fix(parser): parse INSERT ON CONFLICT after a join's trailing ON

The trailing-ON loop of a join (introduced for issue #1302) claimed
ON CONFLICT with its lookahead and parsed conflict as a column, so the
ON CONFLICT clause of INSERT ... SELECT ... JOIN ... ON ... never
reached the INSERT production and DO raised an unexpected-token error.

Gate the loop with a semantic predicate that recognizes the ON CONFLICT
clause shapes (DO, ON CONSTRAINT, parenthesized target with optional
WHERE) and leaves the ON token to the INSERT production.

Fixes #2358

Signed-off-by: 付典 <fudianchn@gmail.com>

Author: fudianchn

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

@@ -1241,6 +1241,65 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
         }
     }
 
+    /**
+     * True when the pending {@code ON} opens the ON CONFLICT clause of the enclosing
+     * INSERT rather than another trailing join condition: after a join, the trailing
+     * ON expressions of Issue #1302 and the INSERT clause claim the same ON token.
+     * The clause shapes are ON CONFLICT DO, ON CONFLICT ON CONSTRAINT and
+     * ON CONFLICT ( target ) [ WHERE ] DO, so the parenthesized target has to be
+     * separated from an expression by scanning past its balanced brackets.
+     */
+    private boolean isInsertOnConflictAhead() {
+        if (getToken(1).kind != K_ON || getToken(2).kind != K_CONFLICT) {
+            return false;
+        }
+        Token t = getToken(3);
+        if (t.kind == K_DO) {
+            return true;
+        }
+        if (t.kind == K_ON) {
+            return getToken(4).kind == K_CONSTRAINT;
+        }
+        if (!"(".equals(t.image)) {
+            return false;
+        }
+        int depth = 1;
+        int i = 4;
+        while (depth > 0) {
+            t = getToken(i++);
+            if (t == null || t.kind == EOF) {
+                return false;
+            }
+            if ("(".equals(t.image)) {
+                depth++;
+            } else if (")".equals(t.image)) {
+                depth--;
+            }
+        }
+        t = getToken(i);
+        if (t.kind == K_DO) {
+            return true;
+        }
+        if (t.kind != K_WHERE) {
+            return false;
+        }
+        // the index predicate ends where the conflict action's DO begins
+        depth = 0;
+        for (i++; ; i++) {
+            t = getToken(i);
+            if (t == null || t.kind == EOF) {
+                return false;
+            }
+            if ("(".equals(t.image)) {
+                depth++;
+            } else if (")".equals(t.image)) {
+                depth--;
+            } else if (t.kind == K_DO && depth == 0) {
+                return true;
+            }
+        }
+    }
+
     private boolean isMySqlDialect() {
         String dialect = getAsString(Feature.dialect);
         return Dialect.MYSQL.name().equals(dialect) || Dialect.MARIADB.name().equals(dialect);
@@ -6925,7 +6984,7 @@ Join JoinerExpression() #JoinerExpression:
         LOOKAHEAD(2) (
                         [ <K_WITHIN> "(" joinWindow = JoinWindow() ")" {join.setJoinWindow(joinWindow);} ]
                         ( <K_ON> onExpression=Expression()  { join.addOnExpression(onExpression); }
-                          ( LOOKAHEAD(2)  <K_ON> onExpression=Expression()  { join.addOnExpression(onExpression); } )*
+                          ( LOOKAHEAD({ getToken(1).kind == K_ON && !isInsertOnConflictAhead() })  <K_ON> onExpression=Expression()  { join.addOnExpression(onExpression); } )*
                         )
                         |
                         (

src/test/java/net/sf/jsqlparser/statement/insert/InsertTest.java

@@ -677,6 +677,66 @@ public void testInsertOnConflictIssue1551() throws JSQLParserException {
                 true);
     }
 
+    @Test
+    public void testInsertOnConflictAfterJoinIssue2358() throws JSQLParserException {
+        String sqlStr = "INSERT INTO conf.supply_info (id, deal_id)\n"
+                + "SELECT uuid_generate_v4(), rep.deal_id\n"
+                + "FROM conf.reports rep\n"
+                + "JOIN conf.orders o ON rep.id = o.report_id\n"
+                + "ON CONFLICT DO NOTHING";
+        Insert insert = (Insert) assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+        PlainSelect plainSelect = insert.getSelect().getPlainSelect();
+        assertEquals(1, plainSelect.getJoins().size());
+        assertEquals(1, plainSelect.getJoins().get(0).getOnExpressions().size());
+        assertEquals(ConflictActionType.DO_NOTHING,
+                insert.getConflictAction().getConflictActionType());
+        assertNull(insert.getConflictTarget());
+
+        assertSqlCanBeParsedAndDeparsed(
+                "INSERT INTO conf.supply_info (id, deal_id)\n"
+                        + "SELECT uuid_generate_v4(), rep.deal_id\n"
+                        + "FROM conf.reports rep\n"
+                        + "JOIN conf.orders o ON rep.id = o.report_id\n"
+                        + "ON CONFLICT (id) DO NOTHING",
+                true);
+
+        assertSqlCanBeParsedAndDeparsed(
+                "INSERT INTO distributors (did, dname)\n"
+                        + "SELECT did, dname FROM staging\n"
+                        + "JOIN suppliers s ON staging.did = s.did\n"
+                        + "ON CONFLICT ON CONSTRAINT distributors_pkey DO NOTHING",
+                true);
+
+        assertSqlCanBeParsedAndDeparsed(
+                "INSERT INTO distributors (did, dname)\n"
+                        + "SELECT did, dname FROM staging\n"
+                        + "JOIN suppliers s ON staging.did = s.did\n"
+                        + "ON CONFLICT (did) DO UPDATE SET dname = EXCLUDED.dname",
+                true);
+
+        assertSqlCanBeParsedAndDeparsed(
+                "INSERT INTO distributors (did, dname)\n"
+                        + "SELECT did, dname FROM staging\n"
+                        + "JOIN suppliers s ON staging.did = s.did\n"
+                        + "ON CONFLICT (did) WHERE is_active DO NOTHING",
+                true);
+    }
+
+    @Test
+    public void testInsertSelectWithTrailingOnExpressionsIssue2358() throws JSQLParserException {
+        String sqlStr = "INSERT INTO supply_info (id, deal_id)\n"
+                + "SELECT rep.deal_id, o.total\n"
+                + "FROM reports rep\n"
+                + "JOIN orders o ON rep.id = o.report_id\n"
+                + "ON o.total > 100";
+        Insert insert = (Insert) assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+        PlainSelect plainSelect = insert.getSelect().getPlainSelect();
+        assertEquals(1, plainSelect.getJoins().size());
+        assertEquals(2, plainSelect.getJoins().get(0).getOnExpressions().size());
+        assertNull(insert.getConflictAction());
+        assertNull(insert.getConflictTarget());
+    }
+
     @Test
     public void insertOnConflictObjectsTest() throws JSQLParserException {
         String sqlStr = "WITH a ( a, b , c ) \n" + "AS (SELECT  1 , 2 , 3 )\n"