Add mechanism for processing invalid XML names (transforming to valid ones)

src/main/java/com/fasterxml/jackson/dataformat/xml/XmlFactory.java

@@ -65,6 +65,8 @@ public class XmlFactory extends JsonFactory
     protected transient XMLOutputFactory _xmlOutputFactory;
 
     protected String _cfgNameForTextElement;
+
+    protected XmlTagProcessor _tagProcessor;
 
     /*
     /**********************************************************
@@ -102,11 +104,18 @@ public XmlFactory(ObjectCodec oc, XMLInputFactory xmlIn, XMLOutputFactory xmlOut
                 xmlIn, xmlOut, null);
     }
 
+    public XmlFactory(ObjectCodec oc, int xpFeatures, int xgFeatures,
+                         XMLInputFactory xmlIn, XMLOutputFactory xmlOut,
+                         String nameForTextElem) {
+        this(oc, xpFeatures, xgFeatures, xmlIn, xmlOut, nameForTextElem, XmlTagProcessors.newPassthroughProcessor());
+    }
+
     protected XmlFactory(ObjectCodec oc, int xpFeatures, int xgFeatures,
             XMLInputFactory xmlIn, XMLOutputFactory xmlOut,
-            String nameForTextElem)
+            String nameForTextElem, XmlTagProcessor tagProcessor)
     {
         super(oc);
+        _tagProcessor = tagProcessor;
         _xmlParserFeatures = xpFeatures;
         _xmlGeneratorFeatures = xgFeatures;
         _cfgNameForTextElement = nameForTextElem;
@@ -140,6 +149,7 @@ protected XmlFactory(XmlFactory src, ObjectCodec oc)
         _cfgNameForTextElement = src._cfgNameForTextElement;
         _xmlInputFactory = src._xmlInputFactory;
         _xmlOutputFactory = src._xmlOutputFactory;
+        _tagProcessor = src._tagProcessor;
     }
 
     /**
@@ -155,6 +165,7 @@ protected XmlFactory(XmlFactoryBuilder b)
         _cfgNameForTextElement = b.nameForTextElement();
         _xmlInputFactory = b.xmlInputFactory();
         _xmlOutputFactory = b.xmlOutputFactory();
+        _tagProcessor = b.xmlTagProcessor();
         _initFactories(_xmlInputFactory, _xmlOutputFactory);
     }
 
@@ -325,6 +336,14 @@ public int getFormatGeneratorFeatures() {
         return _xmlGeneratorFeatures;
     }
 
+    public XmlTagProcessor getXmlTagProcessor() {
+        return _tagProcessor;
+    }
+
+    public void setXmlTagProcessor(XmlTagProcessor _tagProcessor) {
+        this._tagProcessor = _tagProcessor;
+    }
+
     /*
     /******************************************************
     /* Configuration, XML, generator settings
@@ -498,7 +517,7 @@ public ToXmlGenerator createGenerator(OutputStream out, JsonEncoding enc) throws
         ctxt.setEncoding(enc);
         return new ToXmlGenerator(ctxt,
                 _generatorFeatures, _xmlGeneratorFeatures,
-                _objectCodec, _createXmlWriter(ctxt, out));
+                _objectCodec, _createXmlWriter(ctxt, out), _tagProcessor);
     }
 
     @Override
@@ -507,7 +526,7 @@ public ToXmlGenerator createGenerator(Writer out) throws IOException
         final IOContext ctxt = _createContext(_createContentReference(out), false);
         return new ToXmlGenerator(ctxt,
                 _generatorFeatures, _xmlGeneratorFeatures,
-                _objectCodec, _createXmlWriter(ctxt, out));
+                _objectCodec, _createXmlWriter(ctxt, out), _tagProcessor);
     }
 
     @SuppressWarnings("resource")
@@ -519,7 +538,7 @@ public ToXmlGenerator createGenerator(File f, JsonEncoding enc) throws IOExcepti
         final IOContext ctxt = _createContext(_createContentReference(out), true);
         ctxt.setEncoding(enc);
         return new ToXmlGenerator(ctxt, _generatorFeatures, _xmlGeneratorFeatures,
-                _objectCodec, _createXmlWriter(ctxt, out));
+                _objectCodec, _createXmlWriter(ctxt, out), _tagProcessor);
     }
 
