feat: Yuml markdown plugin

markdown/src/main/java/org/apache/zeppelin/markdown/ParamVar.java

@@ -0,0 +1,35 @@
+/*
+ * 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.zeppelin.markdown;
+
+import org.parboiled.support.Var;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ParamVar<K, V> extends Var<Map<K, V>> {
+
+  public ParamVar() {
+    super(new HashMap<K, V>());
+  }
+
+  public boolean put(K key, V value) {
+    get().put(key, value);
+    return true;
+  }
+}

markdown/src/main/java/org/apache/zeppelin/markdown/PegdownParser.java

@@ -21,7 +21,9 @@ import org.pegdown.Extensions;
 import org.pegdown.PegDownProcessor;
 import org.pegdown.plugins.PegDownPlugins;
 
-/** Markdown Parser using pegdown processor. */
+/**
+ * Markdown Parser using pegdown processor.
+ */
 public class PegdownParser implements MarkdownParser {
   private PegDownProcessor processor;
 
@@ -49,7 +51,9 @@ public class PegdownParser implements MarkdownParser {
     return html;
   }
 
-  /** wrap with markdown class div to styling DOM using css. */
+  /**
+   * wrap with markdown class div to styling DOM using css.
+   */
   public static String wrapWithMarkdownClassDiv(String html) {
     return new StringBuilder()
       .append("<div class=\"markdown-body\">\n")

markdown/src/main/java/org/apache/zeppelin/markdown/PegdownYumlPlugin.java

@@ -0,0 +1,137 @@
+/*
+ * 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.zeppelin.markdown;
+
+import static org.apache.commons.lang3.StringUtils.defaultString;
+
+import org.parboiled.BaseParser;
+import org.parboiled.Rule;
+import org.parboiled.support.StringBuilderVar;
+import org.pegdown.Parser;
+import org.pegdown.ast.ExpImageNode;
+import org.pegdown.ast.TextNode;
+import org.pegdown.plugins.BlockPluginParser;
+import org.pegdown.plugins.PegDownPlugins;
+
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.Map;
+
+public class PegdownYumlPlugin extends Parser implements BlockPluginParser {
+
+  public PegdownYumlPlugin() {
+    super(PegdownParser.OPTIONS,
+      PegdownParser.PARSING_TIMEOUT_AS_MILLIS,
+      DefaultParseRunnerProvider);
+  }
+
+  public PegdownYumlPlugin(Integer options,
+                           Long maxParsingTimeInMillis,
+                           ParseRunnerProvider parseRunnerProvider,
+                           PegDownPlugins plugins) {
+    super(options, maxParsingTimeInMillis, parseRunnerProvider, plugins);
+  }
+
+  public static final String TAG = "%%%";
+
+  Rule StartMarker() {
+    return Sequence(Spn1(), TAG, Sp(), "yuml", Sp());
+  }
+
+  String EndMarker() {
+    return TAG;
+  }
+
+  Rule ParameterName() {
+    return FirstOf("type", "style", "scale", "format", "dir");
+  }
+
+  Rule Body() {
+    return OneOrMore(TestNot(TAG), BaseParser.ANY);
+  }
+
+  Rule BlockRule() {
+    ParamVar<String, String> params = new ParamVar<String, String>();
+    StringBuilderVar name = new StringBuilderVar();
+    StringBuilderVar value = new StringBuilderVar();
+    StringBuilderVar body = new StringBuilderVar();
+
+    return NodeSequence(
+      StartMarker(),
+      ZeroOrMore(
+        Sequence(
+          ParameterName(), name.append(match()),
+          String("="),
+          OneOrMore(Alphanumeric()), value.append(match())
+        ),
+        Sp(),
+        params.put(name.getString(), value.getString()),
+        name.clear(), value.clear()
+      )
+      , Body(), body.append(match())
+      , EndMarker()
+      , push(new ExpImageNode("title", createYumlUrl(params.get(), body.getString()), new TextNode("")))
+    );
+  }
+
+  public static String createYumlUrl(Map<String, String> params, String body) {
+    StringBuilder inlined = new StringBuilder();
+    for (String line : body.split("\\r?\\n")) {
+      line = line.trim();
+      if (line.length() > 0) {
+        if (inlined.length() > 0) {
+          inlined.append(", ");
+        }
+        inlined.append(line);
+      }
+    }
+
+    String encodedBody = null;
+    try {
+      encodedBody = URLEncoder.encode(inlined.toString(), "UTF-8");
+    } catch (UnsupportedEncodingException e) {
+      new RuntimeException("Failed to encode YUML markdown body");
+    }
+
+    StringBuilder mergedStyle = new StringBuilder();
+    String style = defaultString(params.get("style"), "scruffy");
+    String type = defaultString(params.get("type"), "class");
+    String format = defaultString(params.get("format"), "svg");
+
+    mergedStyle.append(style);
+
+    if (null != params.get("dir"))
+      mergedStyle.append(";dir:" + params.get("dir"));
+
+    if (null != params.get("scale"))
+      mergedStyle.append(";scale:" + params.get("scale"));
+
+    return new StringBuilder()
+      .append("http://yuml.me/diagram/")
+      .append(mergedStyle.toString() + "/")
+      .append(type + "/")
+      .append(encodedBody)
+      .append("." + format)
+      .toString();
+  }
+
+  @Override
+  public Rule[] blockPluginRules() {
+    return new Rule[]{BlockRule()};
+  }
+}