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"
)
// 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 interface{}
}
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
}