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// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package markdown
import (
"errors"
"strings"
"gopkg.in/yaml.v2"
)
func isYAMLSeparator(line string) bool {
line = strings.TrimSpace(line)
for i := 0; i < len(line); i++ {
if line[i] != '-' {
return false
}
}
return len(line) > 2
}
// ExtractMetadata consumes a markdown file, parses YAML frontmatter,
// and returns the frontmatter metadata separated from the markdown content
func ExtractMetadata(contents string, out interface{}) (string, error) {
var front, body []string
lines := strings.Split(contents, "\n")
for idx, line := range lines {
if idx == 0 {
// First line has to be a separator
if !isYAMLSeparator(line) {
return "", errors.New("frontmatter must start with a separator line")
}
continue
}
if isYAMLSeparator(line) {
front, body = lines[1:idx], lines[idx+1:]
break
}
}
if len(front) == 0 {
return "", errors.New("could not determine metadata")
}
if err := yaml.Unmarshal([]byte(strings.Join(front, "\n")), out); err != nil {
return "", err
}
return strings.Join(body, "\n"), nil
}
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