add pickling support for Pipeline (#110)

Author: hobu

pdal/PyPipeline.cpp

@@ -100,9 +100,6 @@ const PointViewSet& PipelineExecutor::views() const
 
 std::string PipelineExecutor::getPipeline() const
 {
-    if (!m_executed)
-        throw pdal_error("Pipeline has not been executed!");
-
     std::stringstream strm;
     pdal::PipelineWriter::writePipeline(m_manager.getStage(), strm);
     return strm.str();

pdal/pipeline.py

@@ -38,6 +38,13 @@ def __init__(
         self.inputs = arrays
         self.loglevel = loglevel
 
+    def __getstate__(self):
+        state = self.pipeline
+        return state
+
+    def __setstate__(self, state):
+        self.__init__(state)
+
     @property
     def stages(self) -> List[Stage]:
         return list(self._stages)

test/test_pipeline.py

@@ -132,10 +132,6 @@ def test_schema(self, filename):
     def test_pipeline(self, filename):
         """Can we fetch PDAL pipeline string"""
         r = get_pipeline(filename)
-        with pytest.raises(RuntimeError) as info:
-            r.pipeline
-        assert "Pipeline has not been executed" in str(info.value)
-
         r.execute()
         assert json.loads(r.pipeline) == {
             "pipeline": [