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// Copyright 2020 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.
//
// -----------------------------------------------------------------------------
// File: cord.h
// -----------------------------------------------------------------------------
//
// This file defines the `absl::Cord` data structure and operations on that data
// structure. A Cord is a string-like sequence of characters optimized for
// specific use cases. Unlike a `std::string`, which stores an array of
// contiguous characters, Cord data is stored in a structure consisting of
// separate, reference-counted "chunks."
//
// Because a Cord consists of these chunks, data can be added to or removed from
// a Cord during its lifetime. Chunks may also be shared between Cords. Unlike a
// `std::string`, a Cord can therefore accommodate data that changes over its
// lifetime, though it's not quite "mutable"; it can change only in the
// attachment, detachment, or rearrangement of chunks of its constituent data.
//
// A Cord provides some benefit over `std::string` under the following (albeit
// narrow) circumstances:
//
// * Cord data is designed to grow and shrink over a Cord's lifetime. Cord
// provides efficient insertions and deletions at the start and end of the
// character sequences, avoiding copies in those cases. Static data should
// generally be stored as strings.
// * External memory consisting of string-like data can be directly added to
// a Cord without requiring copies or allocations.
// * Cord data may be shared and copied cheaply. Cord provides a copy-on-write
// implementation and cheap sub-Cord operations. Copying a Cord is an O(1)
// operation.
//
// As a consequence to the above, Cord data is generally large. Small data
// should generally use strings, as construction of a Cord requires some
// overhead. Small Cords (<= 15 bytes) are represented inline, but most small
// Cords are expected to grow over their lifetimes.
//
// Note that because a Cord is made up of separate chunked data, random access
// to character data within a Cord is slower than within a `std::string`.
//
// Thread Safety
//
// Cord has the same thread-safety properties as many other types like
// std::string, std::vector<>, int, etc -- it is thread-compatible. In
// particular, if threads do not call non-const methods, then it is safe to call
// const methods without synchronization. Copying a Cord produces a new instance
// that can be used concurrently with the original in arbitrary ways.
#ifndef ABSL_STRINGS_CORD_H_
#define ABSL_STRINGS_CORD_H_
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <iosfwd>
#include <iterator>
#include <string>
#include <type_traits>
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/internal/endian.h"
#include "absl/base/internal/per_thread_tls.h"
#include "absl/base/macros.h"
#include "absl/base/nullability.h"
#include "absl/base/port.h"
#include "absl/container/inlined_vector.h"
#include "absl/crc/internal/crc_cord_state.h"
#include "absl/functional/function_ref.h"
#include "absl/meta/type_traits.h"
#include "absl/strings/cord_analysis.h"
#include "absl/strings/cord_buffer.h"
#include "absl/strings/internal/cord_data_edge.h"
#include "absl/strings/internal/cord_internal.h"
#include "absl/strings/internal/cord_rep_btree.h"
#include "absl/strings/internal/cord_rep_btree_reader.h"
#include "absl/strings/internal/cord_rep_crc.h"
#include "absl/strings/internal/cordz_functions.h"
#include "absl/strings/internal/cordz_info.h"
#include "absl/strings/internal/cordz_statistics.h"
#include "absl/strings/internal/cordz_update_scope.h"
#include "absl/strings/internal/cordz_update_tracker.h"
#include "absl/strings/internal/resize_uninitialized.h"
#include "absl/strings/internal/string_constant.h"
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
class Cord;
class CordTestPeer;
template <typename Releaser>
Cord MakeCordFromExternal(absl::string_view, Releaser&&);
void CopyCordToString(const Cord& src, absl::Nonnull<std::string*> dst);
// Cord memory accounting modes
enum class CordMemoryAccounting {
// Counts the *approximate* number of bytes held in full or in part by this
// Cord (which may not remain the same between invocations). Cords that share
// memory could each be "charged" independently for the same shared memory.
// See also comment on `kTotalMorePrecise` on internally shared memory.
kTotal,
// Counts the *approximate* number of bytes held in full or in part by this
// Cord for the distinct memory held by this cord. This option is similar
// to `kTotal`, except that if the cord has multiple references to the same
// memory, that memory is only counted once.
//
// For example:
// absl::Cord cord;
// cord.Append(some_other_cord);
// cord.Append(some_other_cord);
// // Counts `some_other_cord` twice:
// cord.EstimatedMemoryUsage(kTotal);
// // Counts `some_other_cord` once:
// cord.EstimatedMemoryUsage(kTotalMorePrecise);
//
// The `kTotalMorePrecise` number is more expensive to compute as it requires
// deduplicating all memory references. Applications should prefer to use
// `kFairShare` or `kTotal` unless they really need a more precise estimate
// on "how much memory is potentially held / kept alive by this cord?"
kTotalMorePrecise,
// Counts the *approximate* number of bytes held in full or in part by this
// Cord weighted by the sharing ratio of that data. For example, if some data
// edge is shared by 4 different Cords, then each cord is attributed 1/4th of
// the total memory usage as a 'fair share' of the total memory usage.
kFairShare,
};
// Cord
//
// A Cord is a sequence of characters, designed to be more efficient than a
// `std::string` in certain circumstances: namely, large string data that needs
// to change over its lifetime or shared, especially when such data is shared
// across API boundaries.
//
// A Cord stores its character data in a structure that allows efficient prepend
// and append operations. This makes a Cord useful for large string data sent
// over in a wire format that may need to be prepended or appended at some point
// during the data exchange (e.g. HTTP, protocol buffers). For example, a
// Cord is useful for storing an HTTP request, and prepending an HTTP header to
// such a request.
//
// Cords should not be used for storing general string data, however. They
// require overhead to construct and are slower than strings for random access.
//
// The Cord API provides the following common API operations:
//
// * Create or assign Cords out of existing string data, memory, or other Cords
// * Append and prepend data to an existing Cord
// * Create new Sub-Cords from existing Cord data
// * Swap Cord data and compare Cord equality
// * Write out Cord data by constructing a `std::string`
//
// Additionally, the API provides iterator utilities to iterate through Cord
// data via chunks or character bytes.
//
class Cord {
private:
template <typename T>
using EnableIfString =
absl::enable_if_t<std::is_same<T, std::string>::value, int>;
public:
// Cord::Cord() Constructors.
// Creates an empty Cord.
constexpr Cord() noexcept;
// Creates a Cord from an existing Cord. Cord is copyable and efficiently
// movable. The moved-from state is valid but unspecified.
Cord(const Cord& src);
Cord(Cord&& src) noexcept;
Cord& operator=(const Cord& x);
Cord& operator=(Cord&& x) noexcept;
// Creates a Cord from a `src` string. This constructor is marked explicit to
// prevent implicit Cord constructions from arguments convertible to an
// `absl::string_view`.
explicit Cord(absl::string_view src);
Cord& operator=(absl::string_view src);
// Creates a Cord from a `std::string&&` rvalue. These constructors are
// templated to avoid ambiguities for types that are convertible to both
// `absl::string_view` and `std::string`, such as `const char*`.
template <typename T, EnableIfString<T> = 0>
explicit Cord(T&& src);
template <typename T, EnableIfString<T> = 0>
Cord& operator=(T&& src);
// Cord::~Cord()
//
// Destructs the Cord.
~Cord() {
if (contents_.is_tree()) DestroyCordSlow();
}
// MakeCordFromExternal()
//
// Creates a Cord that takes ownership of external string memory. The
// contents of `data` are not copied to the Cord; instead, the external
// memory is added to the Cord and reference-counted. This data may not be
// changed for the life of the Cord, though it may be prepended or appended
// to.
