Treat ClickHouse range() as a function when followed by a parenthesis

src/languages/clickhouse/clickhouse.formatter.ts

@@ -300,6 +300,9 @@ export const clickhouse: DialectOptions = {
  *    for SELECT GRANTs
  * 2. Formats SET(100) as RESERVED_FUNCTION_NAME instead of RESERVED_KEYWORD
  *    so it appears as a function rather than a statement.
+ * 3. Formats RANGE(...) as RESERVED_FUNCTION_NAME instead of RESERVED_KEYWORD
+ *    so keywordCase does not rewrite the case-sensitive range() function.
+ *    RANGE BETWEEN stays a reserved keyword phrase for window frames.
  */
 function postProcess(tokens: Token[]): Token[] {
   return tokens.map((token, i) => {
@@ -333,6 +336,15 @@ function postProcess(tokens: Token[]): Token[] {
       return { ...token, type: TokenType.RESERVED_FUNCTION_NAME };
     }
 
+    // We should format `range(32)` as-is rather than `RANGE (32)`
+    if (
+      token.type === TokenType.RESERVED_KEYWORD &&
+      token.text === 'RANGE' &&
+      nextToken.type === TokenType.OPEN_PAREN
+    ) {
+      return { ...token, type: TokenType.RESERVED_FUNCTION_NAME };
+    }
+
     return token;
   });
 }

test/clickhouse.test.ts

@@ -449,6 +449,34 @@ describe('ClickhouseFormatter', () => {
           value ASC;
       `);
     });
+
+    it('formats SELECT with window function and RANGE BETWEEN', () => {
+      expect(
+        format(
+          'SELECT part_key, value, groupArray(value) OVER (ORDER BY seq RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) FROM wf_frame;',
+          { keywordCase: 'upper' }
+        )
+      ).toBe(dedent`
+        SELECT
+          part_key,
+          value,
+          groupArray(value) OVER (
+            ORDER BY
+              seq RANGE BETWEEN UNBOUNDED PRECEDING
+              AND CURRENT ROW
+          )
+        FROM
+          wf_frame;
+      `);
+    });
+  });
+
+  // Regression test for issue #980
+  it('does not uppercase the case-sensitive range() function', () => {
+    expect(format('SELECT range(32);', { keywordCase: 'upper' })).toBe(dedent`
+      SELECT
+        range(32);
+    `);
   });
 
   // https://clickhouse.com/docs/sql-reference/statements/create