Initial work on adding operator map

core/src/main/java/org/apache/calcite/sql/dialect/SnowflakeSqlDialect.java

@@ -19,8 +19,9 @@
 import org.apache.calcite.avatica.util.Casing;
 import org.apache.calcite.sql.SqlCall;
 import org.apache.calcite.sql.SqlDialect;
+import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.SqlWriter;
-import org.apache.calcite.sql.fun.SqlLibraryOperators;
+import org.apache.calcite.sql.fun.SqlOperatorMap;
 import org.apache.calcite.sql.parser.SqlParserPos;
 
 /**
@@ -44,19 +45,12 @@ public SnowflakeSqlDialect(Context context) {
       final int rightPrec) {
     switch (call.getKind()) {
     case CHAR_LENGTH:
-      SqlCall lengthCall = SqlLibraryOperators.LENGTH
-          .createCall(SqlParserPos.ZERO, call.getOperandList());
-      super.unparseCall(writer, lengthCall, leftPrec, rightPrec);
-      break;
     case ENDS_WITH:
-      SqlCall endsWithCall = SqlLibraryOperators.ENDSWITH
-          .createCall(SqlParserPos.ZERO, call.getOperandList());
-      super.unparseCall(writer, endsWithCall, leftPrec, rightPrec);
-      break;
     case STARTS_WITH:
-      SqlCall startsWithCall = SqlLibraryOperators.STARTSWITH
-          .createCall(SqlParserPos.ZERO, call.getOperandList());
-      super.unparseCall(writer, startsWithCall, leftPrec, rightPrec);
+      final SqlOperator snowflakeOp = SqlOperatorMap.getMatchingOperator(call.getOperator());
+      assert snowflakeOp != null;
+      final SqlCall snowflakeCall = snowflakeOp.createCall(SqlParserPos.ZERO, call.getOperandList());
+      super.unparseCall(writer, snowflakeCall, leftPrec, rightPrec);
       break;
     default:
       super.unparseCall(writer, call, leftPrec, rightPrec);

core/src/main/java/org/apache/calcite/sql/fun/SqlFunctionAlias.java

@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.calcite.sql.fun;
+
+import org.apache.calcite.sql.SqlFunction;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/** Contains alias data for parameterized tests. */
+  public class SqlFunctionAlias {
+    final SqlFunction function;
+    final List<SqlLibrary> libraries;
+
+    private SqlFunctionAlias(SqlFunction function, List<SqlLibrary> libraries) {
+      this.function = function;
+      this.libraries = libraries;
+    }
+
+    static SqlFunctionAlias of(SqlFunction function) {
+      Field field =
+          lookupField(function.getName(), SqlStdOperatorTable.class,
+              SqlLibraryOperators.class);
+      List<SqlLibrary> libraries = new ArrayList<SqlLibrary>();
+      LibraryOperator libraryOperator = field.getAnnotation(LibraryOperator.class);
+      if (libraryOperator == null) {
+        libraries.add(SqlLibrary.STANDARD);
+      } else {
+        libraries.addAll(Arrays.asList(libraryOperator.libraries()));
+      }
+      return new SqlFunctionAlias(function, libraries);
+    }
+
+    @SuppressWarnings("rawtypes")
+    public static Field lookupField(String name, Class... classes) {
+      for (Class aClass : classes) {
+        try {
+          return aClass.getField(name);
+        } catch (NoSuchFieldException e) {
+          // ignore, and try the next class
+        }
+      }
+      throw new AssertionError("field " + name
+          + " not found in classes" + Arrays.toString(classes));
+    }
+
+    // Used for test naming while running tests in IDE
+    @Override public String toString() {
+      return "function=" + function
+          + ", libraries=" + libraries;
+    }
+  }

core/src/main/java/org/apache/calcite/sql/fun/SqlOperatorMap.java

@@ -0,0 +1,48 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.calcite.sql.fun;
+
+import org.apache.calcite.linq4j.function.*;
+import org.apache.calcite.sql.SqlOperator;
+
+import com.google.common.collect.BiMap;
+import com.google.common.collect.ImmutableBiMap;
+
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import static org.apache.calcite.sql.fun.SqlStdOperatorTable.*;
+
+/** Map an operator to a list of dialect-specific operators it should be unparsed as. */
+public class SqlOperatorMap {
+    public static final BiMap<SqlOperator, SqlOperator> SQL_OPERATOR_MAP =
+      ImmutableBiMap.<SqlOperator, SqlOperator>builder()
+          .put(SqlLibraryOperators.STARTSWITH, SqlLibraryOperators.STARTS_WITH)
+          .put(SqlLibraryOperators.ENDSWITH, SqlLibraryOperators.ENDSWITH)
+          .put(SqlLibraryOperators.LENGTH, CHAR_LENGTH)
+          .build();
+
+
+    public static @Nullable SqlOperator getMatchingOperator(SqlOperator operator) {
+      if (SQL_OPERATOR_MAP.containsKey(operator)) {
+        return SQL_OPERATOR_MAP.get(operator);
+      } else if (SQL_OPERATOR_MAP.containsValue(operator)) {
+        return SQL_OPERATOR_MAP.inverse().get(operator);
+      } else {
+        return null;
+      }
+    }
+}