github.com/cs3org/reva/v2@v2.27.7/pkg/storage/utils/indexer/query_tree.go (about)

     1  // Copyright 2018-2022 CERN
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  //
    15  // In applying this license, CERN does not waive the privileges and immunities
    16  // granted to it by virtue of its status as an Intergovernmental Organization
    17  // or submit itself to any jurisdiction.
    18  
    19  package indexer
    20  
    21  type queryTree struct {
    22  	token *token
    23  	root  bool
    24  	left  *queryTree
    25  	right *queryTree
    26  }
    27  
    28  // token to be resolved by the index
    29  type token struct {
    30  	operator   string // original OData operator. i.e: 'startswith', `or`, `and`.
    31  	filterType string // equivalent operator from OData -> indexer i.e FindByPartial or FindBy.
    32  	operands   []string
    33  }
    34  
    35  // newQueryTree constructs a new tree with a root node.
    36  func newQueryTree() queryTree {
    37  	return queryTree{
    38  		root: true,
    39  	}
    40  }
    41  
    42  // insert populates first the LHS of the tree first, if this is not possible it fills the RHS.
    43  func (t *queryTree) insert(tkn *token) {
    44  	if t != nil && t.root {
    45  		t.left = &queryTree{token: tkn}
    46  		return
    47  	}
    48  
    49  	if t.left == nil {
    50  		t.left = &queryTree{token: tkn}
    51  		return
    52  	}
    53  
    54  	if t.left != nil && t.right == nil {
    55  		t.right = &queryTree{token: tkn}
    56  		return
    57  	}
    58  }