     /*
@@ -543,7 +562,7 @@ public FromXmlParser createParser(XMLStreamReader sr) throws IOException
 
         // false -> not managed
         FromXmlParser xp = new FromXmlParser(_createContext(_createContentReference(sr), false),
-                _parserFeatures, _xmlParserFeatures, _objectCodec, sr);
+                _parserFeatures, _xmlParserFeatures, _objectCodec, sr, _tagProcessor);
         if (_cfgNameForTextElement != null) {
             xp.setXMLTextElementName(_cfgNameForTextElement);
         }
@@ -562,7 +581,7 @@ public ToXmlGenerator createGenerator(XMLStreamWriter sw) throws IOException
         sw = _initializeXmlWriter(sw);
         IOContext ctxt = _createContext(_createContentReference(sw), false);
         return new ToXmlGenerator(ctxt, _generatorFeatures, _xmlGeneratorFeatures,
-                _objectCodec, sw);
+                _objectCodec, sw, _tagProcessor);
     }
 
     /*
@@ -582,7 +601,7 @@ protected FromXmlParser _createParser(InputStream in, IOContext ctxt) throws IOE
         }
         sr = _initializeXmlReader(sr);
         FromXmlParser xp = new FromXmlParser(ctxt, _parserFeatures, _xmlParserFeatures,
-                _objectCodec, sr);
+                _objectCodec, sr, _tagProcessor);
         if (_cfgNameForTextElement != null) {
             xp.setXMLTextElementName(_cfgNameForTextElement);
         }
@@ -600,7 +619,7 @@ protected FromXmlParser _createParser(Reader r, IOContext ctxt) throws IOExcepti
         }
         sr = _initializeXmlReader(sr);
         FromXmlParser xp = new FromXmlParser(ctxt, _parserFeatures, _xmlParserFeatures,
-                _objectCodec, sr);
+                _objectCodec, sr, _tagProcessor);
         if (_cfgNameForTextElement != null) {
             xp.setXMLTextElementName(_cfgNameForTextElement);
         }
@@ -627,7 +646,7 @@ protected FromXmlParser _createParser(char[] data, int offset, int len, IOContex
         }
         sr = _initializeXmlReader(sr);
         FromXmlParser xp = new FromXmlParser(ctxt, _parserFeatures, _xmlParserFeatures,
-                _objectCodec, sr);
+                _objectCodec, sr, _tagProcessor);
         if (_cfgNameForTextElement != null) {
             xp.setXMLTextElementName(_cfgNameForTextElement);
         }
@@ -651,7 +670,7 @@ protected FromXmlParser _createParser(byte[] data, int offset, int len, IOContex
         }
         sr = _initializeXmlReader(sr);
         FromXmlParser xp = new FromXmlParser(ctxt, _parserFeatures, _xmlParserFeatures,
-                _objectCodec, sr);
+                _objectCodec, sr, _tagProcessor);
         if (_cfgNameForTextElement != null) {
             xp.setXMLTextElementName(_cfgNameForTextElement);
         }

src/main/java/com/fasterxml/jackson/dataformat/xml/XmlFactoryBuilder.java

@@ -63,6 +63,13 @@ public class XmlFactoryBuilder extends TSFBuilder<XmlFactory, XmlFactoryBuilder>
      */
     protected ClassLoader _classLoaderForStax;
 
+    /**
+     * See {@link XmlTagProcessor} and {@link XmlTagProcessors}
+     *
+     * @since 2.14
+     */
+    protected XmlTagProcessor _tagProcessor;
+
     /*
     /**********************************************************
     /* Life cycle
@@ -73,6 +80,7 @@ protected XmlFactoryBuilder() {
         _formatParserFeatures = XmlFactory.DEFAULT_XML_PARSER_FEATURE_FLAGS;
         _formatGeneratorFeatures = XmlFactory.DEFAULT_XML_GENERATOR_FEATURE_FLAGS;
         _classLoaderForStax = null;
+        _tagProcessor = XmlTagProcessors.newPassthroughProcessor();
     }
 
     public XmlFactoryBuilder(XmlFactory base) {
@@ -82,6 +90,7 @@ public XmlFactoryBuilder(XmlFactory base) {
         _xmlInputFactory = base._xmlInputFactory;
         _xmlOutputFactory = base._xmlOutputFactory;
         _nameForTextElement = base._cfgNameForTextElement;
+        _tagProcessor = base._tagProcessor;
         _classLoaderForStax = null;
     }
 
