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Utilities including math, charsequence based text processing, sequences etc.

There is a newer version: 1.4.9

package com.expleague.commons.seq;

import org.jetbrains.annotations.NotNull;

import java.lang.reflect.Array;
import java.util.Iterator;
import java.util.stream.BaseStream;

/**
 * User: Manokk
 * Date: 31.08.11
 * Time: 2:45
 */
public interface Seq extends Iterable {
  T at(int i);
  Seq sub(int start, int end);
  Seq sub(int[] indices);
  int length();
  boolean isImmutable();
  Class elementType();

  > S stream();
   A toArray();

  @SafeVarargs
  static  Seq of(T... arr) {
    return new ArraySeq<>(arr);
  }

  abstract class Stub implements Seq {
    @Override
    public String toString() {
      final StringBuilder builder = new StringBuilder();
      final int length = length();
      builder.append('[');
      for (int i = 0; i < length; i++) {
        if (i != 0)
          builder.append(", ");
        builder.append(at(i).toString());
      }
      builder.append(']');
      return builder.toString();
    }

    private int hash = -1;
    @Override
    public int hashCode() {
      if (hash != -1)
        return hash;
      int result = length();
      result <<= 1;
      for (int i = 0; i < length(); i++) {
        result += at(i).hashCode();
        result <<= 2;
      }
      if (result == -1)
        result = 0;
      return hash = result;
    }

    @Override
    public boolean equals(Object obj) {
      if (obj == this)
        return true;
      if (!(obj instanceof Seq))
        return false;
      final Seq other = (Seq)obj;
      if (other.length() != length())
        return false;
      for (int i = 0; i < length(); i++) {
        if (!at(i).equals(other.at(i)))
          return false;
      }
      return true;
    }

    @Override
    public  A toArray() {
      //noinspection unchecked
      final T[] array = (T[])Array.newInstance(elementType(), length());
      for (int i = 0; i < array.length; i++) {
        array[i] = at(i);
      }
      //noinspection unchecked
      return (A)array;
    }

  }

  @NotNull
  @Override
  default Iterator iterator() {
    return new Iterator() {
      private int pos = 0;

      @Override
      public boolean hasNext() {
        return pos < length();
      }

      @Override
      public T next() {
        return at(pos++);
      }
    };
  }
}