Data commit

Task/Range-expansion/Java/range-expansion.java

@@ -0,0 +1,65 @@
+import java.util.*;
+
+class RangeExpander implements Iterator<Integer>, Iterable<Integer> {
+
+    private static final Pattern TOKEN_PATTERN = Pattern.compile("([+-]?\\d+)-([+-]?\\d+)");
+
+    private final Iterator<String> tokensIterator;
+
+    private boolean inRange;
+    private int upperRangeEndpoint;
+    private int nextRangeValue;
+
+    public RangeExpander(String range) {
+        String[] tokens = range.split("\\s*,\\s*");
+        this.tokensIterator = Arrays.asList(tokens).iterator();
+    }
+
+    @Override
+    public boolean hasNext() {
+        return hasNextRangeValue() || this.tokensIterator.hasNext();
+    }
+
+    private boolean hasNextRangeValue() {
+        return this.inRange && this.nextRangeValue <= this.upperRangeEndpoint;
+    }
+
+    @Override
+    public Integer next() {
+        if (!hasNext()) {
+            throw new NoSuchElementException();
+        }
+
+        if (hasNextRangeValue()) {
+            return this.nextRangeValue++;
+        }
+
+        String token = this.tokensIterator.next();
+
+        Matcher matcher = TOKEN_PATTERN.matcher(token);
+        if (matcher.find()) {
+            this.inRange = true;
+            this.upperRangeEndpoint = Integer.valueOf(matcher.group(2));
+            this.nextRangeValue = Integer.valueOf(matcher.group(1));
+            return this.nextRangeValue++;
+        }
+
+        this.inRange = false;
+        return Integer.valueOf(token);
+    }
+
+    @Override
+    public Iterator<Integer> iterator() {
+        return this;
+    }
+
+}
+
+class RangeExpanderTest {
+    public static void main(String[] args) {
+        RangeExpander re = new RangeExpander("-6,-3--1,3-5,7-11,14,15,17-20");
+        for (int i : re) {
+            System.out.print(i + " ");
+        }
+    }
+}