Trie-Based Spell Checker

This project implements a spell checker using a prefix tree (Trie). The program processes three text files to build a dictionary, filter out words, and verify a text file's words against the dictionary.

Description

The program takes three file paths as command-line arguments:

1. Dictionary file: Contains the initial list of words for the dictionary.
2. Filter file: Specifies words to be removed from the dictionary.
3. Text file: Contains the text to be checked against the filtered dictionary.

How It Works

This program processes three input files to perform dictionary management and spell-checking:

1. Load Words into a Trie:

   • Reads words from the dictionary file and inserts them into a Trie structure.
   • Ignores case (e.g., abc and ABC are treated as the same word).
   • Skips invalid entries (e.g., lines containing spaces, numbers, or special characters).
   • Handles duplicate words gracefully by storing only one instance.

2. Filter Words:

   • Reads words from the filter file and removes them from the Trie.
   • Case-insensitivity ensures both abc and ABC are removed as the same word.
   • Skips invalid entries while reporting errors.
   • Accounts for duplicates, ensuring only one removal per word.

3. Check Text File:

   • Reads the text file line by line.
   • Splits lines into words using whitespace as a delimiter.
   • Checks each word against the Trie.
   • Reports words that are not found in the Trie as spelling errors.

4. Generate Summary Statistics:

   • Reports the total number of valid and invalid entries in the dictionary file.
   • Reports the total number of valid and invalid entries in the filter file.
   • Displays the number of words successfully removed from the Trie.
   • Outputs the final count of words remaining in the dictionary.
   • Counts and reports correct and incorrect words in the text file.

Features

• Case-insensitive: Treats uppercase and lowercase letters as equivalent.
• Validation: Reports invalid entries in the dictionary and filter files.
• Error Reporting: Identifies words in the text file that do not exist in the final dictionary.
• Statistics:
  • Number of valid and invalid entries in the dictionary.
  • Number of valid and invalid entries in the filter file.
  • Total words removed from the dictionary.
  • Final dictionary size.
  • Number of correct and incorrect words in the text file.

Assumptions

• Words consist only of English letters (a–z).
• Invalid entries (e.g., containing spaces, numbers, or symbols) are skipped, but processing continues.
• Comment lines (starting with #) and empty lines are ignored.
• Duplicate entries are treated as a single word during processing.

Input File Formats

Dictionary file

Each word is on a separate line. Lines starting with # are comments. Empty lines are ignored.

Filter file

Similar as the dictionary file. Specifies words to be removed from the dictionary.

Text file

Contains one or more lines of text. Words are separated by whitespace.

Example with the sample-inputs

Loading dictionary from .\input\dictionary.txt...
ERROR: incorrect entry "This is an incorrect entry, it has spaces." on line 8
ERROR: incorrect entry " spaceOnTheLeft" on line 9
ERROR: incorrect entry "spaceOnTheRight " on line 10
ERROR: incorrect entry "an0ther1ncorrectW0rd" on line 11

Removing the words listed at .\input\filter.txt...
ERROR: incorrect entry "1234567890" on line 3

Verifying the contents of .\input\text.txt...
SPELLING ERROR: "abc" on line 1
SPELLING ERROR: "abbcd" on line 1
SPELLING ERROR: "xyz" on line 1
SPELLING ERROR: "an0ther1ncorrectW0rd" on line 2

Statistics:
    Dictionary entries: 7 correct, 4 incorrect
        Filter entries: 2 correct, 1 incorrect
  Resultant dictionary: 6
         Words in text: 2 correct, 4 incorrect