feat: make addLink()/rmLink() instance methods

As `addLink()` and `rmLink()` manipulate the DAGNode directly, they
can as well be instance methods.

BREAKING CHANGE: `addLink()` and `rmLink()` are now instance methods.

Prior to this change:

    DAGNode.addLink(node, link)
    DAGNode.rmLink(node, name)

Now:

    node.addLink(link)
    node.rmLink(name)

README.md

@@ -28,15 +28,15 @@
 - [API](#api)
   - [DAGNode functions](#dagnode-functions)
     - [DAGNode constructor](#dagnode-constructor)
-    - [addLink(node, link)](#addlinknode-link)
-    - [rmLink(node, nameOrCid)](#rmlinknode-nameorcid)
   - [DAGNode instance methods and properties](#dagnode-instance-methods-and-properties)
     - [`node.Data`](#nodedata)
     - [`node.Links`](#nodelinks)
     - [`node.size`](#nodesize)
     - [`node.toJSON()`](#nodetojson)
     - [`node.toString()`](#nodetostring)
     - [`node.toDAGLink(options)`](#nodetodaglinkoptions)
+    - [`node.addLink(link)`](#nodeaddlinklink)
+    - [`node.rmLink(nameOrCid)`](#nodermlinknameorcid)
   - [DAGLink functions](#daglink-functions)
     - [DAGLink constructor](#daglink-constructor)
   - [DAGLink instance methods and properties](#daglink-instance-methods-and-properties)
@@ -66,9 +66,6 @@
 ```JavaScript
 const dagPB = require('ipld-dag-pb')
 
-dagPB.DAGNode.addLink // add a Link to a DAGNode, creating a new one
-dagPB.DAGNode.rmLink  // remove a Link to a DAGNode, creating a new one
-
 // IPLD Format specifics
 dagPB.resolver
 dagPB.util
@@ -94,10 +91,10 @@ const link = {
   Tsize: 42
 }
 
-DAGNode.addLink(node, link)
+node.addLink(link)
 console.log('with link', node.toJSON())
 
-DAGNode.rmLink(nodeA, 'I am a link')
+nodeA.rmLink('I am a link')
 console.log('now without link', node.toJSON())
 ```
 
@@ -136,38 +133,6 @@ links can be a single or an array of DAGLinks instances or objects with the foll
 }
 ```
 
-#### addLink(node, link)
-
-- `node` - type: DAGNode
-- `link` - type: DAGLink or DAGLink in its json format
-
-Creates a link on node A. Modifies the node.
-
-`link` can be:
-- DAGLink instance
-- DAGNode instance
-- Object with the following properties:
-
-```JavaScript
-const link = {
-  Name: '<some string>', // optional
-  Tsize: <size in bytes>,
-  Hash: <cid> // can be a String CID, CID buffer or CID object
-}
-
-DAGNode.addLink(node, link)
-```
-
-#### rmLink(node, nameOrCid)
-
-- `node` - type: DAGNode
-- `nameOrCid` - type: String, CID object or CID buffer
-
-Removes a link from the node by name. Modifies the node.
-
-```JavaScript
-DAGNode.rmLink(node, 'Link1')
-```
 
 
 ### DAGNode instance methods and properties
@@ -201,6 +166,37 @@ const link = node.toDAGLink()
 const link = node.toDAGLink({ name: 'name-of-the-link' })
 ```
 
+#### addLink(link)
+
+- `link` - type: DAGLink or DAGLink in its json format
+
+Creates a link on node A. Modifies the node.
+
+`link` can be:
+- DAGLink instance
+- DAGNode instance
+- Object with the following properties:
+
+```JavaScript
+const link = {
+  Name: '<some string>', // optional
+  Tsize: <size in bytes>,
+  Hash: <cid> // can be a String CID, CID buffer or CID object
+}
+
+node.addLink(link)
+```
+
+#### rmLink(nameOrCid)
+
+- `nameOrCid` - type: String, CID object or CID buffer
+
+Removes a link from the node by name. Modifies the node.
+
+```JavaScript
+node.rmLink('Link1')
+```
+
 
 ### DAGLink functions
 

src/dag-node/addLink.js

@@ -2,7 +2,6 @@
 
 const sortLinks = require('./sortLinks')
 const DAGLink = require('../dag-link')
-const DAGNode = require('./index')
 
 const asDAGLink = (link) => {
   if (DAGLink.isDAGLink(link)) {
@@ -11,7 +10,13 @@ const asDAGLink = (link) => {
     return link
   }
 
-  if (DAGNode.isDAGNode(link)) {
+  // DAGNode.isDagNode() would be more appropriate here, but it can't be used
+  // as it would lead to circular dependencies as `addLink` is called from
+  // within the DAGNode object.
+  if (!('cid' in link ||
+        'hash' in link ||
+        'Hash' in link ||
+        'multihash' in link)) {
     throw new Error('Link must be a DAGLink or DAGLink-like. Convert the DAGNode into a DAGLink via `node.toDAGLink()`.')
   }
 

src/dag-node/dagNode.js

@@ -6,6 +6,8 @@ const visibility = require('../visibility')
 const DAGLink = require('../dag-link/dagLink')
 const { serializeDAGNode } = require('../serialize.js')
 const toDAGLink = require('./toDagLink')
+const addLink = require('./addLink')
+const rmLink = require('./rmLink')
 
 class DAGNode {
   constructor (data, links = [], serializedSize = 0) {
@@ -58,6 +60,14 @@ class DAGNode {
     return `DAGNode <data: "${this.Data.toString('base64')}", links: ${this.Links.length}, size: ${this.size}>`
   }
 
