chucheng92 commented on code in PR #3320:
URL: https://github.com/apache/calcite/pull/3320#discussion_r1291653062
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core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java:
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@@ -4107,6 +4113,93 @@ public static List arrayExcept(List list1, List list2) {
return new ArrayList<>(result);
}
+ /** Support the ARRAY_INSERT function. */
+ public static @Nullable List arrayInsert(List baselist, Object pos, Object
val) {
+ if (baselist == null || pos == null) {
+ return null;
+ }
+ int posInt = (int) pos;
+ Object[] baseArray = baselist.toArray();
+ if (posInt == 0) {
+ throw new IllegalArgumentException("The index 0 is invalid. "
+ + "An index shall be either < 0 or > 0 (the first element has index
1)");
+ }
+
+ boolean usePositivePos = posInt > 0;
+
+ if (usePositivePos) {
+ int newArrayLength = Math.max(baseArray.length + 1, posInt);
+
+ if (newArrayLength > MAX_ARRAY_LENGTH) {
+ throw new IndexOutOfBoundsException(
+ String.format(Locale.ROOT, "The new array length %s exceeds the
allowed limit.",
+ newArrayLength));
+ }
+
+ Object[] newArray = new Object[newArrayLength];
+
+ int posIndex = posInt - 1;
+ if (posIndex < baseArray.length) {
+ System.arraycopy(baseArray, 0, newArray, 0, posIndex);
+ newArray[posIndex] = val;
+ System.arraycopy(baseArray, posIndex, newArray, posIndex + 1,
baseArray.length - posIndex);
+ } else {
+ System.arraycopy(baseArray, 0, newArray, 0, baseArray.length);
+ newArray[posIndex] = val;
+ }
+
+ return Arrays.asList(newArray);
+ } else {
+ int posIndex = posInt;
+
+ boolean newPosExtendsArrayLeft = baseArray.length + posIndex < 0;
+
+ if (newPosExtendsArrayLeft) {
+ // special case, if the new position is negative but larger than the
current array size
+ // place the new item at start of array, place the current array
contents at the end
+ // and fill the newly created array elements in middle with a null
+ int newArrayLength = -posIndex + 1;
Review Comment:
> why not just compute using long values?
thanks for suggestions. the `posIndex` should < Integer.MAX_VALUE - 15, we
can simply use Integer to cover it and without overflow. Otherwise, i think
it's a good way to check the parameters in advance.
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