Add support for separate open and close markers, custom fences

Closes GH-3.
Closes GH-2.

Amended-by: Titus Wormer <tituswormer@gmail.com>

lib/compile.js

@@ -1,17 +1,19 @@
 'use strict';
 
+var fence = require('./fence');
+
 module.exports = create;
 
 function create(matter) {
   var type = matter.type;
-  var marker = matter.marker;
-  var fence = marker + marker + marker;
+  var open = fence(matter, 'open');
+  var close = fence(matter, 'close');
 
   frontmatter.displayName = type + 'FrontMatter';
 
   return [type, frontmatter];
 
   function frontmatter(node) {
-    return fence + (node.value ? '\n' + node.value : '') + '\n' + fence;
+    return open + (node.value ? '\n' + node.value : '') + '\n' + close;
   }
 }

lib/fence.js

@@ -0,0 +1,18 @@
+'use strict';
+
+module.exports = fence;
+
+function fence(matter, prop) {
+  var marker;
+
+  if (matter.marker) {
+    marker = pick(matter.marker, prop);
+    return marker + marker + marker;
+  }
+
+  return pick(matter.fence, prop);
+}
+
+function pick(schema, prop) {
+  return typeof schema === 'string' ? schema : schema[prop];
+}

lib/matters.js

@@ -47,8 +47,8 @@ function matter(option) {
     throw fault('Missing `type` in matter `%j`', result);
   }
 
-  if (!own.call(result, 'marker')) {
-    throw fault('Missing `marker` in matter `%j`', result);
+  if (!own.call(result, 'fence') && !own.call(result, 'marker')) {
+    throw fault('Missing `marker` or `fence` in matter `%j`', result);
   }
 
   return result;

lib/parse.js

@@ -1,11 +1,13 @@
 'use strict';
 
+var fence = require('./fence');
+
 module.exports = create;
 
 function create(matter) {
   var name = matter.type + 'FrontMatter';
-  var marker = matter.marker;
-  var fence = marker + marker + marker;
+  var open = fence(matter, 'open');
+  var close = fence(matter, 'close');
   var newline = '\n';
 
   frontmatter.displayName = name;
@@ -14,54 +16,30 @@ function create(matter) {
   return [name, frontmatter];
 
   function frontmatter(eat, value, silent) {
-    var subvalue;
-    var content;
-    var index;
-    var length;
-    var character;
-    var queue;
+    var index = open.length;
+    var offset;
 
-    if (
-      value.charAt(0) !== marker ||
-      value.charAt(1) !== marker ||
-      value.charAt(2) !== marker ||
-      value.charAt(3) !== newline
-    ) {
+    if (value.slice(0, index) !== open || value.charAt(index) !== newline) {
       return;
     }
 
-    subvalue = fence + newline;
-    content = '';
-    queue = '';
-    index = 3;
-    length = value.length;
-
-    while (++index < length) {
-      character = value.charAt(index);
-
-      if (
-        character === marker &&
-        (queue || !content) &&
-        value.charAt(index + 1) === marker &&
-        value.charAt(index + 2) === marker
-      ) {
-        /* istanbul ignore if - never used (yet) */
-        if (silent) {
-          return true;
-        }
+    offset = value.indexOf(close, index);
 
-        subvalue += queue + fence;
+    while (offset !== -1 && value.charAt(offset - 1) !== newline) {
+      index = offset + close.length;
+      offset = value.indexOf(close, index);
+    }
 
-        return eat(subvalue)({type: matter.type, value: content});
+    if (offset !== -1) {
+      /* istanbul ignore if - never used (yet) */
+      if (silent) {
+        return true;
       }
 
-      if (character === newline) {
-        queue += character;
-      } else {
-        subvalue += queue + character;
-        content += queue + character;
-        queue = '';
-      }
+      return eat(value.slice(0, offset + close.length))({
+        type: matter.type,
+        value: value.slice(open.length + 1, offset - 1)
+      });
     }
   }
 }

readme.md

@@ -82,24 +82,107 @@ Adds [tokenizers][] if the [processor][] is configured with
 If you are parsing from a different syntax, or compiling to a different syntax
 (e.g., [`remark-man`][man]) your custom nodes may not be supported.
 
-###### `options`
+##### `options`
 
 One [`preset`][preset] or [`Matter`][matter], or an array of them, defining all
 the supported frontmatters (default: `'yaml'`).
 