+  addLink (link) {
+    return addLink(this, link)
+  }
+
+  rmLink (link) {
+    return rmLink(this, link)
+  }
+
   // @returns {Promise.<DAGLink>}
   toDAGLink (options) {
     return toDAGLink(this, options)

src/dag-node/index.js

@@ -1,5 +1,3 @@
 'use strict'
 
 exports = module.exports = require('./dagNode')
-exports.addLink = require('./addLink')
-exports.rmLink = require('./rmLink')

test/dag-node-test.js

@@ -125,7 +125,7 @@ module.exports = (repo) => {
     it('addLink by DAGNode', async () => {
       const node1 = new DAGNode(Buffer.from('1'))
       const node2 = new DAGNode(Buffer.from('2'))
-      DAGNode.addLink(node1, await node2.toDAGLink())
+      node1.addLink(await node2.toDAGLink())
       expect(node1.Links.length).to.equal(1)
       expect(node1.Links[0].Tsize).to.eql(node2.size)
       expect(node1.Links[0].Name).to.be.eql('')
@@ -135,7 +135,7 @@ module.exports = (repo) => {
       const node1 = new DAGNode(Buffer.from('1'))
       const node2 = new DAGNode(Buffer.from('2'))
       const link = await node2.toDAGLink()
-      DAGNode.addLink(node1, link)
+      node1.addLink(link)
       expect(node1.Links.length).to.equal(1)
       expect(node1.Links[0].Tsize).to.eql(node2.size)
       expect(node1.Links[0].Name).to.be.eql('')
@@ -146,7 +146,7 @@ module.exports = (repo) => {
       const node2 = new DAGNode(Buffer.from('2'))
       const link = await node2.toDAGLink()
       const linkObject = link.toJSON()
-      DAGNode.addLink(node1, linkObject)
+      node1.addLink(linkObject)
       expect(node1.Links.length).to.equal(1)
       expect(node1.Links[0].Tsize).to.eql(node2.size)
       expect(node1.Links[0].Name).to.be.eql('')
@@ -157,7 +157,7 @@ module.exports = (repo) => {
       const node2 = new DAGNode(Buffer.from('2'))
       const link = await node2.toDAGLink({ name: 'banana' })
       expect(node1.Links.length).to.equal(0)
-      DAGNode.addLink(node1, link)
+      node1.addLink(link)
       expect(node1.Links.length).to.equal(1)
       expect(node1.Links[0].Tsize).to.eql(node2.size)
       expect(node1.Links[0].Name).to.eql('banana')
@@ -168,27 +168,24 @@ module.exports = (repo) => {
       expect(node1.Links.length).to.equal(0)
 
       const node2 = new DAGNode(Buffer.from('2'))
-      DAGNode.addLink(node1, await node2.toDAGLink())
+      node1.addLink(await node2.toDAGLink())
       expect(node1.Links.length).to.equal(1)
 
       const node3 = new DAGNode(Buffer.from('3'))
-      DAGNode.addLink(node1, await node3.toDAGLink())
+      node1.addLink(await node3.toDAGLink())
       expect(node1.Links.length).to.equal(2)
     })
 
     it('addLink by DAGNode.Links', async () => {
       const linkName = 'link-name'
       const remote = new DAGNode(Buffer.from('2'))
       const source = new DAGNode(Buffer.from('1'))
-      DAGNode.addLink(
-        source,
-        await remote.toDAGLink({ name: linkName })
-      )
+      source.addLink(await remote.toDAGLink({ name: linkName }))
 
       expect(source.Links.length).to.equal(1)
 
       const target = new DAGNode(null, [], 0)
-      DAGNode.addLink(target, source.Links[0])
+      target.addLink(source.Links[0])
 
       expect(target.Links.length).to.equal(1)
       expect(target.Links[0].Tsize).to.eql(remote.size)
@@ -203,9 +200,9 @@ module.exports = (repo) => {
       const node2 = new DAGNode(Buffer.from('2'))
       const link = await node2.toDAGLink({ name: 'banana' })
 
-      DAGNode.addLink(node1, link)
+      node1.addLink(link)
       expect(node1.Links.length).to.eql(1)
-      DAGNode.rmLink(node1, 'banana')
+      node1.rmLink('banana')
       expect(node1.Links.length).to.eql(0)
       expect(node1.toJSON()).to.eql(withoutLink)
     })
@@ -218,9 +215,9 @@ module.exports = (repo) => {
       const node2 = new DAGNode(Buffer.from('2'))
       const link = await node2.toDAGLink({ name: 'banana' })
 
-      DAGNode.addLink(node1, link)
+      node1.addLink(link)
       expect(node1.Links.length).to.eql(1)
-      DAGNode.rmLink(node1, node1.Links[0].Hash)
+      node1.rmLink(node1.Links[0].Hash)
       expect(node1.Links.length).to.eql(0)
       expect(node1.toJSON()).to.eql(withoutLink)
     })