hugo/common/maps/params.go

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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/spf13/cast"
)
// Params is a map where all keys are lower case.
type Params map[string]interface{}
// Get does a lower case and nested search in this map.
// It will return nil if none found.
func (p Params) Get(indices ...string) interface{} {
v, _, _ := getNested(p, indices)
return v
}
func getNested(m map[string]interface{}, indices []string) (interface{}, string, map[string]interface{}) {
if len(indices) == 0 {
return nil, "", nil
}
first := indices[0]
v, found := m[strings.ToLower(cast.ToString(first))]
if !found {
return nil, "", nil
}
if len(indices) == 1 {
return v, first, m
}
switch m2 := v.(type) {
case Params:
return getNested(m2, indices[1:])
case map[string]interface{}:
return getNested(m2, indices[1:])
default:
return nil, "", nil
}
}
// 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 ...Params) (interface{}, error) {
keyStr = strings.ToLower(keyStr)
// Try exact match first
for _, m := range candidates {
if v, ok := m[keyStr]; ok {
return v, nil
}
}
keySegments := strings.Split(keyStr, separator)
for _, m := range candidates {
if v := m.Get(keySegments...); v != nil {
return v, nil
}
}
return nil, nil
}
func GetNestedParamFn(keyStr, separator string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
keySegments := strings.Split(strings.ToLower(keyStr), separator)
if len(keySegments) == 0 {
return nil, "", nil, nil
}
first := lookupFn(keySegments[0])
if first == nil {
return nil, "", nil, nil
}
if len(keySegments) == 1 {
return first, keySegments[0], nil, nil
}
switch m := first.(type) {
case map[string]interface{}:
v, key, owner := getNested(m, keySegments[1:])
return v, key, owner, nil
case Params:
v, key, owner := getNested(m, keySegments[1:])
return v, key, owner, nil
}
return nil, "", nil, nil
}