C++ MatchExpression::matchType方法代码示例

    static Status _extractFullEqualityMatches(const MatchExpression& root,
                                              const FieldRefSet* fullPathsToExtract,
                                              EqualityMatches* equalities) {

        if (root.matchType() == MatchExpression::EQ) {

            // Extract equality matches
            const EqualityMatchExpression& eqChild =
                static_cast<const EqualityMatchExpression&>(root);

            FieldRef path(eqChild.path());

            if (fullPathsToExtract) {

                FieldRefSet conflictPaths;
                fullPathsToExtract->findConflicts(&path, &conflictPaths);

                // Ignore if this path is unrelated to the full paths
                if (conflictPaths.empty())
                    return Status::OK();

                // Make sure we're a prefix of all the conflict paths
                Status status = checkPathIsPrefixOf(path, conflictPaths);
                if (!status.isOK())
                    return status;
            }

            Status status = checkEqualityConflicts(*equalities, path);
            if (!status.isOK())
                return status;

            equalities->insert(make_pair(eqChild.path(), &eqChild));
        }
        else if (root.matchType() == MatchExpression::AND) {

            // Further explore $and matches
            for (size_t i = 0; i < root.numChildren(); ++i) {
                MatchExpression* child = root.getChild(i);
                Status status = _extractFullEqualityMatches(*child, fullPathsToExtract, equalities);
                if (!status.isOK())
                    return status;
            }
        }

        return Status::OK();
    }

// static
MatchExpression* CanonicalQuery::normalizeTree(MatchExpression* root) {
    // root->isLogical() is true now.  We care about AND, OR, and NOT. NOR currently scares us.
    if (MatchExpression::AND == root->matchType() || MatchExpression::OR == root->matchType()) {
        // We could have AND of AND of AND.  Make sure we clean up our children before merging
        // them.
        // UNITTEST 11738048
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }

        // If any of our children are of the same logical operator that we are, we remove the
        // child's children and append them to ourselves after we examine all children.
        std::vector<MatchExpression*> absorbedChildren;

        for (size_t i = 0; i < root->numChildren();) {
            MatchExpression* child = root->getChild(i);
            if (child->matchType() == root->matchType()) {
                // AND of an AND or OR of an OR.  Absorb child's children into ourself.
                for (size_t j = 0; j < child->numChildren(); ++j) {
                    absorbedChildren.push_back(child->getChild(j));
                }
                // TODO(opt): this is possibly n^2-ish
                root->getChildVector()->erase(root->getChildVector()->begin() + i);
                child->getChildVector()->clear();
                // Note that this only works because we cleared the child's children
                delete child;
                // Don't increment 'i' as the current child 'i' used to be child 'i+1'
            } else {
                ++i;
            }
        }

        root->getChildVector()->insert(
            root->getChildVector()->end(), absorbedChildren.begin(), absorbedChildren.end());

        // AND of 1 thing is the thing, OR of 1 thing is the thing.
        if (1 == root->numChildren()) {
            MatchExpression* ret = root->getChild(0);
            root->getChildVector()->clear();
            delete root;
            return ret;
        }
    } else if (MatchExpression::NOT == root->matchType()) {
        // Normalize the rest of the tree hanging off this NOT node.
        NotMatchExpression* nme = static_cast<NotMatchExpression*>(root);
        MatchExpression* child = nme->releaseChild();
        // normalizeTree(...) takes ownership of 'child', and then
        // transfers ownership of its return value to 'nme'.
        nme->resetChild(normalizeTree(child));
    } else if (MatchExpression::ELEM_MATCH_VALUE == root->matchType()) {
        // Just normalize our children.
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }
    }

    return root;
}

    TEST( MatchExpressionParserText, Parse1 ) {
        BSONObj query = fromjson( "{$text:{$search:\"awesome\", $language:\"english\"}}" );

        StatusWithMatchExpression result = MatchExpressionParser::parse( query );
        ASSERT_TRUE( result.isOK() );

