Optimize speed of MoshiPolymorphic

src/main/java/org/warp/commonutils/moshi/MoshiPolymorphic.java

@@ -24,6 +24,7 @@ import java.util.function.Function;
 import org.apache.commons.lang3.StringUtils;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.warp.commonutils.serialization.UTFUtils;
 
 public abstract class MoshiPolymorphic<OBJ> {
 
@@ -357,6 +358,9 @@ public abstract class MoshiPolymorphic<OBJ> {
 	}
 
 	private static String fixType(String nextString) {
-		return nextString.replaceAll("[^a-zA-Z0-9]", "");
+		if (nextString.length() > 512) {
+			throw new IllegalArgumentException("Input too long: " + nextString.length());
+		}
+		return UTFUtils.keepOnlyASCII(nextString);
 	}
 }

src/main/java/org/warp/commonutils/serialization/UTFUtils.java

@@ -6,16 +6,37 @@ import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 
 public class UTFUtils {
-	public static final void writeUTF(DataOutput out, String utf) throws IOException {
+	public static void writeUTF(DataOutput out, String utf) throws IOException {
 		byte[] bytes = utf.getBytes(StandardCharsets.UTF_8);
 		out.writeInt(bytes.length);
 		out.write(bytes);
 	}
 
-	public static final String readUTF(DataInput in) throws IOException {
+	public static String readUTF(DataInput in) throws IOException {
 		int len = in.readInt();
 		byte[] data = new byte[len];
 		in.readFully(data, 0, len);
 		return new String(data, StandardCharsets.UTF_8);
 	}
+
+	/**
+	 * Keep only ascii alphanumeric letters
+	 */
+	public static String keepOnlyASCII(String nextString) {
+		char[] chars = nextString.toCharArray();
+		//noinspection UnusedAssignment
+		nextString = null;
+		int writeIndex = 0;
+		char c;
+		for (int checkIndex = 0; checkIndex < chars.length; checkIndex++) {
+			c = chars[checkIndex];
+			if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
+				if (writeIndex != checkIndex) {
+					chars[writeIndex] = c;
+				}
+				writeIndex++;
+			}
+		}
+		return new String(chars, 0, writeIndex);
+	}
 }