//
// `MakeCordFromExternal()` takes a callable "releaser" that is invoked when
// the reference count for `data` reaches zero. As noted above, this data must
// remain live until the releaser is invoked. The callable releaser also must:
//
// * be move constructible
// * support `void operator()(absl::string_view) const` or `void operator()`
//
// Example:
//
// Cord MakeCord(BlockPool* pool) {
// Block* block = pool->NewBlock();
// FillBlock(block);
// return absl::MakeCordFromExternal(
// block->ToStringView(),
// [pool, block](absl::string_view v) {
// pool->FreeBlock(block, v);
// });
// }
//
// WARNING: Because a Cord can be reference-counted, it's likely a bug if your
// releaser doesn't do anything. For example, consider the following:
//
// void Foo(const char* buffer, int len) {
// auto c = absl::MakeCordFromExternal(absl::string_view(buffer, len),
// [](absl::string_view) {});
//
// // BUG: If Bar() copies its cord for any reason, including keeping a
// // substring of it, the lifetime of buffer might be extended beyond
// // when Foo() returns.
// Bar(c);
// }
template <typename Releaser>
friend Cord MakeCordFromExternal(absl::string_view data, Releaser&& releaser);
// Cord::Clear()
//
// Releases the Cord data. Any nodes that share data with other Cords, if
// applicable, will have their reference counts reduced by 1.
ABSL_ATTRIBUTE_REINITIALIZES void Clear();
// Cord::Append()
//
// Appends data to the Cord, which may come from another Cord or other string
// data.
void Append(const Cord& src);
void Append(Cord&& src);
void Append(absl::string_view src);
template <typename T, EnableIfString<T> = 0>
void Append(T&& src);
// Appends `buffer` to this cord, unless `buffer` has a zero length in which
// case this method has no effect on this cord instance.
// This method is guaranteed to consume `buffer`.
void Append(CordBuffer buffer);
// Returns a CordBuffer, re-using potential existing capacity in this cord.
//
// Cord instances may have additional unused capacity in the last (or first)
// nodes of the underlying tree to facilitate amortized growth. This method
// allows applications to explicitly use this spare capacity if available,
// or create a new CordBuffer instance otherwise.
// If this cord has a final non-shared node with at least `min_capacity`
// available, then this method will return that buffer including its data
// contents. I.e.; the returned buffer will have a non-zero length, and
// a capacity of at least `buffer.length + min_capacity`. Otherwise, this
// method will return `CordBuffer::CreateWithDefaultLimit(capacity)`.
//
// Below an example of using GetAppendBuffer. Notice that in this example we
// use `GetAppendBuffer()` only on the first iteration. As we know nothing
// about any initial extra capacity in `cord`, we may be able to use the extra
// capacity. But as we add new buffers with fully utilized contents after that
// we avoid calling `GetAppendBuffer()` on subsequent iterations: while this
// works fine, it results in an unnecessary inspection of cord contents:
//
// void AppendRandomDataToCord(absl::Cord &cord, size_t n) {
// bool first = true;
// while (n > 0) {
// CordBuffer buffer = first ? cord.GetAppendBuffer(n)
// : CordBuffer::CreateWithDefaultLimit(n);
// absl::Span<char> data = buffer.available_up_to(n);
// FillRandomValues(data.data(), data.size());
// buffer.IncreaseLengthBy(data.size());
// cord.Append(std::move(buffer));
// n -= data.size();
// first = false;
// }
// }
CordBuffer GetAppendBuffer(size_t capacity, size_t min_capacity = 16);
// Returns a CordBuffer, re-using potential existing capacity in this cord.
//
// This function is identical to `GetAppendBuffer`, except that in the case
// where a new `CordBuffer` is allocated, it is allocated using the provided
// custom limit instead of the default limit. `GetAppendBuffer` will default
// to `CordBuffer::CreateWithDefaultLimit(capacity)` whereas this method
// will default to `CordBuffer::CreateWithCustomLimit(block_size, capacity)`.
// This method is equivalent to `GetAppendBuffer` if `block_size` is zero.
// See the documentation for `CreateWithCustomLimit` for more details on the
// restrictions and legal values for `block_size`.
CordBuffer GetCustomAppendBuffer(size_t block_size, size_t capacity,
size_t min_capacity = 16);
// Cord::Prepend()
//
// Prepends data to the Cord, which may come from another Cord or other string
// data.
void Prepend(const Cord& src);
void Prepend(absl::string_view src);
template <typename T, EnableIfString<T> = 0>
void Prepend(T&& src);
// Prepends `buffer` to this cord, unless `buffer` has a zero length in which
// case this method has no effect on this cord instance.
// This method is guaranteed to consume `buffer`.
void Prepend(CordBuffer buffer);
// Cord::RemovePrefix()
//
// Removes the first `n` bytes of a Cord.
void RemovePrefix(size_t n);
void RemoveSuffix(size_t n);
// Cord::Subcord()
//
// Returns a new Cord representing the subrange [pos, pos + new_size) of
// *this. If pos >= size(), the result is empty(). If
// (pos + new_size) >= size(), the result is the subrange [pos, size()).
Cord Subcord(size_t pos, size_t new_size) const;
// Cord::swap()
//
// Swaps the contents of the Cord with `other`.
void swap(Cord& other) noexcept;
// swap()
//
// Swaps the contents of two Cords.
friend void swap(Cord& x, Cord& y) noexcept { x.swap(y); }
// Cord::size()
//
// Returns the size of the Cord.
size_t size() const;
// Cord::empty()
//
// Determines whether the given Cord is empty, returning `true` if so.
bool empty() const;
// Cord::EstimatedMemoryUsage()
//
// Returns the *approximate* number of bytes held by this cord.
// See CordMemoryAccounting for more information on the accounting method.
size_t EstimatedMemoryUsage(CordMemoryAccounting accounting_method =
CordMemoryAccounting::kTotal) const;
// Cord::Compare()
//
// Compares 'this' Cord with rhs. This function and its relatives treat Cords
// as sequences of unsigned bytes. The comparison is a straightforward
// lexicographic comparison. `Cord::Compare()` returns values as follows:
//
// -1 'this' Cord is smaller
// 0 two Cords are equal
// 1 'this' Cord is larger
int Compare(absl::string_view rhs) const;
int Compare(const Cord& rhs) const;
// Cord::StartsWith()
//
// Determines whether the Cord starts with the passed string data `rhs`.
bool StartsWith(const Cord& rhs) const;
bool StartsWith(absl::string_view rhs) const;
// Cord::EndsWith()
//
// Determines whether the Cord ends with the passed string data `rhs`.
bool EndsWith(absl::string_view rhs) const;
bool EndsWith(const Cord& rhs) const;
// Cord::Contains()
//
// Determines whether the Cord contains the passed string data `rhs`.
bool Contains(absl::string_view rhs) const;
bool Contains(const Cord& rhs) const;
// Cord::operator std::string()
//
// Converts a Cord into a `std::string()`. This operator is marked explicit to
// prevent unintended Cord usage in functions that take a string.
explicit operator std::string() const;
// CopyCordToString()
//
// Copies the contents of a `src` Cord into a `*dst` string.
//
// This function optimizes the case of reusing the destination string since it
// can reuse previously allocated capacity. However, this function does not
// guarantee that pointers previously returned by `dst->data()` remain valid
// even if `*dst` had enough capacity to hold `src`. If `*dst` is a new
// object, prefer to simply use the conversion operator to `std::string`.
friend void CopyCordToString(const Cord& src,
absl::Nonnull<std::string*> dst);
class CharIterator;
//----------------------------------------------------------------------------
// Cord::ChunkIterator
//----------------------------------------------------------------------------
//
// A `Cord::ChunkIterator` allows iteration over the constituent chunks of its
// Cord. Such iteration allows you to perform non-const operations on the data
// of a Cord without modifying it.
