refactor: move TerminalHistory out of XTerm class

Author: javier-godoy

src/main/java/com/flowingcode/vaadin/addons/xterm/TerminalHistory.java

@@ -1,5 +1,6 @@
 package com.flowingcode.vaadin.addons.xterm;
 
+import com.vaadin.flow.component.ComponentUtil;
 import com.vaadin.flow.component.Key;
 import com.vaadin.flow.shared.Registration;
 import java.io.IOException;
@@ -33,8 +34,23 @@ public class TerminalHistory implements Serializable {
 
   private Integer maxSize;
 
-  public <T extends XTermBase & ITerminalConsole> TerminalHistory(T terminal) {
+  protected <T extends XTermBase & ITerminalConsole> TerminalHistory(T terminal) {
+    if (TerminalHistory.of(terminal) != null) {
+      throw new IllegalArgumentException("The terminal already has a history");
+    }
     this.terminal = terminal;
+    ComponentUtil.setData(terminal, TerminalHistory.class, this);
+  }
+
+  /** Returns the command history of the terminal. */
+  public static <T extends XTermBase & ITerminalConsole> TerminalHistory of(T xterm) {
+    return ComponentUtil.getData(xterm, TerminalHistory.class);
+  }
+
+  /** Adds support for command history to the given terminal. */
+  public static <T extends XTermBase & ITerminalConsole> void extend(XTerm xterm) {
+    TerminalHistory history = new TerminalHistory(xterm);
+    history.setEnabled(true);
   }
 
   /**

src/main/java/com/flowingcode/vaadin/addons/xterm/XTerm.java

@@ -29,18 +29,8 @@
 public class XTerm extends XTermBase
     implements ITerminalFit, ITerminalConsole, ITerminalClipboard {
 
-  private TerminalHistory history;
-
   public XTerm() {
     setInsertMode(true);
   }
 
-  /** Returns the terminal history. */
-  public TerminalHistory getHistory() {
-    if (history == null) {
-      history = new TerminalHistory(this);
-    }
-    return history;
-  }
-
 }

src/test/java/com/flowingcode/vaadin/addons/xterm/XtermDemoView.java

@@ -57,7 +57,7 @@ public XtermDemoView() {
     xterm.setPasteWithMiddleClick(true);
     xterm.setPasteWithRightClick(true);
 
-    xterm.getHistory().setEnabled(true);
+    TerminalHistory.extend(xterm);
 
     xterm.addLineListener(
         ev -> {
@@ -109,7 +109,7 @@ public XtermDemoView() {
   private void showHistory() {
     int index = 1;
     StringBuilder sb = new StringBuilder();
-    for (String line : xterm.getHistory().getLines()) {
+    for (String line : TerminalHistory.of(xterm).getLines()) {
       sb.append(String.format("%5s  %s\n", index++, line));
     }
     xterm.write(sb.toString());