Add Golang frontend

README.md

@@ -48,7 +48,7 @@ Usage: JPlag [ options ] [ <root-dir> ... ] [ -new <new-dir> ... ] [ -old <old-d
 
 named arguments:
   -h, --help       show this help message and exit
-  -l               {java,python3,cpp,csharp,rlang,kotlin,char,text,scheme} Select the language to parse the submissions (default: java)
+  -l               {java,python3,cpp,csharp,golang,kotlin,rlang,char,text,scheme} Select the language to parse the submissions (default: java)
   -bc BC           Path of the directory containing the base code (common framework used in all submissions)
   -v               {quiet,long} Verbosity of the logging (default: quiet)
   -d               Debug parser. Non-parsable files will be stored (default: false)

jplag.cli/pom.xml

@@ -12,10 +12,6 @@
             <groupId>de.jplag</groupId>
             <artifactId>jplag</artifactId>
         </dependency>
-        <dependency>
-            <groupId>de.jplag</groupId>
-            <artifactId>jplag</artifactId>
-        </dependency>
         <dependency>
             <groupId>de.jplag</groupId>
             <artifactId>frontend-utils</artifactId>

jplag.frontend.golang/README.md

@@ -0,0 +1,29 @@
+# JPlag Go language frontend
+
+The JPlag Go frontend allows the use of JPlag with submissions in Go. <br>
+It is based on the [Golang ANTLR4 grammar](https://github.com/antlr/grammars-v4/tree/master/golang), licensed under BSD-3.
+
+### Go specification compatibility
+
+The underlying grammar definition does not specify which version of Go it is built on. This is what we know:
+ - Number literal prefixes, a feature of go1.13, are included.
+ - Generics, a feature of go1.18, are _not_ included.
+ - Between go1.13 and go1.18, there were no changes to the syntax. So, the grammar should be fully compatible with go1.17, released in mid-2021.
+
+If the grammar is updated to a more recent<a href="#footnote-1"><sup>1</sup></a> syntax definition, this module should surely be updated as well.
+
+### Token Extraction
+
+The choice of tokens is intended to be similar to the Java or C# frontends. Specifically, among others, it includes a range of nesting structures (class and method declarations, control flow expressions) as well as variable declaration, object creation, assignment, and control flow altering keywords. <br>
+Blocks are distinguished by their context, i.e. there are separate `TokenConstants` for `if` blocks, `for` blocks, class bodies, method bodies, array constructors, and the like.
+
+More syntactic elements of Go may turn out to be helpful to include in the future, especially those that are newly introduced.
+
+### Usage
+
+To use the Go frontend, add the `-l golang` flag in the CLI, or use a `JPlagOption` object set to `LanguageOption.GO_LANG` in the Java API as described in the usage information in the [readme of the main project](https://github.com/jplag/JPlag#usage) and [in the wiki](https://github.com/jplag/JPlag/wiki/1.-How-to-Use-JPlag).
+
+<br>
+
+#### Footnotes
+<section id="footnote-1"><sup>1 </sup>The grammar files are taken from grammar-v4, with the most recent modifiactions in <a href="https://github.com/antlr/grammars-v4/tree/51ecccf87b75e96177287367b96cfa99e9f304b8/golang">commit 51ecccf</a> from April 2022.</section>

jplag.frontend.golang/pom.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>de.jplag</groupId>
+        <artifactId>aggregator</artifactId>
+        <version>${revision}</version>
+    </parent>
+    <artifactId>golang</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>de.jplag</groupId>
+            <artifactId>frontend-utils</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.antlr</groupId>
+            <artifactId>antlr4-runtime</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>de.jplag</groupId>
+            <artifactId>frontend-testutils</artifactId>
+            <version>${revision}</version>
+            <type>test-jar</type>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.antlr</groupId>
+                <artifactId>antlr4-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>antlr4</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>