Add functionality to copy feed and append to it.

.travis.yml

@@ -4,5 +4,4 @@ node_js:
   - "4.0"
   - "0.12"
   - "0.11"
-  - "0.10"
   - "iojs"

index.js

@@ -1,6 +1,7 @@
 var level = require('level')
 var hypercore = require('hypercore')
 var createImportPipeline = require('./lib/import.js')
+var FeedOperations = require('./lib/feedOperations.js')
 
 module.exports = Jawn
 
@@ -14,3 +15,8 @@ function Jawn (opts) {
 Jawn.prototype.createImportPipeline = function (opts) {
   return createImportPipeline(this, opts)
 }
+
+Jawn.prototype.createAppendableFeed = function (feedId, data) {
+  var feed = new FeedOperations(this.core).appendableFeed(feedId)
+  return feed
+}

lib/feedOperations.js

@@ -0,0 +1,80 @@
+module.exports = FeedOperations
+
+function FeedOperations (core) {
+  this.core = core
+  this.replicate = copyOriginal
+
+  function copyOriginal (refFeed, newFeed, resolve, reject) {
+    loop(null)
+
+    function loop (err) {
+      if (err) {
+        console.log(err)
+        if (reject) {
+          return reject()
+        }
+      }
+
+      refFeed.get(newFeed.blocks, function (err, block) {
+        if (err) {
+          console.log(err)
+        }
+
+        if (!block) {
+          return resolve()
+        }
+
+        newFeed.append(block, loop)
+      })
+    }
+  }
+}
+
+FeedOperations.prototype.appendableFeed = function (feedId) {
+  var refFeed = this.core.get(feedId)
+  var newFeed = this.core.add()
+
+  newFeed.append_p = function (data) {
+    return new Promise(function (resolve, reject) {
+      newFeed.append(data, resolve)
+    })
+  }
+
+  newFeed.finalize_p = function () {
+    return new Promise(function (resolve, reject) {
+      newFeed.finalize(resolve)
+    })
+  }
+
+  var copyOriginal = this.replicate
+
+  newFeed.initialize = function () {
+    return new Promise(function (resolve, reject) {
+      copyOriginal(refFeed, newFeed, resolve, reject)
+    })
+  }
+
+  return newFeed
+}
+
+FeedOperations.prototype.replicateFeed = function (feedId, callback) {
+  var refFeed = this.core.get(feedId)
+  var newFeed = this.core.add()
+
+  this.replicate(refFeed, newFeed, callback)
+  return newFeed
+}
+
+// Copies data from reference feed, appends data to new feed and finalizes it
+FeedOperations.prototype.append = function (feedId, data, callback) {
+  var refFeed = this.core.get(feedId)
+  var newFeed = this.core.add()
+
+  this.replicate(refFeed, newFeed, function () {
+    newFeed.append(data, function () {
+      newFeed.finalize(callback)
+    })
+  })
+
+  return newFeed
+}

