SW

v1.0.7 : Read changelog

A solution wiper for programming exercises. Strips solution code from files so students can complete them.

How it works

Mark solution code with paired comment markers. Running sw removes the content between each pair and replaces it with a language-appropriate placeholder (or nothing).

Requires fd for directory scanning. Respects .gitignore and .ignore files.

Markers

--sw-wipe-- — block wipe with placeholder

Content between a pair of --sw-wipe-- lines is removed and replaced with a placeholder:

• Rust: todo!();
• Java: throw new UnsupportedOperationException("TODO: replace me with your solution !");
• PHP / JS / TS: nothing (empty)

// Before
pub fn add(a: i32, b: i32) -> i32 {
    // --sw-wipe--
    a + b
    // --sw-wipe--
}

// After
pub fn add(a: i32, b: i32) -> i32 {
    todo!();
}

--sw-vanish-- — block wipe without placeholder

Like --sw-wipe-- but leaves no placeholder, even in Rust and Java. Useful for struct fields or enum variants where todo!() would be invalid syntax.

// Before
pub struct Point {
    // --sw-vanish--
    pub x: f32,
    pub y: f32,
    // --sw-vanish--
}

// After
pub struct Point {
}

/* --sw-- */ — inline wipe

Removes content between paired /* --sw-- */ markers on the same line. Multiple pairs per line are supported.

// Before
export function greet(name/* --sw-- */, greeting/* --sw-- */) { ... }

// After
export function greet(name, greeting) { ... }

Usage

sw [OPTIONS] [PATHS]...

Argument / Option	Default	Description
[PATHS]...	.	Directories or individual files to process
-e, --extensions <EXT>...	rs,php,js,ts,java	File extensions to scan
--dry-run	—	Validate marker pairing without modifying any files
--fd-bin-path <PATH>	fd	Override the fd binary name or path

Examples:

# Wipe solutions in the current directory
sw

# Wipe only a specific subdirectory
sw exercises/

# Wipe only Rust and TypeScript files
sw -e rs -e ts

# Wipe a single file
sw src/solution.rs

# Check for unpaired markers without touching files
sw --dry-run

# Use fdfind instead of fd (e.g. on Debian/Ubuntu)
sw --fd-bin-path fdfind

Validation

Before modifying any file, sw checks that every marker is properly paired. If an odd number of markers is found in any file, no files are modified and an error is reported listing each violation.

--dry-run runs this validation step only — useful in CI to ensure exercises are correctly annotated.