//
// Generally, you do not instantiate a `Cord::ChunkIterator` directly;
// instead, you create one implicitly through use of the `Cord::Chunks()`
// member function.
//
// The `Cord::ChunkIterator` has the following properties:
//
// * The iterator is invalidated after any non-const operation on the
// Cord object over which it iterates.
// * The `string_view` returned by dereferencing a valid, non-`end()`
// iterator is guaranteed to be non-empty.
// * Two `ChunkIterator` objects can be compared equal if and only if they
// remain valid and iterate over the same Cord.
// * The iterator in this case is a proxy iterator; the `string_view`
// returned by the iterator does not live inside the Cord, and its
// lifetime is limited to the lifetime of the iterator itself. To help
// prevent lifetime issues, `ChunkIterator::reference` is not a true
// reference type and is equivalent to `value_type`.
// * The iterator keeps state that can grow for Cords that contain many
// nodes and are imbalanced due to sharing. Prefer to pass this type by
// const reference instead of by value.
class ChunkIterator {
public:
using iterator_category = std::input_iterator_tag;
using value_type = absl::string_view;
using difference_type = ptrdiff_t;
using pointer = absl::Nonnull<const value_type*>;
using reference = value_type;
ChunkIterator() = default;
ChunkIterator& operator++();
ChunkIterator operator++(int);
bool operator==(const ChunkIterator& other) const;
bool operator!=(const ChunkIterator& other) const;
reference operator*() const;
pointer operator->() const;
friend class Cord;
friend class CharIterator;
private:
using CordRep = absl::cord_internal::CordRep;
using CordRepBtree = absl::cord_internal::CordRepBtree;
using CordRepBtreeReader = absl::cord_internal::CordRepBtreeReader;
// Constructs a `begin()` iterator from `tree`.
explicit ChunkIterator(absl::Nonnull<cord_internal::CordRep*> tree);
// Constructs a `begin()` iterator from `cord`.
explicit ChunkIterator(absl::Nonnull<const Cord*> cord);
// Initializes this instance from a tree. Invoked by constructors.
void InitTree(absl::Nonnull<cord_internal::CordRep*> tree);
// Removes `n` bytes from `current_chunk_`. Expects `n` to be smaller than
// `current_chunk_.size()`.
void RemoveChunkPrefix(size_t n);
Cord AdvanceAndReadBytes(size_t n);
void AdvanceBytes(size_t n);
// Btree specific operator++
ChunkIterator& AdvanceBtree();
void AdvanceBytesBtree(size_t n);
// A view into bytes of the current `CordRep`. It may only be a view to a
// suffix of bytes if this is being used by `CharIterator`.
absl::string_view current_chunk_;
// The current leaf, or `nullptr` if the iterator points to short data.
// If the current chunk is a substring node, current_leaf_ points to the
// underlying flat or external node.
absl::Nullable<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;
// Cord reader for cord btrees. Empty if not traversing a btree.
CordRepBtreeReader btree_reader_;
};
// Cord::chunk_begin()
//
// Returns an iterator to the first chunk of the `Cord`.
//
// Generally, prefer using `Cord::Chunks()` within a range-based for loop for
// iterating over the chunks of a Cord. This method may be useful for getting
// a `ChunkIterator` where range-based for-loops are not useful.
//
// Example:
//
// absl::Cord::ChunkIterator FindAsChunk(const absl::Cord& c,
// absl::string_view s) {
// return std::find(c.chunk_begin(), c.chunk_end(), s);
// }
ChunkIterator chunk_begin() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
// Cord::chunk_end()
//
// Returns an iterator one increment past the last chunk of the `Cord`.
//
// Generally, prefer using `Cord::Chunks()` within a range-based for loop for
// iterating over the chunks of a Cord. This method may be useful for getting
// a `ChunkIterator` where range-based for-loops may not be available.
ChunkIterator chunk_end() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
//----------------------------------------------------------------------------
// Cord::ChunkRange
//----------------------------------------------------------------------------
//
// `ChunkRange` is a helper class for iterating over the chunks of the `Cord`,
// producing an iterator which can be used within a range-based for loop.
// Construction of a `ChunkRange` will return an iterator pointing to the
// first chunk of the Cord. Generally, do not construct a `ChunkRange`
// directly; instead, prefer to use the `Cord::Chunks()` method.
//
// Implementation note: `ChunkRange` is simply a convenience wrapper over
// `Cord::chunk_begin()` and `Cord::chunk_end()`.
class ChunkRange {
public:
// Fulfill minimum c++ container requirements [container.requirements]
// These (partial) container type definitions allow ChunkRange to be used
// in various utilities expecting a subset of [container.requirements].
// For example, the below enables using `::testing::ElementsAre(...)`
using value_type = absl::string_view;
using reference = value_type&;
using const_reference = const value_type&;
using iterator = ChunkIterator;
using const_iterator = ChunkIterator;
explicit ChunkRange(absl::Nonnull<const Cord*> cord) : cord_(cord) {}
ChunkIterator begin() const;
ChunkIterator end() const;
private:
absl::Nonnull<const Cord*> cord_;
};
// Cord::Chunks()
//
// Returns a `Cord::ChunkRange` for iterating over the chunks of a `Cord` with
// a range-based for-loop. For most iteration tasks on a Cord, use
// `Cord::Chunks()` to retrieve this iterator.
//
// Example:
//
// void ProcessChunks(const Cord& cord) {
// for (absl::string_view chunk : cord.Chunks()) { ... }
// }
//
// Note that the ordinary caveats of temporary lifetime extension apply:
//
// void Process() {
// for (absl::string_view chunk : CordFactory().Chunks()) {
// // The temporary Cord returned by CordFactory has been destroyed!
// }
// }
ChunkRange Chunks() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
//----------------------------------------------------------------------------
// Cord::CharIterator
//----------------------------------------------------------------------------
//
// A `Cord::CharIterator` allows iteration over the constituent characters of
// a `Cord`.
//
// Generally, you do not instantiate a `Cord::CharIterator` directly; instead,
// you create one implicitly through use of the `Cord::Chars()` member
// function.
//
// A `Cord::CharIterator` has the following properties:
//
// * The iterator is invalidated after any non-const operation on the
// Cord object over which it iterates.
// * Two `CharIterator` objects can be compared equal if and only if they
// remain valid and iterate over the same Cord.
// * The iterator keeps state that can grow for Cords that contain many
// nodes and are imbalanced due to sharing. Prefer to pass this type by
// const reference instead of by value.
// * This type cannot act as a forward iterator because a `Cord` can reuse
// sections of memory. This fact violates the requirement for forward
// iterators to compare equal if dereferencing them returns the same
// object.
class CharIterator {
public:
using iterator_category = std::input_iterator_tag;
using value_type = char;
using difference_type = ptrdiff_t;
using pointer = absl::Nonnull<const char*>;
using reference = const char&;
CharIterator() = default;
CharIterator& operator++();
CharIterator operator++(int);
bool operator==(const CharIterator& other) const;
bool operator!=(const CharIterator& other) const;
reference operator*() const;
pointer operator->() const;
friend Cord;
private:
explicit CharIterator(absl::Nonnull<const Cord*> cord)
: chunk_iterator_(cord) {}
ChunkIterator chunk_iterator_;
};
// Cord::AdvanceAndRead()
//
// Advances the `Cord::CharIterator` by `n_bytes` and returns the bytes
// advanced as a separate `Cord`. `n_bytes` must be less than or equal to the
// number of bytes within the Cord; otherwise, behavior is undefined. It is
// valid to pass `char_end()` and `0`.
static Cord AdvanceAndRead(absl::Nonnull<CharIterator*> it, size_t n_bytes);
// Cord::Advance()
//
// Advances the `Cord::CharIterator` by `n_bytes`. `n_bytes` must be less than
// or equal to the number of bytes remaining within the Cord; otherwise,
// behavior is undefined. It is valid to pass `char_end()` and `0`.
static void Advance(absl::Nonnull<CharIterator*> it, size_t n_bytes);
// Cord::ChunkRemaining()
//
// Returns the longest contiguous view starting at the iterator's position.
