hugolib: Integrate new page parser

See #5324

3 files changed, 210 insertions, 0 deletions

diff --git a/parser/metadecoders/decoder.go b/parser/metadecoders/decoder.go
new file mode 100644
index 000000000..7527d7a08
--- /dev/null
+++ b/parser/metadecoders/decoder.go
@@ -0,0 +1,95 @@
+// 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"
+
+	"github.com/BurntSushi/toml"
+	"github.com/chaseadamsio/goorgeous"
+	"github.com/gohugoio/hugo/parser/pageparser"
+	"github.com/pkg/errors"
+	yaml "gopkg.in/yaml.v1"
+)
+
+type Format string
+
+const (
+	// These are the supported metdata  formats in Hugo. Most of these are also
+	// supported as /data formats.
+	ORG  Format = "org"
+	JSON Format = "json"
+	TOML Format = "toml"
+	YAML Format = "yaml"
+)
+
+// FormatFromFrontMatterType will return empty if not supported.
+func FormatFromFrontMatterType(typ pageparser.ItemType) Format {
+	switch typ {
+	case pageparser.TypeFrontMatterJSON:
+		return JSON
+	case pageparser.TypeFrontMatterORG:
+		return ORG
+	case pageparser.TypeFrontMatterTOML:
+		return TOML
+	case pageparser.TypeFrontMatterYAML:
+		return YAML
+	default:
+		return ""
+	}
+}
+
+// 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
+	}
+
+	var err error
+
+	switch f {
+	case ORG:
+		m, err = goorgeous.OrgHeaders(data)
+	case JSON:
+		err = json.Unmarshal(data, &m)
+	case TOML:
+		_, err = toml.Decode(string(data), &m)
+	case YAML:
+		err = yaml.Unmarshal(data, &m)
+
+		// 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`.
+		if err == nil {
+			for k, v := range m {
+				if vv, changed := stringifyMapKeys(v); changed {
+					m[k] = vv
+				}
+			}
+		}
+	default:
+		return nil, errors.Errorf("unmarshal of format %q is not supported", f)
+	}
+
+	if err != nil {
+		return nil, errors.Wrapf(err, "unmarshal failed for format %q", f)
+	}
+
+	return m, nil
+
+}
diff --git a/parser/metadecoders/json.go b/parser/metadecoders/json.go
new file mode 100644
index 000000000..21ca8a3b9
--- /dev/null
+++ b/parser/metadecoders/json.go
@@ -0,0 +1,31 @@
+// 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"
+
+// HandleJSONData unmarshals JSON-encoded datum and returns a Go interface
+// representing the encoded data structure.
+func HandleJSONData(datum []byte) (interface{}, error) {
+	if datum == nil {
+		// Package json returns on error on nil input.
+		// Return an empty map to be consistent with our other supported
+		// formats.
+		return make(map[string]interface{}), nil
+	}
+
+	var f interface{}
+	err := json.Unmarshal(datum, &f)
+	return f, err
+}
diff --git a/parser/metadecoders/yaml.go b/parser/metadecoders/yaml.go
new file mode 100644
index 000000000..3a520ac07
--- /dev/null
+++ b/parser/metadecoders/yaml.go
@@ -0,0 +1,84 @@
+// 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.
+
+// The metadecoders package contains functions to decode metadata (e.g. page front matter)
+// from different formats: TOML, YAML, JSON.
+package metadecoders
+
+import (
+	"fmt"
+
+	"github.com/spf13/cast"
+	yaml "gopkg.in/yaml.v1"
+)
+
+// HandleYAMLData unmarshals YAML-encoded datum and returns a Go interface
+// representing the encoded data structure.
+func HandleYAMLData(datum []byte) (interface{}, error) {
+	var m interface{}
+	err := yaml.Unmarshal(datum, &m)
+	if err != nil {
+		return nil, err
+	}
+
+	// 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`.
+	if mm, changed := stringifyMapKeys(m); changed {
+		return mm, nil
+	}
+
+	return m, nil
+}
+
+// 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[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
+}