        MatchExpression* exp = result.getValue();
        ASSERT_EQUALS( MatchExpression::TEXT, exp->matchType() );

        TextMatchExpression* textExp = static_cast<TextMatchExpression*>( exp );
        ASSERT_EQUALS( textExp->getQuery(), "awesome" );
        ASSERT_EQUALS( textExp->getLanguage(), "english" );
    }

    TEST( MatchExpressionParserGeoNear, ParseNear ) {
        BSONObj query = fromjson("{loc:{$near:{$maxDistance:100, "
                                 "$geometry:{type:\"Point\", coordinates:[0,0]}}}}");

        StatusWithMatchExpression result = MatchExpressionParser::parse( query );
        ASSERT_TRUE( result.isOK() );

        MatchExpression* exp = result.getValue();
        ASSERT_EQUALS(MatchExpression::GEO_NEAR, exp->matchType());

        GeoNearMatchExpression* gnexp = static_cast<GeoNearMatchExpression*>(exp);
        ASSERT_EQUALS(gnexp->getData().maxDistance, 100);
    }

// For $near, $nearSphere, and $geoNear syntax of:
// {
//   $near/$nearSphere/$geoNear: [ <x>, <y> ],
//   $minDistance: <distance in radians>,
//   $maxDistance: <distance in radians>
// }
TEST(MatchExpressionParserGeoNear, ParseValidNear) {
    BSONObj query = fromjson("{loc: {$near: [0,0], $maxDistance: 100, $minDistance: 50}}");

    StatusWithMatchExpression result = MatchExpressionParser::parse(query);
    ASSERT_TRUE(result.isOK());

    MatchExpression* exp = result.getValue().get();
    ASSERT_EQ(MatchExpression::GEO_NEAR, exp->matchType());

    GeoNearMatchExpression* gnexp = static_cast<GeoNearMatchExpression*>(exp);
    ASSERT_EQ(gnexp->getData().maxDistance, 100);
    ASSERT_EQ(gnexp->getData().minDistance, 50);
}

// For $near, $nearSphere, and $geoNear syntax of:
// {
//   $near/$nearSphere/$geoNear: [ <x>, <y> ],
//   $minDistance: <distance in radians>,
//   $maxDistance: <distance in radians>
// }
TEST(MatchExpressionParserGeoNear, ParseValidNear) {
    BSONObj query = fromjson("{loc: {$near: [0,0], $maxDistance: 100, $minDistance: 50}}");

    const CollatorInterface* collator = nullptr;
    StatusWithMatchExpression result =
        MatchExpressionParser::parse(query, ExtensionsCallbackDisallowExtensions(), collator);
    ASSERT_TRUE(result.isOK());

    MatchExpression* exp = result.getValue().get();
    ASSERT_EQ(MatchExpression::GEO_NEAR, exp->matchType());

    GeoNearMatchExpression* gnexp = static_cast<GeoNearMatchExpression*>(exp);
    ASSERT_EQ(gnexp->getData().maxDistance, 100);
    ASSERT_EQ(gnexp->getData().minDistance, 50);
}

    // static
    MatchExpression* CanonicalQuery::normalizeTree(MatchExpression* root) {
        // root->isLogical() is true now.  We care about AND and OR.  Negations currently scare us.
        if (MatchExpression::AND == root->matchType() || MatchExpression::OR == root->matchType()) {
            // We could have AND of AND of AND.  Make sure we clean up our children before merging
            // them.
            // UNITTEST 11738048
            for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
                (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
            }

            // If any of our children are of the same logical operator that we are, we remove the
            // child's children and append them to ourselves after we examine all children.
            vector<MatchExpression*> absorbedChildren;

            for (size_t i = 0; i < root->numChildren();) {
                MatchExpression* child = root->getChild(i);
                if (child->matchType() == root->matchType()) {
                    // AND of an AND or OR of an OR.  Absorb child's children into ourself.
                    for (size_t j = 0; j < child->numChildren(); ++j) {
                        absorbedChildren.push_back(child->getChild(j));
                    }
                    // TODO(opt): this is possibly n^2-ish
                    root->getChildVector()->erase(root->getChildVector()->begin() + i);
                    child->getChildVector()->clear();
                    // Note that this only works because we cleared the child's children
                    delete child;
                    // Don't increment 'i' as the current child 'i' used to be child 'i+1'
                }
                else {
                    ++i;
                }
            }

            root->getChildVector()->insert(root->getChildVector()->end(),
                                           absorbedChildren.begin(),
                                           absorbedChildren.end());