//
// `it` must be dereferenceable.
static absl::string_view ChunkRemaining(const CharIterator& it);
// Cord::char_begin()
//
// Returns an iterator to the first character of the `Cord`.
//
// Generally, prefer using `Cord::Chars()` within a range-based for loop for
// iterating over the chunks of a Cord. This method may be useful for getting
// a `CharIterator` where range-based for-loops may not be available.
CharIterator char_begin() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
// Cord::char_end()
//
// Returns an iterator to one past the last character of the `Cord`.
//
// Generally, prefer using `Cord::Chars()` within a range-based for loop for
// iterating over the chunks of a Cord. This method may be useful for getting
// a `CharIterator` where range-based for-loops are not useful.
CharIterator char_end() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
// Cord::CharRange
//
// `CharRange` is a helper class for iterating over the characters of a
// producing an iterator which can be used within a range-based for loop.
// Construction of a `CharRange` will return an iterator pointing to the first
// character of the Cord. Generally, do not construct a `CharRange` directly;
// instead, prefer to use the `Cord::Chars()` method shown below.
//
// Implementation note: `CharRange` is simply a convenience wrapper over
// `Cord::char_begin()` and `Cord::char_end()`.
class CharRange {
public:
// Fulfill minimum c++ container requirements [container.requirements]
// These (partial) container type definitions allow CharRange to be used
// in various utilities expecting a subset of [container.requirements].
// For example, the below enables using `::testing::ElementsAre(...)`
using value_type = char;
using reference = value_type&;
using const_reference = const value_type&;
using iterator = CharIterator;
using const_iterator = CharIterator;
explicit CharRange(absl::Nonnull<const Cord*> cord) : cord_(cord) {}
CharIterator begin() const;
CharIterator end() const;
private:
absl::Nonnull<const Cord*> cord_;
};
// Cord::Chars()
//
// Returns a `Cord::CharRange` for iterating over the characters of a `Cord`
// with a range-based for-loop. For most character-based iteration tasks on a
// Cord, use `Cord::Chars()` to retrieve this iterator.
//
// Example:
//
// void ProcessCord(const Cord& cord) {
// for (char c : cord.Chars()) { ... }
// }
//
// Note that the ordinary caveats of temporary lifetime extension apply:
//
// void Process() {
// for (char c : CordFactory().Chars()) {
// // The temporary Cord returned by CordFactory has been destroyed!
// }
// }
CharRange Chars() const ABSL_ATTRIBUTE_LIFETIME_BOUND;
// Cord::operator[]
//
// Gets the "i"th character of the Cord and returns it, provided that
// 0 <= i < Cord.size().
//
// NOTE: This routine is reasonably efficient. It is roughly
// logarithmic based on the number of chunks that make up the cord. Still,
// if you need to iterate over the contents of a cord, you should
// use a CharIterator/ChunkIterator rather than call operator[] or Get()
// repeatedly in a loop.
char operator[](size_t i) const;
// Cord::TryFlat()
//
// If this cord's representation is a single flat array, returns a
// string_view referencing that array. Otherwise returns nullopt.
absl::optional<absl::string_view> TryFlat() const
ABSL_ATTRIBUTE_LIFETIME_BOUND;
// Cord::Flatten()
//
// Flattens the cord into a single array and returns a view of the data.
//
// If the cord was already flat, the contents are not modified.
absl::string_view Flatten() ABSL_ATTRIBUTE_LIFETIME_BOUND;
// Cord::Find()
//
// Returns an iterator to the first occurrance of the substring `needle`.
//
// If the substring `needle` does not occur, `Cord::char_end()` is returned.
CharIterator Find(absl::string_view needle) const;
CharIterator Find(const absl::Cord& needle) const;
// Supports absl::Cord as a sink object for absl::Format().
friend void AbslFormatFlush(absl::Nonnull<absl::Cord*> cord,
absl::string_view part) {
cord->Append(part);
}
// Support automatic stringification with absl::StrCat and absl::StrFormat.
template <typename Sink>
friend void AbslStringify(Sink& sink, const absl::Cord& cord) {
for (absl::string_view chunk : cord.Chunks()) {
sink.Append(chunk);
}
}
// Cord::SetExpectedChecksum()
//
// Stores a checksum value with this non-empty cord instance, for later
// retrieval.
//
// The expected checksum is a number stored out-of-band, alongside the data.
// It is preserved across copies and assignments, but any mutations to a cord
// will cause it to lose its expected checksum.
//
// The expected checksum is not part of a Cord's value, and does not affect
// operations such as equality or hashing.
//
// This field is intended to store a CRC32C checksum for later validation, to
// help support end-to-end checksum workflows. However, the Cord API itself
// does no CRC validation, and assigns no meaning to this number.
//
// This call has no effect if this cord is empty.
void SetExpectedChecksum(uint32_t crc);
// Returns this cord's expected checksum, if it has one. Otherwise, returns
// nullopt.
absl::optional<uint32_t> ExpectedChecksum() const;
template <typename H>
friend H AbslHashValue(H hash_state, const absl::Cord& c) {
absl::optional<absl::string_view> maybe_flat = c.TryFlat();
if (maybe_flat.has_value()) {
return H::combine(std::move(hash_state), *maybe_flat);
}
return c.HashFragmented(std::move(hash_state));
}
// Create a Cord with the contents of StringConstant<T>::value.
// No allocations will be done and no data will be copied.
// This is an INTERNAL API and subject to change or removal. This API can only
// be used by spelling absl::strings_internal::MakeStringConstant, which is
// also an internal API.
template <typename T>
// NOLINTNEXTLINE(google-explicit-constructor)
constexpr Cord(strings_internal::StringConstant<T>);
private:
using CordRep = absl::cord_internal::CordRep;
using CordRepFlat = absl::cord_internal::CordRepFlat;
using CordzInfo = cord_internal::CordzInfo;
using CordzUpdateScope = cord_internal::CordzUpdateScope;
using CordzUpdateTracker = cord_internal::CordzUpdateTracker;
using InlineData = cord_internal::InlineData;
using MethodIdentifier = CordzUpdateTracker::MethodIdentifier;
// Creates a cord instance with `method` representing the originating
// public API call causing the cord to be created.
explicit Cord(absl::string_view src, MethodIdentifier method);
friend class CordTestPeer;
friend bool operator==(const Cord& lhs, const Cord& rhs);
friend bool operator==(const Cord& lhs, absl::string_view rhs);
friend absl::Nullable<const CordzInfo*> GetCordzInfoForTesting(
const Cord& cord);
// Calls the provided function once for each cord chunk, in order. Unlike
// Chunks(), this API will not allocate memory.
void ForEachChunk(absl::FunctionRef<void(absl::string_view)>) const;
// Allocates new contiguous storage for the contents of the cord. This is
// called by Flatten() when the cord was not already flat.
absl::string_view FlattenSlowPath();
// Actual cord contents are hidden inside the following simple
// class so that we can isolate the bulk of cord.cc from changes
// to the representation.
