Refactor FileParser

src/parser/FileParser.java

@@ -1,11 +1,35 @@
 package parser;
 
+import java.io.IOException;
 import java.util.List;
+import java.util.regex.Pattern;
+import javax.xml.parsers.ParserConfigurationException;
+import org.xml.sax.SAXException;
 import shapes.Shape;
 
-public interface FileParser {
+public abstract class FileParser {
 
-  String getFileExtension();
+  public static String fileExtension;
 
-  List<? extends Shape> parseFile(String path);
+  public static String getFileExtension() {
+    return fileExtension;
+  }
+
+  public FileParser(String path) throws IOException, SAXException, ParserConfigurationException {
+    checkFileExtension(path);
+    parseFile(path);
+  }
+
+  private static void checkFileExtension(String path) throws IllegalArgumentException {
+    Pattern pattern = Pattern.compile("\\." + getFileExtension() + "$");
+    if (!pattern.matcher(path).find()) {
+      throw new IllegalArgumentException(
+          "File to parse is not a ." + getFileExtension() + " file.");
+    }
+  }
+
+  protected abstract void parseFile(String path)
+      throws ParserConfigurationException, IOException, SAXException, IllegalArgumentException;
+
+  public abstract List<? extends Shape> getShapes();
 }

src/parser/SvgParser.java

@@ -1,17 +1,42 @@
 package parser;
 
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.List;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import org.w3c.dom.Document;
+import org.xml.sax.SAXException;
 import shapes.Shape;
 
-public class SvgParser implements FileParser {
+public class SvgParser extends FileParser {
 
-  @Override
-  public String getFileExtension() {
-    return ".svg";
+  private final List<? extends Shape> shapes;
+
+  static {
+    fileExtension = "svg";
+  }
+
+  public SvgParser(String path) throws IOException, SAXException, ParserConfigurationException {
+    super(path);
+    shapes = new ArrayList<>();
   }
 
   @Override
-  public List<? extends Shape> parseFile(String path) {
-    return null;
+  protected void parseFile(String path)
+      throws ParserConfigurationException, IOException, SAXException, IllegalArgumentException {
+    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+    factory.setValidating(true);
+    factory.setIgnoringElementContentWhitespace(true);
+    DocumentBuilder builder = factory.newDocumentBuilder();
+    File file = new File(path);
+    Document doc = builder.parse(file);
+  }
+
+  @Override
+  public List<? extends Shape> getShapes() {
+    return shapes;
   }
 }