aegrep

aegrep is a small Rust command-line tool inspired by grep and the Rust Book's minigrep project. It searches for a pattern in one or more files and prints matching lines with colored, nicely formatted output.

This project is mainly a learning playground for:

• Error handling with custom enums and Result
• Module organization with main.rs, lib.rs, and multiple submodules
• Basic CLI argument parsing
• Simple text searching and line highlighting

Features

• Search for a pattern across one or more files
• Show matches as file:line:col line_content
• Highlight the matched pattern using terminal colors (via owo-colors)
• Custom error type (MyErrors) for argument and I/O errors
• Config struct with a simple builder-style method (with_quiet)

Usage

From the project root:

cargo run -- <pattern> <file> [more_files...]

Examples:

# Search for "fox" in poem.txt
cargo run -- fox poem.txt

# Search in multiple files
cargo run -- error src/main.rs src/lib.rs

If required arguments are missing, the program exits with a descriptive panic message.

Project Structure

src/
  main.rs    # entry point, calls CLI + search
  lib.rs     # library: search logic, single_search, etc.
  cli.rs     # parse_args(): builds Config, returns Result<Config, MyErrors>
  types.rs   # MyErrors enum + Config struct
  pretty.rs  # print_found(): colored, formatted output

• main.rs
  • Calls cli::parse_args() to get a Config
  • On success, calls aegrep::search(...)
• lib.rs
  • Exposes search(...) and wires together single_search, pretty, and errors
• types.rs
  • MyErrors: FileReadError(String), MissingArgsError, etc.
  • Config: { pattern, files, quiet } with Config::new and with_quiet
• pretty.rs
  • Uses owo-colors to highlight the pattern and format the output line

Building and Running

# Build
cargo build

# Run with arguments
cargo run -- pattern file1 [file2 ...]

Run with --release for an optimized binary:

cargo build --release

Future Ideas

• Add a --quiet or -q flag that hooks into Config::with_quiet
• Add case-insensitive search (e.g. --ignore-case)
• Add --line-number / --column toggles
• Add tests for parse_args, search, and matching logic

This project is primarily for learning Rust patterns around CLI tools, error handling, and module organization.