//
// InlineRep holds either a tree pointer, or an array of kMaxInline bytes.
class InlineRep {
public:
static constexpr unsigned char kMaxInline = cord_internal::kMaxInline;
static_assert(kMaxInline >= sizeof(absl::cord_internal::CordRep*), "");
constexpr InlineRep() : data_() {}
explicit InlineRep(InlineData::DefaultInitType init) : data_(init) {}
InlineRep(const InlineRep& src);
InlineRep(InlineRep&& src);
InlineRep& operator=(const InlineRep& src);
InlineRep& operator=(InlineRep&& src) noexcept;
explicit constexpr InlineRep(absl::string_view sv,
absl::Nullable<CordRep*> rep);
void Swap(absl::Nonnull<InlineRep*> rhs);
size_t size() const;
// Returns nullptr if holding pointer
absl::Nullable<const char*> data() const;
// Discards pointer, if any
void set_data(absl::Nonnull<const char*> data, size_t n);
absl::Nonnull<char*> set_data(size_t n); // Write data to the result
// Returns nullptr if holding bytes
absl::Nullable<absl::cord_internal::CordRep*> tree() const;
absl::Nonnull<absl::cord_internal::CordRep*> as_tree() const;
absl::Nonnull<const char*> as_chars() const;
// Returns non-null iff was holding a pointer
absl::Nullable<absl::cord_internal::CordRep*> clear();
// Converts to pointer if necessary.
void reduce_size(size_t n); // REQUIRES: holding data
void remove_prefix(size_t n); // REQUIRES: holding data
void AppendArray(absl::string_view src, MethodIdentifier method);
absl::string_view FindFlatStartPiece() const;
// Creates a CordRepFlat instance from the current inlined data with `extra'
// bytes of desired additional capacity.
absl::Nonnull<CordRepFlat*> MakeFlatWithExtraCapacity(size_t extra);
// Sets the tree value for this instance. `rep` must not be null.
// Requires the current instance to hold a tree, and a lock to be held on
// any CordzInfo referenced by this instance. The latter is enforced through
// the CordzUpdateScope argument. If the current instance is sampled, then
// the CordzInfo instance is updated to reference the new `rep` value.
void SetTree(absl::Nonnull<CordRep*> rep, const CordzUpdateScope& scope);
// Identical to SetTree(), except that `rep` is allowed to be null, in
// which case the current instance is reset to an empty value.
void SetTreeOrEmpty(absl::Nullable<CordRep*> rep,
const CordzUpdateScope& scope);
// Sets the tree value for this instance, and randomly samples this cord.
// This function disregards existing contents in `data_`, and should be
// called when a Cord is 'promoted' from an 'uninitialized' or 'inlined'
// value to a non-inlined (tree / ring) value.
void EmplaceTree(absl::Nonnull<CordRep*> rep, MethodIdentifier method);
// Identical to EmplaceTree, except that it copies the parent stack from
// the provided `parent` data if the parent is sampled.
void EmplaceTree(absl::Nonnull<CordRep*> rep, const InlineData& parent,
MethodIdentifier method);
// Commits the change of a newly created, or updated `rep` root value into
// this cord. `old_rep` indicates the old (inlined or tree) value of the
// cord, and determines if the commit invokes SetTree() or EmplaceTree().
void CommitTree(absl::Nullable<const CordRep*> old_rep,
absl::Nonnull<CordRep*> rep, const CordzUpdateScope& scope,
MethodIdentifier method);
void AppendTreeToInlined(absl::Nonnull<CordRep*> tree,
MethodIdentifier method);
void AppendTreeToTree(absl::Nonnull<CordRep*> tree,
MethodIdentifier method);
void AppendTree(absl::Nonnull<CordRep*> tree, MethodIdentifier method);
void PrependTreeToInlined(absl::Nonnull<CordRep*> tree,
MethodIdentifier method);
void PrependTreeToTree(absl::Nonnull<CordRep*> tree,
MethodIdentifier method);
void PrependTree(absl::Nonnull<CordRep*> tree, MethodIdentifier method);
bool IsSame(const InlineRep& other) const { return data_ == other.data_; }
void CopyTo(absl::Nonnull<std::string*> dst) const {
// memcpy is much faster when operating on a known size. On most supported
// platforms, the small string optimization is large enough that resizing
// to 15 bytes does not cause a memory allocation.
absl::strings_internal::STLStringResizeUninitialized(dst, kMaxInline);
data_.copy_max_inline_to(&(*dst)[0]);
// erase is faster than resize because the logic for memory allocation is
// not needed.
dst->erase(inline_size());
}
// Copies the inline contents into `dst`. Assumes the cord is not empty.
void CopyToArray(absl::Nonnull<char*> dst) const;
bool is_tree() const { return data_.is_tree(); }
// Returns true if the Cord is being profiled by cordz.
bool is_profiled() const { return data_.is_tree() && data_.is_profiled(); }
// Returns the available inlined capacity, or 0 if is_tree() == true.
size_t remaining_inline_capacity() const {
return data_.is_tree() ? 0 : kMaxInline - data_.inline_size();
}
// Returns the profiled CordzInfo, or nullptr if not sampled.
absl::Nullable<absl::cord_internal::CordzInfo*> cordz_info() const {
return data_.cordz_info();
}
// Sets the profiled CordzInfo.
void set_cordz_info(absl::Nonnull<cord_internal::CordzInfo*> cordz_info) {
assert(cordz_info != nullptr);
data_.set_cordz_info(cordz_info);
}
// Resets the current cordz_info to null / empty.
void clear_cordz_info() { data_.clear_cordz_info(); }
private:
friend class Cord;
void AssignSlow(const InlineRep& src);
// Unrefs the tree and stops profiling.
void UnrefTree();
void ResetToEmpty() { data_ = {}; }
void set_inline_size(size_t size) { data_.set_inline_size(size); }
size_t inline_size() const { return data_.inline_size(); }
// Empty cords that carry a checksum have a CordRepCrc node with a null
// child node. The code can avoid lots of special cases where it would
// otherwise transition from tree to inline storage if we just remove the
// CordRepCrc node before mutations. Must never be called inside a
// CordzUpdateScope since it untracks the cordz info.
void MaybeRemoveEmptyCrcNode();
cord_internal::InlineData data_;
};
InlineRep contents_;
// Helper for GetFlat() and TryFlat().
static bool GetFlatAux(absl::Nonnull<absl::cord_internal::CordRep*> rep,
absl::Nonnull<absl::string_view*> fragment);
// Helper for ForEachChunk().
static void ForEachChunkAux(
absl::Nonnull<absl::cord_internal::CordRep*> rep,
absl::FunctionRef<void(absl::string_view)> callback);
// The destructor for non-empty Cords.
void DestroyCordSlow();
// Out-of-line implementation of slower parts of logic.
void CopyToArraySlowPath(absl::Nonnull<char*> dst) const;
int CompareSlowPath(absl::string_view rhs, size_t compared_size,
size_t size_to_compare) const;
int CompareSlowPath(const Cord& rhs, size_t compared_size,
size_t size_to_compare) const;
bool EqualsImpl(absl::string_view rhs, size_t size_to_compare) const;
bool EqualsImpl(const Cord& rhs, size_t size_to_compare) const;
int CompareImpl(const Cord& rhs) const;
template <typename ResultType, typename RHS>
friend ResultType GenericCompare(const Cord& lhs, const RHS& rhs,
size_t size_to_compare);
static absl::string_view GetFirstChunk(const Cord& c);
static absl::string_view GetFirstChunk(absl::string_view sv);
// Returns a new reference to contents_.tree(), or steals an existing
// reference if called on an rvalue.
absl::Nonnull<absl::cord_internal::CordRep*> TakeRep() const&;
absl::Nonnull<absl::cord_internal::CordRep*> TakeRep() &&;
// Helper for Append().
template <typename C>
void AppendImpl(C&& src);
// Appends / Prepends `src` to this instance, using precise sizing.
