Support stream1.

README.md

@@ -83,8 +83,6 @@ The API is the same of a streams 3 [`Transform`][transform], with some major dif
    have `_readableState` nor `_writableState`.
 3. it does not have a `read(n)` method, nor it emits the
    `'readable'` event, the data is pushed whenever ready.
-4. it only works with streams 2 and streams 3 implementations, not with
-   streams 1 (through, split, etc).
 
 <a name="acknowledgements"></a>
 ## Acknowledgements

package.json

@@ -37,6 +37,7 @@
     "standard": "^8.6.0",
     "tap-spec": "^4.1.1",
     "tape": "^4.6.3",
+    "through": "^2.3.8",
     "through2": "^2.0.3"
   },
   "dependencies": {

syncthrough.js

@@ -16,7 +16,7 @@ function SyncThrough (transform, flush) {
   this._flush = flush || passthrough
   this._destination = null
   this._inFlight = undefined
-  this._ended = false
+  this.writable = true
   this._endEmitted = false
   this._destinationNeedsEnd = true
   this._lastPush = true
@@ -42,7 +42,7 @@ function deferPiping (that) {
   }
 
   that.pipe(new OnData(that))
-  if (that._ended & !that._endEmitted) {
+  if (!that.writable & !that._endEmitted) {
     that.emit('end')
   }
 }
@@ -103,7 +103,7 @@ SyncThrough.prototype.unpipe = function (dest) {
 }
 
 SyncThrough.prototype.write = function (chunk) {
-  if (this._ended) {
+  if (!this.writable) {
     this.emit('error', new Error('write after EOF'))
     return false
   }
@@ -146,8 +146,8 @@ SyncThrough.prototype.end = function (chunk) {
 }
 
 function doEnd (that) {
-  if (!that._ended) {
-    that._ended = true
+  if (that.writable) {
+    that.writable = false
     if (that._destination) {
       that._endEmitted = true
       that.emit('end')