Add support for optional mid-matter parsing

Closes GH-6.

Reviewed-by: Titus Wormer <[email protected]>

lib/parse.js

@@ -9,9 +9,10 @@ function create(matter) {
   var open = fence(matter, 'open')
   var close = fence(matter, 'close')
   var newline = '\n'
+  var anywhere = matter.anywhere
 
   frontmatter.displayName = name
-  frontmatter.onlyAtStart = true
+  frontmatter.onlyAtStart = typeof anywhere === 'boolean' ? !anywhere : true
 
   return [name, frontmatter]
 

readme.md

@@ -107,6 +107,9 @@ An object with a `type` and either a `marker` or a `fence`:
     the complete fence.  By providing an object with `open` and `close`
     different values can be used for opening and closing fences.  This can be
     used too if fences contain different characters or lengths other than 3
+*   `anywhere` (`boolean`, default: `false`) – if `true`, matter can be
+    found anywhere in the document.  If `false` (default), only matter at the
+    start of the document is recognised.
 
 ###### Example
 

test/fixtures/custom-yaml-anywhere/config.json

@@ -0,0 +1 @@
+{"type": "yaml", "marker": "-", "anywhere": true}

test/fixtures/custom-yaml-anywhere/input.md

@@ -0,0 +1,7 @@
+# YAML not at the top
+
+---
+title: post
+---
+
+some text

test/fixtures/custom-yaml-anywhere/output.md

@@ -0,0 +1,7 @@
+# YAML not at the top
+
+---
+title: post
+---
+
+some text

test/fixtures/custom-yaml-anywhere/tree.json

@@ -0,0 +1,108 @@
+{
+  "type": "root",
+  "children": [
+    {
+      "type": "heading",
+      "depth": 1,
+      "children": [
+        {
+          "type": "text",
+          "value": "YAML not at the top",
+          "position": {
+            "start": {
+              "line": 1,
+              "column": 3,
+              "offset": 2
+            },
+            "end": {
+              "line": 1,
+              "column": 22,
+              "offset": 21
+            },
+            "indent": []
+          }
+        }
+      ],
+      "position": {
+        "start": {
+          "line": 1,
+          "column": 1,
+          "offset": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 22,
+          "offset": 21
+        },
+        "indent": []
+      }
+    },
+    {
+      "type": "yaml",
+      "value": "title: post",
+      "position": {
+        "start": {
+          "line": 3,
+          "column": 1,
+          "offset": 23
+        },
+        "end": {
+          "line": 5,
+          "column": 4,
+          "offset": 42
+        },
+        "indent": [
+          1,
+          1
+        ]
+      }
+    },
+    {
+      "type": "paragraph",
+      "children": [
+        {
+          "type": "text",
+          "value": "some text",
+          "position": {
+            "start": {
+              "line": 7,
+              "column": 1,
+              "offset": 44
+            },
+            "end": {
+              "line": 7,
+              "column": 10,
+              "offset": 53
+            },
+            "indent": []
+          }
+        }
+      ],
+      "position": {
+        "start": {
+          "line": 7,
+          "column": 1,
+          "offset": 44
+        },
+        "end": {
+          "line": 7,
+          "column": 10,
+          "offset": 53
+        },
+        "indent": []
+      }
+    }
+  ],
+  "position": {
+    "start": {
+      "line": 1,
+      "column": 1,
+      "offset": 0
+    },
+    "end": {
+      "line": 8,
+      "column": 1,
+      "offset": 54
+    }
+  }
+}