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//
// Copyright 2023 gRPC 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
//
// http://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.
//
#ifndef GRPC_SRC_CORE_LIB_GPRPP_REF_COUNTED_STRING_H
#define GRPC_SRC_CORE_LIB_GPRPP_REF_COUNTED_STRING_H
#include <grpc/support/port_platform.h>
#include <stddef.h>
#include <string>
#include "absl/strings/string_view.h"
#include "src/core/lib/gprpp/ref_counted.h"
#include "src/core/lib/gprpp/ref_counted_ptr.h"
namespace grpc_core {
// An immutable reference counted string.
class RefCountedString {
public:
static RefCountedPtr<RefCountedString> Make(absl::string_view src);
// Not copyable.
RefCountedString(const RefCountedString&) = delete;
RefCountedString& operator=(const RefCountedString&) = delete;
// Provide the same interface as RefCounted<>.
// We reimplement this instead of inheritting to make pointer math
// easier in Make().
RefCountedPtr<RefCountedString> Ref() {
IncrementRefCount();
return RefCountedPtr<RefCountedString>(this);
}
void Unref() {
if (header_.rc.Unref()) Destroy();
}
absl::string_view as_string_view() const {
return absl::string_view(payload_, header_.length);
}
char* c_str() { return payload_; }
private:
// Allow RefCountedPtr<> to access IncrementRefCount().
template <typename T>
friend class RefCountedPtr;
explicit RefCountedString(absl::string_view src);
void IncrementRefCount() { header_.rc.Ref(); }
void Destroy();
struct Header {
RefCount rc;
size_t length;
};
Header header_;
char payload_[];
};
// Wrapper around RefCountedPtr<RefCountedString> to give value semantics,
// especially to overloaded operators.
class RefCountedStringValue {
public:
RefCountedStringValue() : str_{} {}
explicit RefCountedStringValue(absl::string_view str)
: str_(RefCountedString::Make(str)) {}
absl::string_view as_string_view() const {
return str_ == nullptr ? absl::string_view() : str_->as_string_view();
}
const char* c_str() const { return str_ == nullptr ? "" : str_->c_str(); }
private:
RefCountedPtr<RefCountedString> str_;
};
inline bool operator==(const RefCountedStringValue& lhs,
absl::string_view rhs) {
return lhs.as_string_view() == rhs;
}
inline bool operator==(absl::string_view lhs,
const RefCountedStringValue& rhs) {
return lhs == rhs.as_string_view();
}
inline bool operator==(const RefCountedStringValue& lhs,
const RefCountedStringValue& rhs) {
return lhs.as_string_view() == rhs.as_string_view();
}
inline bool operator!=(const RefCountedStringValue& lhs,
absl::string_view rhs) {
return lhs.as_string_view() != rhs;
}
inline bool operator!=(absl::string_view lhs,
const RefCountedStringValue& rhs) {
return lhs != rhs.as_string_view();
}
inline bool operator!=(const RefCountedStringValue& lhs,
const RefCountedStringValue& rhs) {
return lhs.as_string_view() != rhs.as_string_view();
}
inline bool operator<(const RefCountedStringValue& lhs, absl::string_view rhs) {
return lhs.as_string_view() < rhs;
}
inline bool operator<(absl::string_view lhs, const RefCountedStringValue& rhs) {
return lhs < rhs.as_string_view();
}
inline bool operator<(const RefCountedStringValue& lhs,
const RefCountedStringValue& rhs) {
return lhs.as_string_view() < rhs.as_string_view();
}
inline bool operator>(const RefCountedStringValue& lhs, absl::string_view rhs) {
return lhs.as_string_view() > rhs;
}
inline bool operator>(absl::string_view lhs, const RefCountedStringValue& rhs) {
return lhs > rhs.as_string_view();
}
inline bool operator>(const RefCountedStringValue& lhs,
const RefCountedStringValue& rhs) {
return lhs.as_string_view() > rhs.as_string_view();
}
// A sorting functor to support heterogeneous lookups in sorted containers.
struct RefCountedStringValueLessThan {
using is_transparent = void;
bool operator()(const RefCountedStringValue& lhs,
const RefCountedStringValue& rhs) const {
return lhs < rhs;
}
bool operator()(absl::string_view lhs,
const RefCountedStringValue& rhs) const {
return lhs < rhs;
}
bool operator()(const RefCountedStringValue& lhs,
absl::string_view rhs) const {
return lhs < rhs;
}
};
} // namespace grpc_core
#endif // GRPC_SRC_CORE_LIB_GPRPP_REF_COUNTED_STRING_H
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