Refactor collectors

  * Define a common iterface
  * Use generic types
  * Remove some duplicated code
  * Simplify InfoItemSearchCollector and remove unused methods
  * SearchResult: Make fields final

Author: coffeemakr

src/main/java/org/schabi/newpipe/extractor/Collector.java

@@ -0,0 +1,46 @@
+package org.schabi.newpipe.extractor;
+
+import org.schabi.newpipe.extractor.exceptions.ParsingException;
+
+import java.util.List;
+
+/**
+ * Collectors are used to simplify the collection of information
+ * from extractors
+ * @param <I> the item type
+ * @param <E> the extractor type
+ */
+public interface Collector<I, E> {
+
+    /**
+     * Try to add an extractor to the collection
+     * @param extractor the extractor to add
+     */
+    void commit(E extractor);
+
+    /**
+     * Try to extract the item from an extractor without adding it to the collection
+     * @param extractor the extractor to use
+     * @return the item
+     * @throws ParsingException thrown if there is an error extracting the
+     *                          <b>required</b> fields of the item.
+     */
+    I extract(E extractor) throws ParsingException;
+
+    /**
+     * Get all items
+     * @return the items
+     */
+    List<I> getItemList();
+
+    /**
+     * Get all errors
+     * @return the errors
+     */
+    List<Throwable> getErrors();
+
+    /**
+     * Reset all collected items and errors
+     */
+    void reset();
+}

src/main/java/org/schabi/newpipe/extractor/Extractor.java

@@ -32,6 +32,8 @@ public abstract class Extractor {
     private String cleanUrl;
 
     public Extractor(StreamingService service, String url) throws ExtractionException {
+        if(service == null) throw new NullPointerException("service is null");
+        if(url == null) throw new NullPointerException("url is null");
         this.service = service;
         this.originalUrl = url;
     }
@@ -53,6 +55,10 @@ public String getOriginalUrl() {
         return originalUrl;
     }
 
+    /**
+     * Get a clean url and as a fallback the original url.
+     * @return the clean url or the original url
+     */
     public String getCleanUrl() {
         if (cleanUrl != null && !cleanUrl.isEmpty()) return cleanUrl;
 

src/main/java/org/schabi/newpipe/extractor/InfoItem.java

@@ -20,8 +20,6 @@
  * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-import org.schabi.newpipe.extractor.stream.StreamType;
-
 import java.io.Serializable;
 
 public abstract class InfoItem implements Serializable {

src/main/java/org/schabi/newpipe/extractor/InfoItemCollector.java

@@ -1,8 +1,9 @@
 package org.schabi.newpipe.extractor;
 
-import org.schabi.newpipe.extractor.exceptions.ExtractionException;
+import org.schabi.newpipe.extractor.exceptions.ParsingException;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /*
@@ -25,42 +26,66 @@
  * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-public abstract class InfoItemCollector {
-    private List<InfoItem> itemList = new ArrayList<>();
-    private List<Throwable> errors = new ArrayList<>();
-    private int serviceId = -1;
+public abstract class InfoItemCollector<I extends InfoItem, E> implements Collector<I,E> {
 
+    private final List<I> itemList = new ArrayList<>();
+    private final List<Throwable> errors = new ArrayList<>();
+    private final int serviceId;
+
+    /**
+     * Create a new collector
+     * @param serviceId the service id
+     */
     public InfoItemCollector(int serviceId) {
         this.serviceId = serviceId;
     }
 
-    public List<InfoItem> getItemList() {
-        return itemList;
+    @Override
+    public List<I> getItemList() {
+        return Collections.unmodifiableList(itemList);
     }
 
+    @Override
     public List<Throwable> getErrors() {
-        return errors;
+        return Collections.unmodifiableList(errors);
     }
 
-    protected void addFromCollector(InfoItemCollector otherC) throws ExtractionException {
-        if (serviceId != otherC.serviceId) {
-            throw new ExtractionException("Service Id does not equal: "
-                    + NewPipe.getNameOfService(serviceId)
-                    + " and " + NewPipe.getNameOfService((otherC.serviceId)));
-        }
-        errors.addAll(otherC.errors);
-        itemList.addAll(otherC.itemList);
+    @Override
+    public void reset() {
+        itemList.clear();
+        errors.clear();
     }
 
