fix(parser): support leading CONTENT/DOCUMENT keyword in XMLPARSE (#2501)

Author: dengliming

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

@@ -657,6 +657,38 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
         }
     }
 
+    /**
+     * XML constructor functions take a bare leading keyword before their first argument,
+     * e.g. XMLPARSE(CONTENT expr), XMLPARSE(DOCUMENT expr), XMLELEMENT(NAME ident, ...).
+     * Guarded by the function name so that CONTENT/DOCUMENT/NAME stay plain identifiers
+     * everywhere else, e.g. f(content).
+     */
+    private void consumeXmlLeadingKeyword(Function function) {
+        String name = function.getName();
+        if (name == null) {
+            return;
+        }
+        name = name.toUpperCase(java.util.Locale.ROOT);
+        if (!"XMLPARSE".equals(name) && !"XMLELEMENT".equals(name) && !"XMLFOREST".equals(name)) {
+            return;
+        }
+        Token token = getToken(1);
+        if (token.kind != S_IDENTIFIER && token.kind != K_NAME) {
+            return;
+        }
+        String keyword = token.image.toUpperCase(java.util.Locale.ROOT);
+        if (!"CONTENT".equals(keyword) && !"DOCUMENT".equals(keyword) && !"NAME".equals(keyword)) {
+            return;
+        }
+        // only a bare leading keyword: an expression must follow
+        Token next = getToken(2);
+        if (next.kind == EOF || ")".equals(next.image) || ",".equals(next.image)
+                || ".".equals(next.image) || "(".equals(next.image)) {
+            return;
+        }
+        function.setExtraKeyword(getNextToken().image);
+    }
+
     private boolean isKeywordArgumentAhead() {
         Token t = getToken(1);
         if (t.kind == EOF || t.image.equals(")")) return false;
@@ -10154,9 +10186,9 @@ Function InternalFunction(boolean escaped):
 }
 {
     [ LOOKAHEAD(2) prefixToken = <K_APPROXIMATE> ]
-    funcName = RelObjectNames() { if (prefixToken!=null) funcName.getNames().add(0, prefixToken.image ); }
+    funcName = RelObjectNames() { if (prefixToken!=null) funcName.getNames().add(0, prefixToken.image ); retval.setName(funcName.getNames()); }
 
-    "("
+    "(" { consumeXmlLeadingKeyword(retval); }
     [
         LOOKAHEAD(2) [
             LOOKAHEAD(2) (

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

@@ -0,0 +1,65 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2026 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.statement.select;
+
+import net.sf.jsqlparser.JSQLParserException;
+import org.junit.jupiter.api.Test;
+
+import static net.sf.jsqlparser.test.TestUtils.assertSqlCanBeParsedAndDeparsed;
+
+/**
+ * XML constructor functions taking a bare leading keyword before their first argument, e.g.
+ * {@code XMLPARSE(CONTENT expr)}.
+ */
+public class SelectXMLParseTest {
+
+    @Test
+    public void testXmlParseContent() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT xmlparse(content a) FROM mytable");
+    }
+
+    @Test
+    public void testXmlParseDocument() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT xmlparse(document a) FROM mytable");
+    }
+
+    @Test
+    public void testXmlParseUpperCaseKeyword() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT xmlparse(CONTENT a) FROM mytable");
+    }
+
+    @Test
+    public void testXmlAggWithXmlParse() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed(
+                "SELECT xmlagg(xmlparse(content sn.CODE || ',') ORDER BY sn.CODE).getclobval() AS SN FROM GV_SYS_CODEINFO sn");
+    }
+
+    @Test
+    public void testXmlElementName() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT xmlelement(name a, b) FROM mytable");
+    }
+
+    @Test
+    public void testXmlForestName() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT xmlforest(name a) FROM mytable");
+    }
+
+    /**
+     * CONTENT, DOCUMENT and NAME must stay plain identifiers everywhere else.
+     */
+    @Test
+    public void testKeywordsRemainIdentifiers() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT content, document, name FROM mytable");
+        assertSqlCanBeParsedAndDeparsed("SELECT content FROM content c WHERE c.document = 1");
+        assertSqlCanBeParsedAndDeparsed("SELECT t.name AS document FROM mytable t");
+        assertSqlCanBeParsedAndDeparsed("SELECT f(content) FROM mytable");
+        assertSqlCanBeParsedAndDeparsed("SELECT xmlparse(content) FROM mytable");
+    }
+}