "using" directives and operator!=
manually.
- StringMapIterBase has a SFINAE-based constructor to construct a
const iterator from a non-const one just like DenseMapIterator.
- We now rely on compiler-generated copy and assignment operators.
>From 2acfa1ad795eac48ea106ae2d0af2a398c9b3eb5 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <k...@google.com>
Date: Fri, 29 Aug 2025 13:56:48 -0700
Subject: [PATCH] [ADT] Refactor StringMap iterators (NFC)
StringMap has four iterator classes:
- StringMapIterBase
- StringMapIterator
- StringMapConstIterator
- StringMapKeyIterator
This patch consolidates the first three into one class, namely
StringMapIterBase, adds a boolean template parameter to indicate
desired constness, and then use "using" directives to specialize the
common class:
using const_iterator = StringMapIterBase<ValueTy, true>;
using iterator = StringMapIterBase<ValueTy, false>;
just like how we simplified DenseMapIterator.
Remarks:
- This patch drops CRTP and iterator_facade_base for simplicity. For
fairly simple forward iterators, iterator_facade_base doesn't buy us
much. We just have to write a few "using" directives and operator!=
manually.
- StringMapIterBase has a SFINAE-based constructor to construct a
const iterator from a non-const one just like DenseMapIterator.
- We now rely on compiler-generated copy and assignment operators.
---
.../fuchsia/MultipleInheritanceCheck.cpp | 2 +-
clang/lib/Driver/OffloadBundler.cpp | 3 +-
llvm/include/llvm/ADT/StringMap.h | 98 +++++++------------
3 files changed, 39 insertions(+), 64 deletions(-)
diff --git a/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
b/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
index 36b6007b58a51..4382f9df5336e 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
@@ -39,7 +39,7 @@ bool MultipleInheritanceCheck::getInterfaceStatus(const
CXXRecordDecl *Node,
bool &IsInterface) const {
assert(Node->getIdentifier());
StringRef Name = Node->getIdentifier()->getName();
- llvm::StringMapConstIterator<bool> Pair = InterfaceMap.find(Name);
+ auto Pair = InterfaceMap.find(Name);
if (Pair == InterfaceMap.end())
return false;
IsInterface = Pair->second;
diff --git a/clang/lib/Driver/OffloadBundler.cpp
b/clang/lib/Driver/OffloadBundler.cpp
index e83aee01b75cb..f69ac41dddb3e 100644
--- a/clang/lib/Driver/OffloadBundler.cpp
+++ b/clang/lib/Driver/OffloadBundler.cpp
@@ -1936,8 +1936,7 @@ Error OffloadBundler::UnbundleArchive() {
/// Write out an archive for each target
for (auto &Target : BundlerConfig.TargetNames) {
StringRef FileName = TargetOutputFileNameMap[Target];
- StringMapIterator<std::vector<llvm::NewArchiveMember>> CurArchiveMembers =
- OutputArchivesMap.find(Target);
+ auto CurArchiveMembers = OutputArchivesMap.find(Target);
if (CurArchiveMembers != OutputArchivesMap.end()) {
if (Error WriteErr = writeArchive(FileName,
CurArchiveMembers->getValue(),
SymtabWritingMode::NormalSymtab,
diff --git a/llvm/include/llvm/ADT/StringMap.h
b/llvm/include/llvm/ADT/StringMap.h
index dbc0485967ac6..aabe8cd7903c8 100644
--- a/llvm/include/llvm/ADT/StringMap.h
+++ b/llvm/include/llvm/ADT/StringMap.h
@@ -21,11 +21,11 @@
#include "llvm/Support/PointerLikeTypeTraits.h"
#include <initializer_list>
#include <iterator>
+#include <type_traits>
namespace llvm {
-template <typename ValueTy> class StringMapConstIterator;
-template <typename ValueTy> class StringMapIterator;
+template <typename ValueTy, bool IsConst> class StringMapIterBase;
template <typename ValueTy> class StringMapKeyIterator;
/// StringMapImpl - This is the base class of StringMap that is shared among
@@ -217,8 +217,8 @@ class LLVM_ALLOCATORHOLDER_EMPTYBASE StringMap
using value_type = StringMapEntry<ValueTy>;
using size_type = size_t;
- using const_iterator = StringMapConstIterator<ValueTy>;
- using iterator = StringMapIterator<ValueTy>;
+ using const_iterator = StringMapIterBase<ValueTy, true>;
+ using iterator = StringMapIterBase<ValueTy, false>;
iterator begin() { return iterator(TheTable, NumBuckets == 0); }
iterator end() { return iterator(TheTable + NumBuckets, true); }