-    protected void addError(Exception e) {
-        errors.add(e);
+    /**
+     * Add an error
+     * @param error the error
+     */
+    protected void addError(Exception error) {
+        errors.add(error);
     }
 
-    protected void addItem(InfoItem item) {
+    /**
+     * Add an item
+     * @param item the item
+     */
+    protected void addItem(I item) {
         itemList.add(item);
     }
 
-    protected int getServiceId() {
+    /**
+     * Get the service id
+     * @return the service id
+     */
+    public int getServiceId() {
         return serviceId;
     }
+
+    @Override
+    public void commit(E extractor) {
+        try {
+            addItem(extract(extractor));
+        } catch (ParsingException e) {
+            addError(e);
+        }
+    }
 }

src/main/java/org/schabi/newpipe/extractor/ListExtractor.java

@@ -87,6 +87,18 @@ public NextItemsResult(List<InfoItem> nextItemsList, String nextItemsUrl, List<T
         public boolean hasMoreStreams() {
             return nextItemsUrl != null && !nextItemsUrl.isEmpty();
         }
+
+        public List<InfoItem> getNextItemsList() {
+            return nextItemsList;
+        }
+
+        public String getNextItemsUrl() {
+            return nextItemsUrl;
+        }
+
+        public List<Throwable> getErrors() {
+            return errors;
+        }
     }
 
 }

src/main/java/org/schabi/newpipe/extractor/ListInfo.java

@@ -11,23 +11,23 @@ public ListInfo(int serviceId, String id, String url, String name) {
         super(serviceId, id, url, name);
     }
 
-    public List<InfoItem> getRelated_streams() {
+    public List<InfoItem> getRelatedStreams() {
         return related_streams;
     }
 
     public void setRelatedStreams(List<InfoItem> related_streams) {
         this.related_streams = related_streams;
     }
 
-    public boolean isHas_more_streams() {
+    public boolean hasMoreStreams() {
         return has_more_streams;
     }
 
     public void setHasMoreStreams(boolean has_more_streams) {
         this.has_more_streams = has_more_streams;
     }
 
-    public String getNext_streams_url() {
+    public String getNextStreamsUrl() {
         return next_streams_url;
     }
 

src/main/java/org/schabi/newpipe/extractor/channel/ChannelInfoItemCollector.java

@@ -23,11 +23,12 @@
  * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-public class ChannelInfoItemCollector extends InfoItemCollector {
+public class ChannelInfoItemCollector extends InfoItemCollector<ChannelInfoItem, ChannelInfoItemExtractor> {
     public ChannelInfoItemCollector(int serviceId) {
         super(serviceId);
     }
 
+    @Override
     public ChannelInfoItem extract(ChannelInfoItemExtractor extractor) throws ParsingException {
         // important information
         int serviceId = getServiceId();
@@ -60,12 +61,4 @@ public ChannelInfoItem extract(ChannelInfoItemExtractor extractor) throws Parsin
         }
         return resultItem;
     }
-
-    public void commit(ChannelInfoItemExtractor extractor) throws ParsingException {
-        try {
-            addItem(extract(extractor));
-        } catch (Exception e) {
-            addError(e);
-        }
-    }
 }

src/main/java/org/schabi/newpipe/extractor/playlist/PlaylistInfoItemCollector.java

@@ -3,11 +3,13 @@
 import org.schabi.newpipe.extractor.InfoItemCollector;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 
-public class PlaylistInfoItemCollector extends InfoItemCollector {
+public class PlaylistInfoItemCollector extends InfoItemCollector<PlaylistInfoItem, PlaylistInfoItemExtractor> {
+
     public PlaylistInfoItemCollector(int serviceId) {
         super(serviceId);
     }
 
+    @Override
     public PlaylistInfoItem extract(PlaylistInfoItemExtractor extractor) throws ParsingException {
 
