added front matter parser for markdown

backend/task/src/utils/front_matter.rs

@@ -0,0 +1,55 @@
+// derived from https://github.com/EstebanBorai/yaml-front-matter
+use serde::de::DeserializeOwned;
+
+pub struct Document<T: DeserializeOwned> {
+    pub metadata: T,
+    pub content: String,
+}
+
+pub struct YamlFrontMatter;
+impl YamlFrontMatter {
+    pub fn parse<T: DeserializeOwned>(
+        markdown: &str,
+    ) -> Result<Document<T>, Box<dyn std::error::Error>> {
+        let yaml = YamlFrontMatter::extract(markdown)?;
+        let metadata = serde_yaml::from_str::<T>(yaml.0.as_str())?;
+
+        Ok(Document {
+            metadata,
+            content: yaml.1,
+        })
+    }
+
+    fn extract(markdown: &str) -> Result<(String, String), Box<dyn std::error::Error>> {
+        let mut front_matter = String::default();
+        let mut sentinel = false;
+        let mut front_matter_lines = 0;
+        let lines = markdown.lines();
+
+        for line in lines.clone() {
+            front_matter_lines += 1;
+
+            if line.trim() == "---" {
+                if sentinel {
+                    break;
+                }
+
+                sentinel = true;
+                continue;
+            }
+
+            if sentinel {
+                front_matter.push_str(line);
+                front_matter.push('\n');
+            }
+        }
+
+        Ok((
+            front_matter,
+            lines
+                .skip(front_matter_lines)
+                .collect::<Vec<&str>>()
+                .join("\n"),
+        ))
+    }
+}

backend/task/src/utils/mod.rs

@@ -0,0 +1 @@
+pub mod front_matter;