            // AND of 1 thing is the thing, OR of 1 thing is the thing.
            if (1 == root->numChildren()) {
                MatchExpression* ret = root->getChild(0);
                root->getChildVector()->clear();
                delete root;
                return ret;
            }
        }

        return root;
    }

    // static
    void QueryPlannerIXSelect::stripUnneededAssignments(MatchExpression* node,
                                                        const std::vector<IndexEntry>& indices) {
        if (MatchExpression::AND == node->matchType()) {
            for (size_t i = 0; i < node->numChildren(); i++) {
                MatchExpression* child = node->getChild(i);

                if (MatchExpression::EQ != child->matchType()) {
                    continue;
                }

                if (!child->getTag()) {
                    continue;
                }

                // We found a EQ child of an AND which is tagged.
                RelevantTag* rt = static_cast<RelevantTag*>(child->getTag());

                // Look through all of the indices for which this predicate can be answered with
                // the leading field of the index.
                for (std::vector<size_t>::const_iterator i = rt->first.begin();
                        i != rt->first.end(); ++i) {
                    size_t index = *i;

                    if (indices[index].unique && 1 == indices[index].keyPattern.nFields()) {
                        // Found an EQ predicate which can use a single-field unique index.
                        // Clear assignments from the entire tree, and add back a single assignment
                        // for 'child' to the unique index.
                        clearAssignments(node);
                        RelevantTag* newRt = static_cast<RelevantTag*>(child->getTag());
                        newRt->first.push_back(index);

                        // Tag state has been reset in the entire subtree at 'root'; nothing
                        // else for us to do.
                        return;
                    }
                }
            }
        }

        for (size_t i = 0; i < node->numChildren(); i++) {
            stripUnneededAssignments(node->getChild(i), indices);
        }
    }

TEST(MatchExpressionParserGeoNear, ParseValidNearSphere) {
    BSONObj query = fromjson("{loc: {$nearSphere: [0,0], $maxDistance: 100, $minDistance: 50}}");

    const CollatorInterface* collator = nullptr;
    const boost::intrusive_ptr<ExpressionContextForTest> expCtx(new ExpressionContextForTest());
    StatusWithMatchExpression result =
        MatchExpressionParser::parse(query,
                                     collator,
                                     expCtx,
                                     ExtensionsCallbackNoop(),
                                     MatchExpressionParser::kAllowAllSpecialFeatures);
    ASSERT_TRUE(result.isOK());

    MatchExpression* exp = result.getValue().get();
    ASSERT_EQ(MatchExpression::GEO_NEAR, exp->matchType());

    GeoNearMatchExpression* gnexp = static_cast<GeoNearMatchExpression*>(exp);
    ASSERT_EQ(gnexp->getData().maxDistance, 100);
    ASSERT_EQ(gnexp->getData().minDistance, 50);
}

    /**
     * Traverse the subtree rooted at 'node' to remove invalid RelevantTag assignments to text index
     * 'idx', which has prefix paths 'prefixPaths'.
     */
    static void stripInvalidAssignmentsToTextIndex(MatchExpression* node,
                                                   size_t idx,
            const unordered_set<StringData, StringData::Hasher>& prefixPaths) {

        // If we're here, there are prefixPaths and node is either:
        // 1. a text pred which we can't use as we have nothing over its prefix, or
        // 2. a non-text pred which we can't use as we don't have a text pred AND-related.
        if (Indexability::nodeCanUseIndexOnOwnField(node)) {
            removeIndexRelevantTag(node, idx);
            return;
        }