         String name = extractor.getName();
@@ -33,12 +35,4 @@ public PlaylistInfoItem extract(PlaylistInfoItemExtractor extractor) throws Pars
         }
         return resultItem;
     }
-
-    public void commit(PlaylistInfoItemExtractor extractor) throws ParsingException {
-        try {
-            addItem(extract(extractor));
-        } catch (Exception e) {
-            addError(e);
-        }
-    }
 }

src/main/java/org/schabi/newpipe/extractor/search/InfoItemSearchCollector.java

@@ -1,10 +1,10 @@
 package org.schabi.newpipe.extractor.search;
 
-import org.schabi.newpipe.extractor.InfoItemCollector;
+import org.schabi.newpipe.extractor.*;
 import org.schabi.newpipe.extractor.channel.ChannelInfoItemCollector;
 import org.schabi.newpipe.extractor.channel.ChannelInfoItemExtractor;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
-import org.schabi.newpipe.extractor.exceptions.FoundAdException;
+import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.playlist.PlaylistInfoItemCollector;
 import org.schabi.newpipe.extractor.playlist.PlaylistInfoItemExtractor;
 import org.schabi.newpipe.extractor.stream.StreamInfoItemCollector;
@@ -30,13 +30,23 @@
  * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-public class InfoItemSearchCollector extends InfoItemCollector {
+/**
+ * Collector for search results
+ *
+ * This collector can handle the following extractor types:
+ * <ul>
+ *     <li>{@link StreamInfoItemExtractor}</li>
+ *     <li>{@link ChannelInfoItemExtractor}</li>
+ *     <li>{@link PlaylistInfoItemExtractor}</li>
+ * </ul>
+ * Calling {@link #extract(InfoItemExtractor)} or {@link #commit(Object)} with any
+ * other extractor type will raise an exception.
+ */
+public class InfoItemSearchCollector extends InfoItemCollector<InfoItem, InfoItemExtractor> {
     private String suggestion = "";
-    private StreamInfoItemCollector streamCollector;
-    private ChannelInfoItemCollector userCollector;
-    private PlaylistInfoItemCollector playlistCollector;
-
-    private SearchResult result = new SearchResult();
+    private final StreamInfoItemCollector streamCollector;
+    private final ChannelInfoItemCollector userCollector;
+    private final PlaylistInfoItemCollector playlistCollector;
 
     InfoItemSearchCollector(int serviceId) {
         super(serviceId);
@@ -50,43 +60,20 @@ public void setSuggestion(String suggestion) {
     }
 
     public SearchResult getSearchResult() throws ExtractionException {
-
-        addFromCollector(userCollector);
-        addFromCollector(streamCollector);
-        addFromCollector(playlistCollector);
-
-        result.suggestion = suggestion;
-        result.errors = getErrors();
-        return result;
-    }
-
-    public void commit(StreamInfoItemExtractor extractor) {
-        try {
-            result.resultList.add(streamCollector.extract(extractor));
-        } catch (FoundAdException ae) {
-            System.err.println("Found ad");
-        } catch (Exception e) {
-            addError(e);
-        }
-    }
-
-    public void commit(ChannelInfoItemExtractor extractor) {
-        try {
-            result.resultList.add(userCollector.extract(extractor));
-        } catch (FoundAdException ae) {
-            System.err.println("Found ad");
-        } catch (Exception e) {
-            addError(e);
-        }
+        return new SearchResult(getServiceId(), suggestion, getItemList(), getErrors());
     }
 
-    public void commit(PlaylistInfoItemExtractor extractor) {
-        try {
-            result.resultList.add(playlistCollector.extract(extractor));
-        } catch (FoundAdException ae) {
-            System.err.println("Found ad");
-        } catch (Exception e) {
-            addError(e);
+    @Override
+    public InfoItem extract(InfoItemExtractor extractor) throws ParsingException {
+        // Use the corresponding collector for each item extractor type
+        if(extractor instanceof StreamInfoItemExtractor) {
+            return streamCollector.extract((StreamInfoItemExtractor) extractor);
+        } else if(extractor instanceof ChannelInfoItemExtractor) {
+            return userCollector.extract((ChannelInfoItemExtractor) extractor);
+        } else if(extractor instanceof PlaylistInfoItemExtractor) {
+            return playlistCollector.extract((PlaylistInfoItemExtractor) extractor);
+        } else {
+            throw new IllegalArgumentException("Invalid extractor type: " + extractor);
         }
     }
 }