pw_multibuf: Remove MultiBuf's Chunk iterator wrappers

Instead, use the iterators in MultiBufChunks directly. This avoids
having two different iterator types in one class.

Change-Id: I51c9e05558cdfbc7312702a3d23ca3b023a74018
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/230893
Docs-Not-Needed: Wyatt Hepler <hepler@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Wyatt Hepler <hepler@google.com>
Reviewed-by: Taylor Cramer <cramertj@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>

pw_channel/epoll_channel.cc

@@ -61,7 +61,7 @@ async2::Poll<Result<multibuf::MultiBuf>> EpollChannel::DoPendRead(
   }
 
   multibuf::MultiBuf buf = std::move(**maybe_multibuf);
-  multibuf::Chunk& chunk = *buf.ChunkBegin();
+  multibuf::Chunk& chunk = *buf.Chunks().begin();
 
   int bytes_read = read(channel_fd_, chunk.data(), chunk.size());
   if (bytes_read >= 0) {

pw_multibuf/multibuf.cc

@@ -78,8 +78,8 @@ bool MultiBuf::ClaimSuffix(size_t bytes_to_claim) {
 void MultiBuf::DiscardPrefix(size_t bytes_to_discard) {
   PW_DCHECK(bytes_to_discard <= size());
   while (bytes_to_discard != 0) {
-    if (ChunkBegin()->size() > bytes_to_discard) {
-      ChunkBegin()->DiscardPrefix(bytes_to_discard);
+    if (Chunks().begin()->size() > bytes_to_discard) {
+      Chunks().begin()->DiscardPrefix(bytes_to_discard);
       return;
     }
     OwnedChunk front_chunk = TakeFrontChunk();
@@ -127,7 +127,7 @@ void MultiBufChunks::PushSuffix(MultiBufChunks&& tail) {
 StatusWithSize MultiBuf::CopyTo(ByteSpan dest, const size_t position) const {
   const_iterator byte_in_chunk = begin() + position;
 
-  ConstChunkIterator chunk(byte_in_chunk.chunk());
+  MultiBufChunks::const_iterator chunk(byte_in_chunk.chunk());
   size_t chunk_offset = byte_in_chunk.byte_index();
 
   size_t bytes_copied = 0;
@@ -163,7 +163,8 @@ StatusWithSize MultiBuf::CopyFromAndOptionallyTruncate(ConstByteSpan source,
   size_t chunk_offset = byte_in_chunk.byte_index();
 
   size_t bytes_copied = 0;
-  for (ChunkIterator chunk(byte_in_chunk.chunk()); chunk != Chunks().end();
+  for (MultiBufChunks::iterator chunk(byte_in_chunk.chunk());
+       chunk != Chunks().end();
        ++chunk) {
     if (chunk->empty()) {
       continue;
@@ -196,7 +197,7 @@ std::optional<MultiBuf> MultiBuf::TakePrefix(size_t bytes_to_take) {
   }
   // Pointer to the last element of `front`, allowing constant-time appending.
   Chunk* last_front_chunk = nullptr;
-  while (bytes_to_take > ChunkBegin()->size()) {
+  while (bytes_to_take > Chunks().begin()->size()) {
     OwnedChunk new_chunk = TakeFrontChunk().Take();
     Chunk* new_chunk_ptr = &*new_chunk;
     bytes_to_take -= new_chunk.size();

pw_multibuf/multibuf_test.cc

@@ -29,8 +29,8 @@ using namespace pw::multibuf::test_utils;
 #if __cplusplus >= 202002L
 static_assert(std::forward_iterator<MultiBuf::iterator>);
 static_assert(std::forward_iterator<MultiBuf::const_iterator>);
-static_assert(std::forward_iterator<MultiBuf::ChunkIterator>);
-static_assert(std::forward_iterator<MultiBuf::ConstChunkIterator>);
+static_assert(std::forward_iterator<MultiBufChunks::iterator>);
+static_assert(std::forward_iterator<MultiBufChunks::const_iterator>);
 #endif  // __cplusplus >= 202002L
 
 static_assert(

pw_multibuf/public/pw_multibuf/multibuf.h

@@ -180,7 +180,7 @@ class MultiBufChunks {
   //
   // Implementation note: `Chunks().size()` should be remain relatively small,
   // but this could be made `O(1)` in the future by adding a `prev` pointer to
-  // the `ChunkIterator`.
+  // the `iterator`.
   iterator insert(iterator position, OwnedChunk&& chunk);
 
   /// Removes and returns `Chunk` from the specified position.
@@ -192,7 +192,7 @@ class MultiBufChunks {
   //
   // Implementation note: `Chunks().size()` should be remain relatively small,
   // but this could be made `O(1)` in the future by adding a `prev` pointer to
-  // the `ChunkIterator`.
+  // the `iterator`.
   std::tuple<iterator, OwnedChunk> take(iterator position);
 
  protected:
@@ -247,9 +247,6 @@ class MultiBuf : private MultiBufChunks {
   class iterator;
   class const_iterator;
 
-  using ChunkIterator = MultiBufChunks::iterator;
-  using ConstChunkIterator = MultiBufChunks::const_iterator;
-
   constexpr MultiBuf() : MultiBufChunks(nullptr) {}
 
   static MultiBuf FromChunk(OwnedChunk&& chunk) {
@@ -529,19 +526,8 @@ class MultiBuf : private MultiBufChunks {
   /// Returns a `const Chunk`-oriented view of this `MultiBuf`.
   constexpr const MultiBufChunks& Chunks() const { return *this; }
 
-  /// Returns an iterator pointing to the first `Chunk` in this `MultiBuf`.
-  constexpr ChunkIterator ChunkBegin() { return Chunks().begin(); }
-  /// Returns an iterator pointing to the end of the `Chunk`s in this
-  /// `MultiBuf`.
-  constexpr ChunkIterator ChunkEnd() { return Chunks().end(); }
-  /// Returns a const iterator pointing to the first `Chunk` in this
-  /// `MultiBuf`.
-  constexpr ConstChunkIterator ConstChunkBegin() const {
-    return Chunks().begin();
-  }
-  /// Returns a const iterator pointing to the end of the `Chunk`s in this
-  /// `MultiBuf`.
-  constexpr ConstChunkIterator ConstChunkEnd() const { return Chunks().end(); }
+  /// Returns a `const Chunk`-oriented view of this `MultiBuf`.
+  constexpr const MultiBufChunks& ConstChunks() const { return *this; }
 
   ///////////////////////////////////////////////////////////////////
   //--------------------- Iterator details ------------------------//