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75 lines
2.9 KiB
75 lines
2.9 KiB
7 months ago
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/*
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* Copyright (C) 2018 The Android Open Source Project
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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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*/
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#ifndef LIBTEXTCLASSIFIER_UTILS_GRAMMAR_SEMANTICS_COMPOSER_H_
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#define LIBTEXTCLASSIFIER_UTILS_GRAMMAR_SEMANTICS_COMPOSER_H_
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#include <unordered_map>
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#include <vector>
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#include "utils/base/arena.h"
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#include "utils/base/status.h"
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#include "utils/base/statusor.h"
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#include "utils/flatbuffers/flatbuffers.h"
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#include "utils/grammar/parsing/derivation.h"
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#include "utils/grammar/parsing/parse-tree.h"
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#include "utils/grammar/semantics/eval-context.h"
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#include "utils/grammar/semantics/evaluator.h"
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#include "utils/grammar/semantics/expression_generated.h"
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#include "utils/grammar/semantics/value.h"
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#include "utils/grammar/text-context.h"
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namespace libtextclassifier3::grammar {
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// Semantic value composer.
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// It evaluates a semantic expression of a syntactic parse tree as a semantic
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// value.
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// It evaluates the constituents of a rule match and applies them to semantic
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// expression, calling out to semantic functions that implement the basic
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// building blocks.
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class SemanticComposer : public SemanticExpressionEvaluator {
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public:
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// Expects a flatbuffer schema that describes the possible result values of
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// an evaluation.
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explicit SemanticComposer(const reflection::Schema* semantic_values_schema);
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// Evaluates a semantic expression that is associated with the root of a parse
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// tree.
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StatusOr<const SemanticValue*> Eval(const TextContext& text_context,
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const Derivation& derivation,
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UnsafeArena* arena) const;
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// Applies a semantic expression to a list of constituents and
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// produces an output semantic value.
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StatusOr<const SemanticValue*> Apply(const EvalContext& context,
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const SemanticExpression* expression,
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UnsafeArena* arena) const override;
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private:
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// Evaluates a semantic expression against a parse tree.
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StatusOr<const SemanticValue*> Eval(const TextContext& text_context,
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const SemanticExpressionNode* derivation,
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UnsafeArena* arena) const;
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std::unordered_map<SemanticExpression_::Expression,
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std::unique_ptr<SemanticExpressionEvaluator>>
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evaluators_;
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};
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} // namespace libtextclassifier3::grammar
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#endif // LIBTEXTCLASSIFIER_UTILS_GRAMMAR_SEMANTICS_COMPOSER_H_
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