feat(parser): add support for ClickHouse [LEFT] ARRAY JOIN syntax (#2482)

* feat(Join): add array join support to Join class

* feat(parser): add support for ClickHouse ARRAY JOIN syntax and deparsing

* fix(parser): correct array literal parsing in JSqlParserCC.jjt

* style: apply spotless code formatting

Author: watashi-00

src/main/java/net/sf/jsqlparser/statement/select/Join.java

@@ -40,6 +40,7 @@ public class Join extends ASTNodeAccessImpl {
     private boolean straight = false;
     private boolean apply = false;
     private boolean fetch = false;
+    private boolean array = false;
     private FromItem fromItem;
     private KSQLJoinWindow joinWindow;
 
@@ -73,7 +74,10 @@ public boolean isInnerJoin() {
                         || cross
 
                         /* Natural Join */
-                        || natural);
+                        || natural
+
+                        /* Array Join */
+                        || array);
     }
 
     /**
@@ -337,6 +341,19 @@ public Join withCross(boolean cross) {
         return this;
     }
 
+    public boolean isArray() {
+        return array;
+    }
+
+    public void setArray(boolean array) {
+        this.array = array;
+    }
+
+    public Join withArray(boolean array) {
+        this.setArray(array);
+        return this;
+    }
+
     /**
      * Returns the right item of the join
      */
@@ -489,6 +506,10 @@ public String toString() {
                 builder.append("SEMI ");
             }
 
+            if (isArray()) {
+                builder.append("ARRAY ");
+            }
+
             if (isStraight()) {
                 builder.append("STRAIGHT_JOIN ");
             } else if (isApply()) {

src/main/java/net/sf/jsqlparser/util/deparser/SelectDeParser.java

@@ -683,6 +683,10 @@ public void deparseJoin(Join join) {
                 builder.append(" SEMI");
             }
 
+            if (join.isArray()) {
+                builder.append(" ARRAY");
+            }
+
             if (join.isStraight()) {
                 builder.append(" STRAIGHT_JOIN ");
             } else if (join.isApply()) {

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -829,9 +829,11 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
             case K_CONNECT:  return nextKind != K_BY;
             case K_START:    return nextKind != K_WITH;
             case K_LEFT:     return nextKind != K_JOIN && nextKind != K_OUTER
-                                    && nextKind != K_SEMI;
+                                    && nextKind != K_SEMI && nextKind != K_ARRAY_LITERAL;
             case K_RIGHT:    return nextKind != K_JOIN && nextKind != K_OUTER
-                                    && nextKind != K_SEMI;
+                                    && nextKind != K_SEMI && nextKind != K_ARRAY_LITERAL;
+            case K_ARRAY_LITERAL:
+                             return nextKind != K_JOIN;
             case K_ALL:      return nextKind != K_JOIN;
             case K_ANY:      return nextKind != OPENING_BRACKET;
             case K_SOME:     return nextKind != OPENING_BRACKET;
@@ -993,29 +995,17 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
         // String-literal alias:  SELECT col 'myAlias'
         if (kind == S_CHAR_LITERAL) return true;
 
-        // Base identifier tokens
-        if (kind == S_IDENTIFIER || kind == S_QUOTED_IDENTIFIER
-                || kind == DATA_TYPE || kind == K_DATETIMELITERAL
-                || kind == K_DATE_LITERAL) {
-            return true;
-        }
-
         // OPTION (...) introduces a query hint clause, not an alias
         if (kind == K_OPTION && getToken(2).kind == OPENING_BRACKET) {
             return false;
         }
 
-        // Non-reserved keywords
-        if (kind >= MIN_NON_RESERVED_WORD && kind <= MAX_NON_RESERVED_WORD) {
-            return true;
-        }
-
         // For reserved keywords in alias position, skip the structural-
         // keyword whitelist and go directly to follower disambiguation.
         // Only check keywords that are actually in RelObjectName's token
         // alternatives — don't fire for brackets, operators, literals, etc.
         switch (kind) {
-            case K_ALL: case K_ANY: case K_CASEWHEN: case K_CONNECT:
+            case K_ALL: case K_ARRAY_LITERAL: case K_ANY: case K_CASEWHEN: case K_CONNECT:
             case K_CREATE: case K_DEFAULT:
             case K_GLOBAL: case K_GROUP: case K_GROUPING: case K_IF:
             case K_IIF: case K_IGNORE: case K_IN: case K_INTERVAL:
@@ -1026,8 +1016,22 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
             case K_TOP: case K_VALUE: case K_VALUES:
                 return isReservedKeywordSafeByFollower();
             default:
-                return false;
+                break;
         }
+
+        // Base identifier tokens
+        if (kind == S_IDENTIFIER || kind == S_QUOTED_IDENTIFIER
+                || kind == DATA_TYPE || kind == K_DATETIMELITERAL
+                || kind == K_DATE_LITERAL) {
+            return true;
+        }
+
+        // Non-reserved keywords
+        if (kind >= MIN_NON_RESERVED_WORD && kind <= MAX_NON_RESERVED_WORD) {
+            return true;
+        }
+
+        return false;
     }
 
     /**
@@ -6492,6 +6496,8 @@ Join JoinerExpression() #JoinerExpression:
         <K_OUTER> { join.setOuter(true); }
     ]
 
+    [ <K_ARRAY_LITERAL> { join.setArray(true); } ]
+
     (
         (
             [ joinHint=JoinHint() {join.setJoinHint(joinHint); } ]

src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java

@@ -6527,4 +6527,33 @@ void testIssue2445FunctionWithBracketParameters() throws JSQLParserException {
                         "                                  , cast(ex.value_date - f.appraisal_date AS DECIMAL) / 365 )";
         TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
     }
+
+    @Test
+    void testClickHouseArrayJoin() throws Exception {
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT s, x FROM t LEFT ARRAY JOIN arr AS x",
+                true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT s, x FROM t ARRAY JOIN arr AS x", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT s, arr FROM t ARRAY JOIN arr", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT s, arr FROM t LEFT ARRAY JOIN arr", true);
+
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT s, x, o.name FROM t LEFT ARRAY JOIN arr AS x INNER JOIN other_table o ON t.id = o.t_id",
+                true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "WITH exploded AS (SELECT s, x FROM t LEFT ARRAY JOIN arr AS x) SELECT * FROM exploded",
+                true);
+
+        PlainSelect selectLeft =
+                (PlainSelect) CCJSqlParserUtil.parse("SELECT s, x FROM t LEFT ARRAY JOIN arr AS x");
+        Join joinLeft = selectLeft.getJoins().get(0);
+        Assertions.assertTrue(joinLeft.isArray(), "Should be an array join");
+        Assertions.assertTrue(joinLeft.isLeft(), "Should be a left join");
+
+        PlainSelect selectInner =
+                (PlainSelect) CCJSqlParserUtil.parse("SELECT s, x FROM t ARRAY JOIN arr AS x");
+        Join joinInner = selectInner.getJoins().get(0);
+        Assertions.assertTrue(joinInner.isArray(), "Should be an array join");
+        Assertions.assertFalse(joinInner.isLeft(), "Should not be a left join");
+    }
+
 }