[DOXIA-734] Restore handling of XHTML 1.0 obsolete attributes/elements

apache · Mar 15, 2024 · dc29416 · dc29416
1 parent 6091eef
commit dc29416
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Showing 6 changed files with 402 additions and 172 deletions.
diff --git a/doxia-core/src/main/java/org/apache/maven/doxia/parser/AbstractXmlParser.java b/doxia-core/src/main/java/org/apache/maven/doxia/parser/AbstractXmlParser.java
@@ -379,11 +379,14 @@ protected void handleEntity(XmlPullParser parser, Sink sink) throws XmlPullParse
      * method.
      */
     protected void handleUnknown(XmlPullParser parser, Sink sink, int type) {
-        Object[] required = new Object[] {type};
-
         SinkEventAttributeSet attribs = getAttributesFromParser(parser);
 
-        sink.unknown(parser.getName(), required, attribs);
+        handleUnknown(parser.getName(), attribs, sink, type);
+    }
+
+    protected void handleUnknown(String elementName, SinkEventAttributeSet attribs, Sink sink, int type) {
+        Object[] required = new Object[] {type};
+        sink.unknown(elementName, required, attribs);
     }
 
     /**

diff --git a/doxia-core/src/main/java/org/apache/maven/doxia/parser/Xhtml1BaseParser.java b/doxia-core/src/main/java/org/apache/maven/doxia/parser/Xhtml1BaseParser.java
@@ -0,0 +1,180 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.doxia.parser;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.UnaryOperator;
+
+import org.apache.maven.doxia.sink.Sink;
+import org.apache.maven.doxia.sink.impl.SinkEventAttributeSet;
+import org.codehaus.plexus.util.xml.pull.XmlPullParser;
+
+/**
+ * Acts as bridge between legacy parsers relying on <a href="https://www.w3.org/TR/xhtml1/">XHTML 1.0 Transitional (based on HTML4)</a>
+ * and the {@link Xhtml5BaseParser} only supporting (X)HTML5 elements/attributes.
+ *
+ * Adds support for elements/attributes which <a href="https://html.spec.whatwg.org/#non-conforming-features">became obsolete in HTML5</a> but are
+ * commonly used for XDoc/FML.
+ *
+ * @see <a href="https://www.w3.org/TR/html5-diff/">HTML5 Differences from HTML4</a>.
+ */
+public class Xhtml1BaseParser extends Xhtml5BaseParser {
+
+    private static final class AttributeMapping {
+        private final String sourceName;
+        private final String targetName;
+        private final UnaryOperator<String> valueMapper;
+        private final MergeSemantics mergeSemantics;
+
+        enum MergeSemantics {
+            OVERWRITE,
+            IGNORE,
+            PREPEND
+        }
+
+        AttributeMapping(String sourceAttribute, String targetAttribute, MergeSemantics mergeSemantics) {
+            this(sourceAttribute, targetAttribute, UnaryOperator.identity(), mergeSemantics);
+        }
+
+        AttributeMapping(
+                String sourceName,
+                String targetName,
+                UnaryOperator<String> valueMapper,
+                MergeSemantics mergeSemantics) {
+            super();
+            this.sourceName = sourceName;
+            this.targetName = targetName;
+            this.valueMapper = valueMapper;
+            this.mergeSemantics = mergeSemantics;
+        }
+
+        public String getSourceName() {
+            return sourceName;
+        }
+
+        public String getTargetName() {
+            return targetName;
+        }
+
+        public UnaryOperator<String> getValueMapper() {
+            return valueMapper;
+        }
+
+        public String mergeValue(String oldValue, String newValue) {
+            final String mergedValue;
+            switch (mergeSemantics) {
+                case IGNORE:
+                    mergedValue = oldValue;
+                    break;
+                case OVERWRITE:
+                    mergedValue = newValue;
+                    break;
+                default:
+                    mergedValue = newValue + " " + oldValue;
+            }
+            return mergedValue;
+        }
+    }
+
+    static final String mapAlignToStyle(String alignValue) {
