Add syntax highlighting framework

src/main/java/app/controllers/EditorController.java

@@ -1,17 +1,20 @@
 package app.controllers;
 
 import java.net.URL;
+import java.util.Collection;
 import java.util.ResourceBundle;
 
 import com.google.common.eventbus.EventBus;
 
 import org.fxmisc.richtext.CodeArea;
 import org.fxmisc.richtext.LineNumberFactory;
+import org.fxmisc.richtext.model.StyleSpans;
 import org.fxmisc.richtext.model.TwoDimensional.Bias;
 import org.fxmisc.richtext.model.TwoDimensional.Position;
 
 import app.events.EditorChangedEvent;
 import app.model.Model;
+import app.service.LanguageOperations;
 import javafx.fxml.FXML;
 import javafx.fxml.Initializable;
 import javafx.scene.input.KeyEvent;
@@ -43,6 +46,10 @@ public class EditorController implements Initializable, Controller {
     this.model = model;
   }
 
+  public void setHighlighting(StyleSpans<Collection<String>> highlighting) {
+    this.editor.setStyleSpans(0, highlighting);
+  }
+
   /**
    * Handles events from the editor, and reflects them in the model
    * @param event The object containing metadata of the event
@@ -57,6 +64,10 @@ public class EditorController implements Initializable, Controller {
         pos.getMajor() + 1,
         pos.getMinor()
       ));
+    this.setHighlighting(
+      LanguageOperations.syntaxHighlight(
+        this.editor.getText(),
+        Model.getLanguage()));
   }
 
 }

src/main/java/app/languages/Java.java

@@ -0,0 +1,71 @@
+package app.languages;
+
+import java.net.URL;
+import java.util.AbstractMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+import app.model.ProgrammingLanguage;
+
+public class Java implements ProgrammingLanguage {
+
+  private String name = "Java";
+  private URL iconPath = this.getClass().getResource("");
+
+  private static final String[] keywords = new String[] {
+    "abstract", "assert", "boolean", "break", "byte",
+    "case", "catch", "char", "class", "const",
+    "continue", "default", "do", "double", "else",
+    "enum", "extends", "final", "finally", "float",
+    "for", "goto", "if", "implements", "import",
+    "instanceof", "int", "interface", "long", "native",
+    "new", "package", "private", "protected", "public",
+    "return", "short", "static", "strictfp", "super",
+    "switch", "synchronized", "throw", "throws",
+    "transient", "try", "void", "volatile", "while"
+  };
+
+  private static Entry<Pattern, String> e(String k, String v) {
+    return new AbstractMap.SimpleEntry<>(Pattern.compile(k), v);
+  }
+
+  private static final Map<Pattern, String> pattern = 
+    Map.ofEntries(
+      e("\\b(" + String.join("|", keywords) + ")\\b", "keyword"), // <public>, <static>, ....
+      e("this", "this"),                          // <this>
+      e("true", "true"),                          // <true>
+      e("false", "false"),                        // <false>
+      e("\\(|\\)", "paranthesis"),                // <(*)>
+      e("\\{|\\}", "curlyBrackets"),              // <{*}>
+      e("\\[|\\]", "squareBrackets"),             // <[*]>
+      e(";", "semiColon"),                        // <;>
+      e("[A-Z]\\w+", "identifier"),               // <ClassName> or <InterfaceName>
+      e("\\.\\w+", "property"),                   // <.property>
+      e("(?<=this\\.)?\\w+(?=\\(*\\))", "method") // <this.function(*)>
+    );
+
+  public String getName() {
+    return this.name;
+  }
+
+  public URL getIcon() {
+    return this.iconPath;
+  }
+
+  public Map<Pattern, String> getPatternMap() {
+    return Java.pattern;
+  }
+
+  // https://stackoverflow.com/questions/16517689/java-regex-capturing-groups-indexes/16582083
+
+  public Pattern getPattern() {
+    return Pattern.compile(
+      Java.pattern
+        .entrySet()
+        .stream()
+        .map(e -> String.format("(?<%s>%s)", e.getValue(), e.getKey()))
+        .collect(Collectors.joining("|")));
+  }
+}

src/main/java/app/model/Model.java

@@ -1,7 +1,5 @@
 package app.model;
 
-import app.languages.Java;
-
 /**
  * Data model of the application
  */

src/main/java/app/service/LanguageOperations.java

@@ -0,0 +1,51 @@
+package app.service;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.regex.Matcher;
+
+import org.fxmisc.richtext.model.StyleSpans;
+import org.fxmisc.richtext.model.StyleSpansBuilder;
+
+import app.model.ProgrammingLanguage;
+
+public class LanguageOperations {
+  
+  private static String getMatch(Matcher m, Collection<String> kws) {
+    return kws
+      .stream()
+      .filter(keyword -> m.group(keyword) != null)
+      .findFirst()
+      .orElse(""); // This is not possible, but is needed to convert Optional<String> to String
+  }
+
+  public static StyleSpans<Collection<String>> 
+    syntaxHighlight(String text, ProgrammingLanguage language) {
+    Matcher matcher = language.getPattern().matcher(text);
+    StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
+
+    int lastKwEnd = 0;
+    while(matcher.find()) {
+      String styleClass = getMatch(matcher, language.getPatternMap().values());
+
+      spansBuilder.add(
+        Collections.emptyList(),
+        matcher.start() - lastKwEnd
+      );
+      spansBuilder.add(
+        Collections.singleton(styleClass),
+        matcher.end() - matcher.start()
+      );
+
+      lastKwEnd = matcher.end();
+    }
+
+    spansBuilder.add(
+      Collections.emptyList(),
+      text.length() - lastKwEnd
+    );
+
+    return spansBuilder.create();
+  }
+
+}