feat: support multiple roots (#93)

It's never been clear why js-ipfs doesn't support multiple roots when
go-ipfs does.

This PR removes the check for multiple roots so if you import five
files without a leading directory in their paths or with the `wrapWithDirectory`
option, you'll get five CIDs back instead of an error.

BREAKING CHANGE: Importing files that would result in multiple roots no longer throws an error

Author: achingbrain

packages/ipfs-unixfs-importer/src/tree-builder.js

@@ -4,8 +4,6 @@ const DirFlat = require('./dir-flat')
 const flatToShard = require('./flat-to-shard')
 const Dir = require('./dir')
 const toPathComponents = require('./utils/to-path-components')
-const errCode = require('err-code')
-const first = require('it-first')
 
 async function addToTree (elem, tree, options) {
   const pathElems = toPathComponents(elem.path || '')
@@ -51,6 +49,18 @@ async function addToTree (elem, tree, options) {
   return tree
 }
 
+async function * flushAndYield (tree, block) {
+  if (!(tree instanceof Dir)) {
+    if (tree && tree.unixfs && tree.unixfs.isDirectory()) {
+      yield tree
+    }
+
+    return
+  }
+
+  yield * tree.flush(tree.path, block)
+}
+
 async function * treeBuilder (source, block, options) {
   let tree = new DirFlat({
     root: true,
@@ -72,29 +82,17 @@ async function * treeBuilder (source, block, options) {
     }
   }
 
-  if (!options.wrapWithDirectory) {
-    if (tree.childCount() > 1) {
-      throw errCode(new Error('detected more than one root'), 'ERR_MORE_THAN_ONE_ROOT')
-    }
-
-    const unwrapped = await first(tree.eachChildSeries())
-
-    if (!unwrapped) {
-      return
-    }
-
-    tree = unwrapped.child
-  }
+  if (options.wrapWithDirectory) {
+    yield * flushAndYield(tree, block)
+  } else {
+    for await (const unwrapped of tree.eachChildSeries()) {
+      if (!unwrapped) {
+        continue
+      }
 
-  if (!(tree instanceof Dir)) {
-    if (tree && tree.unixfs && tree.unixfs.isDirectory()) {
-      yield tree
+      yield * flushAndYield(unwrapped.child, block)
     }
-
-    return
   }
-
-  yield * tree.flush(tree.path, block)
 }
 
 module.exports = treeBuilder

packages/ipfs-unixfs-importer/test/importer.spec.js

@@ -376,20 +376,16 @@ strategies.forEach((strategy) => {
       expect(files[0].cid.toBaseEncodedString()).to.eql('QmbFMke1KXqnYyBBWxB74N4c5SBnJMVAiMNRcGu6x1AwQH')
     })
 
-    it('fails on more than one root', async () => {
-      try {
-        await all(importer([{
-          path: 'beep/200Bytes.txt',
-          content: smallFile
-        }, {
-          path: 'boop/200Bytes.txt',
-          content: bigFile
-        }], block, options))
+    it('supports more than one root', async () => {
+      const files = await all(importer([{
+        path: '200Bytes.txt',
+        content: smallFile
+      }, {
+        path: '200Bytes.txt',
+        content: bigFile
+      }], block, options))
 
-        throw new Error('No error was thrown')
-      } catch (err) {
-        expect(err.code).to.equal('ERR_MORE_THAN_ONE_ROOT')
-      }
+      expect(files).to.have.lengthOf(2)
     })
 
     it('accepts strings as content', async () => {