From dd136858f1ea40ad3c94191d647487fa4f31926c Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel@debian.org>
Date: Fri, 18 Oct 2024 20:33:49 +0200
Subject: Adding upstream version 9.0.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>
---
 modules/markup/markdown/meta.go | 103 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 modules/markup/markdown/meta.go

(limited to 'modules/markup/markdown/meta.go')

diff --git a/modules/markup/markdown/meta.go b/modules/markup/markdown/meta.go
new file mode 100644
index 0000000..e76b253
--- /dev/null
+++ b/modules/markup/markdown/meta.go
@@ -0,0 +1,103 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package markdown
+
+import (
+	"bytes"
+	"errors"
+	"unicode"
+	"unicode/utf8"
+
+	"gopkg.in/yaml.v3"
+)
+
+func isYAMLSeparator(line []byte) bool {
+	idx := 0
+	for ; idx < len(line); idx++ {
+		if line[idx] >= utf8.RuneSelf {
+			r, sz := utf8.DecodeRune(line[idx:])
+			if !unicode.IsSpace(r) {
+				return false
+			}
+			idx += sz
+			continue
+		}
+		if line[idx] != ' ' {
+			break
+		}
+	}
+	dashCount := 0
+	for ; idx < len(line); idx++ {
+		if line[idx] != '-' {
+			break
+		}
+		dashCount++
+	}
+	if dashCount < 3 {
+		return false
+	}
+	for ; idx < len(line); idx++ {
+		if line[idx] >= utf8.RuneSelf {
+			r, sz := utf8.DecodeRune(line[idx:])
+			if !unicode.IsSpace(r) {
+				return false
+			}
+			idx += sz
+			continue
+		}
+		if line[idx] != ' ' {
+			return false
+		}
+	}
+	return true
+}
+
+// ExtractMetadata consumes a markdown file, parses YAML frontmatter,
+// and returns the frontmatter metadata separated from the markdown content
+func ExtractMetadata(contents string, out any) (string, error) {
+	body, err := ExtractMetadataBytes([]byte(contents), out)
+	return string(body), err
+}
+
+// ExtractMetadata consumes a markdown file, parses YAML frontmatter,
+// and returns the frontmatter metadata separated from the markdown content
+func ExtractMetadataBytes(contents []byte, out any) ([]byte, error) {
+	var front, body []byte
+
+	start, end := 0, len(contents)
+	idx := bytes.IndexByte(contents[start:], '\n')
+	if idx >= 0 {
+		end = start + idx
+	}
+	line := contents[start:end]
+
+	if !isYAMLSeparator(line) {
+		return contents, errors.New("frontmatter must start with a separator line")
+	}
+	frontMatterStart := end + 1
+	for start = frontMatterStart; start < len(contents); start = end + 1 {
+		end = len(contents)
+		idx := bytes.IndexByte(contents[start:], '\n')
+		if idx >= 0 {
+			end = start + idx
+		}
+		line := contents[start:end]
+		if isYAMLSeparator(line) {
+			front = contents[frontMatterStart:start]
+			if end+1 < len(contents) {
+				body = contents[end+1:]
+			}
+			break
+		}
+	}
+
+	if len(front) == 0 {
+		return contents, errors.New("could not determine metadata")
+	}
+
+	if err := yaml.Unmarshal(front, out); err != nil {
+		return contents, err
+	}
+	return body, nil
+}
-- 
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