macroguo-ghy commented on code in PR #3459:
URL: https://github.com/apache/calcite/pull/3459#discussion_r1349635823
##########
site/_docs/reference.md:
##########
@@ -2769,6 +2769,7 @@ BigQuery's type system uses confusingly different names
for types and functions:
| b | TO_HEX(binary) | Converts *binary* into
a hexadecimal varchar
| b | FROM_HEX(varchar) | Converts a
hexadecimal-encoded *varchar* into bytes
| b o | LTRIM(string) | Returns *string* with
all blanks removed from the start
+| s | MAP(key, value [, key, value]*) | Returns a map with the
given key/value pairs
Review Comment:
Empty map is a legal functon. Please add `MAP()` to the documentation.
##########
core/src/main/codegen/templates/Parser.jj:
##########
@@ -4886,14 +4886,21 @@ SqlNode MapConstructor() :
{
<MAP> { s = span(); }
(
- LOOKAHEAD(1)
- <LPAREN>
- // by sub query "MAP (SELECT empno, deptno FROM emp)"
- e = LeafQueryOrExpr(ExprContext.ACCEPT_QUERY)
- <RPAREN>
+ (
+ // empty map function call: "map()"
+ LOOKAHEAD(2)
+ <LPAREN> <RPAREN> { args = SqlNodeList.EMPTY; }
+ |
+ args = ParenthesizedQueryOrCommaList(ExprContext.ACCEPT_ALL)
+ )
{
- return SqlStdOperatorTable.MAP_QUERY.createCall(
- s.end(this), e);
+ if (args.size() == 1 && args.get(0).isA(SqlKind.QUERY)) {
+ // MAP query constructor e.g. "MAP (SELECT empno, deptno FROM
emps)"
+ return SqlStdOperatorTable.MAP_QUERY.createCall(s.end(this),
args.get(0));
+ } else {
+ // MAP function e.g. "MAP(1, 2)" equivalent to standard
"MAP[1, 2]"
+ return SqlLibraryOperators.MAP.createCall(s.end(this),
args.getList());
Review Comment:
I think we can check if the size of args is an even number.
##########
core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java:
##########
@@ -1077,6 +1079,38 @@ private static RelDataType
arrayReturnType(SqlOperatorBinding opBinding) {
SqlLibraryOperators::arrayReturnType,
OperandTypes.SAME_VARIADIC);
+ private static RelDataType mapReturnType(SqlOperatorBinding opBinding) {
+ Pair<@Nullable RelDataType, @Nullable RelDataType> type =
+ getComponentTypes(
+ opBinding.getTypeFactory(), opBinding.collectOperandTypes());
+ return SqlTypeUtil.createMapType(
+ opBinding.getTypeFactory(),
+ requireNonNull(type.left, "inferred key type"),
+ requireNonNull(type.right, "inferred value type"),
+ false);
+ }
+
+ private static Pair<@Nullable RelDataType, @Nullable RelDataType>
getComponentTypes(
+ RelDataTypeFactory typeFactory,
+ List<RelDataType> argTypes) {
+ // special case, allows empty map
+ if (argTypes.size() == 0) {
+ return Pair.of(typeFactory.createUnknownType(),
typeFactory.createUnknownType());
Review Comment:
There is a subtle difference between `unknown` and `any`, can you please
explain why `unknown` is used?
##########
testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java:
##########
@@ -6604,11 +6605,44 @@ private static void checkIf(SqlOperatorFixture f) {
// test operands not in same type family.
f.checkFails("^map_concat(map[1, null], array[1])^",
"Parameters must be of the same type", false);
+
+ // 2. check with map function, map(k, v ...)
Review Comment:
Can you please add some tests with `map()`, like `map_concat(map('foo', 1),
map())`, `map_keys(map())` or `cast(map() as MAP<INTEGER, INTEGER>)`.
Because the type of `map()` is `MAP<UNKNOWN, UNKNOWN>`, I am not sure if
unknown component type will cause an error.
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