@@ -431,14 +431,19 @@ class LLVM_ALLOCATORHOLDER_EMPTYBASE StringMap
}
};
-template <typename DerivedTy, typename ValueTy>
-class StringMapIterBase
- : public iterator_facade_base<DerivedTy, std::forward_iterator_tag,
- ValueTy> {
-protected:
+template <typename ValueTy, bool IsConst> class StringMapIterBase {
+ using EntryTy = std::conditional_t<IsConst, const StringMapEntry<ValueTy>,
+ StringMapEntry<ValueTy>>;
+
StringMapEntryBase **Ptr = nullptr;
public:
+ using iterator_category = std::forward_iterator_tag;
+ using value_type = EntryTy;
+ using difference_type = std::ptrdiff_t;
+ using pointer = value_type *;
+ using reference = value_type &;
+
StringMapIterBase() = default;
explicit StringMapIterBase(StringMapEntryBase **Bucket,
@@ -448,85 +453,56 @@ class StringMapIterBase
AdvancePastEmptyBuckets();
}
- DerivedTy &operator=(const DerivedTy &Other) {
- Ptr = Other.Ptr;
- return static_cast<DerivedTy &>(*this);
- }
-
- friend bool operator==(const DerivedTy &LHS, const DerivedTy &RHS) {
- return LHS.Ptr == RHS.Ptr;
- }
+ reference operator*() const { return *static_cast<EntryTy *>(*Ptr); }
+ pointer operator->() const { return &operator*(); }
- DerivedTy &operator++() { // Preincrement
+ StringMapIterBase &operator++() { // Preincrement
++Ptr;
AdvancePastEmptyBuckets();
- return static_cast<DerivedTy &>(*this);
+ return *this;
}
- DerivedTy operator++(int) { // Post-increment
- DerivedTy Tmp(Ptr);
+ StringMapIterBase operator++(int) { // Post-increment
+ StringMapIterBase Tmp(*this);
++*this;
return Tmp;
}
-private:
- void AdvancePastEmptyBuckets() {
- while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
- ++Ptr;
+ template <bool ToConst,
+ typename = typename std::enable_if<!IsConst && ToConst>::type>
+ operator StringMapIterBase<ValueTy, ToConst>() const {
+ return StringMapIterBase<ValueTy, ToConst>(Ptr, true);
}
-};
-
-template <typename ValueTy>
-class StringMapConstIterator
- : public StringMapIterBase<StringMapConstIterator<ValueTy>,
- const StringMapEntry<ValueTy>> {
- using base = StringMapIterBase<StringMapConstIterator<ValueTy>,
- const StringMapEntry<ValueTy>>;
-
-public:
- StringMapConstIterator() = default;
- explicit StringMapConstIterator(StringMapEntryBase **Bucket,
- bool NoAdvance = false)
- : base(Bucket, NoAdvance) {}
- const StringMapEntry<ValueTy> &operator*() const {
- return *static_cast<const StringMapEntry<ValueTy> *>(*this->Ptr);
+ friend bool operator==(const StringMapIterBase &LHS,
+ const StringMapIterBase &RHS) {
+ return LHS.Ptr == RHS.Ptr;
}
-};
-
-template <typename ValueTy>
-class StringMapIterator : public StringMapIterBase<StringMapIterator<ValueTy>,
- StringMapEntry<ValueTy>> {
- using base =
- StringMapIterBase<StringMapIterator<ValueTy>, StringMapEntry<ValueTy>>;
-public:
- StringMapIterator() = default;
- explicit StringMapIterator(StringMapEntryBase **Bucket,
- bool NoAdvance = false)
- : base(Bucket, NoAdvance) {}
-
- StringMapEntry<ValueTy> &operator*() const {
- return *static_cast<StringMapEntry<ValueTy> *>(*this->Ptr);
+ friend bool operator!=(const StringMapIterBase &LHS,
+ const StringMapIterBase &RHS) {
+ return !(LHS == RHS);
}
- operator StringMapConstIterator<ValueTy>() const {
- return StringMapConstIterator<ValueTy>(this->Ptr, true);
+private:
+ void AdvancePastEmptyBuckets() {
+ while (*Ptr == nullptr || *Ptr == StringMapImpl::getTombstoneVal())
+ ++Ptr;
}
};
template <typename ValueTy>
class StringMapKeyIterator
: public iterator_adaptor_base<StringMapKeyIterator<ValueTy>,
- StringMapConstIterator<ValueTy>,
+ StringMapIterBase<ValueTy, true>,
std::forward_iterator_tag, StringRef> {
using base = iterator_adaptor_base<StringMapKeyIterator<ValueTy>,
- StringMapConstIterator<ValueTy>,
+ StringMapIterBase<ValueTy, true>,
std::forward_iterator_tag, StringRef>;
public:
StringMapKeyIterator() = default;
- explicit StringMapKeyIterator(StringMapConstIterator<ValueTy> Iter)
+ explicit StringMapKeyIterator(StringMapIterBase<ValueTy, true> Iter)
: base(std::move(Iter)) {}
StringRef operator*() const { return this->wrapped()->getKey(); }
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