chucheng92 commented on code in PR #3459:
URL: https://github.com/apache/calcite/pull/3459#discussion_r1358158316
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core/src/main/java/org/apache/calcite/sql/type/OperandTypes.java:
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@@ -1221,6 +1225,53 @@ private static class MapFromEntriesOperandTypeChecker
}
}
+ /**
+ * Operand type-checking strategy for a MAP function, it allows empty map.
+ */
+ private static class MapFunctionOperandTypeChecker
+ extends SameOperandTypeChecker {
+
+ MapFunctionOperandTypeChecker() {
+ super(-1);
+ }
+
+ @Override public boolean checkOperandTypes(final SqlCallBinding
callBinding,
+ final boolean throwOnFailure) {
+ final List<RelDataType> argTypes =
+ SqlTypeUtil.deriveType(callBinding, callBinding.operands());
+ // allows empty map
+ if (argTypes.size() == 0) {
+ return true;
+ }
+ // the size of map arg types must be even.
+ if (argTypes.size() % 2 > 0) {
+ throw
callBinding.newValidationError(RESOURCE.mapRequiresEvenArgCount());
+ }
+ final Pair<@Nullable RelDataType, @Nullable RelDataType> componentType =
+ getComponentTypes(
+ callBinding.getTypeFactory(), argTypes);
+ // check key type & value type
+ if (null == componentType.left || null == componentType.right) {
+ if (throwOnFailure) {
+ throw
callBinding.newValidationError(RESOURCE.needSameTypeParameter());
+ }
+ return false;
+ }
+ return true;
+ }
+
+ /**
+ * Extract the key type and value type of arg types.
+ */
+ private static Pair<@Nullable RelDataType, @Nullable RelDataType>
getComponentTypes(
+ RelDataTypeFactory typeFactory,
+ List<RelDataType> argTypes) {
+ return Pair.of(
+ typeFactory.leastRestrictive(Util.quotientList(argTypes, 2, 0)),
Review Comment:
Util.quotientList(argTypes, 2, 0):
This extracts all elements at even indices from argTypes.
It represents the types of keys in the map as they are placed at even
positions
e.g. 0, 2, 4, etc. details please see Util.quotientList.
std MapValueConstructor has same logic. see:
https://github.com/apache/calcite/blob/5151168e9a9035595939c2ae0f21a06984229209/core/src/main/java/org/apache/calcite/sql/fun/SqlMapValueConstructor.java#L90
I've added some comments here for better readability.
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