LineIterator

package com.moozvine.strings;


import com.google.common.collect.ImmutableList;

import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

public final class LineIterator {
  private LineIterator(){}

  public static Iterator<String> of(final String value) {
    final List<String> lines = ImmutableList.copyOf(value.split("\n"));
    return lines.iterator();
  }

  public static Iterable<String> toIterable(final String value) {
    return new Iterable<String>() {
      @Override public Iterator<String> iterator() {
        return of(value);
      }
    };
  }

  public static Iterator<String> of(final StringBuilder value) {
    return new Iterator<String>() {
      boolean hasNext = true;
      boolean removed = false;
      int start = 0;
      int end = -1;
      @Override public boolean hasNext() {
        return hasNext;
      }

      @Override public String next() {
        removed = false;
        if (!hasNext) {
          throw new NoSuchElementException();
        }
        start = end + 1;
        end = value.indexOf("\n", start);
        if (end == -1) {
          hasNext = false;
        }
        return value.substring(
            start,
            end == -1 ? value.length() : end);
      }

      @Override public void remove() {
        if (removed) {
          throw new IllegalStateException("Multiple calls to remove() without and intervening call to next().");
        }
        value.delete(
            start,
            end == -1 ? value.length() : end + 1);
        end = start - 1;
        removed = true;
      }
    };
  }

  public static Iterable<String> toIterable(final StringBuilder value) {
    return new Iterable<String>() {
      @Override public Iterator<String> iterator() {
        return of(value);
      }
    };
  }
}