Fix spreading of lists and list items

Related to syntax-tree/mdast#4.
Related to remarkjs/remark#349.
Related to remarkjs/remark#350.
Related to remarkjs/remark#364.

Closes GH-23.

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

lib/footer.js

@@ -12,23 +12,36 @@ function generateFootnotes(h) {
   var index = -1
   var listItems = []
   var def
+  var backReference
+  var content
+  var tail
 
   if (!length) {
     return null
   }
 
   while (++index < length) {
     def = footnotes[index]
+    content = def.children.concat()
+    tail = content[content.length - 1]
+    backReference = {
+      type: 'link',
+      url: '#fnref-' + def.identifier,
+      data: {hProperties: {className: ['footnote-backref']}},
+      children: [{type: 'text', value: '↩'}]
+    }
+
+    if (!tail || tail.type !== 'paragraph') {
+      tail = {type: 'paragraph', children: []}
+      content.push(tail)
+    }
+
+    tail.children.push(backReference)
 
     listItems[index] = {
       type: 'listItem',
       data: {hProperties: {id: 'fn-' + def.identifier}},
-      children: def.children.concat({
-        type: 'link',
-        url: '#fnref-' + def.identifier,
-        data: {hProperties: {className: ['footnote-backref']}},
-        children: [{type: 'text', value: '↩'}]
-      }),
+      children: content,
       position: def.position
     }
   }
@@ -40,11 +53,7 @@ function generateFootnotes(h) {
     wrap(
       [
         thematicBreak(h),
-        list(h, {
-          type: 'list',
-          ordered: true,
-          children: listItems
-        })
+        list(h, {type: 'list', ordered: true, children: listItems})
       ],
       true
     )

lib/handlers/list-item.js

@@ -9,27 +9,40 @@ var all = require('../all')
 function listItem(h, node, parent) {
   var children = node.children
   var head = children[0]
+  var raw = all(h, node)
+  var loose = parent ? listLoose(parent) : listItemLoose(node)
   var props = {}
-  var single = false
   var result
   var container
+  var index
+  var length
+  var child
 
-  if (
-    (!parent || !parent.loose) &&
-    children.length === 1 &&
-    head.type === 'paragraph'
-  ) {
-    single = true
-  }
+  /* Tight lists should not render 'paragraph' nodes as 'p' tags */
+  if (loose) {
+    result = raw
+  } else {
+    result = []
+    length = raw.length
+    index = -1
+
+    while (++index < length) {
+      child = raw[index]
 
-  result = all(h, single ? head : node)
+      if (child.tagName === 'p') {
+        result = result.concat(child.children)
+      } else {
+        result.push(child)
+      }
+    }
+  }
 
   if (typeof node.checked === 'boolean') {
-    if (!single && (!head || head.type !== 'paragraph')) {
+    if (loose && (!head || head.type !== 'paragraph')) {
       result.unshift(h(null, 'p', []))
     }
 
-    container = single ? result : result[0].children
+    container = loose ? result[0].children : result
 
     if (container.length !== 0) {
       container.unshift(u('text', ' '))
@@ -47,9 +60,30 @@ function listItem(h, node, parent) {
     props.className = ['task-list-item']
   }
 
-  if (!single && result.length !== 0) {
+  if (loose && result.length !== 0) {
     result = wrap(result, true)
   }
 
   return h(node, 'li', props, result)
 }
+
+function listLoose(node) {
+  var loose = node.spread
+  var children = node.children
+  var length = children.length
+  var index = -1
+
+  while (!loose && ++index < length) {
+    loose = listItemLoose(children[index])
+  }
+
+  return loose
+}
+
+function listItemLoose(node) {
+  var spread = node.spread
+
+  return spread === undefined || spread === null
+    ? node.children.length > 1
+    : spread
+}

test/footnote-definition.js

@@ -7,13 +7,9 @@ var to = require('..')
 test('FootnoteDefinition', function(t) {
   t.equal(
     to(
-      u(
-        'footnoteDefinition',
-        {
-          identifier: 'zulu'
-        },
-        [u('paragraph', [u('text', 'alpha')])]
-      )
+      u('footnoteDefinition', {identifier: 'zulu'}, [
+        u('paragraph', [u('text', 'alpha')])
+      ])
     ),
     null,
     'should ignore `footnoteDefinition`'