Added functions for get_selected_streams (#100)

* Added functions for get_selected_streams

* refactor functions onto class; pylint

Author: Kyle Allan

singer/__init__.py

@@ -55,7 +55,10 @@
     resolve_schema_references
 )
 
-from singer.catalog import Catalog
+from singer.catalog import (
+    Catalog,
+    CatalogEntry
+)
 from singer.schema import Schema
 
 from singer.bookmarks import (

singer/catalog.py

@@ -1,9 +1,14 @@
 '''Provides an object model for a Singer Catalog.'''
-
 import json
 import sys
 
-from singer.schema import Schema
+from . import metadata as metadata_module
+from .bookmarks import get_currently_syncing
+from .logger import get_logger
+from .schema import Schema
+
+LOGGER = get_logger()
+
 
 # pylint: disable=too-many-instance-attributes
 class CatalogEntry():
@@ -33,7 +38,9 @@ def __eq__(self, other):
         return self.__dict__ == other.__dict__
 
     def is_selected(self):
-        return self.schema.selected  # pylint: disable=no-member
+        mdata = metadata_module.to_map(self.metadata)
+        # pylint: disable=no-member
+        return self.schema.selected or metadata_module.get(mdata, (), 'selected')
 
     def to_dict(self):
         result = {}
@@ -116,3 +123,27 @@ def get_stream(self, tap_stream_id):
             if stream.tap_stream_id == tap_stream_id:
                 return stream
         return None
+
+    def _shuffle_streams(self, state):
+        currently_syncing = get_currently_syncing(state)
+
+        if currently_syncing is None:
+            return self.streams
+
+        matching_index = 0
+        for i, catalog_entry in enumerate(self.streams):
+            if catalog_entry.tap_stream_id == currently_syncing:
+                matching_index = i
+                break
+        top_half = self.streams[matching_index:]
+        bottom_half = self.streams[:matching_index]
+        return top_half + bottom_half
+
+
+    def get_selected_streams(self, state):
+        for stream in self._shuffle_streams(state):
+            if not stream.is_selected():
+                LOGGER.info('Skipping stream: %s', stream.tap_stream_id)
+                continue
+
+            yield stream

tests/test_catalog.py

@@ -3,6 +3,40 @@
 from singer.schema import Schema
 from singer.catalog import Catalog, CatalogEntry
 
+class TestGetSelectedStreams(unittest.TestCase):
+    def test_one_selected_stream(self):
+        selected_entry = CatalogEntry(tap_stream_id='a',
+                                      schema=Schema(),
+                                      metadata=[{'metadata':
+                                                 {'selected': True},
+                                                 'breadcrumb': []}])
+        catalog = Catalog(
+            [selected_entry,
+             CatalogEntry(tap_stream_id='b',schema=Schema(),metadata=[]),
+             CatalogEntry(tap_stream_id='c',schema=Schema(),metadata=[])])
+        state = {}
+        selected_streams = catalog.get_selected_streams(state)
+        self.assertEquals([e for e in selected_streams],[selected_entry])
+
+    def test_resumes_currently_syncing_stream(self):
+        selected_entry_a = CatalogEntry(tap_stream_id='a',
+                                      schema=Schema(),
+                                      metadata=[{'metadata':
+                                                 {'selected': True},
+                                                 'breadcrumb': []}])
+        selected_entry_c = CatalogEntry(tap_stream_id='c',
+                                        schema=Schema(),
+                                        metadata=[{'metadata':
+                                                   {'selected': True},
+                                                   'breadcrumb': []}])
+        catalog = Catalog(
+            [selected_entry_a,
+             CatalogEntry(tap_stream_id='b',schema=Schema(),metadata=[]),
+             selected_entry_c])
+        state = {'currently_syncing': 'c'}
+        selected_streams = catalog.get_selected_streams(state)
+        self.assertEquals([e for e in selected_streams][0],selected_entry_c)
+
 class TestToDictAndFromDict(unittest.TestCase):
 
     dict_form = {
@@ -89,7 +123,7 @@ def test_from_dict(self):
 
     def test_to_dict(self):
         self.assertEqual(self.dict_form, self.obj_form.to_dict())
-        
+
 
 class TestGetStream(unittest.TestCase):
     def test(self):