EmojiInterpolator.java

package humanize.emoji;

import static humanize.text.util.InterpolationHelper.interpolate;
import humanize.spi.MessageFormat;
import humanize.text.util.Replacer;
import humanize.text.util.UnicodeInterpolator;

import java.util.regex.Pattern;

import com.google.common.base.Preconditions;
import com.google.common.base.Strings;

/**
 * <p>
 * Sexy and easy text interpolation of Unicode emoji code points and aliases.
 * </p>
 * <h5>Examples:</h5>
 * 
 * <pre>
 * EmojiInterpolator.interpolateAlias("<img src=\"imgs/{0}.png\" title=\"{1}\" />", "Hi :sparkles:!");
 * // == "Hi <img src=\"imgs/2728.png\" title=\"sparkles\" />!"
 * 
 * EmojiInterpolator.interpolateUnicode("<img src=\"imgs/{0}.png\" />",
 *         "Lorem ipsum \u2639 dolorem\uD83D\uDD36 and dolorem sit amet");
 * // ==
 * // "Lorem ipsum <img src=\"imgs/2639.png\" /> dolorem<img src=\"imgs/1f536.png\" /> and dolorem sit amet"
 * 
 * </pre>
 * 
 * @see Emoji
 * 
 */
public final class EmojiInterpolator
{

    private static final Pattern EMOJI_ALIAS = Pattern.compile(":([\\w\\s-]+):");

    public static UnicodeInterpolator createEmojiInterpolator(String pattern)
    {
        UnicodeInterpolator ui = new UnicodeInterpolator(new EmojiCodePointReplacer(pattern));
        ui.addRange(0x20a0, 0x32ff);
        ui.addRange(0x1f000, 0x1ffff);
        ui.addRange(0xfe4e5, 0xfe4ee);
        return ui;
    }

    public static String interpolateAlias(String pattern, String text)
    {
        return interpolate(text, EmojiInterpolator.EMOJI_ALIAS, new EmojiAliasReplacer(pattern));
    }

    public static String interpolateUnicode(String pattern, String text)
    {
        Preconditions.checkNotNull(pattern, "Pattern is required.");

        if (Strings.isNullOrEmpty(text))
        {
            return text;
        }

        UnicodeInterpolator ui = createEmojiInterpolator(pattern);
        return ui.escape(text);
    }

    private EmojiInterpolator()
    {
        //
    }

    private final static class EmojiAliasReplacer extends MessageFormatReplacer
    {
        public EmojiAliasReplacer(String pattern)
        {
            super(pattern);
        }

        @Override
        public String replace(String alias)
        {
            // TODO better by 'de facto' standard aliases for compatibility?
            EmojiChar echar = Emoji.singleByAnnotations(alias);
            String code = echar == null ? Strings.nullToEmpty(alias) : echar.getCode().toLowerCase();

            return msgFormat.render(code, alias);
        }
    }

    private final static class EmojiCodePointReplacer extends MessageFormatReplacer
    {
        public EmojiCodePointReplacer(String pattern)
        {
            super(pattern);
        }

        @Override
        public String replace(String code)
        {
            EmojiChar echar = Emoji.findByHexCode(Strings.nullToEmpty(code));
            Preconditions.checkArgument(echar != null, "Code point not found [%s]", code);
            return msgFormat.render(code, echar.getName());
        }
    }

    private static class MessageFormatReplacer implements Replacer
    {
        protected final MessageFormat msgFormat;

        public MessageFormatReplacer(String pattern)
        {
            this.msgFormat = new MessageFormat(pattern);
        }

        @Override
        public String replace(String in)
        {
            return msgFormat.render(Strings.nullToEmpty(in).toLowerCase());
        }
    }

}