Handle case-insensitive document declaration in the XML parser

Current we are strict on the document declaration for files which are parsed by the XML parser, the document declaration must be in upper case. Going forward support document declarations regardless of their case.

We want to do this to allow the XML to parse HTML files, which aren't as strict in their formatting

rewrite-xml/src/main/antlr/XMLLexer.g4

@@ -65,7 +65,7 @@ DTD_CLOSE        :  '>'    -> popMode ;
 DTD_SUBSET_OPEN  :  '['    -> pushMode(INSIDE_DTD_SUBSET) ;
 DTD_S            :   S     -> skip ;
 
-DOCTYPE          :  'DOCTYPE' ;
+DOCTYPE options { caseInsensitive = true; }         :  'DOCTYPE' ;
 
 DTD_NAME         :  Name   -> type(Name) ;
 DTD_STRING       :  STRING -> type(STRING) ;

rewrite-xml/src/main/java/org/openrewrite/xml/internal/XmlParserVisitor.java

@@ -359,6 +359,7 @@ public Xml.DocTypeDecl visitDoctypedecl(XMLParser.DoctypedeclContext ctx) {
                     prefix,
                     Markers.EMPTY,
                     name,
+                    ctx.DOCTYPE().getText(),
                     externalId,
                     internalSubset == null ? emptyList() : internalSubset,
                     externalSubsets,

rewrite-xml/src/main/java/org/openrewrite/xml/internal/XmlPrinter.java

@@ -155,7 +155,7 @@ public Xml visitCharData(Xml.CharData charData, PrintOutputCapture<P> p) {
     @Override
     public Xml visitDocTypeDecl(Xml.DocTypeDecl docTypeDecl, PrintOutputCapture<P> p) {
         beforeSyntax(docTypeDecl, p);
-        p.append("<!DOCTYPE");
+        p.append("<!" + docTypeDecl.getDocumentDeclaration());
         visit(docTypeDecl.getName(), p);
         visit(docTypeDecl.getExternalId(), p);
         visit(docTypeDecl.getInternalSubset(), p);

rewrite-xml/src/main/java/org/openrewrite/xml/internal/grammar/XMLLexer.tokens

@@ -36,7 +36,6 @@ STRING=35
 Name=36
 '?'=8
 '<'=10
-'DOCTYPE'=17
 '/>'=29
 '%@'=31
 '%'=32

rewrite-xml/src/main/java/org/openrewrite/xml/internal/grammar/XMLParser.interp

@@ -16,7 +16,7 @@ null
 null
 null
 null
-'DOCTYPE'
+null
 null
 null
 null

rewrite-xml/src/main/java/org/openrewrite/xml/internal/grammar/XMLParser.java

@@ -59,9 +59,8 @@ private static String[] makeRuleNames() {
 	private static String[] makeLiteralNames() {
 		return new String[] {
 			null, null, null, null, null, null, null, null, "'?'", null, "'<'", null, 
-			null, null, null, null, null, "'DOCTYPE'", null, null, null, null, null, 
-			null, null, null, null, null, null, "'/>'", null, "'%@'", "'%'", "'/'", 
-			"'='"
+			null, null, null, null, null, null, null, null, null, null, null, null, 
+			null, null, null, null, null, "'/>'", null, "'%@'", "'%'", "'/'", "'='"
 		};
 	}
 	private static final String[] _LITERAL_NAMES = makeLiteralNames();

rewrite-xml/src/main/java/org/openrewrite/xml/internal/grammar/XMLParser.tokens

@@ -36,7 +36,6 @@ STRING=35
 Name=36
 '?'=8
 '<'=10
-'DOCTYPE'=17
 '/>'=29
 '%@'=31
 '%'=32

rewrite-xml/src/main/java/org/openrewrite/xml/tree/Xml.java

@@ -15,6 +15,7 @@
  */
 package org.openrewrite.xml.tree;
 
+import com.fasterxml.jackson.annotation.JsonCreator;
 import lombok.*;
 import lombok.experimental.FieldDefaults;
 import org.apache.commons.text.StringEscapeUtils;
@@ -32,7 +33,10 @@
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
-import java.util.*;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
 import java.util.stream.Collectors;
 
 import static java.util.Collections.emptyList;
@@ -651,6 +655,7 @@ public String toString() {
     @Value
     @EqualsAndHashCode(callSuper = false, onlyExplicitlyIncluded = true)
     @With
+    @AllArgsConstructor(onConstructor_ = {@JsonCreator})
     class DocTypeDecl implements Xml, Misc {
         @EqualsAndHashCode.Include
         UUID id;
@@ -669,6 +674,7 @@ public String getPrefix() {
 
         Markers markers;
         Ident name;
+        String documentDeclaration;
 
         @Nullable
         Ident externalId;
@@ -683,6 +689,18 @@ public String getPrefix() {
          */
         String beforeTagDelimiterPrefix;
 
+        public DocTypeDecl(UUID id, String prefix, Markers markers, Ident name, Ident externalId, List<Ident> internalSubset, ExternalSubsets externalSubsets, String beforeTagDelimiterPrefix) {
+            this(id,
+                    prefix,
+                    markers,
+                    name,
+                    "DOCTYPE",
+                    externalId,
+                    internalSubset,
+                    externalSubsets,
+                    beforeTagDelimiterPrefix);
+        }
+
         @Value
         @EqualsAndHashCode(callSuper = false, onlyExplicitlyIncluded = true)
         @With

rewrite-xml/src/test/java/org/openrewrite/xml/XmlParserTest.java

@@ -76,6 +76,23 @@ void jsp() {
         );
     }
 
+    @Test
+    void lowerCaseDocType() {
+        rewriteRun(
+          xml(
+            //language=html
+            """
+              <!doctype html>
+              <html lang="en">
+                <body>
+                  <h2><s:property value="messageStore.message" /></h2>
+                </body>
+              </html>
+              """
+          )
+        );
+    }
+
     @Issue("https://github.com/openrewrite/rewrite/issues/2189")
     @Test
     void specialCharacters() {