Java TreePVector.empty方法代码示例

import org.pcollections.TreePVector; //导入方法依赖的package包/类
@Override
public PVector<V> applyUnsafe(JsonParser p) throws IOException {
    List<V> values = new LinkedList<>();

    /*
     * If we are in the root context (not inside an object or list) then we need to consume the next token
     * before attempting to call child deserialisers.
     */
    if (p.getParsingContext().inRoot()) {
        if (p.nextToken() == JsonToken.END_ARRAY) {
            return TreePVector.empty();
        }
    }

    if (JsonToken.VALUE_NULL != p.getCurrentToken()) {
        /*
         * When the parser has hit the end of input nextToken() will always return null.
         * So need to prevent infinite loops we check the parser closed flag.
         */
        while (!p.isClosed() && (p.nextToken() != JsonToken.END_ARRAY)) {
            values.add(itemDeserialiser.apply(p));
        }
    }
    return TreePVector.from(values);
}
 

import org.pcollections.TreePVector; //导入方法依赖的package包/类
private CompletionStage<PSequence<Chirp>> recentChirps(PSequence<String> userIds) {
  int limit = 10;
  PSequence<CompletionStage<PSequence<Chirp>>> results = TreePVector.empty();
  for (String userId : userIds) {
    CompletionStage<PSequence<Chirp>> result = db
        .selectAll("SELECT * FROM chirp WHERE userId = ? ORDER BY timestamp DESC LIMIT ?", userId, limit)
        .thenApply(rows -> {
          List<Chirp> chirps = rows.stream().map(this::mapChirp).collect(Collectors.toList());
          return TreePVector.from(chirps);
        });
    results = results.plus(result);
  }

  CompletionStage<PSequence<Chirp>> combined = null;
  for (CompletionStage<PSequence<Chirp>> chirpsFromOneUser : results) {
    if (combined == null) {
      combined = chirpsFromOneUser;
    } else {
      combined = combined.thenCombine(chirpsFromOneUser, (a, b) -> a.plusAll(b));
    }
  }

  CompletionStage<PSequence<Chirp>> sortedLimited = combined.thenApply(all -> {
    List<Chirp> allSorted = new ArrayList<>(all);
    // reverse order
    Collections.sort(allSorted, (a, b) -> b.getTimestamp().compareTo(a.getTimestamp()));
    List<Chirp> limited = allSorted.stream().limit(limit).collect(Collectors.toList());
    List<Chirp> reversed = new ArrayList<>(limited);
    Collections.reverse(reversed);
    return TreePVector.from(reversed);
  });

  return sortedLimited;
}
 

import org.pcollections.TreePVector; //导入方法依赖的package包/类
@Value.Default
default PSequence<String> getFriends() {
  return TreePVector.empty();
}
 

import org.pcollections.TreePVector; //导入方法依赖的package包/类
@AutoReducer.InitialState
List<Note> initialState() {
    return TreePVector.empty();
}
 

import org.pcollections.TreePVector; //导入方法依赖的package包/类
private AnInstance(Class<? extends T> klass) {
    this.klass = klass;
    matchers = TreePVector.empty();
}
 

import org.pcollections.TreePVector; //导入方法依赖的package包/类
@Value.Lazy @Override public PSequence<L> getLabels() {
    return TreePVector.empty();
}