adds support for setting tags in fenced code blocks

Author: jacoscaz

README.md

@@ -21,6 +21,7 @@ as YAML frontmatter.
     - [Frontmatter tags](#frontmatter-tags)
     - [Metadata file tags](#metadata-file-tags)
     - [Heading tags](#heading-tags)
+    - [Tags in code blocks](#tags-in-code-blocks)
     - [Filtering by tag](#filtering-by-tag)
     - [Filtering by checked state](#filtering-by-checked-state)
     - [Sorting by tag](#sorting-by-tag)
@@ -233,6 +234,43 @@ a pending task   | bar     | foo    | 20241010-foo.md | 20241010
 a completed task | baz     | foo    | 20241010-foo.md | 20241010
 ```
 
+### Tags in code blocks
+
+YAML fenced code blocks can also be used to set tags at the heading
+level when using the `taskparser` language identifier. Given:
+
+~~~markdown
+# primary
+
+```taskparser
+client: foo
+project: bar
+```
+
+- [ ] a pending task
+
+## secondary
+
+```taskparser
+project: baz
+```
+
+- [X] a completed task
+~~~
+
+`taskparser` will produce:
+
+```
+$ taskparser -t text,client,project /foo/bar
+```
+
+```
+text             | client | project
+----             | ------ | -------
+a pending task   | foo    | bar    
+a completed task | foo    | baz  
+```
+
 ### Filtering by tag
 
 `taskparser` accepts filter expression via the `-f` argument:

src/parse.ts

@@ -1,5 +1,5 @@
 
-import type { Parent, Node, Yaml, ListItem, Text, Heading } from 'mdast';
+import type { Parent, Node, Yaml, ListItem, Text, Heading, Code } from 'mdast';
 import type { TagMap, Task, Worklog, ParseContext, ParseFileContext } from './types.js';
 
 import { readdir, readFile, stat } from 'node:fs/promises';
@@ -90,6 +90,16 @@ const parseYamlNode = (node: Yaml, ctx: ParseFileContext, item: Task | Worklog |
   }
 };
 
+const parseCodeNode = (node: Code, ctx: ParseFileContext, item: Task | Worklog | null) => {
+  if (node.lang === 'taskparser' && ctx.heading) {
+    try {
+      extractTagsFromYaml(node.value, ctx.heading.tags);
+    } catch (err) {
+      throw new Error(`could not parse YAML code block in file ${ctx.file}: ${(err as Error).message}`);
+    }
+  }
+};
+
 const parseNode = (node: Node, ctx: ParseFileContext, item: Task | Worklog | null) => {
   switch (node.type) {
     case 'yaml': 
@@ -101,6 +111,9 @@ const parseNode = (node: Node, ctx: ParseFileContext, item: Task | Worklog | nul
     case 'heading':
       parseHeadingNode(node as Heading, ctx, item);
       break;
+    case 'code':
+      parseCodeNode(node as Code, ctx, item);
+      break;
     default:
       if ('children' in node) {
         parseParentNode(node as Parent, ctx, item);

tests/018-code-block-tags/20240101-frontmatter-tags.md

@@ -0,0 +1,17 @@
+
+# primary
+
+```taskparser
+client: foo
+project: bar
+```
+
+- [ ] a pending task
+
+## secondary
+
+```taskparser
+project: baz
+```
+
+- [X] a completed task

tests/018-code-block-tags/test-info.json

@@ -0,0 +1,4 @@
+{
+  "description": "should parse frontmatter tags",
+  "argv": ["-t", "text,date,client,project"]
+}

tests/018-code-block-tags/test-stdout

@@ -0,0 +1,4 @@
+text             | date     | client | project
+----             | ----     | ------ | -------
+a pending task   | 20240101 | foo    | bar    
+a completed task | 20240101 | foo    | baz