        // Do not traverse tree beyond negation node.
        if (node->matchType() == MatchExpression::NOT
            || node->matchType() == MatchExpression::NOR) {

            return;
        }

        // For anything to use a text index with prefixes, we require that:
        // 1. The text pred exists in an AND,
        // 2. The non-text preds that use the text index's prefixes are also in that AND.

        if (node->matchType() != MatchExpression::AND) {
            // It's an OR or some kind of array operator.
            for (size_t i = 0; i < node->numChildren(); ++i) {
                stripInvalidAssignmentsToTextIndex(node->getChild(i), idx, prefixPaths);
            }
            return;
        }

        // If we're here, we're an AND.  Determine whether the children satisfy the index prefix for
        // the text index.
        invariant(node->matchType() == MatchExpression::AND);

        bool hasText = false;

        // The AND must have an EQ predicate for each prefix path.  When we encounter a child with a
        // tag we remove it from childrenPrefixPaths.  All children exist if this set is empty at
        // the end.
        unordered_set<StringData, StringData::Hasher> childrenPrefixPaths = prefixPaths;

        for (size_t i = 0; i < node->numChildren(); ++i) {
            MatchExpression* child = node->getChild(i);
            RelevantTag* tag = static_cast<RelevantTag*>(child->getTag());

            if (NULL == tag) {
                // 'child' could be a logical operator.  Maybe there are some assignments hiding
                // inside.
                stripInvalidAssignmentsToTextIndex(child, idx, prefixPaths);
                continue;
            }

            bool inFirst = tag->first.end() != std::find(tag->first.begin(),
                                                         tag->first.end(),
                                                         idx);

            bool inNotFirst = tag->notFirst.end() != std::find(tag->notFirst.begin(),
                                                               tag->notFirst.end(),
                                                               idx);

            if (inFirst || inNotFirst) {
                // Great!  'child' was assigned to our index.
                if (child->matchType() == MatchExpression::TEXT) {
                    hasText = true;
                }
                else {
                    childrenPrefixPaths.erase(child->path());
                    // One fewer prefix we're looking for, possibly.  Note that we could have a
                    // suffix assignment on the index and wind up here.  In this case the erase
                    // above won't do anything since a suffix isn't a prefix.
                }
            }
            else {
                // Recurse on the children to ensure that they're not hiding any assignments
                // to idx.
                stripInvalidAssignmentsToTextIndex(child, idx, prefixPaths);
            }
        }

        // Our prereqs for using the text index were not satisfied so we remove the assignments from
        // all children of the AND.
        if (!hasText || !childrenPrefixPaths.empty()) {
            for (size_t i = 0; i < node->numChildren(); ++i) {
                stripInvalidAssignmentsToTextIndex(node->getChild(i), idx, prefixPaths);
            }
        }
    }

    static void stripInvalidAssignmentsTo2dsphereIndex(MatchExpression* node, size_t idx) {

        if (Indexability::nodeCanUseIndexOnOwnField(node)) {
            removeIndexRelevantTag(node, idx);
            return;
        }

        const MatchExpression::MatchType nodeType = node->matchType();

        // Don't bother peeking inside of negations.
        if (MatchExpression::NOT == nodeType || MatchExpression::NOR == nodeType) {
            return;
        }

        if (MatchExpression::AND != nodeType) {
            // It's an OR or some kind of array operator.
            for (size_t i = 0; i < node->numChildren(); ++i) {
                stripInvalidAssignmentsTo2dsphereIndex(node->getChild(i), idx);
            }
            return;
        }

        bool hasGeoField = false;

        for (size_t i = 0; i < node->numChildren(); ++i) {
            MatchExpression* child = node->getChild(i);
            RelevantTag* tag = static_cast<RelevantTag*>(child->getTag());

            if (NULL == tag) {
                // 'child' could be a logical operator.  Maybe there are some assignments hiding
                // inside.
                stripInvalidAssignmentsTo2dsphereIndex(child, idx);
                continue;
            }

            bool inFirst = tag->first.end() != std::find(tag->first.begin(),
                                                         tag->first.end(),
                                                         idx);

            bool inNotFirst = tag->notFirst.end() != std::find(tag->notFirst.begin(),
                                                               tag->notFirst.end(),
                                                               idx);

