NumberModel with Command Pattern

Command.java

/*
 * Copyright (c) 2014. BlueSkyFish <blueskyfish@kirchnerei.de>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package kirchnerei.number.model;

/**
 * Interface for a command
 */
public interface Command {

	/**
	 * Executes the command
	 */
	void doIt();

	/**
	 * Undo the command
	 */
	void undo();

	/**
	 * Creates a exact copy from the command with a new cursor position.
	 *
	 * @param cursor the new cursor position
	 * @return a copy of the command
	 */
	Command clone(int cursor);
}

DeleteCommand.java

/*
 * Copyright (c) 2014. BlueSkyFish <blueskyfish@kirchnerei.de>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package kirchnerei.number.model;

/**
 * Deletes an sign on the cursor position.
 */
public class DeleteCommand implements Command {

	private final StringBuilder text;

	private final int cursor;

	private char sign;

	public DeleteCommand(int cursor, StringBuilder text) {
		this.text = text;
		this.cursor = cursor;
	}

	@Override
	public void doIt() {
		int start = cursor - 1;
		sign = text.charAt(start);
		text.deleteCharAt(start);
	}

	@Override
	public void undo() {
		text.insert(cursor - 1, sign);
	}

	@Override
	public Command clone(int cursor) {
		return new DeleteCommand(cursor, text);
	}
}

InsertCommand.java

/*
 * Copyright (c) 2014. BlueSkyFish <blueskyfish@kirchnerei.de>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package kirchnerei.number.model;

/**
 *  Insert a digit sign.
 */
public class InsertCommand implements Command {

	private final char sign;

	private final int cursor;

	private final StringBuilder text;

	public InsertCommand(char sign, int cursor, StringBuilder text) {
		this.sign = sign;
		this.cursor = cursor;
		this.text = text;
	}

	@Override
	public void doIt() {
		text.insert(cursor, sign);
	}

	@Override
	public void undo() {
		text.deleteCharAt(cursor);
	}

	@Override
	public Command clone(int cursor) {
		return new InsertCommand(sign, cursor, text);
	}
}

NumberModel.java

/*
 * Copyright (c) 2014. Mulder3 BlueSkyFish <blueskyfish@kirchnerei.de>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package kirchnerei.number.model;

import java.util.Stack;

/**
 * The number model contains a string with digit signs. Also an undo stack is available.
 */
public class NumberModel {

	private static final int DEFAULT_CAPACITY = 32;

	private final Stack<Command> commands;

	private final StringBuilder text;

	private int cursor = 0;

	public NumberModel() {
		this(DEFAULT_CAPACITY);
	}

	public NumberModel(int capacity) {
		this.commands = new Stack<Command>();
		this.text = new StringBuilder(capacity);
	}

	public NumberModel(String template, int capacity) {
		this(capacity);
		this.setTemplate(template);
	}

	/**
	 * Set the template into the internal text. Only digit signs will be insert.
	 *
	 * @param template the template (e.g: "27.08.2012")
	 */
	public final void setTemplate(String template) {
		text.setLength(0);
		for (char ch : template.toCharArray()) {
			if (Character.isDigit(ch)) {
				text.append(ch);
			}
		}
	}

	/**
	 * Move the cursor to the given position. If the new position is outside of the range, then correct the position.
	 *
	 * @param cursor the new position
	 */
	public void cursorMove(int cursor) {
		this.cursor = cursor;
		adjustCursorPosition();
	}

	/**
	 * Returns the current position
	 * @return the position
	 */
	public int getCursorPosition() {
		return cursor;
	}

	/**
	 * Insert the digit sign at the cursor position.
	 *
	 * @param sign the digit
	 * @return the current cursor position after insert, or -1 when the sign is not a digit
	 */
	public int insert(char sign) {
		if (Character.isDigit(sign)) {

			InsertCommand cmd = new InsertCommand(sign, cursor, text);
			commands.push(cmd);
			cmd.doIt();
			cursor++;
			adjustCursorPosition();
			return cursor;
		}
		return -1;
	}

	/**
	 * Delete the sign on the current cursor position. If the cursor is on the position 0 then returns -1.
	 *
	 * @return the current cursor position after deleting (may be the same position as before), or -1 if the cursor is at 0.
	 */
	public int delete() {
		if (cursor > 0) {

			DeleteCommand cmd = new DeleteCommand(cursor, text);
			commands.push(cmd);
			cmd.doIt();
			adjustCursorPosition();
			return cursor;
		}
		return -1;
	}

	/**
	 * Takes the last change and update the text again.
	 *
	 * @return the current cursor position or -1 when the command stack is empty.
	 */
	public int repeat() {
		if (!commands.isEmpty()) {
			Command cmd = commands.peek();
			Command repCmd = cmd.clone(cursor);
			commands.push(repCmd);
			repCmd.doIt();
			if (repCmd instanceof InsertCommand) {
				cursor++;
			}
			adjustCursorPosition();
			return cursor;
		}
		return -1;
	}

	/**
	 * Undo the last change.
	 */
	public int undo() {
		if (!commands.isEmpty()) {
			Command cmd = commands.pop();
			cmd.undo();
			adjustCursorPosition();
			return cursor;
		}
		return -1;
	}

	@Override
	public String toString() {
		return text.toString();
	}

	/**
	 * Copy the digit text into a template. If the sign in the template is <code>#</code> then set the sign from
	 * the digit text.
	 *
	 * <pre><code>
	 *
	 * NumberModel model = new NumberModel();
	 *
	 * model.insert("2");
	 * model.insert("1");
	 * model.insert("0");
	 * model.insert("8");
	 * model.insert("2");
	 * model.insert("0");
	 * model.insert("1");
	 * model.insert("4");
	 *
	 * assertEquals("21082014", model.toString());
	 *
	 * assertEquals("21.08.2014", model.toString("##.##.####"));
	 *
	 * </code></pre>
	 *
	 * @param template the template
	 * @return the merged text.
	 */
	public String toString(String template) {
		StringBuilder sb = new StringBuilder(template);
		int index = 0;
		for (int i = 0; i < template.length() && index < text.length() ; i++) {
			char ch = sb.charAt(i);
			if (ch == '#') {
				char sign = text.charAt(index++);
				sb.deleteCharAt(i).insert(i, sign);
			}
		}
		return sb.toString();
	}

	private void adjustCursorPosition() {
		if (cursor < 0) {
			cursor = 0;
		}
		if (cursor > text.length()) {
			cursor = text.length();
		}
	}
}