+        switch (alignValue) {
+            case "center":
+            case "left":
+            case "right":
+                return "text-align: " + alignValue + ";";
+            default:
+                return null;
+        }
+    }
+
+    /**
+     * All obsolete attributes in a map with key = affected element name, value = collection if {@link AttributeMapping}s
+     */
+    private static final Map<String, Collection<AttributeMapping>> ATTRIBUTE_MAPPING_TABLE = new HashMap<>();
+
+    /**
+     * All obsolete elements in a map with key = obsolete element name, value = non-obsolete replacement element name
+     */
+    private static final Map<String, String> ELEMENT_MAPPING_TABLE = new HashMap<>();
+
+    static {
+        ATTRIBUTE_MAPPING_TABLE.put(
+                "a", Collections.singleton(new AttributeMapping("name", "id", AttributeMapping.MergeSemantics.IGNORE)));
+
+        Collection<AttributeMapping> tableMappings = Arrays.asList(
+                new AttributeMapping(
+                        "border",
+                        "class",
+                        (v) -> (v != null && !v.equals("0")) ? "bodyTableBorder" : null,
+                        AttributeMapping.MergeSemantics.PREPEND),
+                new AttributeMapping(
+                        "align", "style", Xhtml1BaseParser::mapAlignToStyle, AttributeMapping.MergeSemantics.PREPEND));
+        ATTRIBUTE_MAPPING_TABLE.put("table", tableMappings);
+        ATTRIBUTE_MAPPING_TABLE.put(
+                "td",
+                Collections.singleton(new AttributeMapping(
+                        "align", "style", Xhtml1BaseParser::mapAlignToStyle, AttributeMapping.MergeSemantics.PREPEND)));
+        ATTRIBUTE_MAPPING_TABLE.put(
+                "th",
+                Collections.singleton(new AttributeMapping(
+                        "align", "style", Xhtml1BaseParser::mapAlignToStyle, AttributeMapping.MergeSemantics.PREPEND)));
+        ELEMENT_MAPPING_TABLE.put("tt", "code");
+        ELEMENT_MAPPING_TABLE.put("strike", "del");
+    }
+
+    /**
+     * Translates obsolete XHTML 1.0 attributes/elements to valid XHTML5 ones before calling the underlying {@link Xhtml5BaseParser}.
+     */
+    @Override
+    protected boolean baseStartTag(XmlPullParser parser, Sink sink) {
+        SinkEventAttributeSet attribs = getAttributesFromParser(parser);
+        String elementName = parser.getName();
+        Collection<AttributeMapping> attributeMappings = ATTRIBUTE_MAPPING_TABLE.get(elementName);
+        if (attributeMappings != null) {
+            for (AttributeMapping attributeMapping : attributeMappings) {
+                String attributeValue = (String) attribs.getAttribute(attributeMapping.getSourceName());
+                if (attributeValue != null) {
+                    String newValue = attributeMapping.getValueMapper().apply(attributeValue);
+                    if (newValue != null) {
+                        String oldValue = (String) attribs.getAttribute(attributeMapping.getTargetName());
+                        if (oldValue != null) {
+                            newValue = attributeMapping.mergeValue(oldValue, newValue);
+                        }
+                        attribs.addAttribute(attributeMapping.getTargetName(), newValue);
+                    }
+                    attribs.removeAttribute(attributeMapping.getSourceName());
+                }
+            }
+        }
+        String mappedElementName = ELEMENT_MAPPING_TABLE.getOrDefault(elementName, elementName);
+        return super.baseStartTag(mappedElementName, attribs, sink);
+    }
+
+    @Override
+    protected boolean baseEndTag(XmlPullParser parser, Sink sink) {
+        SinkEventAttributeSet attribs = getAttributesFromParser(parser);
+        String elementName = parser.getName();
+        String mappedElementName = ELEMENT_MAPPING_TABLE.getOrDefault(elementName, elementName);
+        return super.baseEndTag(mappedElementName, attribs, sink);
+    }
+}