Fix long hang after importing history.

Turns out historyContains was getting called for the webkit backend multiple
times when the browser starts. This was calling `url in history`, which was
enumerating the entire history as `__contains__` was not defined.

qutebrowser/browser/history.py

@@ -83,6 +83,9 @@ class WebHistory(sql.SqlTable):
     def __repr__(self):
         return utils.get_repr(self, length=len(self))
 
+    def __contains__(self, url):
+        return self.contains('url', url)
+
     def _add_entry(self, entry):
         """Add an entry to the in-memory database."""
         self.insert([entry.url_str(), entry.title, entry.atime,

qutebrowser/misc/sql.py

@@ -139,6 +139,17 @@ class SqlTable(QObject):
             rec = result.record()
             yield self.Entry(*[rec.value(i) for i in range(rec.count())])
 
+    def contains(self, field, value):
+        """Return whether the table contains the matching item.
+
+        Args:
+            field: Field to match.
+            value: Value to check for the given field.
+        """
+        query = run_query("SELECT * FROM {} where {} = ? LIMIT 1"
+                          .format(self._name, field), [value])
+        return query.next()
+
     def __len__(self):
         """Return the count of rows in the table."""
         result = run_query("SELECT count(*) FROM {}".format(self._name))

tests/unit/browser/webkit/test_history.py

@@ -63,6 +63,14 @@ def test_len(hist):
     assert len(hist) == 1
 
 
+def test_contains(hist):
+    hist.add_url(QUrl('http://www.example.com/'), title='Title', atime=12345)
+    assert 'http://www.example.com/' in hist
+    assert not 'www.example.com' in hist
+    assert not 'Title' in hist
+    assert not 12345 in hist
+
+
 def test_get_recent(hist):
     hist.add_url(QUrl('http://www.qutebrowser.org/'), atime=67890)
     hist.add_url(QUrl('http://example.com/'), atime=12345)

tests/unit/misc/test_sql.py

@@ -88,6 +88,22 @@ def test_len():
     assert len(table) == 3
 
 
+def test_contains():
+    table = sql.SqlTable('Foo', ['name', 'val', 'lucky'])
+    table.insert(['one', 1, False])
+    table.insert(['nine', 9, False])
+    table.insert(['thirteen', 13, True])
+    assert table.contains('name', 'one')
+    assert table.contains('name', 'thirteen')
+    assert table.contains('val', 9)
+    assert table.contains('lucky', False)
+    assert table.contains('lucky', True)
+    assert not table.contains('name', 'oone')
+    assert not table.contains('name', 1)
+    assert not table.contains('name', '*')
+    assert not table.contains('val', 10)
+
+
 def test_delete_all(qtbot):
     table = sql.SqlTable('Foo', ['name', 'val', 'lucky'])
     table.insert(['one', 1, False])