session-android/src/org/thoughtcrime/securesms/components/emoji/parsing/EmojiTree.java

/**
 * Copyright (c) 2014-present Vincent DURMONT vdurmont@gmail.com
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package org.thoughtcrime.securesms.components.emoji.parsing;

import android.support.annotation.Nullable;

import java.util.HashMap;
import java.util.Map;

/**
 * Based in part on code from emoji-java
 */
public class EmojiTree {

  private final EmojiTreeNode root = new EmojiTreeNode();

  public void add(String emojiEncoding, EmojiDrawInfo emoji) {
    EmojiTreeNode tree = root;

    for (char c: emojiEncoding.toCharArray()) {
      if (!tree.hasChild(c)) {
        tree.addChild(c);
      }

      tree = tree.getChild(c);
    }

    tree.setEmoji(emoji);
  }

  public Matches isEmoji(CharSequence sequence, int startPosition, int endPosition) {
    if (sequence == null) {
      return Matches.POSSIBLY;
    }

    EmojiTreeNode tree = root;

    for (int i=startPosition; i<endPosition; i++) {
      char character = sequence.charAt(i);

      if (!tree.hasChild(character)) {
        return Matches.IMPOSSIBLE;
      }

      tree = tree.getChild(character);
    }

    return tree.isEndOfEmoji() ? Matches.EXACTLY : Matches.POSSIBLY;
  }

  public @Nullable EmojiDrawInfo getEmoji(CharSequence unicode, int startPosition, int endPostiion) {
    EmojiTreeNode tree = root;

    for (int i=startPosition; i<endPostiion; i++) {
      char character = unicode.charAt(i);

      if (!tree.hasChild(character)) {
        return null;
      }

      tree = tree.getChild(character);
    }

    return tree.getEmoji();
  }


  private static class EmojiTreeNode {

    private Map<Character, EmojiTreeNode> children = new HashMap<>();
    private EmojiDrawInfo emoji;

    public void setEmoji(EmojiDrawInfo emoji) {
      this.emoji = emoji;
    }

    public @Nullable EmojiDrawInfo getEmoji() {
      return emoji;
    }

    boolean hasChild(char child) {
      return children.containsKey(child);
    }

    void addChild(char child) {
      children.put(child, new EmojiTreeNode());
    }

    EmojiTreeNode getChild(char child) {
      return children.get(child);
    }

    boolean isEndOfEmoji() {
      return emoji != null;
    }
  }

  public enum Matches {
    EXACTLY, POSSIBLY, IMPOSSIBLE;

    public boolean exactMatch() {
      return this == EXACTLY;
    }

    public boolean impossibleMatch() {
      return this == IMPOSSIBLE;
    }
  }

}