Add manifest

index.js

@@ -6,12 +6,35 @@ var AbstractIterator = require('abstract-leveldown').AbstractIterator
 var inherits = require('inherits')
 var Codec = require('level-codec')
 var EncodingError = require('level-errors').EncodingError
+var rangeMethods = ['approximateSize', 'compactRange']
 
 module.exports = DB.default = DB
 
 function DB (db, opts) {
   if (!(this instanceof DB)) return new DB(db, opts)
-  AbstractLevelDOWN.call(this, '')
+
+  var manifest = db.supports || {}
+  var additionalMethods = manifest.additionalMethods || {}
+
+  AbstractLevelDOWN.call(this, manifest)
+
+  this.supports.encodings = true
+  this.supports.additionalMethods = {}
+
+  rangeMethods.forEach(function (m) {
+    // TODO (future major): remove this fallback
+    var fallback = typeof db[m] === 'function'
+
+    if (additionalMethods[m] || fallback) {
+      this.supports.additionalMethods[m] = true
+
+      this[m] = function (start, end, opts, cb) {
+        start = this.codec.encodeKey(start, opts)
+        end = this.codec.encodeKey(end, opts)
+        return this.db[m](start, end, opts, cb)
+      }
+    }
+  }, this)
 
   opts = opts || {}
   if (typeof opts.keyEncoding === 'undefined') opts.keyEncoding = 'utf8'
@@ -84,12 +107,6 @@ DB.prototype._clear = function (opts, callback) {
   this.db.clear(opts, callback)
 }
 
-DB.prototype.approximateSize = function (start, end, opts, cb) {
-  start = this.codec.encodeKey(start, opts)
-  end = this.codec.encodeKey(end, opts)
-  return this.db.approximateSize(start, end, opts, cb)
-}
-
 function Iterator (db, opts) {
   AbstractIterator.call(this, db)
   this.codec = db.codec

package.json

@@ -12,7 +12,7 @@
     "prepublishOnly": "npm run dependency-check"
   },
   "dependencies": {
-    "abstract-leveldown": "^6.1.1",
+    "abstract-leveldown": "^6.2.1",
     "inherits": "^2.0.3",
     "level-codec": "^9.0.0",
     "level-errors": "^2.0.0"

test/index.js

@@ -579,17 +579,68 @@ test('iterator catches decoding error from valueEncoding', function (t) {
   })
 })
 
-test('approximateSize() encodes start and end', function (t) {
-  t.plan(2)
+test('proxies approximateSize() if it exists', function (t) {
+  t.is(typeof encdown({ approximateSize: noop }).approximateSize, 'function')
+  t.ok(encdown({ approximateSize: noop }).supports.additionalMethods.approximateSize)
+  t.is(encdown({}).approximateSize, undefined)
+  t.notOk(encdown({}).supports.additionalMethods.approximateSize)
+  t.end()
+})
 
-  var down = {
+test('proxies compactRange() if it exists', function (t) {
+  t.is(typeof encdown({ compactRange: noop }).compactRange, 'function')
+  t.ok(encdown({ compactRange: noop }).supports.additionalMethods.compactRange)
+  t.is(encdown({}).compactRange, undefined)
+  t.notOk(encdown({}).supports.additionalMethods.compactRange)
+  t.end()
+})
+
+test('encodes start and end of approximateSize()', function (t) {
+  var db = encdown({
     approximateSize: function (start, end) {
       t.is(start, '1')
       t.is(end, '2')
+      t.end()
     }
-  }
+  })
+
+  db.approximateSize(1, 2, noop)
+})
+
+test('encodes start and end of compactRange()', function (t) {
+  var db = encdown({
+    compactRange: function (start, end) {
+      t.is(start, '1')
+      t.is(end, '2')
+      t.end()
+    }
+  })
+
+  db.compactRange(1, 2, noop)
+})
+
+test('encodes start and end of approximateSize() with custom encoding', function (t) {
+  var db = encdown({
+    approximateSize: function (start, end) {
+      t.is(start, '"a"')
+      t.is(end, '"b"')
+      t.end()
+    }
+  })
+
+  db.approximateSize('a', 'b', { keyEncoding: 'json' }, noop)
+})
+
+test('encodes start and end of compactRange() with custom encoding', function (t) {
+  var db = encdown({
+    compactRange: function (start, end) {
+      t.is(start, '"a"')
+      t.is(end, '"b"')
+      t.end()
+    }
+  })
 
-  encdown(down).approximateSize(1, 2, noop)
+  db.compactRange('a', 'b', { keyEncoding: 'json' }, noop)
 })
 
 test('encodes seek target', function (t) {