90 lines
3.2 KiB
C
90 lines
3.2 KiB
C
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// Copyright 2021 The Tint 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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// http://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 FUZZERS_TINT_AST_FUZZER_NODE_ID_MAP_H_
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#define FUZZERS_TINT_AST_FUZZER_NODE_ID_MAP_H_
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#include <unordered_map>
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#include "src/program.h"
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namespace tint {
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namespace fuzzers {
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namespace ast_fuzzer {
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/// Contains a one-to-one mapping between the nodes in the AST of the program
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/// and their ids.
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///
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/// The motivation for having this mapping is:
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/// - To be able to uniquely identify a node in the AST. This will be used
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/// to record transformations in the protobuf messages.
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/// - When the AST is being modified, only the mapping for the modified nodes
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/// must be affected. That is, if some node is unchanged, it must have the
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/// same id defined in this class.
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///
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/// This class achieves these goals partially. Concretely, the only way to
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/// change the AST is by cloning it since all instances of `tint::ast::` classes
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/// are immutable. This will invalidate all the pointers to the AST nodes which
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/// are used in this class. To overcome this, a new instance of this class is
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/// created with all the cloned nodes and the old instance is discarded.
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class NodeIdMap {
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public:
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/// Type of the id used by this map.
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using IdType = uint32_t;
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/// Creates an empty map.
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NodeIdMap();
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/// @brief Initializes this instance with all the nodes in the `program`.
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/// @param program - must be valid.
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explicit NodeIdMap(const tint::Program& program);
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/// @brief Returns a node for the given `id`.
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/// @param id - any value is accepted.
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/// @return a pointer to some node if `id` exists in this map.
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/// @return `nullptr` otherwise.
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const ast::Node* GetNode(IdType id) const;
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/// @brief Returns an id of the given `node`.
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/// @param node - can be a `nullptr`.
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/// @return not equal to 0 if `node` exists in this map.
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/// @return 0 otherwise.
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IdType GetId(const ast::Node* node) const;
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/// @brief Adds a mapping from `node` to `id` to this map.
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/// @param node - may not be a `nullptr` and can't be present in this map.
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/// @param id - may not be 0 and can't be present in this map.
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void Add(const ast::Node* node, IdType id);
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/// @brief Returns an id that is guaranteed to be unoccupied in this map.
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///
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/// This will effectively increase the counter. This means that two
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/// consecutive calls to this method will return different ids.
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///
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/// @return an unoccupied id.
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IdType TakeFreshId();
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private:
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IdType fresh_id_ = 1;
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std::unordered_map<const ast::Node*, IdType> node_to_id_;
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std::unordered_map<IdType, const ast::Node*> id_to_node_;
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};
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} // namespace ast_fuzzer
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} // namespace fuzzers
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} // namespace tint
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#endif // FUZZERS_TINT_AST_FUZZER_NODE_ID_MAP_H_
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