Export of internal Abseil changes

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3b43586da865534cf86401d2cae09c65c60b8474 by Abseil Team <absl-team@google.com>:

Introduce CordRepRingReader class

PiperOrigin-RevId: 353070937

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0bff6e4bcca34fdd1e6610da5fb3c37fd49b2940 by Abseil Team <absl-team@google.com>:

Fix docstring typo "Exmaple" -> "Example"

PiperOrigin-RevId: 352927688

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1ef4e0a1100cfa7bc9d9e8f155acf0e469348b56 by Abseil Team <absl-team@google.com>:

Refactor tree initialization of ChunkIterator and CordReader

PiperOrigin-RevId: 352916786

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919c3eb175b87294184a405785eef4fab520d47e by Abseil Team <absl-team@google.com>:

Disable `preserve_most` when compiling with sanitizers.

PiperOrigin-RevId: 352890630
GitOrigin-RevId: 3b43586da865534cf86401d2cae09c65c60b8474
Change-Id: I8a733494b353af69a46862a4019a7f9b40148f49

1 files changed, 18 insertions, 2 deletions

diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 9d8764a0..abef98fe 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -367,9 +367,15 @@ class Cord {
     // the inlined vector size (47 exists for backward compatibility).
     using Stack = absl::InlinedVector<absl::cord_internal::CordRep*, 47>;
 
+    // Constructs a `begin()` iterator from `tree`. `tree` must not be null.
+    explicit ChunkIterator(cord_internal::CordRep* tree);
+
     // Constructs a `begin()` iterator from `cord`.
     explicit ChunkIterator(const Cord* cord);
 
+    // Initializes this instance from a tree. Invoked by constructors.
+    void InitTree(cord_internal::CordRep* tree);
+
     // Removes `n` bytes from `current_chunk_`. Expects `n` to be smaller than
     // `current_chunk_.size()`.
     void RemoveChunkPrefix(size_t n);
@@ -1100,11 +1106,20 @@ inline bool Cord::StartsWith(absl::string_view rhs) const {
   return EqualsImpl(rhs, rhs_size);
 }
 
+inline void Cord::ChunkIterator::InitTree(cord_internal::CordRep* tree) {
+  stack_of_right_children_.push_back(tree);
+  operator++();
+}
+
+inline Cord::ChunkIterator::ChunkIterator(cord_internal::CordRep* tree)
+    : bytes_remaining_(tree->length) {
+  InitTree(tree);
+}
+
 inline Cord::ChunkIterator::ChunkIterator(const Cord* cord)
     : bytes_remaining_(cord->size()) {
   if (cord->contents_.is_tree()) {
-    stack_of_right_children_.push_back(cord->contents_.as_tree());
-    operator++();
+    InitTree(cord->contents_.as_tree());
   } else {
     current_chunk_ =
         absl::string_view(cord->contents_.data(), bytes_remaining_);
@@ -1155,6 +1170,7 @@ inline void Cord::ChunkIterator::RemoveChunkPrefix(size_t n) {
 }
 
 inline void Cord::ChunkIterator::AdvanceBytes(size_t n) {
+  assert(bytes_remaining_ >= n);
   if (ABSL_PREDICT_TRUE(n < current_chunk_.size())) {
     RemoveChunkPrefix(n);
   } else if (n != 0) {