            // If there is an index assignment...
            if (inFirst || inNotFirst) {
                // And it's a geo predicate...
                if (MatchExpression::GEO == child->matchType() ||
                    MatchExpression::GEO_NEAR == child->matchType()) {

                    hasGeoField = true;
                }
            }
            else {
                // Recurse on the children to ensure that they're not hiding any assignments
                // to idx.
                stripInvalidAssignmentsTo2dsphereIndex(child, idx);
            }
        }

        // If there isn't a geo predicate our results aren't a subset of what's in the geo index, so
        // if we use the index we'll miss results.
        if (!hasGeoField) {
            for (size_t i = 0; i < node->numChildren(); ++i) {
                stripInvalidAssignmentsTo2dsphereIndex(node->getChild(i), idx);
            }
        }
    }

// static
MatchExpression* CanonicalQuery::normalizeTree(MatchExpression* root) {
    if (MatchExpression::AND == root->matchType() || MatchExpression::OR == root->matchType()) {
        // We could have AND of AND of AND.  Make sure we clean up our children before merging them.
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }

        // If any of our children are of the same logical operator that we are, we remove the
        // child's children and append them to ourselves after we examine all children.
        std::vector<MatchExpression*> absorbedChildren;

        for (size_t i = 0; i < root->numChildren();) {
            MatchExpression* child = root->getChild(i);
            if (child->matchType() == root->matchType()) {
                // AND of an AND or OR of an OR.  Absorb child's children into ourself.
                for (size_t j = 0; j < child->numChildren(); ++j) {
                    absorbedChildren.push_back(child->getChild(j));
                }
                // TODO(opt): this is possibly n^2-ish
                root->getChildVector()->erase(root->getChildVector()->begin() + i);
                child->getChildVector()->clear();
                // Note that this only works because we cleared the child's children
                delete child;
                // Don't increment 'i' as the current child 'i' used to be child 'i+1'
            } else {
                ++i;
            }
        }

        root->getChildVector()->insert(
            root->getChildVector()->end(), absorbedChildren.begin(), absorbedChildren.end());

        // AND of 1 thing is the thing, OR of 1 thing is the thing.
        if (1 == root->numChildren()) {
            MatchExpression* ret = root->getChild(0);
            root->getChildVector()->clear();
            delete root;
            return ret;
        }
    } else if (MatchExpression::NOR == root->matchType()) {
        // First clean up children.
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }

        // NOR of one thing is NOT of the thing.
        if (1 == root->numChildren()) {
            // Detach the child and assume ownership.
            std::unique_ptr<MatchExpression> child(root->getChild(0));
            root->getChildVector()->clear();

            // Delete the root when this goes out of scope.
            std::unique_ptr<NorMatchExpression> ownedRoot(static_cast<NorMatchExpression*>(root));

            // Make a NOT to be the new root and transfer ownership of the child to it.
            auto newRoot = stdx::make_unique<NotMatchExpression>();
            newRoot->init(child.release()).transitional_ignore();

            return newRoot.release();
        }
    } else if (MatchExpression::NOT == root->matchType()) {
        // Normalize the rest of the tree hanging off this NOT node.
        NotMatchExpression* nme = static_cast<NotMatchExpression*>(root);
        MatchExpression* child = nme->releaseChild();
        // normalizeTree(...) takes ownership of 'child', and then
        // transfers ownership of its return value to 'nme'.
        nme->resetChild(normalizeTree(child));
    } else if (MatchExpression::ELEM_MATCH_OBJECT == root->matchType()) {
        // Normalize the rest of the tree hanging off this ELEM_MATCH_OBJECT node.
        ElemMatchObjectMatchExpression* emome = static_cast<ElemMatchObjectMatchExpression*>(root);
        auto child = emome->releaseChild();
        // normalizeTree(...) takes ownership of 'child', and then
        // transfers ownership of its return value to 'emome'.
        emome->resetChild(std::unique_ptr<MatchExpression>(normalizeTree(child.release())));
    } else if (MatchExpression::ELEM_MATCH_VALUE == root->matchType()) {
        // Just normalize our children.
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }
    } else if (MatchExpression::MATCH_IN == root->matchType()) {
        std::unique_ptr<InMatchExpression> in(static_cast<InMatchExpression*>(root));

