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 (
"fmt"
"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
}
// Set overwrites values in p with values in pp for common or new keys.
// This is done recursively.
func (p Params) Set(pp Params) {
for k, v := range pp {
vv, found := p[k]
if !found {
p[k] = v
} else {
switch vvv := vv.(type) {
case Params:
if pv, ok := v.(Params); ok {
vvv.Set(pv)
} else {
p[k] = v
}
default:
p[k] = v
}
}
}
}
// IsZero returns true if p is considered empty.
func (p Params) IsZero() bool {
if p == nil || len(p) == 0 {
return true
}
if len(p) > 1 {
return false
}
for k, _ := range p {
return k == mergeStrategyKey
}
return false
}
// Merge transfers values from pp to p for new keys.
// This is done recursively.
func (p Params) Merge(pp Params) {
p.merge("", pp)
}
func (p Params) merge(ps ParamsMergeStrategy, pp Params) {
ns, found := p.GetMergeStrategy()
var ms = ns
if !found && ps != "" {
ms = ps
}
noUpdate := ms == ParamsMergeStrategyNone
noUpdate = noUpdate || (ps != "" && ps == ParamsMergeStrategyShallow)
for k, v := range pp {
if k == mergeStrategyKey {
continue
}
vv, found := p[k]
if found {
// Key matches, if both sides are Params, we try to merge.
if vvv, ok := vv.(Params); ok {
if pv, ok := v.(Params); ok {
vvv.merge(ms, pv)
}
}
} else if !noUpdate {
p[k] = v
}
}
}
func (p Params) GetMergeStrategy() (ParamsMergeStrategy, bool) {
if v, found := p[mergeStrategyKey]; found {
if s, ok := v.(ParamsMergeStrategy); ok {
return s, true
}
}
return ParamsMergeStrategyShallow, false
}
func (p Params) DeleteMergeStrategy() bool {
if _, found := p[mergeStrategyKey]; found {
delete(p, mergeStrategyKey)
return true
}
return false
}
func (p Params) SetDefaultMergeStrategy(s ParamsMergeStrategy) {
switch s {
case ParamsMergeStrategyDeep, ParamsMergeStrategyNone, ParamsMergeStrategyShallow:
default:
panic(fmt.Sprintf("invalid merge strategy %q", s))
}
p[mergeStrategyKey] = s
}
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 {
if len(indices) == 1 {
return nil, first, m
}
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(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
}
// ParamsMergeStrategy tells what strategy to use in Params.Merge.
type ParamsMergeStrategy string
const (
// Do not merge.
ParamsMergeStrategyNone ParamsMergeStrategy = "none"
// Only add new keys.
ParamsMergeStrategyShallow ParamsMergeStrategy = "shallow"
// Add new keys, merge existing.
ParamsMergeStrategyDeep ParamsMergeStrategy = "deep"
mergeStrategyKey = "_merge"
)
func toMergeStrategy(v interface{}) ParamsMergeStrategy {
s := ParamsMergeStrategy(cast.ToString(v))
switch s {
case ParamsMergeStrategyDeep, ParamsMergeStrategyNone, ParamsMergeStrategyShallow:
return s
default:
return ParamsMergeStrategyDeep
}
}
// PrepareParams
// * makes all the keys in the given map lower cased and will do so
// * This will modify the map given.
// * Any nested map[interface{}]interface{}, map[string]interface{},map[string]string will be converted to Params.
// * Any _merge value will be converted to proper type and value.
func PrepareParams(m Params) {
for k, v := range m {
var retyped bool
lKey := strings.ToLower(k)
if lKey == mergeStrategyKey {
v = toMergeStrategy(v)
retyped = true
} else {
switch vv := v.(type) {
case map[interface{}]interface{}:
var p Params = cast.ToStringMap(v)
v = p
PrepareParams(p)
retyped = true
case map[string]interface{}:
var p Params = v.(map[string]interface{})
v = p
PrepareParams(p)
retyped = true
case map[string]string:
p := make(Params)
for k, v := range vv {
p[k] = v
}
v = p
PrepareParams(p)
retyped = true
}
}
if retyped || k != lKey {
delete(m, k)
m[lKey] = v
}
}
}