// This method does explicitly not attempt to use any spare capacity
// in any pending last added private owned flat.
// Requires `src` to be <= kMaxFlatLength.
void AppendPrecise(absl::string_view src, MethodIdentifier method);
void PrependPrecise(absl::string_view src, MethodIdentifier method);
CordBuffer GetAppendBufferSlowPath(size_t block_size, size_t capacity,
size_t min_capacity);
// Prepends the provided data to this instance. `method` contains the public
// API method for this action which is tracked for Cordz sampling purposes.
void PrependArray(absl::string_view src, MethodIdentifier method);
// Assigns the value in 'src' to this instance, 'stealing' its contents.
// Requires src.length() > kMaxBytesToCopy.
Cord& AssignLargeString(std::string&& src);
// Helper for AbslHashValue().
template <typename H>
H HashFragmented(H hash_state) const {
typename H::AbslInternalPiecewiseCombiner combiner;
ForEachChunk([&combiner, &hash_state](absl::string_view chunk) {
hash_state = combiner.add_buffer(std::move(hash_state), chunk.data(),
chunk.size());
});
return H::combine(combiner.finalize(std::move(hash_state)), size());
}
friend class CrcCord;
void SetCrcCordState(crc_internal::CrcCordState state);
absl::Nullable<const crc_internal::CrcCordState*> MaybeGetCrcCordState()
const;
CharIterator FindImpl(CharIterator it, absl::string_view needle) const;
};
ABSL_NAMESPACE_END
} // namespace absl
namespace absl {
ABSL_NAMESPACE_BEGIN
// allow a Cord to be logged
extern std::ostream& operator<<(std::ostream& out, const Cord& cord);
// ------------------------------------------------------------------
// Internal details follow. Clients should ignore.
namespace cord_internal {
// Does non-template-specific `CordRepExternal` initialization.
// Requires `data` to be non-empty.
void InitializeCordRepExternal(absl::string_view data,
absl::Nonnull<CordRepExternal*> rep);
// Creates a new `CordRep` that owns `data` and `releaser` and returns a pointer
// to it. Requires `data` to be non-empty.
template <typename Releaser>
// NOLINTNEXTLINE - suppress clang-tidy raw pointer return.
absl::Nonnull<CordRep*> NewExternalRep(absl::string_view data,
Releaser&& releaser) {
assert(!data.empty());
using ReleaserType = absl::decay_t<Releaser>;
CordRepExternal* rep = new CordRepExternalImpl<ReleaserType>(
std::forward<Releaser>(releaser), 0);
InitializeCordRepExternal(data, rep);
return rep;
}
// Overload for function reference types that dispatches using a function
// pointer because there are no `alignof()` or `sizeof()` a function reference.
// NOLINTNEXTLINE - suppress clang-tidy raw pointer return.
inline absl::Nonnull<CordRep*> NewExternalRep(absl::string_view data,
void (&releaser)(absl::string_view)) {
return NewExternalRep(data, &releaser);
}
} // namespace cord_internal
template <typename Releaser>
Cord MakeCordFromExternal(absl::string_view data, Releaser&& releaser) {
Cord cord;
if (ABSL_PREDICT_TRUE(!data.empty())) {
cord.contents_.EmplaceTree(::absl::cord_internal::NewExternalRep(
data, std::forward<Releaser>(releaser)),
Cord::MethodIdentifier::kMakeCordFromExternal);
} else {
using ReleaserType = absl::decay_t<Releaser>;
cord_internal::InvokeReleaser(
cord_internal::Rank0{}, ReleaserType(std::forward<Releaser>(releaser)),
data);
}
return cord;
}
constexpr Cord::InlineRep::InlineRep(absl::string_view sv,
absl::Nullable<CordRep*> rep)
: data_(sv, rep) {}
inline Cord::InlineRep::InlineRep(const Cord::InlineRep& src)
: data_(InlineData::kDefaultInit) {
if (CordRep* tree = src.tree()) {
EmplaceTree(CordRep::Ref(tree), src.data_,
CordzUpdateTracker::kConstructorCord);
} else {
data_ = src.data_;
}
}
inline Cord::InlineRep::InlineRep(Cord::InlineRep&& src) : data_(src.data_) {
src.ResetToEmpty();
}
inline Cord::InlineRep& Cord::InlineRep::operator=(const Cord::InlineRep& src) {
if (this == &src) {
return *this;
}
if (!is_tree() && !src.is_tree()) {
data_ = src.data_;
return *this;
}
AssignSlow(src);
return *this;
}
inline Cord::InlineRep& Cord::InlineRep::operator=(
Cord::InlineRep&& src) noexcept {
if (is_tree()) {
UnrefTree();
}
data_ = src.data_;
src.ResetToEmpty();
return *this;
}
inline void Cord::InlineRep::Swap(absl::Nonnull<Cord::InlineRep*> rhs) {
if (rhs == this) {
return;
}
std::swap(data_, rhs->data_);
}
inline absl::Nullable<const char*> Cord::InlineRep::data() const {
return is_tree() ? nullptr : data_.as_chars();
}
inline absl::Nonnull<const char*> Cord::InlineRep::as_chars() const {
assert(!data_.is_tree());
return data_.as_chars();
}
inline absl::Nonnull<absl::cord_internal::CordRep*> Cord::InlineRep::as_tree()
const {
assert(data_.is_tree());
return data_.as_tree();
}
inline absl::Nullable<absl::cord_internal::CordRep*> Cord::InlineRep::tree()
const {
if (is_tree()) {
return as_tree();
} else {
return nullptr;
}
}
inline size_t Cord::InlineRep::size() const {
return is_tree() ? as_tree()->length : inline_size();
}
inline absl::Nonnull<cord_internal::CordRepFlat*>
Cord::InlineRep::MakeFlatWithExtraCapacity(size_t extra) {
static_assert(cord_internal::kMinFlatLength >= sizeof(data_), "");
size_t len = data_.inline_size();
auto* result = CordRepFlat::New(len + extra);
result->length = len;
data_.copy_max_inline_to(result->Data());
return result;
}
inline void Cord::InlineRep::EmplaceTree(absl::Nonnull<CordRep*> rep,
MethodIdentifier method) {
assert(rep);
data_.make_tree(rep);
CordzInfo::MaybeTrackCord(data_, method);
}
inline void Cord::InlineRep::EmplaceTree(absl::Nonnull<CordRep*> rep,
const InlineData& parent,
MethodIdentifier method) {
data_.make_tree(rep);
CordzInfo::MaybeTrackCord(data_, parent, method);
}
inline void Cord::InlineRep::SetTree(absl::Nonnull<CordRep*> rep,
const CordzUpdateScope& scope) {
assert(rep);
assert(data_.is_tree());
data_.set_tree(rep);
scope.SetCordRep(rep);
}
inline void Cord::InlineRep::SetTreeOrEmpty(absl::Nullable<CordRep*> rep,
const CordzUpdateScope& scope) {
assert(data_.is_tree());
if (rep) {
data_.set_tree(rep);
} else {
data_ = {};
}
scope.SetCordRep(rep);
}
inline void Cord::InlineRep::CommitTree(absl::Nullable<const CordRep*> old_rep,
absl::Nonnull<CordRep*> rep,
const CordzUpdateScope& scope,
MethodIdentifier method) {
if (old_rep) {
SetTree(rep, scope);
} else {
EmplaceTree(rep, method);
}
}
inline absl::Nullable<absl::cord_internal::CordRep*> Cord::InlineRep::clear() {
if (is_tree()) {
CordzInfo::MaybeUntrackCord(cordz_info());
}
absl::cord_internal::CordRep* result = tree();
ResetToEmpty();
return result;
}
inline void Cord::InlineRep::CopyToArray(absl::Nonnull<char*> dst) const {
assert(!is_tree());
size_t n = inline_size();
assert(n != 0);
cord_internal::SmallMemmove(dst, data_.as_chars(), n);
