104 lines
2.2 KiB
Go
104 lines
2.2 KiB
Go
// Copyright 2020 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package markdown
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import (
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"bytes"
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"errors"
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"unicode"
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"unicode/utf8"
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"gopkg.in/yaml.v3"
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)
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func isYAMLSeparator(line []byte) bool {
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idx := 0
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for ; idx < len(line); idx++ {
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if line[idx] >= utf8.RuneSelf {
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r, sz := utf8.DecodeRune(line[idx:])
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if !unicode.IsSpace(r) {
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return false
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}
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idx += sz
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continue
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}
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if line[idx] != ' ' {
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break
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}
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}
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dashCount := 0
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for ; idx < len(line); idx++ {
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if line[idx] != '-' {
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break
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}
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dashCount++
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}
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if dashCount < 3 {
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return false
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}
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for ; idx < len(line); idx++ {
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if line[idx] >= utf8.RuneSelf {
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r, sz := utf8.DecodeRune(line[idx:])
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if !unicode.IsSpace(r) {
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return false
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}
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idx += sz
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continue
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}
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if line[idx] != ' ' {
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return false
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}
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}
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return true
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}
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// ExtractMetadata consumes a markdown file, parses YAML frontmatter,
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// and returns the frontmatter metadata separated from the markdown content
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func ExtractMetadata(contents string, out interface{}) (string, error) {
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body, err := ExtractMetadataBytes([]byte(contents), out)
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return string(body), err
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}
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// ExtractMetadata consumes a markdown file, parses YAML frontmatter,
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// and returns the frontmatter metadata separated from the markdown content
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func ExtractMetadataBytes(contents []byte, out interface{}) ([]byte, error) {
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var front, body []byte
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start, end := 0, len(contents)
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idx := bytes.IndexByte(contents[start:], '\n')
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if idx >= 0 {
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end = start + idx
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}
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line := contents[start:end]
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if !isYAMLSeparator(line) {
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return contents, errors.New("frontmatter must start with a separator line")
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}
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frontMatterStart := end + 1
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for start = frontMatterStart; start < len(contents); start = end + 1 {
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end = len(contents)
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idx := bytes.IndexByte(contents[start:], '\n')
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if idx >= 0 {
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end = start + idx
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}
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line := contents[start:end]
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if isYAMLSeparator(line) {
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front = contents[frontMatterStart:start]
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if end+1 < len(contents) {
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body = contents[end+1:]
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}
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break
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}
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}
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if len(front) == 0 {
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return contents, errors.New("could not determine metadata")
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}
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if err := yaml.Unmarshal(front, out); err != nil {
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return contents, err
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}
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return body, nil
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}
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