refactor: store codecs by their code

Instead of storing a codec by their name, use their code instead.

The tests are changed from `base1` to `blake2b-8` as codecs for different
bases are no longer part of multicodec, but are part of multibase now.

BREAKING CHANGE: The `codec` parameter in `options.loadFormat()` is a number

Instead of returnign the name of the codec as string, the codec code (a number)
is now returned.

So if you e.g. check within the function for a certain format, it changes from:

    async loadFormat (codec) {
      if (codec !== 'dag-cbor') …
    }

To:

    async loadFormat (codec) {
      if (codec !== multicodec.DAG_CBOR) …
    }

Author: vmx

package.json

@@ -61,6 +61,7 @@
     "ipld-dag-pb": "~0.15.2",
     "ipld-raw": "^2.0.1",
     "merge-options": "^1.0.1",
+    "multicodec": "~0.5.0",
     "pull-defer": "~0.2.3",
     "pull-stream": "^3.6.9",
     "pull-traverse": "^1.0.3"

src/index.js

@@ -11,6 +11,7 @@ const mergeOptions = require('merge-options')
 const ipldDagCbor = require('ipld-dag-cbor')
 const ipldDagPb = require('ipld-dag-pb')
 const ipldRaw = require('ipld-raw')
+const multicodec = require('multicodec')
 const { fancyIterator } = require('./util')
 
 function noop () {}
@@ -31,36 +32,40 @@ class IPLDResolver {
     this.support = {}
 
     // Adds support for an IPLD format
-    this.support.add = (multicodec, resolver, util) => {
-      if (this.resolvers[multicodec]) {
-        throw new Error('Resolver already exists for codec "' + multicodec + '"')
+    this.support.add = (codec, resolver, util) => {
+      if (this.resolvers[codec]) {
+        const codecName = multicodec.print[codec]
+        throw new Error(`Resolver already exists for codec "${codecName}"`)
       }
 
-      this.resolvers[multicodec] = {
+      this.resolvers[codec] = {
         resolver: resolver,
         util: util
       }
     }
 
     if (options.loadFormat === undefined) {
       this.support.load = async (codec) => {
-        throw new Error(`No resolver found for codec "${codec}"`)
+        const codecName = multicodec.print[codec]
+        throw new Error(`No resolver found for codec "${codecName}"`)
       }
     } else {
       this.support.load = options.loadFormat
     }
 
-    this.support.rm = (multicodec) => {
-      if (this.resolvers[multicodec]) {
-        delete this.resolvers[multicodec]
+    this.support.rm = (codec) => {
+      if (this.resolvers[codec]) {
+        delete this.resolvers[codec]
       }
     }
 
     // Enable all supplied formats
     for (const format of options.formats) {
       const { resolver, util } = format
-      const multicodec = resolver.multicodec
-      this.support.add(multicodec, resolver, util)
+      // IPLD Formats are using strings instead of constants for the multicodec
+      const codecBuffer = multicodec.getCodeVarint(resolver.multicodec)
+      const codec = multicodec.getCode(codecBuffer)
+      this.support.add(codec, resolver, util)
     }
   }
 
@@ -325,6 +330,13 @@ class IPLDResolver {
   /* internals */
   /*           */
   async _getFormat (codec) {
+    // TODO vmx 2019-01-24: Once all CIDs support accessing the codec code
+    // instead of the name, remove this part
+    if (typeof codec === 'string') {
+      const constantName = codec.toUpperCase().replace(/-/g, '_')
+      codec = multicodec[constantName]
+    }
+
     if (this.resolvers[codec]) {
       return this.resolvers[codec]
     }

test/basics.js

@@ -39,10 +39,14 @@ module.exports = (repo) => {
       const bs = new BlockService(repo)
       const r = new IPLDResolver({ blockService: bs })
       // choosing a format that is not supported
-      const cid = new CID(1, 'base1', multihash.encode(Buffer.from('abcd', 'hex'), 'sha1'))
+      const cid = new CID(
+        1,
+        'blake2b-8',
+        multihash.encode(Buffer.from('abcd', 'hex'), 'sha1')
+      )
       const result = r.resolve(cid, '')
       await expect(result.next()).to.be.rejectedWith(
-        'No resolver found for codec "base1"')
+        'No resolver found for codec "blake2b-8"')
     })
 
     // TODO vmx 2018-11-29 Change this test to use `get()`.
@@ -62,9 +66,9 @@ module.exports = (repo) => {
       const bs = new BlockService(repo)
       const r = new IPLDResolver({ blockService: bs })
       // choosing a format that is not supported
-      r.put(null, { format: 'base1' }, (err, result) => {
+      r.put(null, { format: 'blake2b-8' }, (err, result) => {
         expect(err).to.exist()
-        expect(err.message).to.eql('No resolver found for codec "base1"')
+        expect(err.message).to.eql('No resolver found for codec "blake2b-8"')
         done()
       })
     })
@@ -83,10 +87,14 @@ module.exports = (repo) => {
       const bs = new BlockService(repo)
       const r = new IPLDResolver({ blockService: bs })
       // choosing a format that is not supported
-      const cid = new CID(1, 'base1', multihash.encode(Buffer.from('abcd', 'hex'), 'sha1'))
+      const cid = new CID(
+        1,
+        'blake2b-8',
+        multihash.encode(Buffer.from('abcd', 'hex'), 'sha1')
+      )
       r._put(cid, null, (err, result) => {
         expect(err).to.exist()
-        expect(err.message).to.eql('No resolver found for codec "base1"')
+        expect(err.message).to.eql('No resolver found for codec "blake2b-8"')
         done()
       })
     })
@@ -95,12 +103,16 @@ module.exports = (repo) => {
       const bs = new BlockService(repo)
       const r = new IPLDResolver({ blockService: bs })
       // choosing a format that is not supported
-      const cid = new CID(1, 'base1', multihash.encode(Buffer.from('abcd', 'hex'), 'sha1'))
+      const cid = new CID(
+        1,
+        'blake2b-8',
+        multihash.encode(Buffer.from('abcd', 'hex'), 'sha1')
+      )
       pull(
         r.treeStream(cid, '/', {}),
         pull.collect(function (err) {
           expect(err).to.exist()
-          expect(err.message).to.eql('No resolver found for codec "base1"')
+          expect(err.message).to.eql('No resolver found for codec "blake2b-8"')
           done()
         })
       )

test/format-support.js

@@ -9,6 +9,7 @@ chai.use(dirtyChai)
 chai.use(chaiAsProised)
 const BlockService = require('ipfs-block-service')
 const dagCBOR = require('ipld-dag-cbor')
+const multicodec = require('multicodec')
 
 const IPLDResolver = require('../src')
 
@@ -49,7 +50,9 @@ module.exports = (repo) => {
           blockService: bs,
           formats: [],
           async loadFormat (codec) {
-            if (codec !== 'dag-cbor') throw new Error('unexpected codec')
+            if (codec !== multicodec.DAG_CBOR) {
+              throw new Error('unexpected codec')
+            }
             throw new Error(errMsg)
           }
         })
@@ -64,7 +67,9 @@ module.exports = (repo) => {
           blockService: bs,
           formats: [],
           async loadFormat (codec) {
-            if (codec !== 'dag-cbor') throw new Error('unexpected codec')
+            if (codec !== multicodec.DAG_CBOR) {
+              throw new Error('unexpected codec')
+            }
             return dagCBOR
           }
         })