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// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package maps
import (
"strings"
"github.com/pkg/errors"
"github.com/spf13/cast"
)
// GetNestedParam gets the first match of the keyStr in the candidates given.
// It will first try the exact match and then try to find it as a nested map value,
// using the given separator, e.g. "mymap.name".
// It assumes that all the maps given have lower cased keys.
func GetNestedParam(keyStr, separator string, candidates ...map[string]interface{}) (interface{}, error) {
keyStr = strings.ToLower(keyStr)
lookupFn := func(key string) interface{} {
for _, m := range candidates {
if v, ok := m[key]; ok {
return v
}
}
return nil
}
v, _, _, err := GetNestedParamFn(keyStr, separator, lookupFn)
return v, err
}
func GetNestedParamFn(keyStr, separator string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
result, _ := traverseDirectParams(keyStr, lookupFn)
if result != nil {
return result, keyStr, nil, nil
}
keySegments := strings.Split(keyStr, separator)
if len(keySegments) == 1 {
return nil, keyStr, nil, nil
}
return traverseNestedParams(keySegments, lookupFn)
}
func traverseDirectParams(keyStr string, lookupFn func(key string) interface{}) (interface{}, error) {
return lookupFn(keyStr), nil
}
func traverseNestedParams(keySegments []string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
firstKey, rest := keySegments[0], keySegments[1:]
result := lookupFn(firstKey)
if result == nil || len(rest) == 0 {
return result, firstKey, nil, nil
}
switch m := result.(type) {
case map[string]interface{}:
v, key, owner := traverseParams(rest, m)
return v, key, owner, nil
default:
return nil, "", nil, errors.Errorf("unsupported Params type: %T", result)
}
}
func traverseParams(keys []string, m map[string]interface{}) (interface{}, string, map[string]interface{}) {
// Shift first element off.
firstKey, rest := keys[0], keys[1:]
result := m[firstKey]
// No point in continuing here.
if result == nil {
return result, "", nil
}
if len(rest) == 0 {
// That was the last key.
return result, firstKey, m
}
// That was not the last key.
return traverseParams(rest, cast.ToStringMap(result))
}
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