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101 lines
2.4 KiB
101 lines
2.4 KiB
6 years ago
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/*
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* Minio Cloud Storage, (C) 2019 Minio, Inc.
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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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package sql
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import (
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"errors"
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"github.com/bcicen/jstream"
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)
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var (
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errKeyLookup = errors.New("Cannot look up key in non-object value")
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errIndexLookup = errors.New("Cannot look up array index in non-array value")
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errWildcardObjectLookup = errors.New("Object wildcard used on non-object value")
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errWildcardArrayLookup = errors.New("Array wildcard used on non-array value")
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errWilcardObjectUsageInvalid = errors.New("Invalid usage of object wildcard")
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)
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func jsonpathEval(p []*JSONPathElement, v interface{}) (r interface{}, err error) {
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// fmt.Printf("JPATHexpr: %v jsonobj: %v\n\n", p, v)
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if len(p) == 0 || v == nil {
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return v, nil
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}
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switch {
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case p[0].Key != nil:
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key := p[0].Key.keyString()
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kvs, ok := v.(jstream.KVS)
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if !ok {
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return nil, errKeyLookup
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}
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for _, kv := range kvs {
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if kv.Key == key {
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return jsonpathEval(p[1:], kv.Value)
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}
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}
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// Key not found - return nil result
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return nil, nil
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case p[0].Index != nil:
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idx := *p[0].Index
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arr, ok := v.([]interface{})
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if !ok {
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return nil, errIndexLookup
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}
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if idx >= len(arr) {
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return nil, nil
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}
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return jsonpathEval(p[1:], arr[idx])
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case p[0].ObjectWildcard:
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kvs, ok := v.(jstream.KVS)
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if !ok {
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return nil, errWildcardObjectLookup
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}
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if len(p[1:]) > 0 {
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return nil, errWilcardObjectUsageInvalid
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}
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return kvs, nil
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case p[0].ArrayWildcard:
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arr, ok := v.([]interface{})
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if !ok {
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return nil, errWildcardArrayLookup
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}
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// Lookup remainder of path in each array element and
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// make result array.
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var result []interface{}
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for _, a := range arr {
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rval, err := jsonpathEval(p[1:], a)
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if err != nil {
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return nil, err
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}
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result = append(result, rval)
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}
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return result, nil
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}
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panic("cannot reach here")
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}
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