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mcvisitors/content.php

+<h1>Compositional Language Engineering using<br>Generated, Extensible, Static Type-Safe Visitors</h1>
+
+<p>Robert Heim, Pedram Mir Seyed Nazari, Bernhard Rumpe, and Andreas Wortmann</p>
+
+<!--<h2>Publications</h2>-->
+<h2>Abstract</h2>
+<p>
+Language workbenches usually produce infrastructure to represent models
+as abstract syntax trees (AST) and employ analysis, transformation,
+and code generation techniques largely based on visitors. The visitor
+pattern and its derivatives suffer from the expression problem when it
+comes to extensibility and reuse. Current approaches either forsake
+static type safety, require features unavailable in popular
+object-oriented languages (e.g., open classes), or rely on procedural
+abstraction and thereby give up the object-oriented data encapsulation
+(the AST) itself. Our approach to visitors exploits knowledge about the
+AST structure under development and generation of statically type-safe
+external visitor interfaces that support extensibility in two
+dimensions: defining new operations by implementing the interface and
+extending the underlying data structure, usually without requiring
+adaptation of existing implemented visitors. We present a concept of
+visitor development for language engineering that enables an adaptable
+traversal and provides hook points for implementing concrete visitors.
+This approach is applicable to single DSL implementation and to
+language composition. It thus enables a transparent, easy to use, and
+static type-safe solution for the typical use cases of language
+analysis and transformation.
+</p>
+
+<h2>Supporting materials</h2>
+
+<p>The Maven project in <a href="visitors.zip">visitors.zip</a>
+demonstrates usage of the visitor infrastructure of the language workbench
+<a href="http://www.monticore.de">MontiCore</a>.
+It consists of three (simplified) languages:</p>
+<ul>
+  <li><b>Classdiagram</b><br>Grammar: visitors.zip/visitors/src/main/grammars/de/monticore/visitors/CD.mc4</li>
+  <li><b>Automaton</b><br>Grammar: visitors.zip/visitors/src/main/grammars/de/monticore/visitors/Automaton.mc4</li>
+  <li><b>Classdiagram with embedded automata</b><br>Grammar: visitors.zip/tree/master/visitors/src/main/grammars/de/monticore/visitors/&shy;CDWithAutomaton.mc4</li>
+</ul>
+
+<h3>Requirements</h3>
+<ul>
+  <li>Java 8 SDK</li>
+  <li>Maven 3+</li>
+</ul>
+
+<h3>Build</h3>
+<p>Extract the visitor.zip. To build the project run <code>mvn clean install</code> from the visitor folder that contains the <code>pom.xml</code>. MontiCore generates files to folder <code>visitors/target/generated-sources/monticore/sourcecode</code>. Put this folder on the class path after building the project.</p>
+
+<h3>Examples</h3>
+<p>All languages define pretty printers:</p>
+<ul>
+  <li><b>CDPrettyPrinter</b><br>visitors.zip/visitors/src/main/java/de/monticore/visitors/cd/CDPrettyPrinter.java</li>
+  <li><b>AutomatonPrettyPrinter</b><br>visitors.zip/visitors/src/main/java/de/monticore/visitors/automaton/AutomatonPrettyPrinter.java</li>
+  <li><b>CDWithAutomatonPrettyPrinter</b><br>visitors.zip/visitors/src/main/java/de/monticore/visitors/cdwithautomaton/&shy;CDWithAutomatonPrettyPrinter.java</li>
+</ul>
+
+<p>The pretty printer for classdiagrams with automata is composed of the other ones.
+The CDWithAutomatonTest [1] demonstrates its usage and usage of a method counter [2].<br>
+<br>
+[1] visitors.zip/visitors/src/test/java/de/monticore/visitors/CDWithAutomatonTest.java<br>
+[2] visitors.zip/visitors/src/main/java/de/monticore/visitors/cdwithautomaton/MethodCounter.java
+</p>

mcvisitors/index.php

+<?php
+
+$ROOT_PATH = "../../";
+
+$TITLE = "SE@RWTH : Compositional Language Engineering using Generated, Extensible, Static Type-Safe Visitors";
+
+include ($ROOT_PATH."layout/lib.php");
+
+include ($ROOT_PATH."layout/header.php");
+
+include ("content.php");
+
+include ($ROOT_PATH."layout/footer.php");
+
+?>
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