xref: /aosp_15_r20/external/libtextclassifier/native/utils/grammar/parsing/derivation.cc (revision 993b0882672172b81d12fad7a7ac0c3e5c824a12)

/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * 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.
 */

#include "utils/grammar/parsing/derivation.h"

#include <algorithm>
#include <vector>

namespace libtextclassifier3::grammar {

bool Derivation::IsValid() const {
  bool result = true;
  Traverse(parse_tree, [&result](const ParseTree* node) {
    if (node->type != ParseTree::Type::kAssertion) {
      // Only validation if all checks so far passed.
      return result;
    }
    // Positive assertions are by definition fulfilled,
    // fail if the assertion is negative.
    if (static_cast<const AssertionNode*>(node)->negative) {
      result = false;
    }
    return result;
  });
  return result;
}

std::vector<Derivation> ValidDeduplicatedDerivations(
    const std::vector<Derivation>& derivations) {
  std::vector<Derivation> result;
  for (const Derivation& derivation :
       DeduplicateDerivations<Derivation>(derivations)) {
    // Check that asserts are fulfilled.
    if (derivation.IsValid()) {
      result.push_back(derivation);
    }
  }
  return result;
}

}  // namespace libtextclassifier3::grammar