@@ -133,6 +142,10 @@ protected ClassLoader staxClassLoader() {
                 getClass().getClassLoader() : _classLoaderForStax;
     }
 
+    public XmlTagProcessor xmlTagProcessor() {
+        return _tagProcessor;
+    }
+
     // // // Parser features
 
     public XmlFactoryBuilder enable(FromXmlParser.Feature f) {
@@ -253,6 +266,14 @@ public XmlFactoryBuilder staxClassLoader(ClassLoader cl) {
         _classLoaderForStax = cl;
         return _this();
     }
+
+    /**
+     * @since 2.14
+     */
+    public XmlFactoryBuilder xmlTagProcessor(XmlTagProcessor tagProcessor) {
+        _tagProcessor = tagProcessor;
+        return _this();
+    }
 
     // // // Actual construction
 

src/main/java/com/fasterxml/jackson/dataformat/xml/XmlMapper.java

@@ -108,6 +108,14 @@ public Builder defaultUseWrapper(boolean state) {
             _mapper.setDefaultUseWrapper(state);
             return this;
         }
+
+        /**
+         * @since 2.14
+         */
+        public Builder xmlTagProcessor(XmlTagProcessor tagProcessor) {
+            _mapper.setXmlTagProcessor(tagProcessor);
+            return this;
+        }
     }
 
     protected final static JacksonXmlModule DEFAULT_XML_MODULE = new JacksonXmlModule();
@@ -280,6 +288,20 @@ public XmlMapper setDefaultUseWrapper(boolean state) {
         return this;
     }
 
+    /**
+     * @since 2.14
+     */
+    public void setXmlTagProcessor(XmlTagProcessor tagProcessor) {
+        ((XmlFactory)_jsonFactory).setXmlTagProcessor(tagProcessor);
+    }
+
+    /**
+     * @since 2.14
+     */
+    public XmlTagProcessor getXmlTagProcessor() {
+        return ((XmlFactory)_jsonFactory).getXmlTagProcessor();
+    }
+
     /*
     /**********************************************************
     /* Access to configuration settings

src/main/java/com/fasterxml/jackson/dataformat/xml/XmlTagProcessor.java

@@ -0,0 +1,60 @@
+package com.fasterxml.jackson.dataformat.xml;
+
+import java.io.Serializable;
+
+/**
+ * XML tag name processor primarily used for dealing with tag names
+ * containing invalid characters. Invalid characters in tags can,
+ * for instance, easily appear in map keys.
+ * <p>
+ * Processors should be set in the {@link XmlMapper#setXmlTagProcessor(XmlTagProcessor)}
+ * and/or the {@link XmlMapper.Builder#xmlTagProcessor(XmlTagProcessor)} methods.
+ * <p>
+ * See {@link XmlTagProcessors} for default processors.
+ *
+ * @since 2.14
+ */
+public interface XmlTagProcessor extends Serializable {
+
+    /**
+     * Representation of an XML tag name
+     */
+    class XmlTagName {
+        public final String namespace;
+        public final String localPart;
+
+        public XmlTagName(String namespace, String localPart) {
+            this.namespace = namespace;
+            this.localPart = localPart;
+        }
+    }
+
+
+    /**
+     * Used during XML serialization.
+     * <p>
+     * This method should process the provided {@link XmlTagName} and
+     * escape / encode invalid XML characters.
+     *
+     * @param tag The tag to encode
+     * @return The encoded tag name
+     */
+    XmlTagName encodeTag(XmlTagName tag);
+
+
+    /**
+     * Used during XML deserialization.
+     * <p>
+     * This method should process the provided {@link XmlTagName} and
+     * revert the encoding done in the {@link #encodeTag(XmlTagName)}
+     * method.
+     * <p>
+     * Note: Depending on the use case, it is not always required (or
+     * even possible) to reverse an encoding with 100% accuracy.
+     *
+     * @param tag The tag to encode
+     * @return The encoded tag name
+     */
+    XmlTagName decodeTag(XmlTagName tag);
+
+}