test/feedOperations.js

@@ -0,0 +1,147 @@
+var test = require('tape')
+var Jawn = require('../')
+var memdb = require('memdb')
+var FeedOps = require('../lib/feedOperations.js')
+
+test('Create appendable feed and copy data from reference feed', function (t) {
+  var jawn = freshJawn()
+  var feed = jawn.core.add()
+
+  storeDataInFeed(feed, ['hello'])
+  .then(function () {
+    // Verify feed was finalized and has an id
+    console.log('Finalized with id ' + feed.id.toString('hex'))
+    // Create appendable feed
+    var feedOperations = new FeedOps(jawn.core)
+    var appfeed = feedOperations.appendableFeed(feed.id)
+    // Copy data from reference feed, finalize it, then verify the feed has the same number of blocks as the reference
+    appfeed.initialize().then(function () {
+      return appfeed.finalize_p()
+    })
+    .then(function () {
+      t.same(appfeed.blocks, feed.blocks, 'testing')
+      t.end()
+    })
+  })
+})
+
+test('Create appendable feeed, copy data from reference feed and append to feed', function (t) {
+  var jawn = freshJawn()
+  var feed = jawn.core.add()
+  var expected = ['hello', 'there', 'goodbye']
+
+  storeDataInFeed(feed, ['hello', 'there'])
+  .then(function () {
+    console.log('Finalized with id ' + feed.id.toString('hex'))
+
+    var appfeed = new FeedOps(jawn.core).appendableFeed(feed.id)
+
+    // Copy data from original feed with initialize(), then append an additional block and finalize
+    appfeed.initialize().then(function () {
+      return appfeed.append_p('goodbye')
+    })
+    .then(function () {
+      return appfeed.finalize_p()
+    })
+    .then(function () {
+      // Verify the feed has the correct number of blocks, and the blocks match what was expected
+      t.same(appfeed.blocks, expected.length, 'Correct number of blocks')
+
+      for (var i = 0; i < appfeed.blocks; i++) {
+        appfeed.get(i, function (err, block) {
+          if (err) {
+            console.log(err)
+          }
+          t.same(block.toString(), expected.shift(), 'Feed block match')
+          if (expected.length === 0) {
+            t.end()
+          }
+        })
+      }
+    })
+  })
+})
+
+test('Create appendable feed without promises, copy data from reference feed', function (t) {
+  var jawn = freshJawn()
+  var feed = jawn.core.add()
+
+  storeDataInFeed(feed, ['hello', 'there'])
+  .then(function () {
+    var appFeed = new FeedOps(jawn.core).replicateFeed(feed.id, finalizeCallback)
+    function finalizeCallback () {
+      appFeed.finalize(function () {
+        t.same(appFeed.blocks, feed.blocks, 'Correct number of blocks')
+        t.end()
+      })
+    }
+  })
+})
+
+test('Append data to feed without promises', function (t) {
+  var jawn = freshJawn()
+  var feed = jawn.core.add()
+  var expected = ['hello', 'there', 'goodbye']
+
+  storeDataInFeed(feed, ['hello', 'there'])
+  .then(function () {
+    var appFeed = new FeedOps(jawn.core).append(feed.id, ['goodbye'], testCallback)
+    function testCallback () {
+      t.same(appFeed.blocks, expected.length, 'Correct number of blocks in appended feed')
+      testFeedContents(appFeed, expected, t)
+    }
+  })
+})
+
+function testFeedContents (feed, expected, t) {
+  var blockNumber = 0
+  feed.get(0, loop)
+
+  function loop (err, block) {
+    if (err) {
+      console.log(err)
+    }
+
+    blockNumber += 1
+
+    if (block) {
+      t.same(block.toString(), expected.shift(), 'Feed block matches expected value')
+    }
+
+    if (expected.length === 0) {
+      return t.end()
+    }
+
+    feed.get(blockNumber, loop)
+  }
+}
+
+// Create a feed, store data in it and finalize it.
+function storeDataInFeed (feed, data) {
+  feed.pappend = function (data) {
+    return new Promise(function (resolve, reject) {
+      feed.append(data, resolve)
+    })
+  }
+
+  feed.pfinalize = function () {
+    return new Promise(function (resolve, reject) {
+      feed.finalize(resolve)
+    })
+  }
+
+  return new Promise(function (resolve, reject) {
+    feed.pappend(data).then(function () {
+      console.log('Appended')
+      return feed
+    })
+    .then(function (feed) {
+      return feed.pfinalize()
+    })
+    .then(resolve)
+  })
+}
+
+function freshJawn () {
+  return new Jawn({db: memdb()})
+}

test/import.js

@@ -30,7 +30,7 @@ test('import json to jawn', function (t) {
 test('import csv to jawn', function (t) {
   var jawn = freshJawn()
   importFromFile(jawn, 'sample.csv', {'format': 'csv'})
-  var importStream = importFromFile(jawn, 'sample.csv', {'format': 'csv'}, verify)
+  var importStream = importFromFile(jawn, 'sample.csv', {'format': 'csv'})
   var expected = [
     '{"Type of Experience":"Writing software in any programming language","Little/No Experience":"1","Some Experience":"5","Very Familiar":"4"}',
     '{"Type of Experience":"Frontend Web Development","Little/No Experience":"4","Some Experience":"3","Very Familiar":"3"}',