moving front matter parsing (and creation) to parse package

parser/frontmatter.go

@@ -0,0 +1,129 @@
+// Copyright © 2013 Steve Francia <spf@spf13.com>.
+//
+// Licensed under the Simple Public 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://opensource.org/licenses/Simple-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 (
+	"bytes"
+	"encoding/json"
+	"fmt"
+
+	"github.com/BurntSushi/toml"
+	"launchpad.net/goyaml"
+)
+
+type FrontmatterType struct {
+	markstart, markend []byte
+	Parse              func([]byte) (interface{}, error)
+	includeMark        bool
+}
+
+func InterfaceToFrontMatter(in interface{}, mark rune) ([]byte, error) {
+	if in == nil {
+		return []byte{}, fmt.Errorf("input was nil")
+	}
+
+	b := new(bytes.Buffer)
+
+	switch mark {
+	case rune(YAML_LEAD[0]):
+		_, err := b.Write([]byte(YAML_DELIM_UNIX))
+		if err != nil {
+			return nil, err
+		}
+		by, err := goyaml.Marshal(in)
+		if err != nil {
+			return nil, err
+		}
+		b.Write(by)
+		_, err = b.Write([]byte(YAML_DELIM_UNIX))
+		if err != nil {
+			return nil, err
+		}
+		return b.Bytes(), nil
+	case rune(TOML_LEAD[0]):
+		_, err := b.Write([]byte(TOML_DELIM_UNIX))
+		if err != nil {
+			return nil, err
+		}
+
+		err = toml.NewEncoder(b).Encode(in)
+		if err != nil {
+			fmt.Println("toml encoder failed", in)
+			fmt.Println(err)
+			return nil, err
+		}
+		_, err = b.Write([]byte("\n" + TOML_DELIM_UNIX))
+		if err != nil {
+			return nil, err
+		}
+		return b.Bytes(), nil
+	case rune(JSON_LEAD[0]):
+		by, err := json.MarshalIndent(in, "", "   ")
+		if err != nil {
+			fmt.Println("json encoder failed", in)
+			fmt.Println(err)
+			return nil, err
+		}
+		b.Write(by)
+		_, err = b.Write([]byte("\n"))
+		if err != nil {
+			return nil, err
+		}
+		return b.Bytes(), nil
+	default:
+		return nil, fmt.Errorf("Unsupported Format provided")
+	}
+}
+
+func DetectFrontMatter(mark rune) (f *FrontmatterType) {
+	switch mark {
+	case '-':
+		return &FrontmatterType{[]byte(YAML_DELIM), []byte(YAML_DELIM), HandleYamlMetaData, false}
+	case '+':
+		return &FrontmatterType{[]byte(TOML_DELIM), []byte(TOML_DELIM), HandleTomlMetaData, false}
+	case '{':
+		return &FrontmatterType{[]byte{'{'}, []byte{'}'}, HandleJsonMetaData, true}
+	default:
+		return nil
+	}
+}
+
+func HandleTomlMetaData(datum []byte) (interface{}, error) {
+	m := map[string]interface{}{}
+	datum = removeTomlIdentifier(datum)
+	if _, err := toml.Decode(string(datum), &m); err != nil {
+		return m, err
+	}
+	return m, nil
+}
+
+func removeTomlIdentifier(datum []byte) []byte {
+	return bytes.Replace(datum, []byte(TOML_DELIM), []byte(""), -1)
+}
+
+func HandleYamlMetaData(datum []byte) (interface{}, error) {
+	m := map[string]interface{}{}
+	if err := goyaml.Unmarshal(datum, &m); err != nil {
+		return m, err
+	}
+	return m, nil
+}
+
+func HandleJsonMetaData(datum []byte) (interface{}, error) {
+	var f interface{}
+	if err := json.Unmarshal(datum, &f); err != nil {
+		return f, err
+	}
+	return f, nil
+}