        // IN of 1 regex is the regex.
        if (in->getRegexes().size() == 1 && in->getEqualities().empty()) {
            RegexMatchExpression* childRe = in->getRegexes().begin()->get();
            invariant(!childRe->getTag());

            // Create a new RegexMatchExpression, because 'childRe' does not have a path.
            auto re = stdx::make_unique<RegexMatchExpression>();
            re->init(in->path(), childRe->getString(), childRe->getFlags()).transitional_ignore();
            if (in->getTag()) {
                re->setTag(in->getTag()->clone());
            }
            return normalizeTree(re.release());
        }

        // IN of 1 equality is the equality.
        if (in->getEqualities().size() == 1 && in->getRegexes().empty()) {
            auto eq = stdx::make_unique<EqualityMatchExpression>();
//.........这里部分代码省略.........

//.........这里部分代码省略.........

        QLOG() << "rated tree" << endl;
        QLOG() << query.root()->toString() << endl;

        // If there is a GEO_NEAR it must have an index it can use directly.
        // XXX: move into data access?
        MatchExpression* gnNode = NULL;
        if (QueryPlannerCommon::hasNode(query.root(), MatchExpression::GEO_NEAR, &gnNode)) {
            // No index for GEO_NEAR?  No query.
            RelevantTag* tag = static_cast<RelevantTag*>(gnNode->getTag());
            if (0 == tag->first.size() && 0 == tag->notFirst.size()) {
                return;
            }

            GeoNearMatchExpression* gnme = static_cast<GeoNearMatchExpression*>(gnNode);

            vector<size_t> newFirst;

            // 2d + GEO_NEAR is annoying.  Because 2d's GEO_NEAR isn't streaming we have to embed
            // the full query tree inside it as a matcher.
            for (size_t i = 0; i < tag->first.size(); ++i) {
                // GEO_NEAR has a non-2d index it can use.  We can deal w/that in normal planning.
                if (!is2DIndex(relevantIndices[tag->first[i]].keyPattern)) {
                    newFirst.push_back(i);
                    continue;
                }

                // If we're here, GEO_NEAR has a 2d index.  We create a 2dgeonear plan with the
                // entire tree as a filter, if possible.

                GeoNear2DNode* solnRoot = new GeoNear2DNode();
                solnRoot->nq = gnme->getData();

                if (MatchExpression::GEO_NEAR != query.root()->matchType()) {
                    // root is an AND, clone and delete the GEO_NEAR child.
                    MatchExpression* filterTree = query.root()->shallowClone();
                    verify(MatchExpression::AND == filterTree->matchType());

                    bool foundChild = false;
                    for (size_t i = 0; i < filterTree->numChildren(); ++i) {
                        if (MatchExpression::GEO_NEAR == filterTree->getChild(i)->matchType()) {
                            foundChild = true;
                            filterTree->getChildVector()->erase(filterTree->getChildVector()->begin() + i);
                            break;
                        }
                    }
                    verify(foundChild);
                    solnRoot->filter.reset(filterTree);
                }

                solnRoot->numWanted = query.getParsed().getNumToReturn();
                if (0 == solnRoot->numWanted) {
                    solnRoot->numWanted = 100;
                }
                solnRoot->indexKeyPattern = relevantIndices[tag->first[i]].keyPattern;

                // Remove the 2d index.  2d can only be the first field, and we know there is
                // only one GEO_NEAR, so we don't care if anyone else was assigned it; it'll
                // only be first for gnNode.
                tag->first.erase(tag->first.begin() + i);

                QuerySolution* soln = QueryPlannerAnalysis::analyzeDataAccess(query, params, solnRoot);

                if (NULL != soln) {
                    out->push_back(soln);
                }

    bool PlanEnumerator::prepMemo(MatchExpression* node) {
        if (Indexability::nodeCanUseIndexOnOwnField(node)) {
            // We only get here if our parent is an OR, an array operator, or we're the root.

