Stack-Based Text Editor

This project was implemented without the use of any AI tools.

A console-based text editor implemented in Java that supports insert, delete, and replace operations with full undo/redo functionality using a dual-stack approach.

Features

• insert <text> <position> — inserts text starting at the given index
• delete <position> <length> — removes characters from position for given length
• replace <text> <position> <length> — replaces characters at position with new text
• undo — reverts the last operation
• redo — reapplies the last undone operation

How It Works

Two stacks (undoStack and redoStack) hold Action objects that store operation type, new text, old text, and position. Every edit pushes to undoStack and clears redoStack. Undo pops from undoStack, applies the inverse operation, and pushes to redoStack. Redo does the reverse.

Commands are read from actions.txt, one per line.

File Structure

File	Description
TextEditor.java	Core editor logic — insert, delete, replace, undo, redo
TextDriver.java	Reads actions.txt and drives the editor
Action.java	Stores metadata for each edit operation
Stack.java	Stack interface
LinkedStack.java	Linked-list-based stack implementation
SinglyLinkedList.java	Underlying singly linked list

Stack.java, LinkedStack.java, and SinglyLinkedList.java are from Data Structures and Algorithms in Java (Goodrich, Tamassia, Goldwasser).

Running

1. Place your commands in actions.txt in the project root.
2. Compile all .java files.
3. Run TextDriver.

javac *.java
java TextDriver

Example actions.txt

insert Hello 0
insert World 5
delete 5 1
undo
redo

Sample Output

Inserted: 'Hello' Between index 0 and 4
[H][e][l][l][o]

Inserted: ' World' Between index 5 and 10
[H][e][l][l][o][ ][W][o][r][l][d]

Deleted: ' ' Between index 5 and 5
[H][e][l][l][o][W][o][r][l][d]

Inserted: ',' Between index 5 and 5
[H][e][l][l][o][,][W][o][r][l][d]

Undo - Action: insert - New Text: null - Old Text: ,
[H][e][l][l][o][W][o][r][l][d]

Redo - Action: delete - New Text: , - Old Text: null
[H][e][l][l][o][,][W][o][r][l][d]

Replaced: Java, Between index 6 and 10
[H][e][l][l][o][,][J][a][v][a][ ]

Final Text: Hello,Java