64 lines
2.2 KiB
C++
64 lines
2.2 KiB
C++
// Copyright 2022 The Abseil Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_STRINGS_INTERNAL_CORD_DATA_EDGE_H_
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#define ABSL_STRINGS_INTERNAL_CORD_DATA_EDGE_H_
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#include <cassert>
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#include <cstddef>
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#include "absl/base/config.h"
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#include "absl/strings/internal/cord_internal.h"
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#include "absl/strings/internal/cord_rep_flat.h"
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#include "absl/strings/string_view.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace cord_internal {
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// Returns true if the provided rep is a FLAT, EXTERNAL or a SUBSTRING node
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// holding a FLAT or EXTERNAL child rep. Requires `rep != nullptr`.
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inline bool IsDataEdge(const CordRep* edge) {
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assert(edge != nullptr);
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// The fast path is that `edge` is an EXTERNAL or FLAT node, making the below
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// if a single, well predicted branch. We then repeat the FLAT or EXTERNAL
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// check in the slow path of the SUBSTRING check to optimize for the hot path.
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if (edge->tag == EXTERNAL || edge->tag >= FLAT) return true;
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if (edge->tag == SUBSTRING) edge = edge->substring()->child;
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return edge->tag == EXTERNAL || edge->tag >= FLAT;
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}
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// Returns the `absl::string_view` data reference for the provided data edge.
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// Requires 'IsDataEdge(edge) == true`.
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inline absl::string_view EdgeData(const CordRep* edge) {
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assert(IsDataEdge(edge));
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size_t offset = 0;
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const size_t length = edge->length;
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if (edge->IsSubstring()) {
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offset = edge->substring()->start;
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edge = edge->substring()->child;
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}
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return edge->tag >= FLAT
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? absl::string_view{edge->flat()->Data() + offset, length}
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: absl::string_view{edge->external()->base + offset, length};
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}
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} // namespace cord_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_STRINGS_INTERNAL_CORD_DATA_EDGE_H_
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