Keep lambda a plain identifier outside DuckDB lambdas

As a keyword token, LAMBDA stopped parsing where only plain identifiers are
accepted: `CAST(a AS lambda)`, `COLLATE lambda`, `CREATE TABLE t (a lambda)`,
`ALTER TABLE t DROP COLUMN lambda`, `ALTER TABLE t RENAME lambda TO x`.
`isDuckDBLambdaAhead()` recognises `lambda name [, name ...] :` contextually,
as `isKeywordAhead()` does for other words, so no token is needed.

Author: Jules Ivanic

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

@@ -1599,6 +1599,33 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
         catch (IllegalArgumentException exception) { throw new ParseException("Unknown " + type.getSimpleName() + ": " + value); }
     }
 
+    /**
+     * DuckDB's lambda x, y : expr. LAMBDA stays a plain identifier, so a column, type or alias
+     * named lambda keeps parsing: only LAMBDA followed by names separated by commas and a ":" is
+     * a lambda.
+     */
+    private boolean isDuckDBLambdaAhead() {
+        if (getToken(1).kind != S_IDENTIFIER || !isKeywordAhead("LAMBDA")) {
+            return false;
+        }
+        int offset = 2;
+        while (true) {
+            int kind = getToken(offset).kind;
+            if (kind != S_IDENTIFIER && kind != S_QUOTED_IDENTIFIER && kind != DATA_TYPE
+                    && (kind < MIN_NON_RESERVED_WORD || kind > MAX_NON_RESERVED_WORD)) {
+                return false;
+            }
+            String next = getToken(offset + 1).image;
+            if (":".equals(next)) {
+                return true;
+            }
+            if (!",".equals(next)) {
+                return false;
+            }
+            offset += 2;
+        }
+    }
+
     private boolean isKeywordAhead(String keyword) {
         Token token = getToken(1);
         return token.kind != EOF && token.image != null && keyword.equalsIgnoreCase(token.image);
@@ -2601,7 +2628,6 @@ String NonReservedWord() :
       | tk=<K_KEYS:"KEYS">
       | tk=<K_KILL:"KILL">
       | tk=<K_FN:"FN">
-      | tk=<K_LAMBDA: "LAMBDA">
       | tk=<K_LAST: "LAST">
       | tk=<K_LEADING:"LEADING">
       | tk=<K_LESS:"LESS">
@@ -11432,8 +11458,7 @@ Expression PrimaryExpression() #PrimaryExpression:
                   retval=CharacterSetIntroducedString()
 
         // DuckDB's lambda x, y : expr, before Column() which would take LAMBDA as a column name
-        | LOOKAHEAD( <K_LAMBDA> RelObjectName() ( "," RelObjectName() )* ":", {!interrupted} )
-                  retval=DuckDBLambdaExpression()
+        | LOOKAHEAD({ !interrupted && isDuckDBLambdaAhead() }) retval=DuckDBLambdaExpression()
 
         | LOOKAHEAD(2, {!interrupted}) retval=Column()
             [
@@ -13279,7 +13304,7 @@ LambdaExpression DuckDBLambdaExpression() #LambdaExpression:
     LambdaExpression lambdaExpression;
 }
 {
-    <K_LAMBDA> s = RelObjectName() { identifiers.add(s); }
+    <S_IDENTIFIER> s = RelObjectName() { identifiers.add(s); }
     ( "," s = RelObjectName() { identifiers.add(s); } )*
     ":"
     expression = Expression()

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

@@ -723,10 +723,26 @@ void testLambdaKeywordExpression() throws JSQLParserException {
         Assertions.assertEquals(Arrays.asList("acc", "x"), lambda.getIdentifiers());
     }
 
+    @Test
+    void testLambdaKeywordFollowedByArguments() throws JSQLParserException {
+        PlainSelect select = (PlainSelect) TestUtils.assertSqlCanBeParsedAndDeparsed(
+                "SELECT f(l, lambda x : x + 1, 2) FROM t", true);
+        Function function = select.getSelectItem(0).getExpression(Function.class);
+
+        Assertions.assertEquals(3, function.getParameters().size());
+        Assertions.assertEquals("x + 1",
+                ((LambdaExpression) function.getParameters().get(1)).getExpression().toString());
+    }
+
     @Test
     void testLambdaAsIdentifier() throws JSQLParserException {
         TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT lambda FROM t", true);
         TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT lambda x, y FROM t", true);
         TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT t.lambda FROM lambda t", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT CAST(a AS lambda) FROM t", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT 'a' COLLATE lambda FROM t", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("CREATE TABLE t (a lambda)", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("ALTER TABLE t DROP COLUMN lambda", true);
+        TestUtils.assertSqlCanBeParsedAndDeparsed("ALTER TABLE t RENAME lambda TO x", true);
     }
 }