1 2 /** 3 * Copyright (C) 2018-present MongoDB, Inc. 4 * 5 * This program is free software: you can redistribute it and/or modify 6 * it under the terms of the Server Side Public License, version 1, 7 * as published by MongoDB, Inc. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * Server Side Public License for more details. 13 * 14 * You should have received a copy of the Server Side Public License 15 * along with this program. If not, see 16 * <http://www.mongodb.com/licensing/server-side-public-license>. 17 * 18 * As a special exception, the copyright holders give permission to link the 19 * code of portions of this program with the OpenSSL library under certain 20 * conditions as described in each individual source file and distribute 21 * linked combinations including the program with the OpenSSL library. You 22 * must comply with the Server Side Public License in all respects for 23 * all of the code used other than as permitted herein. If you modify file(s) 24 * with this exception, you may extend this exception to your version of the 25 * file(s), but you are not obligated to do so. If you do not wish to do so, 26 * delete this exception statement from your version. If you delete this 27 * exception statement from all source files in the program, then also delete 28 * it in the license file. 29 */ 30 31 #pragma once 32 33 #include "mongo/db/matcher/expression_array.h" 34 #include "mongo/db/matcher/expression_with_placeholder.h" 35 #include "mongo/stdx/memory.h" 36 37 namespace mongo { 38 39 /** 40 * Matches arrays based on whether or not a specific element in the array matches a sub-expression. 41 */ 42 class InternalSchemaMatchArrayIndexMatchExpression final : public ArrayMatchingMatchExpression { 43 public: 44 static constexpr StringData kName = "$_internalSchemaMatchArrayIndex"_sd; 45 InternalSchemaMatchArrayIndexMatchExpression()46 InternalSchemaMatchArrayIndexMatchExpression() 47 : ArrayMatchingMatchExpression(MatchExpression::INTERNAL_SCHEMA_MATCH_ARRAY_INDEX) {} 48 49 Status init(StringData path, 50 long long index, 51 std::unique_ptr<ExpressionWithPlaceholder> expression); 52 53 void debugString(StringBuilder& debug, int level) const final; 54 55 bool equivalent(const MatchExpression* expr) const final; 56 57 /** 58 * Matches 'array' if the element at '_index' matches '_expression', or if its size is less than 59 * '_index'. 60 */ matchesArray(const BSONObj & array,MatchDetails * details)61 bool matchesArray(const BSONObj& array, MatchDetails* details) const final { 62 BSONElement element; 63 auto iterator = BSONObjIterator(array); 64 65 // Skip ahead to the element we want, bailing early if there aren't enough elements. 66 for (auto i = 0LL; i <= _index; ++i) { 67 if (!iterator.more()) { 68 return true; 69 } 70 element = iterator.next(); 71 } 72 73 return _expression->matchesBSONElement(element, details); 74 } 75 76 void serialize(BSONObjBuilder* builder) const final; 77 78 std::unique_ptr<MatchExpression> shallowClone() const final; 79 getChildVector()80 std::vector<MatchExpression*>* getChildVector() final { 81 return nullptr; 82 } 83 numChildren()84 size_t numChildren() const final { 85 return 1; 86 } 87 getChild(size_t i)88 MatchExpression* getChild(size_t i) const final { 89 invariant(i == 0); 90 return _expression->getFilter(); 91 } 92 93 private: 94 ExpressionOptimizerFunc getOptimizer() const final; 95 96 long long _index = 0; 97 std::unique_ptr<ExpressionWithPlaceholder> _expression; 98 }; 99 100 } // namespace mongo 101