#242 - Keep comments at front matter root

src/panelWebView/components/Metadata.tsx

@@ -107,8 +107,6 @@ const Metadata: React.FunctionComponent<IMetadataProps> = ({settings, metadata,
       } else if (field.type === 'string') {
         const textValue = parent[field.name];
 
-        console.log(textValue, parent, field)
-
         let limit = -1;
         if (field.name === 'title') {
           limit = settings?.seo.title;

src/parsers/FrontMatterParser.ts

@@ -14,9 +14,11 @@ export interface ParsedFrontMatter {
 }
 
 export class FrontMatterParser {
+  public static currentContent: string | null = null;
 
   public static fromFile(content: string): ParsedFrontMatter {
     const format = getFormatOpts(this.getLanguage());
+    FrontMatterParser.currentContent = content;
     const result = matter(content, { ...Engines, ...format });
     // in the absent of a body when serializing an entry we use an empty one
     // when calling `toFile`, so we don't want to add it when parsing.

src/parsers/ParserEngines.ts

@@ -1,5 +1,6 @@
+import * as yaml from 'yaml';
 import * as toml from '@iarna/toml';
-import { Format } from '.';
+import { Format, FrontMatterParser } from '.';
 
 export const getFormatOpts = (format: string): Format => {
   const formats: { [prop: string]: Format} = {
@@ -20,6 +21,82 @@ export const Engines = {
       stringify: (value: any) => {
         return toml.stringify(value);
       }
+    },
+    yaml: {
+      parse: (value: string) => {
+        return yaml.parse(value);
+      },
+      stringify: (obj: any, options?: any) => {
+        // Do our own parsing to keep the comments
+        if (FrontMatterParser.currentContent) {
+          const originalContent = FrontMatterParser.currentContent;
+          FrontMatterParser.currentContent = null;
+
+          const frontMatter = getMatter(originalContent);
+          if (frontMatter) {
+            const docYaml = yaml.parseDocument(frontMatter);
+
+            // Update all the new values
+            for (const key in obj) {
+              docYaml.set(key, obj[key]);
+            }
+
+            // Check if there are values to remove
+            for (const key in docYaml.toJSON()) {
+              if (!obj[key]) {
+                docYaml.delete(key);
+              }
+            }
+
+            return docYaml.toString();
+          }
+        }
+
+        return yaml.stringify(obj, options);
+      }
     }
   }
-}
+}
+
+/**
+ * Retrieve the front matter from the content
+ * @param value 
+ * @returns 
+ */
+const getMatter = (value: string): string | null => {
+  const open = "---";
+  const close = '\n' + "---";
+
+  let str = value;
+
+  // get the length of the opening delimiter
+  const openLen = open.length;
+  if (!startsWith(str, open, openLen)) {
+    return null;
+  }
+
+  // if the next character after the opening delimiter is
+  // a character from the delimiter, then it's not a front-
+  // matter delimiter
+  if (str.charAt(openLen) === open.slice(-1)) {
+    return null;
+  }
+
+  // strip the opening delimiter
+  str = str.slice(openLen);
+  const len = str.length;
+
+  // get the index of the closing delimiter
+  let closeIndex = str.indexOf(close);
+  if (closeIndex === -1) {
+    closeIndex = len;
+  }
+
+  // get the raw front-matter block
+  return str.slice(0, closeIndex);
+}
+
+const startsWith = (str: string, substr: string, len: number) => {
+  if (typeof len !== 'number') len = substr.length;
+  return str.slice(0, len) === substr;
+};