file-editor

Clean, chain-friendly text-file editing for Rust • edition 2024

file-editor is a zero-dependency library that makes it painless to create, modify and query UTF-8 text files.
All mutating methods return &mut self, so edits compose naturally:

use file_editor::Editor;

fn main() -> std::io::Result<()> {
    Editor::create("notes.txt")?               // new file
        .append("Rust 🦀 is fun\n")
        .prepend("# My Notes\n")
        .insert_after("# My Notes", "========\n", true)
        .replace("fun", "blazingly fast")
        .save()?;                              // explicit flush
    Ok(())
}

Feature table

Verb	Method	Notes
Create / open	`Editor::create`, `Editor::open`
Rename	`rename`
Prepend / append	`prepend`, `append`
Insert before / after	`insert_before`, `insert_aftersame_indent` flag keeps indentation
Replace one marker	`replace_marker`
Search pattern	`find_lines` → 1-based line numbers
Erase, replace, mask	`erase`, `replace`, `mask`
Save to disk	`save`

Road-map → regex feature, streaming mode, companion CLI.

Install

cargo add file-editor          # latest on crates.io

Requires Rust 1.85 (edition 2024) or newer.

Workflow

Task	Command
Build	`cargo build`
Run all tests & doctests	`cargo test`
Format	`cargo fmt --all`
Lint (deny warnings)	`cargo clippy --all-targets -- -D warnings`
Coverage (HTML)	`cargo llvm-cov --workspace --open`(one-time `cargo install cargo-llvm-cov`)
Generate docs	`cargo doc --no-deps --open`

CI executes the same steps (see .github/workflows/ci.yml).

Runnable examples

All live in examples/ and write their output to examples/sandbox/ (ignored by git):

Example	Demonstrates
`basic.rs`	End-to-end mini workflow
`create.rs`	`create` + `append`
`open_rename.rs`	`open`, `rename`
`prepend.rs`, `append.rs`	header / footer insertion
`insert_before.rs`	block insertion above a marker
`insert_after.rs`	block insertion below a marker
`replace_marker.rs`	in-place marker replacement
`find_lines.rs`	pattern search
`erase.rs`	deleting fragments
`replace.rs`, `mask.rs`	global replacements / masking

Run any of them with:

cargo run --example insert_after

Contributing

Fork & clone
cargo fmt --check && cargo clippy --all-targets -- -D warnings
Add or update tests in tests/ (use the tempfile crate)
Open a PR describing what and why

All contributions are released under the MIT licence.

Licence

Licensed under the MIT License. See LICENSE.