hugo/parser/metadecoders/decoder.go

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// Copyright 2018 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 metadecoders
import (
"encoding/json"
"fmt"
"github.com/gohugoio/hugo/common/herrors"
"github.com/BurntSushi/toml"
"github.com/chaseadamsio/goorgeous"
"github.com/pkg/errors"
"github.com/spf13/cast"
yaml "gopkg.in/yaml.v2"
)
// UnmarshalToMap will unmarshall data in format f into a new map. This is
// what's needed for Hugo's front matter decoding.
func UnmarshalToMap(data []byte, f Format) (map[string]interface{}, error) {
m := make(map[string]interface{})
if data == nil {
return m, nil
}
err := unmarshal(data, f, &m)
return m, err
}
// Unmarshal will unmarshall data in format f into an interface{}.
// This is what's needed for Hugo's /data handling.
func Unmarshal(data []byte, f Format) (interface{}, error) {
if data == nil {
return make(map[string]interface{}), nil
}
var v interface{}
err := unmarshal(data, f, &v)
return v, err
}
// unmarshal unmarshals data in format f into v.
func unmarshal(data []byte, f Format, v interface{}) error {
var err error
switch f {
case ORG:
vv, err := goorgeous.OrgHeaders(data)
if err != nil {
return toFileError(f, errors.Wrap(err, "failed to unmarshal ORG headers"))
}
switch v.(type) {
case *map[string]interface{}:
*v.(*map[string]interface{}) = vv
default:
*v.(*interface{}) = vv
}
case JSON:
err = json.Unmarshal(data, v)
case TOML:
err = toml.Unmarshal(data, v)
case YAML:
err = yaml.Unmarshal(data, v)
if err != nil {
return toFileError(f, errors.Wrap(err, "failed to unmarshal YAML"))
}
// To support boolean keys, the YAML package unmarshals maps to
// map[interface{}]interface{}. Here we recurse through the result
// and change all maps to map[string]interface{} like we would've
// gotten from `json`.
var ptr interface{}
switch v.(type) {
case *map[string]interface{}:
ptr = *v.(*map[string]interface{})
case *interface{}:
ptr = *v.(*interface{})
default:
return errors.Errorf("unknown type %T in YAML unmarshal", v)
}
if mm, changed := stringifyMapKeys(ptr); changed {
switch v.(type) {
case *map[string]interface{}:
*v.(*map[string]interface{}) = mm.(map[string]interface{})
case *interface{}:
*v.(*interface{}) = mm
}
}
default:
return errors.Errorf("unmarshal of format %q is not supported", f)
}
if err == nil {
return nil
}
return toFileError(f, errors.Wrap(err, "unmarshal failed"))
}
func toFileError(f Format, err error) error {
return herrors.ToFileError(string(f), err)
}
// stringifyMapKeys recurses into in and changes all instances of
// map[interface{}]interface{} to map[string]interface{}. This is useful to
// work around the impedence mismatch between JSON and YAML unmarshaling that's
// described here: https://github.com/go-yaml/yaml/issues/139
//
// Inspired by https://github.com/stripe/stripe-mock, MIT licensed
func stringifyMapKeys(in interface{}) (interface{}, bool) {
switch in := in.(type) {
case []interface{}:
for i, v := range in {
if vv, replaced := stringifyMapKeys(v); replaced {
in[i] = vv
}
}
case map[string]interface{}:
for k, v := range in {
if vv, changed := stringifyMapKeys(v); changed {
in[k] = vv
}
}
case map[interface{}]interface{}:
res := make(map[string]interface{})
var (
ok bool
err error
)
for k, v := range in {
var ks string
if ks, ok = k.(string); !ok {
ks, err = cast.ToStringE(k)
if err != nil {
ks = fmt.Sprintf("%v", k)
}
}
if vv, replaced := stringifyMapKeys(v); replaced {
res[ks] = vv
} else {
res[ks] = v
}
}
return res, true
}
return nil, false
}