Represent nested types (ARRAY, MAP, etc) by converting all elements t…

…o VARIANT

Signed-off-by: Mihai Budiu <mbudiu@feldera.com>

core/src/main/java/org/apache/calcite/runtime/rtti/GenericSqlTypeRtti.java

@@ -74,6 +74,10 @@ public GenericSqlTypeRtti(RuntimeSqlTypeName typeName, RuntimeTypeInformation...
   }
 
   public RuntimeTypeInformation getTypeArgument(int index) {
-    return this.typeArguments[index];
+    return typeArguments[index];
+  }
+
+  public int getArgumentCount() {
+    return typeArguments.length;
   }
 }

core/src/main/java/org/apache/calcite/runtime/rtti/RowSqlTypeRtti.java

@@ -23,12 +23,12 @@
 
 /** Runtime type information for a ROW type. */
 public class RowSqlTypeRtti extends RuntimeTypeInformation {
-  private final Map.Entry<String, RuntimeTypeInformation>[] fieldNames;
+  private final Map.Entry<String, RuntimeTypeInformation>[] fields;
 
   @SafeVarargs
-  public RowSqlTypeRtti(Map.Entry<String, RuntimeTypeInformation>... fieldNames) {
+  public RowSqlTypeRtti(Map.Entry<String, RuntimeTypeInformation>... fields) {
     super(RuntimeSqlTypeName.ROW);
-    this.fieldNames = fieldNames;
+    this.fields = fields;
   }
 
   @Override public String getTypeString()  {
@@ -41,7 +41,7 @@ public RowSqlTypeRtti(Map.Entry<String, RuntimeTypeInformation>... fieldNames) {
     StringBuilder builder = new StringBuilder();
     builder.append("new RowSqlTypeRtti(");
     boolean first = true;
-    for (Map.Entry<String, RuntimeTypeInformation> arg : this.fieldNames) {
+    for (Map.Entry<String, RuntimeTypeInformation> arg : this.fields) {
       if (!first) {
         builder.append(", ");
       }
@@ -61,11 +61,20 @@ public RowSqlTypeRtti(Map.Entry<String, RuntimeTypeInformation>... fieldNames) {
     }
 
     RowSqlTypeRtti that = (RowSqlTypeRtti) o;
-    return Arrays.equals(fieldNames, that.fieldNames);
+    return Arrays.equals(fields, that.fields);
   }
 
   @Override public int hashCode() {
-    return Arrays.hashCode(fieldNames);
+    return Arrays.hashCode(fields);
+  }
+
+  /** Get the field with the specified index. */
+  public Map.Entry<String, RuntimeTypeInformation> getField(int index) {
+    return this.fields[index];
+  }
+
+  public int size() {
+    return this.fields.length;
   }
 
   /** Return the runtime type information of the associated field,
@@ -76,13 +85,13 @@ public RowSqlTypeRtti(Map.Entry<String, RuntimeTypeInformation>... fieldNames) {
   public @Nullable RuntimeTypeInformation getFieldType(Object index) {
     if (index instanceof Integer) {
       int intIndex = (Integer) index;
-      if (intIndex < 0 || intIndex >= this.fieldNames.length) {
+      if (intIndex < 0 || intIndex >= this.fields.length) {
         return null;
       }
-      return this.fieldNames[intIndex].getValue();
+      return this.fields[intIndex].getValue();
     } else if (index instanceof String) {
       String stringIndex = (String) index;
-      for (Map.Entry<String, RuntimeTypeInformation> field : this.fieldNames) {
+      for (Map.Entry<String, RuntimeTypeInformation> field : this.fields) {
         if (field.getKey().equalsIgnoreCase(stringIndex)) {
           return field.getValue();
         }

core/src/main/java/org/apache/calcite/runtime/rtti/RuntimeTypeInformation.java

@@ -56,6 +56,8 @@ public enum RuntimeSqlTypeName {
     TIMESTAMP_TZ(false),
     INTERVAL_LONG(false),
     INTERVAL_SHORT(false),
+    // "Name" is used for structure field names
+    NAME(false),
     // CHAR is represented as VARCHAR
     VARCHAR(false),
     // BINARY is represented as VARBINARY
@@ -118,6 +120,11 @@ public boolean isScalar() {
     }
   }
 
+  public GenericSqlTypeRtti asGeneric() {
+    assert this instanceof GenericSqlTypeRtti;
+    return (GenericSqlTypeRtti) this;
+  }
+
   /**
    * Creates and returns an expression that creates a runtime type that
    * reflects the information in the statically-known type 'type'.