Add JsonStringTopicReader (#2032)

* Add JsonStringTopicReader

src/main/java/io/anserini/search/topicreader/JsonStringTopicReader.java

@@ -0,0 +1,56 @@
+/*
+ * Anserini: A Lucene toolkit for reproducible information retrieval research
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package io.anserini.search.topicreader;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JsonStringTopicReader extends TopicReader<String> {
+
+  public JsonStringTopicReader(Path topicFile) {
+    super(topicFile);
+  }
+
+  @Override
+  public SortedMap<String, Map<String, String>> read(BufferedReader reader) throws IOException {
+    SortedMap<String, Map<String, String>> map = new TreeMap<>();
+    String line;
+    ObjectMapper mapper = new ObjectMapper();
+    while ((line = reader.readLine()) != null) {
+      line = line.trim();
+      JsonNode lineNode = mapper.readerFor(JsonNode.class).readTree(line);
+      String topicID = lineNode.get("id").asText();
+
+      Map<String, String> fields = new HashMap<>();
+      lineNode.fields().forEachRemaining( e -> {
+	      if ("id".equals(e.getKey())) return; //skip id
+	      fields.put(e.getKey(), e.getValue().asText());
+      });
+      map.put(topicID, fields);
+    }
+    return map;
+  }
+}

src/test/java/io/anserini/search/topicreader/JsonStringTopicReaderTest.java

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+/*
+ * Anserini: A Lucene toolkit for reproducible information retrieval research
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.anserini.search.topicreader;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.util.Map;
+import java.util.SortedMap;
+
+import static org.junit.Assert.assertEquals;
+
+public class JsonStringTopicReaderTest {
+
+  @Test
+  public void test() throws IOException {
+    TopicReader<String> reader = new JsonStringTopicReader(
+        Paths.get("src/test/resources/sample_topics/stringID_topics.jsonl"));
+
+    SortedMap<String, Map<String, String>> topics = reader.read();
+
+    assertEquals(2, topics.keySet().size());
+    assertEquals("topic1", topics.firstKey());
+    assertEquals("topic2", topics.lastKey());
+    assertEquals("this is the contents 1.", topics.get(topics.firstKey()).get("contents"));
+    assertEquals("topic1 field1 content", topics.get(topics.firstKey()).get("field1"));
+    assertEquals("topic1 field2 content", topics.get(topics.firstKey()).get("field2"));
+    assertEquals("this is the contents 2.", topics.get(topics.lastKey()).get("contents"));
+    assertEquals("topic2 field1 content", topics.get(topics.lastKey()).get("field1"));
+    assertEquals("topic2 field2 content", topics.get(topics.lastKey()).get("field2"));
+
+  }
+}

src/test/resources/sample_topics/stringID_topics.jsonl

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+{"id": "topic1", "contents": "this is the contents 1.", "field1": "topic1 field1 content", "field2": "topic1 field2 content"}
+{"id": "topic2", "contents": "this is the contents 2.", "field1": "topic2 field1 content", "field2": "topic2 field2 content"}