| // Copyright 2021 The Abseil Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include <cstdint> |
| |
| #include "absl/base/config.h" |
| #include "absl/container/inlined_vector.h" |
| #include "absl/strings/internal/cord_internal.h" |
| #include "absl/strings/internal/cord_rep_flat.h" |
| |
| namespace absl { |
| ABSL_NAMESPACE_BEGIN |
| namespace cord_internal { |
| |
| CordRepConcat::ExtractResult CordRepConcat::ExtractAppendBuffer( |
| CordRepConcat* tree, size_t extra_capacity) { |
| absl::InlinedVector<CordRepConcat*, kInlinedVectorSize> stack; |
| CordRepConcat* concat = tree; |
| CordRep* rep = concat->right; |
| |
| // Dive down the tree, making sure no edges are shared |
| while (concat->refcount.IsOne() && rep->IsConcat()) { |
| stack.push_back(concat); |
| concat = rep->concat(); |
| rep = concat->right; |
| } |
| // Validate we ended on a non shared flat. |
| if (concat->refcount.IsOne() && rep->IsFlat() && |
| rep->refcount.IsOne()) { |
| // Verify it has at least the requested extra capacity |
| CordRepFlat* flat = rep->flat(); |
| size_t remaining = flat->Capacity() - flat->length; |
| if (extra_capacity > remaining) return {tree, nullptr}; |
| |
| // Check if we have a parent to adjust, or if we must return the left node. |
| rep = concat->left; |
| if (!stack.empty()) { |
| stack.back()->right = rep; |
| for (CordRepConcat* parent : stack) { |
| parent->length -= flat->length; |
| } |
| rep = tree; |
| } |
| delete concat; |
| return {rep, flat}; |
| } |
| return {tree, nullptr}; |
| } |
| |
| } // namespace cord_internal |
| ABSL_NAMESPACE_END |
| } // namespace absl |