/
jsonpath.go
129 lines (113 loc) · 3.43 KB
/
jsonpath.go
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// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package sql
import (
"errors"
"github.com/bcicen/jstream"
"github.com/minio/simdjson-go"
)
var (
errKeyLookup = errors.New("Cannot look up key in non-object value")
errIndexLookup = errors.New("Cannot look up array index in non-array value")
errWildcardObjectLookup = errors.New("Object wildcard used on non-object value")
errWildcardArrayLookup = errors.New("Array wildcard used on non-array value")
errWildcardObjectUsageInvalid = errors.New("Invalid usage of object wildcard")
)
// jsonpathEval evaluates a JSON path and returns the value at the path.
// If the value should be considered flat (from wildcards) any array returned should be considered individual values.
func jsonpathEval(p []*JSONPathElement, v interface{}) (r interface{}, flat bool, err error) {
// fmt.Printf("JPATHexpr: %v jsonobj: %v\n\n", p, v)
if len(p) == 0 || v == nil {
return v, false, nil
}
switch {
case p[0].Key != nil:
key := p[0].Key.keyString()
switch kvs := v.(type) {
case jstream.KVS:
for _, kv := range kvs {
if kv.Key == key {
return jsonpathEval(p[1:], kv.Value)
}
}
// Key not found - return nil result
return Missing{}, false, nil
case simdjson.Object:
elem := kvs.FindKey(key, nil)
if elem == nil {
// Key not found - return nil result
return Missing{}, false, nil
}
val, err := IterToValue(elem.Iter)
if err != nil {
return nil, false, err
}
return jsonpathEval(p[1:], val)
default:
return nil, false, errKeyLookup
}
case p[0].Index != nil:
idx := *p[0].Index
arr, ok := v.([]interface{})
if !ok {
return nil, false, errIndexLookup
}
if idx >= len(arr) {
return nil, false, nil
}
return jsonpathEval(p[1:], arr[idx])
case p[0].ObjectWildcard:
switch kvs := v.(type) {
case jstream.KVS:
if len(p[1:]) > 0 {
return nil, false, errWildcardObjectUsageInvalid
}
return kvs, false, nil
case simdjson.Object:
if len(p[1:]) > 0 {
return nil, false, errWildcardObjectUsageInvalid
}
return kvs, false, nil
default:
return nil, false, errWildcardObjectLookup
}
case p[0].ArrayWildcard:
arr, ok := v.([]interface{})
if !ok {
return nil, false, errWildcardArrayLookup
}
// Lookup remainder of path in each array element and
// make result array.
var result []interface{}
for _, a := range arr {
rval, flatten, err := jsonpathEval(p[1:], a)
if err != nil {
return nil, false, err
}
if flatten {
// Flatten if array.
if arr, ok := rval.([]interface{}); ok {
result = append(result, arr...)
continue
}
}
result = append(result, rval)
}
return result, true, nil
}
panic("cannot reach here")
}