            // If we have no index tag there are no indices we can use.
            if (NULL == node->getTag()) { return false; }

            RelevantTag* rt = static_cast<RelevantTag*>(node->getTag());
            // In order to definitely use an index it must be prefixed with our field.
            // We don't consider notFirst indices here because we must be AND-related to a node
            // that uses the first spot in that index, and we currently do not know that
            // unless we're in an AND node.
            if (0 == rt->first.size()) { return false; }

            // We know we can use an index, so grab a memo spot.
            size_t myMemoID;
            NodeAssignment* assign;
            allocateAssignment(node, &assign, &myMemoID);

            assign->pred.reset(new PredicateAssignment());
            assign->pred->expr = node;
            assign->pred->first.swap(rt->first);
            return true;
        }
        else if (MatchExpression::OR == node->matchType()) {
            // For an OR to be indexed, all its children must be indexed.
            for (size_t i = 0; i < node->numChildren(); ++i) {
                if (!prepMemo(node->getChild(i))) {
                    return false;
                }
            }

            // If we're here we're fully indexed and can be in the memo.
            size_t myMemoID;
            NodeAssignment* assign;
            allocateAssignment(node, &assign, &myMemoID);

            OrAssignment* orAssignment = new OrAssignment();
            for (size_t i = 0; i < node->numChildren(); ++i) {
                orAssignment->subnodes.push_back(_nodeToId[node->getChild(i)]);
            }
            assign->orAssignment.reset(orAssignment);
            return true;
        }
        else if (MatchExpression::AND == node->matchType() || Indexability::arrayUsesIndexOnChildren(node)) {
            // map from idx id to children that have a pred over it.
            unordered_map<IndexID, vector<MatchExpression*> > idxToFirst;
            unordered_map<IndexID, vector<MatchExpression*> > idxToNotFirst;

            vector<MemoID> subnodes;

            for (size_t i = 0; i < node->numChildren(); ++i) {
                MatchExpression* child = node->getChild(i);

                if (Indexability::nodeCanUseIndexOnOwnField(child)) {
                    RelevantTag* rt = static_cast<RelevantTag*>(child->getTag());
                    for (size_t j = 0; j < rt->first.size(); ++j) {
                        idxToFirst[rt->first[j]].push_back(child);
                    }
                    for (size_t j = 0 ; j< rt->notFirst.size(); ++j) {
                        idxToNotFirst[rt->notFirst[j]].push_back(child);
                    }
                }
                else {
                    if (prepMemo(child)) {
                        verify(_nodeToId.end() != _nodeToId.find(child));
                        size_t childID = _nodeToId[child];
                        subnodes.push_back(childID);
                    }
                }
            }

            if (idxToFirst.empty() && (subnodes.size() == 0)) { return false; }

            AndAssignment* newAndAssignment = new AndAssignment();
            newAndAssignment->subnodes.swap(subnodes);

            // At this point we know how many indices the AND's predicate children are over.
            newAndAssignment->predChoices.resize(idxToFirst.size());

            // This iterates through the predChoices.
            size_t predChoicesIdx = 0;

            // For each FIRST, we assign nodes to it.
            for (unordered_map<IndexID, vector<MatchExpression*> >::iterator it = idxToFirst.begin(); it != idxToFirst.end(); ++it) {
                OneIndexAssignment* assign = &newAndAssignment->predChoices[predChoicesIdx];
                ++predChoicesIdx;

                // Fill out the OneIndexAssignment with the preds that are over the first field.
                assign->index = it->first;
                // We can swap because we're never touching idxToFirst again after this loop over it.
                assign->preds.swap(it->second);
                // If it's a multikey index, we can't intersect the bounds, so we only want one pred.
                if ((*_indices)[it->first].multikey) {
                    // XXX: pick a better pred than the first one that happens to wander in.
                    // XXX: see and3.js, indexq.js, arrayfind7.js
                    QLOG() << "Index " << (*_indices)[it->first].keyPattern.toString()
                         << " is multikey but has >1 pred possible, should be smarter"
                         << " here and pick the best one"
                         << endl;
//.........这里部分代码省略.........