}
inline void Cord::InlineRep::MaybeRemoveEmptyCrcNode() {
CordRep* rep = tree();
if (rep == nullptr || ABSL_PREDICT_TRUE(rep->length > 0)) {
return;
}
assert(rep->IsCrc());
assert(rep->crc()->child == nullptr);
CordzInfo::MaybeUntrackCord(cordz_info());
CordRep::Unref(rep);
ResetToEmpty();
}
constexpr inline Cord::Cord() noexcept {}
inline Cord::Cord(absl::string_view src)
: Cord(src, CordzUpdateTracker::kConstructorString) {}
template <typename T>
constexpr Cord::Cord(strings_internal::StringConstant<T>)
: contents_(strings_internal::StringConstant<T>::value,
strings_internal::StringConstant<T>::value.size() <=
cord_internal::kMaxInline
? nullptr
: &cord_internal::ConstInitExternalStorage<
strings_internal::StringConstant<T>>::value) {}
inline Cord& Cord::operator=(const Cord& x) {
contents_ = x.contents_;
return *this;
}
template <typename T, Cord::EnableIfString<T>>
Cord& Cord::operator=(T&& src) {
if (src.size() <= cord_internal::kMaxBytesToCopy) {
return operator=(absl::string_view(src));
} else {
return AssignLargeString(std::forward<T>(src));
}
}
inline Cord::Cord(const Cord& src) : contents_(src.contents_) {}
inline Cord::Cord(Cord&& src) noexcept : contents_(std::move(src.contents_)) {}
inline void Cord::swap(Cord& other) noexcept {
contents_.Swap(&other.contents_);
}
inline Cord& Cord::operator=(Cord&& x) noexcept {
contents_ = std::move(x.contents_);
return *this;
}
extern template Cord::Cord(std::string&& src);
inline size_t Cord::size() const {
// Length is 1st field in str.rep_
return contents_.size();
}
inline bool Cord::empty() const { return size() == 0; }
inline size_t Cord::EstimatedMemoryUsage(
CordMemoryAccounting accounting_method) const {
size_t result = sizeof(Cord);
if (const absl::cord_internal::CordRep* rep = contents_.tree()) {
switch (accounting_method) {
case CordMemoryAccounting::kFairShare:
result += cord_internal::GetEstimatedFairShareMemoryUsage(rep);
break;
case CordMemoryAccounting::kTotalMorePrecise:
result += cord_internal::GetMorePreciseMemoryUsage(rep);
break;
case CordMemoryAccounting::kTotal:
result += cord_internal::GetEstimatedMemoryUsage(rep);
break;
}
}
return result;
}
inline absl::optional<absl::string_view> Cord::TryFlat() const {
absl::cord_internal::CordRep* rep = contents_.tree();
if (rep == nullptr) {
return absl::string_view(contents_.data(), contents_.size());
}
absl::string_view fragment;
if (GetFlatAux(rep, &fragment)) {
return fragment;
}
return absl::nullopt;
}
inline absl::string_view Cord::Flatten() {
absl::cord_internal::CordRep* rep = contents_.tree();
if (rep == nullptr) {
return absl::string_view(contents_.data(), contents_.size());
} else {
absl::string_view already_flat_contents;
if (GetFlatAux(rep, &already_flat_contents)) {
return already_flat_contents;
}
}
return FlattenSlowPath();
}
inline void Cord::Append(absl::string_view src) {
contents_.AppendArray(src, CordzUpdateTracker::kAppendString);
}
inline void Cord::Prepend(absl::string_view src) {
PrependArray(src, CordzUpdateTracker::kPrependString);
}
inline void Cord::Append(CordBuffer buffer) {
if (ABSL_PREDICT_FALSE(buffer.length() == 0)) return;
absl::string_view short_value;
if (CordRep* rep = buffer.ConsumeValue(short_value)) {
contents_.AppendTree(rep, CordzUpdateTracker::kAppendCordBuffer);
} else {
AppendPrecise(short_value, CordzUpdateTracker::kAppendCordBuffer);
}
}
inline void Cord::Prepend(CordBuffer buffer) {
if (ABSL_PREDICT_FALSE(buffer.length() == 0)) return;
absl::string_view short_value;
if (CordRep* rep = buffer.ConsumeValue(short_value)) {
contents_.PrependTree(rep, CordzUpdateTracker::kPrependCordBuffer);
} else {
PrependPrecise(short_value, CordzUpdateTracker::kPrependCordBuffer);
}
}
inline CordBuffer Cord::GetAppendBuffer(size_t capacity, size_t min_capacity) {
if (empty()) return CordBuffer::CreateWithDefaultLimit(capacity);
return GetAppendBufferSlowPath(0, capacity, min_capacity);
}
inline CordBuffer Cord::GetCustomAppendBuffer(size_t block_size,
size_t capacity,
size_t min_capacity) {
if (empty()) {
return block_size ? CordBuffer::CreateWithCustomLimit(block_size, capacity)
: CordBuffer::CreateWithDefaultLimit(capacity);
}
return GetAppendBufferSlowPath(block_size, capacity, min_capacity);
}
extern template void Cord::Append(std::string&& src);
extern template void Cord::Prepend(std::string&& src);
inline int Cord::Compare(const Cord& rhs) const {
if (!contents_.is_tree() && !rhs.contents_.is_tree()) {
return contents_.data_.Compare(rhs.contents_.data_);
}
return CompareImpl(rhs);
}
// Does 'this' cord start/end with rhs
inline bool Cord::StartsWith(const Cord& rhs) const {
if (contents_.IsSame(rhs.contents_)) return true;
size_t rhs_size = rhs.size();
if (size() < rhs_size) return false;
return EqualsImpl(rhs, rhs_size);
}
inline bool Cord::StartsWith(absl::string_view rhs) const {
size_t rhs_size = rhs.size();
if (size() < rhs_size) return false;
return EqualsImpl(rhs, rhs_size);
}
inline void Cord::ChunkIterator::InitTree(
absl::Nonnull<cord_internal::CordRep*> tree) {
tree = cord_internal::SkipCrcNode(tree);
if (tree->tag == cord_internal::BTREE) {
current_chunk_ = btree_reader_.Init(tree->btree());
} else {
current_leaf_ = tree;
current_chunk_ = cord_internal::EdgeData(tree);
}
}
inline Cord::ChunkIterator::ChunkIterator(
absl::Nonnull<cord_internal::CordRep*> tree) {
bytes_remaining_ = tree->length;
InitTree(tree);
}
inline Cord::ChunkIterator::ChunkIterator(absl::Nonnull<const Cord*> cord) {
if (CordRep* tree = cord->contents_.tree()) {
bytes_remaining_ = tree->length;
if (ABSL_PREDICT_TRUE(bytes_remaining_ != 0)) {
InitTree(tree);
} else {
current_chunk_ = {};
}
} else {
bytes_remaining_ = cord->contents_.inline_size();
current_chunk_ = {cord->contents_.data(), bytes_remaining_};
}
}
inline Cord::ChunkIterator& Cord::ChunkIterator::AdvanceBtree() {
current_chunk_ = btree_reader_.Next();
return *this;
}
inline void Cord::ChunkIterator::AdvanceBytesBtree(size_t n) {
assert(n >= current_chunk_.size());
bytes_remaining_ -= n;
if (bytes_remaining_) {
if (n == current_chunk_.size()) {
current_chunk_ = btree_reader_.Next();
} else {
size_t offset = btree_reader_.length() - bytes_remaining_;
current_chunk_ = btree_reader_.Seek(offset);
}
} else {
current_chunk_ = {};
}
}
inline Cord::ChunkIterator& Cord::ChunkIterator::operator++() {
ABSL_HARDENING_ASSERT(bytes_remaining_ > 0 &&
"Attempted to iterate past `end()`");
assert(bytes_remaining_ >= current_chunk_.size());
bytes_remaining_ -= current_chunk_.size();
if (bytes_remaining_ > 0) {
if (btree_reader_) {
return AdvanceBtree();
} else {
assert(!current_chunk_.empty()); // Called on invalid iterator.
