diff options
Diffstat (limited to 'absl/strings/cord.h')
-rw-r--r-- | absl/strings/cord.h | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/absl/strings/cord.h b/absl/strings/cord.h index 5fc61a73..7136f034 100644 --- a/absl/strings/cord.h +++ b/absl/strings/cord.h @@ -82,7 +82,6 @@ #include "absl/strings/internal/string_constant.h" #include "absl/strings/string_view.h" #include "absl/types/optional.h" -#include "absl/types/variant.h" namespace absl { ABSL_NAMESPACE_BEGIN @@ -362,7 +361,11 @@ class Cord { friend class CharIterator; private: - using Stack = absl::InlinedVector<absl::cord_internal::CordRep*, 4>; + // Stack of right children of concat nodes that we have to visit. + // Keep this at the end of the structure to avoid cache-thrashing. + // TODO(jgm): Benchmark to see if there's a more optimal value than 47 for + // the inlined vector size (47 exists for backward compatibility). + using Stack = absl::InlinedVector<absl::cord_internal::CordRep*, 47>; // Constructs a `begin()` iterator from `cord`. explicit ChunkIterator(const Cord* cord); @@ -389,10 +392,8 @@ class Cord { absl::cord_internal::CordRep* current_leaf_ = nullptr; // The number of bytes left in the `Cord` over which we are iterating. size_t bytes_remaining_ = 0; - // Context of this chunk iterator, can be one of: - // - monostate: iterator holds only one chunk or is empty. - // - Stack : iterator holds a concat / substring tree - absl::variant<absl::monostate, Stack> context_; + // See 'Stack' alias definition. + Stack stack_of_right_children_; }; // Cord::ChunkIterator::chunk_begin() @@ -1108,8 +1109,7 @@ inline Cord::ChunkIterator::ChunkIterator(const Cord* cord) : bytes_remaining_(cord->size()) { if (cord->empty()) return; if (cord->contents_.is_tree()) { - Stack& stack_of_right_children = context_.emplace<Stack>(); - stack_of_right_children.push_back(cord->contents_.tree()); + stack_of_right_children_.push_back(cord->contents_.tree()); operator++(); } else { current_chunk_ = absl::string_view(cord->contents_.data(), cord->size()); @@ -1122,9 +1122,7 @@ inline Cord::ChunkIterator& Cord::ChunkIterator::operator++() { assert(bytes_remaining_ >= current_chunk_.size()); bytes_remaining_ -= current_chunk_.size(); if (bytes_remaining_ > 0) { - if (absl::holds_alternative<Stack>(context_)) { - return AdvanceStack(); - } + return AdvanceStack(); } else { current_chunk_ = {}; } |