LUCENE-10403: Add ArrayUtil#grow(T[]) (#644)

lucene/CHANGES.txt

@@ -142,6 +142,8 @@ New Features
 * LUCENE-10385: Implement Weight#count on IndexSortSortedNumericDocValuesRangeQuery
   to speed up computing the number of hits when possible. (Luca Cavanna, Adrien Grand)
 
+* LUCENE-10403: Add ArrayUtil#grow(T[]). (Greg Miller)
+
 Improvements
 ---------------------
 

lucene/analysis/common/src/java/org/apache/lucene/analysis/synonym/SynonymFilter.java

@@ -192,7 +192,7 @@ public final class SynonymFilter extends TokenFilter {
 
     public void add(char[] output, int offset, int len, int endOffset, int posLength) {
       if (count == outputs.length) {
-        outputs = ArrayUtil.grow(outputs, count + 1);
+        outputs = ArrayUtil.grow(outputs);
       }
       if (count == endOffsets.length) {
         final int[] next = new int[ArrayUtil.oversize(1 + count, Integer.BYTES)];

lucene/core/src/java/org/apache/lucene/util/ArrayUtil.java

@@ -223,6 +223,11 @@ public final class ArrayUtil {
     return copy;
   }
 
+  /** Returns a larger array, generally over-allocating exponentially */
+  public static <T> T[] grow(T[] array) {
+    return grow(array, 1 + array.length);
+  }
+
   /**
    * Returns an array whose size is at least {@code minSize}, generally over-allocating
    * exponentially

lucene/core/src/java/org/apache/lucene/util/fst/FSTCompiler.java

@@ -713,7 +713,7 @@ public class FSTCompiler<T> {
               + " numArcs="
               + numArcs;
       if (numArcs == arcs.length) {
-        final Arc<T>[] newArcs = ArrayUtil.grow(arcs, numArcs + 1);
+        final Arc<T>[] newArcs = ArrayUtil.grow(arcs);
         for (int arcIdx = numArcs; arcIdx < newArcs.length; arcIdx++) {
           newArcs[arcIdx] = new Arc<>();
         }