Fix mapping of references without definitions

* CommonMark seems to have changed in that it now always maps
  undefined references back to markdown

Closes GH-20.
Closes GH-21.

Author: rubys

lib/failsafe.js

@@ -3,16 +3,22 @@
 module.exports = imageReference
 
 var normalize = require('mdurl/encode')
-var failsafe = require('../failsafe')
+var revert = require('../revert')
 
 /* Transform a reference to an image. */
 function imageReference(h, node) {
   var def = h.definition(node.identifier)
-  var props = {src: normalize((def && def.url) || ''), alt: node.alt}
+  var props
 
-  if (def && def.title !== null && def.title !== undefined) {
+  if (!def) {
+    return revert(h, node)
+  }
+
+  props = {src: normalize(def.url || ''), alt: node.alt}
+
+  if (def.title !== null && def.title !== undefined) {
     props.title = def.title
   }
 
-  return failsafe(h, node, def) || h(node, 'img', props)
+  return h(node, 'img', props)
 }

lib/handlers/image-reference.js

@@ -3,17 +3,23 @@
 module.exports = linkReference
 
 var normalize = require('mdurl/encode')
-var failsafe = require('../failsafe')
+var revert = require('../revert')
 var all = require('../all')
 
 /* Transform a reference to a link. */
 function linkReference(h, node) {
   var def = h.definition(node.identifier)
-  var props = {href: normalize((def && def.url) || '')}
+  var props
 
-  if (def && def.title !== null && def.title !== undefined) {
+  if (!def) {
+    return revert(h, node)
+  }
+
+  props = {href: normalize(def.url || '')}
+
+  if (def.title !== null && def.title !== undefined) {
     props.title = def.title
   }
 
-  return failsafe(h, node, def) || h(node, 'a', props, all(h, node))
+  return h(node, 'a', props, all(h, node))
 }

lib/handlers/link-reference.js

@@ -0,0 +1,44 @@
+'use strict'
+
+module.exports = revert
+
+var u = require('unist-builder')
+var all = require('./all')
+
+/* Return the content of a reference without definition as markdown. */
+function revert(h, node) {
+  var subtype = node.referenceType
+  var suffix = ']'
+  var contents
+  var head
+  var tail
+
+  if (subtype === 'collapsed') {
+    suffix += '[]'
+  } else if (subtype === 'full') {
+    suffix += '[' + node.identifier + ']'
+  }
+
+  if (node.type === 'imageReference') {
+    return u('text', '![' + node.alt + suffix)
+  }
+
+  contents = all(h, node)
+  head = contents[0]
+
+  if (head && head.type === 'text') {
+    head.value = '[' + head.value
+  } else {
+    contents.unshift(u('text', '['))
+  }
+
+  tail = contents[contents.length - 1]
+
+  if (tail && tail.type === 'text') {
+    tail.value += suffix
+  } else {
+    contents.push(u('text', suffix))
+  }
+
+  return contents
+}

lib/revert.js

@@ -6,12 +6,7 @@ var to = require('..')
 
 test('ImageReference', function(t) {
   t.deepEqual(
-    to(
-      u('imageReference', {
-        identifier: 'charlie',
-        alt: 'charlie'
-      })
-    ),
+    to(u('imageReference', {identifier: 'charlie', alt: 'charlie'})),
     u('text', '![charlie]'),
     'should fall back on `imageReference`s without definition'
   )
@@ -24,18 +19,8 @@ test('ImageReference', function(t) {
         alt: 'golf'
       })
     ),
-    u(
-      'element',
-      {
-        tagName: 'img',
-        properties: {
-          src: '',
-          alt: 'golf'
-        }
-      },
-      []
-    ),
-    'should not fall back on full `imageReference`s'
+    u('text', '![golf][foxtrot]'),
+    'should fall back on full `imageReference`s'
   )
 
   t.deepEqual(
@@ -46,18 +31,8 @@ test('ImageReference', function(t) {
         alt: 'india'
       })
     ),
-    u(
-      'element',
-      {
-        tagName: 'img',
-        properties: {
-          src: '',
-          alt: 'india'
-        }
-      },
-      []
-    ),
-    'should not fall back on collapsed `imageReference`s'
+    u('text', '![india][]'),
+    'should fall back on collapsed `imageReference`s'
   )
 
   t.deepEqual(

test/image-reference.js

@@ -6,77 +6,49 @@ var to = require('..')
 
 test('LinkReference', function(t) {
   t.deepEqual(
-    to(
-      u(
-        'linkReference',
-        {
-          identifier: 'bravo'
-        },
-        [u('text', 'bravo')]
-      )
-    ),
-    [u('text', '['), u('text', 'bravo'), u('text', ']')],
+    to(u('linkReference', {identifier: 'bravo'}, [u('text', 'bravo')])),
+    [u('text', '[bravo]')],
     'should fall back on `linkReference`s without definition'
   )
 
   t.deepEqual(
     to(
-      u(
-        'linkReference',
-        {
-          identifier: 'delta',
-          referenceType: 'full'
-        },
-        [u('text', 'echo')]
-      )
-    ),
-    u(
-      'element',
-      {
-        tagName: 'a',
-        properties: {
-          href: ''
-        }
-      },
-      [u('text', 'echo')]
+      u('linkReference', {identifier: 'delta', referenceType: 'full'}, [
+        u('text', 'echo')
+      ])
     ),
-    'should not fall back on full `linkReference`s'
+    [u('text', '[echo][delta]')],
+    'should fall back on full `linkReference`s'
   )
 
   t.deepEqual(
     to(
-      u(
-        'linkReference',
-        {
-          identifier: 'hotel',
-          referenceType: 'collapsed'
-        },
-        [u('text', 'hotel')]
-      )
+      u('linkReference', {identifier: 'hotel', referenceType: 'collapsed'}, [
+        u('text', 'hotel')
+      ])
     ),
-    u(
-      'element',
-      {
-        tagName: 'a',
-        properties: {
-          href: ''
-        }
-      },
-      [u('text', 'hotel')]
+    [u('text', '[hotel][]')],
+    'should fall back on collapsed `linkReference`s'
+  )
+
+  t.deepEqual(
+    to(
+      u('linkReference', {identifier: 'bravo', referenceType: 'full'}, [
+        u('inlineCode', 'alpha')
+      ])
     ),
-    'should not fall back on collapsed `linkReference`s'
+    [
+      u('text', '['),
+      u('element', {tagName: 'code', properties: {}}, [u('text', 'alpha')]),
+      u('text', '][bravo]')
+    ],
+    'should support link references with non-text content'
   )
 
   t.deepEqual(
     to(
       u('paragraph', [
-        u(
-          'linkReference',
-          {
-            identifier: 'juliett'
-          },
-          [u('text', 'kilo')]
-        ),
+        u('linkReference', {identifier: 'juliett'}, [u('text', 'kilo')]),
         u('definition', {
           identifier: 'juliett',
           url: 'http://kilo.lima/mike',
@@ -89,10 +61,7 @@ test('LinkReference', function(t) {
         'element',
         {
           tagName: 'a',
-          properties: {
-            href: 'http://kilo.lima/mike',
-            title: 'november'
-          }
+          properties: {href: 'http://kilo.lima/mike', title: 'november'}
         },
         [u('text', 'kilo')]
       )