hugo/parser/lowercase_camel_json.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 parser
import (
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"bytes"
"encoding/json"
"regexp"
"unicode"
"unicode/utf8"
"github.com/gohugoio/hugo/common/hreflect"
)
// Regexp definitions
var (
keyMatchRegex = regexp.MustCompile(`\"(\w+)\":`)
wordBarrierRegex = regexp.MustCompile(`(\w)([A-Z])`)
)
// Code adapted from https://gist.github.com/piersy/b9934790a8892db1a603820c0c23e4a7
type LowerCaseCamelJSONMarshaller struct {
Value any
}
func (c LowerCaseCamelJSONMarshaller) MarshalJSON() ([]byte, error) {
marshalled, err := json.Marshal(c.Value)
converted := keyMatchRegex.ReplaceAllFunc(
marshalled,
func(match []byte) []byte {
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// Attributes on the form XML, JSON etc.
if bytes.Equal(match, bytes.ToUpper(match)) {
return bytes.ToLower(match)
}
// Empty keys are valid JSON, only lowercase if we do not have an
// empty key.
if len(match) > 2 {
// Decode first rune after the double quotes
r, width := utf8.DecodeRune(match[1:])
r = unicode.ToLower(r)
utf8.EncodeRune(match[1:width+1], r)
}
return match
},
)
return converted, err
}
type ReplacingJSONMarshaller struct {
Value any
KeysToLower bool
OmitEmpty bool
}
func (c ReplacingJSONMarshaller) MarshalJSON() ([]byte, error) {
converted, err := json.Marshal(c.Value)
if c.KeysToLower {
converted = keyMatchRegex.ReplaceAllFunc(
converted,
func(match []byte) []byte {
return bytes.ToLower(match)
},
)
}
if c.OmitEmpty {
// It's tricky to do this with a regexp, so convert it to a map, remove zero values and convert back.
var m map[string]interface{}
err = json.Unmarshal(converted, &m)
if err != nil {
return nil, err
}
var removeZeroVAlues func(m map[string]any)
removeZeroVAlues = func(m map[string]any) {
for k, v := range m {
if !hreflect.IsTruthful(v) {
delete(m, k)
} else {
switch v.(type) {
case map[string]interface{}:
removeZeroVAlues(v.(map[string]any))
case []interface{}:
for _, vv := range v.([]interface{}) {
if m, ok := vv.(map[string]any); ok {
removeZeroVAlues(m)
}
}
}
}
}
}
removeZeroVAlues(m)
converted, err = json.Marshal(m)
}
return converted, err
}