Properly end all iterators.

This fixes leftover code from the old iterator library.
The internal method AsyncIterator#_end should not be called directly.
Instead, #close should handle the end of an iterator.
This fixes #21,
in which incorrectly closing the federated client dropped results.

Author: RubenVerborgh

lib/triple-pattern-fragments/federated/FederatedFragmentsClient.js

@@ -90,7 +90,7 @@ function CompoundFragment(fragments, options) {
       delete fragments[index];
       // If no fragments are pending anymore, the iterator ends
       if (--fragmentsPending === 0)
-        compoundFragment._end();
+        compoundFragment.close();
     });
     fragment.once('end', fragmentDone);
 
@@ -128,7 +128,7 @@ CompoundFragment.prototype._read = function (count, done) {
 CompoundFragment.prototype.empty = function () {
   if (!this.getProperty('metadata'))
     this.setProperty('metadata', { totalTriples: 0 });
-  this._end();
+  this.close();
 };
 
 // Returns a textual representation of the fragment

lib/writers/SparqlJSONResultWriter.js

@@ -38,8 +38,8 @@ SparqlJSONResultWriter.prototype._writeBindings = function (result) {
 };
 
 SparqlJSONResultWriter.prototype._writeBoolean = function (result) {
-  this._end = SparqlResultWriter.prototype._end; // prevent other characters from being written
   this._push('"boolean":' + result + '}\n');
+  this._flush = SparqlResultWriter.prototype._flush; // do not write the bindings tail
 };
 
 SparqlJSONResultWriter.prototype._flush = function (done) {

test/sparql/UnionIterator-test.js

@@ -225,7 +225,7 @@ describe('UnionIterator', function () {
 
     describe('after the first source has ended', function () {
       before(function () {
-        sourceA._end();
+        sourceA.close();
       });
 
       it('should not have ended', function () {
@@ -255,7 +255,7 @@ describe('UnionIterator', function () {
     describe('after the second source has ended', function () {
       before(function (done) {
         iterator.on('end', done);
-        sourceB._end();
+        sourceB.close();
       });
 
       it('should have ended', function () {