    Status UpdateDriver::populateDocumentWithQueryFields(const CanonicalQuery* query,
                                                         mutablebson::Document& doc) const {

        MatchExpression* root = query->root();

        MatchExpression::MatchType rootType = root->matchType();

        // These copies are needed until we apply the modifiers at the end.
        std::vector<BSONObj> copies;

        // We only care about equality and "and"ed equality fields, everything else is ignored
        if (rootType != MatchExpression::EQ && rootType != MatchExpression::AND)
            return Status::OK();

        if (isDocReplacement()) {
            BSONElement idElem = query->getQueryObj().getField("_id");

            // Replacement mods need the _id field copied explicitly.
            if (idElem.ok()) {
                mb::Element elem = doc.makeElement(idElem);
                return doc.root().pushFront(elem);
            }

            return Status::OK();
        }

        // Create a new UpdateDriver to create the base doc from the query
        Options opts;
        opts.logOp = false;
        opts.multi = false;
        opts.upsert = true;
        opts.modOptions = modOptions();

        UpdateDriver insertDriver(opts);
        insertDriver.setContext(ModifierInterface::ExecInfo::INSERT_CONTEXT);

        // If we are a single equality match query
        if (root->matchType() == MatchExpression::EQ) {
            EqualityMatchExpression* eqMatch =
                    static_cast<EqualityMatchExpression*>(root);

            const BSONElement matchData = eqMatch->getData();
            BSONElement childElem = matchData;

            // Make copy to new path if not the same field name (for cases like $all)
            if (!root->path().empty() && matchData.fieldNameStringData() != root->path()) {
                BSONObjBuilder copyBuilder;
                copyBuilder.appendAs(eqMatch->getData(), root->path());
                const BSONObj copy = copyBuilder.obj();
                copies.push_back(copy);
                childElem = copy[root->path()];
            }

            // Add this element as a $set modifier
            Status s = insertDriver.addAndParse(modifiertable::MOD_SET,
                                                childElem);
            if (!s.isOK())
                return s;

        }
        else {

            // parse query $set mods, including only equality stuff
            for (size_t i = 0; i < root->numChildren(); ++i) {
                MatchExpression* child = root->getChild(i);
                if (child->matchType() == MatchExpression::EQ) {
                    EqualityMatchExpression* eqMatch =
                            static_cast<EqualityMatchExpression*>(child);

                    const BSONElement matchData = eqMatch->getData();
                    BSONElement childElem = matchData;

                    // Make copy to new path if not the same field name (for cases like $all)
                    if (!child->path().empty() &&
                            matchData.fieldNameStringData() != child->path()) {
                        BSONObjBuilder copyBuilder;
                        copyBuilder.appendAs(eqMatch->getData(), child->path());
                        const BSONObj copy = copyBuilder.obj();
                        copies.push_back(copy);
                        childElem = copy[child->path()];
                    }

                    // Add this element as a $set modifier
                    Status s = insertDriver.addAndParse(modifiertable::MOD_SET,
                                                        childElem);
                    if (!s.isOK())
                        return s;
                }
            }
        }

        // update the document with base field
        Status s = insertDriver.update(StringData(), &doc);
        copies.clear();
        if (!s.isOK()) {
            return Status(ErrorCodes::UnsupportedFormat,
                          str::stream() << "Cannot create base during"
                                           " insert of update. Caused by :"
                                        << s.toString());
        }
//.........这里部分代码省略.........