}
current_chunk_ = {};
}
return *this;
}
inline Cord::ChunkIterator Cord::ChunkIterator::operator++(int) {
ChunkIterator tmp(*this);
operator++();
return tmp;
}
inline bool Cord::ChunkIterator::operator==(const ChunkIterator& other) const {
return bytes_remaining_ == other.bytes_remaining_;
}
inline bool Cord::ChunkIterator::operator!=(const ChunkIterator& other) const {
return !(*this == other);
}
inline Cord::ChunkIterator::reference Cord::ChunkIterator::operator*() const {
ABSL_HARDENING_ASSERT(bytes_remaining_ != 0);
return current_chunk_;
}
inline Cord::ChunkIterator::pointer Cord::ChunkIterator::operator->() const {
ABSL_HARDENING_ASSERT(bytes_remaining_ != 0);
return &current_chunk_;
}
inline void Cord::ChunkIterator::RemoveChunkPrefix(size_t n) {
assert(n < current_chunk_.size());
current_chunk_.remove_prefix(n);
bytes_remaining_ -= 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) {
if (btree_reader_) {
AdvanceBytesBtree(n);
} else {
bytes_remaining_ = 0;
}
}
}
inline Cord::ChunkIterator Cord::chunk_begin() const {
return ChunkIterator(this);
}
inline Cord::ChunkIterator Cord::chunk_end() const { return ChunkIterator(); }
inline Cord::ChunkIterator Cord::ChunkRange::begin() const {
return cord_->chunk_begin();
}
inline Cord::ChunkIterator Cord::ChunkRange::end() const {
return cord_->chunk_end();
}
inline Cord::ChunkRange Cord::Chunks() const { return ChunkRange(this); }
inline Cord::CharIterator& Cord::CharIterator::operator++() {
if (ABSL_PREDICT_TRUE(chunk_iterator_->size() > 1)) {
chunk_iterator_.RemoveChunkPrefix(1);
} else {
++chunk_iterator_;
}
return *this;
}
inline Cord::CharIterator Cord::CharIterator::operator++(int) {
CharIterator tmp(*this);
operator++();
return tmp;
}
inline bool Cord::CharIterator::operator==(const CharIterator& other) const {
return chunk_iterator_ == other.chunk_iterator_;
}
inline bool Cord::CharIterator::operator!=(const CharIterator& other) const {
return !(*this == other);
}
inline Cord::CharIterator::reference Cord::CharIterator::operator*() const {
return *chunk_iterator_->data();
}
inline Cord::CharIterator::pointer Cord::CharIterator::operator->() const {
return chunk_iterator_->data();
}
inline Cord Cord::AdvanceAndRead(absl::Nonnull<CharIterator*> it,
size_t n_bytes) {
assert(it != nullptr);
return it->chunk_iterator_.AdvanceAndReadBytes(n_bytes);
}
inline void Cord::Advance(absl::Nonnull<CharIterator*> it, size_t n_bytes) {
assert(it != nullptr);
it->chunk_iterator_.AdvanceBytes(n_bytes);
}
inline absl::string_view Cord::ChunkRemaining(const CharIterator& it) {
return *it.chunk_iterator_;
}
inline Cord::CharIterator Cord::char_begin() const {
return CharIterator(this);
}
inline Cord::CharIterator Cord::char_end() const { return CharIterator(); }
inline Cord::CharIterator Cord::CharRange::begin() const {
return cord_->char_begin();
}
inline Cord::CharIterator Cord::CharRange::end() const {
return cord_->char_end();
}
inline Cord::CharRange Cord::Chars() const { return CharRange(this); }
inline void Cord::ForEachChunk(
absl::FunctionRef<void(absl::string_view)> callback) const {
absl::cord_internal::CordRep* rep = contents_.tree();
if (rep == nullptr) {
callback(absl::string_view(contents_.data(), contents_.size()));
} else {
ForEachChunkAux(rep, callback);
}
}
// Nonmember Cord-to-Cord relational operators.
inline bool operator==(const Cord& lhs, const Cord& rhs) {
if (lhs.contents_.IsSame(rhs.contents_)) return true;
size_t rhs_size = rhs.size();
if (lhs.size() != rhs_size) return false;
return lhs.EqualsImpl(rhs, rhs_size);
}
inline bool operator!=(const Cord& x, const Cord& y) { return !(x == y); }
inline bool operator<(const Cord& x, const Cord& y) { return x.Compare(y) < 0; }
inline bool operator>(const Cord& x, const Cord& y) { return x.Compare(y) > 0; }
inline bool operator<=(const Cord& x, const Cord& y) {
return x.Compare(y) <= 0;
}
inline bool operator>=(const Cord& x, const Cord& y) {
return x.Compare(y) >= 0;
}
// Nonmember Cord-to-absl::string_view relational operators.
//
// Due to implicit conversions, these also enable comparisons of Cord with
// std::string and const char*.
inline bool operator==(const Cord& lhs, absl::string_view rhs) {
size_t lhs_size = lhs.size();
size_t rhs_size = rhs.size();
if (lhs_size != rhs_size) return false;
return lhs.EqualsImpl(rhs, rhs_size);
}
inline bool operator==(absl::string_view x, const Cord& y) { return y == x; }
inline bool operator!=(const Cord& x, absl::string_view y) { return !(x == y); }
inline bool operator!=(absl::string_view x, const Cord& y) { return !(x == y); }
inline bool operator<(const Cord& x, absl::string_view y) {
return x.Compare(y) < 0;
}
inline bool operator<(absl::string_view x, const Cord& y) {
return y.Compare(x) > 0;
}
inline bool operator>(const Cord& x, absl::string_view y) { return y < x; }
inline bool operator>(absl::string_view x, const Cord& y) { return y < x; }
inline bool operator<=(const Cord& x, absl::string_view y) { return !(y < x); }
inline bool operator<=(absl::string_view x, const Cord& y) { return !(y < x); }
inline bool operator>=(const Cord& x, absl::string_view y) { return !(x < y); }
inline bool operator>=(absl::string_view x, const Cord& y) { return !(x < y); }
// Some internals exposed to test code.
namespace strings_internal {
class CordTestAccess {
public:
static size_t FlatOverhead();
static size_t MaxFlatLength();
static size_t SizeofCordRepExternal();
static size_t SizeofCordRepSubstring();
static size_t FlatTagToLength(uint8_t tag);
static uint8_t LengthToTag(size_t s);
};
} // namespace strings_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_STRINGS_CORD_H_