-###### `preset`
+##### `preset`
 
 Either `'yaml'` or `'toml'`:
 
 *   `'yaml'` — [`matter`][matter] defined as `{type: 'yaml', marker: '-'}`
 *   `'toml'` — [`matter`][matter] defined as `{type: 'toml', marker: '+'}`
 
-###### `Matter`
+##### `Matter`
 
-An object with a `type` and a `marker`:
+An object with a `type` and either a `marker` or a `fence`:
 
 *   `type` (`string`) — Node type to parse to in [mdast][] and compile from
-*   `marker` (`string`) — Character used for fences
+*   `marker` (`string` or `{open: string, close: string}`) — Character used
+    to construct fences.  By providing an object with `open` and `close`.
+    different characters can be used for opening and closing fences.  For
+    example the character `'-'` will result in `'---'` being used as the fence
+*   `fence` (`string` or `{open: string, close: string}`) — String used as
+    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
+
+###### Example
+
+For `{type: 'yaml', marker: '-'}`:
+
+```yaml
+---
+key: value
+---
+```
+
+Yields:
+
+```json
+{
+  "type": "yaml",
+  "value": "key: value"
+}
+```
+
+###### Example
+
+For `{type: 'custom', marker: {open: '<', close: '>'}}`:
+
+```text
+<<<
+data
+>>>
+```
+
+Yields:
+
+```json
+{
+  "type": "custom",
+  "value": "data"
+}
+```
+
+###### Example
+
+For `{type: 'custom', fence: '+=+=+=+'}`:
+
+```text
++=+=+=+
+data
++=+=+=+
+```
+
+Yields:
+
+```json
+{
+  "type": "custom",
+  "value": "dats"
+}
+```
+
+###### Example
+
+For `{type: 'json', fence: {open: '{', close: '}'}}`:
+
+```json
+{
+  "key": "value"
+}
+```
+
+Yields:
+
+```json
+{
+  "type": "json",
+  "value": "\"key\": \"value\""
+}
+```
 
 ## Related
 

test/fixtures/custom-fence-long/config.json

@@ -0,0 +1 @@
+[{"type": "jsonml", "fence": "=f-e*n_c$e"}]

test/fixtures/custom-fence-long/input.md

@@ -0,0 +1,8 @@
+=f-e*n_c$e
+{
+  title: "Custom",
+  // A comment ***
+}
+=f-e*n_c$e
+
+# Deep

test/fixtures/custom-fence-long/tree.json

@@ -0,0 +1,76 @@
+{
+  "type": "root",
+  "children": [
+    {
+      "type": "jsonml",
+      "value": "{\n  title: \"Custom\",\n  // A comment ***\n}",
+      "position": {
+        "start": {
+          "line": 1,
+          "column": 1,
+          "offset": 0
+        },
+        "end": {
+          "line": 6,
+          "column": 11,
+          "offset": 63
+        },
+        "indent": [
+          1,
+          1,
+          1,
+          1,
+          1
+        ]
+      }
+    },
+    {
+      "type": "heading",
+      "depth": 1,
+      "children": [
+        {
+          "type": "text",
+          "value": "Deep",
+          "position": {
+            "start": {
+              "line": 8,
+              "column": 3,
+              "offset": 67
+            },
+            "end": {
+              "line": 8,
+              "column": 7,
+              "offset": 71
+            },
+            "indent": []
+          }
+        }
+      ],
+      "position": {
+        "start": {
+          "line": 8,
+          "column": 1,
+          "offset": 65
+        },
+        "end": {
+          "line": 8,
+          "column": 7,
+          "offset": 71
+        },
+        "indent": []
+      }
+    }
+  ],
+  "position": {
+    "start": {
+      "line": 1,
+      "column": 1,
+      "offset": 0
+    },
+    "end": {
+      "line": 9,
+      "column": 1,
+      "offset": 72
+    }
+  }
+}

test/fixtures/custom-fence-openclose/config.json

@@ -0,0 +1 @@
+[{"type": "jsonml", "fence": {"open": "$$OPEN", "close": "CLOSE##"}}]

test/fixtures/custom-fence-openclose/input.md

@@ -0,0 +1,8 @@
+$$OPEN
+{
+  title: "Custom",
+  // A comment ***
+}
+CLOSE##
+
+# Deep