[GitHub] [calcite] olivrlee commented on a diff in pull request #3168: CALCITE-5662/ Allow CAST(BOOLEAN as INTEGER)

["olivrlee (via GitHub)" <gi...@apache.org>]

olivrlee commented on code in PR #3168:
URL: https://github.com/apache/calcite/pull/3168#discussion_r1178198833


##########
core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java:
##########
@@ -955,6 +961,52 @@ public static boolean canCastFrom(
     return rules.canApplyFrom(toTypeName, fromTypeName);
   }
 
+  /**
+   * Compares two types and returns true if fromType can be cast to toType or if the connection
+   * conformance allows exceptions.
+   *
+   * @param toType   target of assignment
+   * @param fromType source of assignment
+   * @param coerce   if true, the SQL rules for CAST are used; if false, the
+   *                 rules are similar to Java; e.g. you can't assign short x =
+   *                 (int) y, and you can't assign int x = (String) z.
+   * @param conformance value for connection conformance
+   * @return true if cast is legal or connection conformance allows exceptions
+   */
+  public static boolean canCastFrom(
+      RelDataType toType,
+      RelDataType fromType,
+      boolean coerce,
+      SqlConformance conformance) {
+    if (castingBooleanToNumber(toType, fromType)) {
+      return conformance.allowLenientBooleanCastTypes();
+    } else {
+      return canCastFrom(toType, fromType, coerce);
+    }
+  }
+
+  /**
+   * Returns whether the attempted cast is from a BOOLEAN to a NUMERIC where
+   * NUMERIC is one of [TINYINT, SMALLINT, INTEGER, BIGINT].
+   * @param toType Target of assignment
+   * @param fromType Source of assignment
+   * @return true iff fromType is boolean and toType is one of [TINYINT, SMALLINT, INTEGER, BIGINT]
+   */
+  public static boolean castingBooleanToNumber(
+      RelDataType toType,
+      RelDataType fromType) {
+    // These following types support casting from booleans in some dialects such as BigQuery.
+    List<String> numericTypes =
+            ImmutableList.of(TINYINT,
+            SMALLINT,
+            INTEGER,
+            BIGINT)
+        .stream().map(type -> type.toString()).collect(Collectors.toList());
+

Review Comment:
   Thanks for the review! Updated. 



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