Start experimenting with lanterna

src/main/LispMain.java

@@ -3,6 +3,7 @@ package main;
 import java.util.function.Function;
 
 import interpreter.*;
+import terminal.LispTerminal;
 
 public class LispMain {
 
@@ -15,8 +16,12 @@ public class LispMain {
     private LispMain() {}
 
     public static void main(String[] args) {
-        LispInterpreter interpreter = buildInterpreter(args);
-        interpreter.interpret();
+        LispTerminal terminal = new LispTerminal();
+
+        terminal.run();
+
+        // LispInterpreter interpreter = buildInterpreter(args);
+        // interpreter.interpret();
     }
 
     private static LispInterpreter buildInterpreter(String[] args) {

src/terminal/LispTerminal.java

@@ -0,0 +1,137 @@
+package terminal;
+
+import java.io.IOException;
+
+import com.googlecode.lanterna.TerminalPosition;
+import com.googlecode.lanterna.input.*;
+import com.googlecode.lanterna.terminal.*;
+
+public class LispTerminal implements Runnable {
+
+    private IOSafeTerminal terminal;
+    private boolean isFinished;
+    private String currentLine;
+
+    public LispTerminal() {
+        try {
+            Terminal unsafe = new DefaultTerminalFactory().createTerminal();
+            this.terminal = IOSafeTerminalAdapter.createRuntimeExceptionConvertingAdapter(unsafe);
+        } catch (IOException e) {
+            // TODO
+            e.printStackTrace();
+        }
+
+        this.isFinished = false;
+        this.currentLine = "";
+    }
+
+    public void run() {
+        while (!isFinished) {
+            handleKeyStroke(getKeyStroke());
+            terminal.flush();
+        }
+
+        terminal.close();
+    }
+
+    private KeyStroke getKeyStroke() {
+        KeyStroke keyStroke = null;
+
+        try {
+            keyStroke = terminal.readInput();
+        } catch (IllegalStateException e) {
+            // TODO - lantera is trying to exit private mode on ctrl-c (which we didn't enter)
+            terminal.putCharacter('`');
+            isFinished = true;
+        }
+
+        return keyStroke;
+    }
+
+    private void handleKeyStroke(KeyStroke keyStroke) {
+        if (keyStroke == null)
+            return;
+
+        KeyType keyType = keyStroke.getKeyType();
+
+        if (keyType == KeyType.ArrowLeft)
+            moveCursorLeft();
+        else if (keyType == KeyType.ArrowRight)
+            moveCursorRight();
+        else if (keyType == KeyType.Enter)
+            doEnter();
+        else if (keyType == KeyType.Backspace)
+            doBackspace();
+        else if (keyType == KeyType.Delete)
+            doDelete();
+        else if (keyType == KeyType.Character)
+            doCharacter(keyStroke);
+    }
+
+    private void doEnter() {
+        terminal.putCharacter('\n');
+        currentLine = "";
+    }
+
+    private void moveCursorLeft() {
+        TerminalPosition cursorPosition = terminal.getCursorPosition();
+        terminal.setCursorPosition(cursorPosition.withRelativeColumn(-1));
+    }
+
+    private void moveCursorRight() {
+        TerminalPosition cursorPosition = terminal.getCursorPosition();
+
+        if (cursorPosition.getColumn() < currentLine.length())
+            terminal.setCursorPosition(cursorPosition.withRelativeColumn(1));
+    }
+
+    private void doBackspace() {
+        TerminalPosition cursorPosition = terminal.getCursorPosition();
+
+        if (cursorPosition.getColumn() > 0) {
+            String remaining = currentLine.substring(cursorPosition.getColumn(), currentLine.length());
+            currentLine = currentLine.substring(0, cursorPosition.getColumn() - 1) + remaining;
+            terminal.setCursorPosition(cursorPosition.withRelativeColumn(-1));
+
+            for (char c : remaining.toCharArray())
+                terminal.putCharacter(c);
+
+            terminal.putCharacter(' ');
+            terminal.setCursorPosition(cursorPosition.withRelativeColumn(-1));
+        }
+    }
+
+    private void doDelete() {
+        TerminalPosition cursorPosition = terminal.getCursorPosition();
+
+        if (cursorPosition.getColumn() < currentLine.length()) {
+            String remaining = currentLine.substring(cursorPosition.getColumn() + 1, currentLine.length());
+            currentLine = currentLine.substring(0, cursorPosition.getColumn()) + remaining;
+
+            for (char c : remaining.toCharArray())
+                terminal.putCharacter(c);
+
+            terminal.putCharacter(' ');
+            terminal.setCursorPosition(cursorPosition);
+        }
+    }
+
+    private void doCharacter(KeyStroke keyStroke) {
+        TerminalPosition cursorPosition = terminal.getCursorPosition();
+
+        if (cursorPosition.getColumn() < currentLine.length()) {
+            String remaining = keyStroke.getCharacter()
+                               + currentLine.substring(cursorPosition.getColumn(), currentLine.length());
+            currentLine = currentLine.substring(0, cursorPosition.getColumn()) + remaining;
+
+            for (char c : remaining.toCharArray())
+                terminal.putCharacter(c);
+
+            terminal.setCursorPosition(cursorPosition.withRelativeColumn(1));
+        } else {
+            terminal.putCharacter(keyStroke.getCharacter());
+            currentLine += keyStroke.getCharacter();
+        }
+    }
+
+}