performance improvements

pom.xml

@@ -2,7 +2,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>org.hashids</groupId>
   <artifactId>hashids</artifactId>
-  <version>1.0.3-SNAPSHOT</version>
+  <version>1.0.4-SNAPSHOT</version>
   <packaging>jar</packaging>
   <name>hashids</name>
   <description>Implementing Hashids algorithm v1.0.0 version(http://hashids.org)</description>
@@ -190,6 +190,18 @@
       <version>4.12</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.openjdk.jmh</groupId>
+      <artifactId>jmh-core</artifactId>
+      <version>1.9</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.openjdk.jmh</groupId>
+      <artifactId>jmh-generator-annprocess</artifactId>
+      <version>1.9</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <contributors>
@@ -207,5 +219,9 @@
       <name>Matthias Vill</name>
       <url>https://github.com/TheConstructor</url>
     </contributor>
+    <contributor>
+      <name>Mihai Cazacu</name>
+      <url>https://github.com/cazacugmihai</url>
+    </contributor>
   </contributors>
 </project>

src/main/java/org/hashids/CharUtils.java

@@ -0,0 +1,112 @@
+package org.hashids;
+
+import static java.lang.System.arraycopy;
+import static java.util.Arrays.copyOf;
+
+public final class CharUtils {
+
+  private CharUtils() {
+    throw new UnsupportedOperationException();
+  }
+
+  public static char[] concatenate(char[] arrA, char[] arrB, char[] arrC) {
+    final char[] result = new char[arrA.length + arrB.length + arrC.length];
+
+    arraycopy(arrA, 0, result, 0, arrA.length);
+    arraycopy(arrB, 0, result, arrA.length, arrB.length);
+    arraycopy(arrC, 0, result, arrA.length + arrB.length, arrC.length);
+
+    return result;
+  }
+
+  public static char[] concatenate(char[] arrA, char[] arrB, int bFrom, int bTo) {
+    final int bCopyLength = bTo - bFrom;
+    final char[] result = new char[arrA.length + bCopyLength];
+
+    arraycopy(arrA, 0, result, 0, arrA.length);
+    arraycopy(arrB, bFrom, result, arrA.length, bCopyLength);
+
+    return result;
+  }
+
+  public static int indexOf(char[] source, char c) {
+    int i = 0;
+
+    for (final char s : source) {
+      if (s == c) {
+        break;
+      }
+      i++;
+    }
+
+    return i;
+  }
+
+  public static char[] cleanup(char[] source, char[] allowedChars) {
+    if ((source == null) || (allowedChars == null)) {
+      return source;
+    }
+
+    final char[] result = new char[source.length];
+    int i = 0;
+
+    for (final char s : source) {
+      for (final char a : allowedChars) {
+        if (s == a) {
+          result[i++] = s;
+          break;
+        }
+      }
+    }
+
+    return copyOf(result, i);
+  }
+
+  public static char[] removeAll(char[] source, char[] charsToRemove) {
+    if ((source == null) || (charsToRemove == null)) {
+      return source;
+    }
+
+    final char[] result = new char[source.length];
+    int i = 0;
+    boolean found;
+
+    for (final char s : source) {
+      found = false;
+
+      for (final char c : charsToRemove) {
+        if (s == c) {
+          found = true;
+          break;
+        }
+      }
+
+      if (!found) {
+        result[i++] = s;
+      }
+    }
+
+    return copyOf(result, i);
+  }
+
+  public static boolean validate(char[] source, char[] allowedChars) {
+    boolean found;
+
+    for (final char s : source) {
+      found = false;
+
+      for (final char a : allowedChars) {
+        if (s == a) {
+          found = true;
+          break;
+        }
+      }
+
+      if (!found) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+}