Add AnalysisResult.would_block() (fixes #889)

Author: niklasf

chess/engine.py

@@ -2601,6 +2601,19 @@ async def get(self) -> InfoDict:
 
         return info
 
+    def would_block(self) -> bool:
+        """
+        Checks if calling :func:`~chess.engine.AnalysisResult.get()`,
+        calling :func:`~chess.engine.AnalysisResult.next()`,
+        calling :func:`~chess.engine.AnalysisResult.wait()`, or advancing the
+        iterator one step would require waiting for the engine.
+
+        All of these functions would return immediately information is pending
+        (queue is not :func:`empty <chess.engine.AnalysisResult.empty()>`)
+        or if the search is finished.
+        """
+        return not self._seen_kork and self._queue.empty()
+
     def empty(self) -> bool:
         """
         Checks if all information has been consumed.
@@ -2891,6 +2904,14 @@ def wait(self) -> BestMove:
             future = asyncio.run_coroutine_threadsafe(self.inner.wait(), self.simple_engine.protocol.loop)
         return future.result()
 
+    def would_block(self) -> bool:
+        async def _would_block() -> bool:
+            return self.inner.would_block()
+
+        with self.simple_engine._not_shut_down():
+            future = asyncio.run_coroutine_threadsafe(_would_block(), self.simple_engine.protocol.loop)
+        return future.result()
+
     def empty(self) -> bool:
         async def _empty() -> bool:
             return self.inner.empty()

test.py

@@ -2986,7 +2986,10 @@ def test_sf_analysis(self):
                 for info in analysis:
                     if "score" in info and info["score"].white() >= chess.engine.Mate(+2):
                         break
+
             analysis.wait()
+            self.assertFalse(analysis.would_block())
+
             self.assertEqual(analysis.info["score"].relative, chess.engine.Mate(+2))
             self.assertEqual(analysis.multipv[0]["score"].black(), chess.engine.Mate(-2))
 
@@ -2997,6 +3000,7 @@ def test_sf_analysis(self):
                 was_really_empty = False
             self.assertEqual(was_really_empty, was_empty)
             self.assertTrue(analysis.empty())
+            self.assertFalse(analysis.would_block())
             for info in analysis:
                 self.fail("all info should have been consumed")
 
@@ -3174,8 +3178,10 @@ async def main():
             mock.expect("go infinite")
             mock.expect("stop", ["bestmove e2e4"])
             result = await protocol.analysis(chess.Board())
+            self.assertTrue(result.would_block())
             result.stop()
             best = await result.wait()
+            self.assertFalse(result.would_block())
             self.assertEqual(best.move, chess.Move.from_uci("e2e4"))
             self.assertTrue(best.ponder is None)
             mock.assert_done()