chaf – Not a finder. A filter.

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✨ What is chaf?

chaf is a text filtering tool with the following features:

1. Logical expressions for condition specification
2. Instead of "searching" like grep, it "excludes" specified lines
3. Supports standard input/output, making it pipe-friendly
4. Uses stdin when no input file is provided
5. Invert exclusion with --invert to act like grep
6. Display summary report with --report
7. Not as fast as grep, but can process ~10 million lines in a few seconds

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💡 Why was it created?

While grep -v is convenient, expressing complex exclusion rules becomes unreadable.
For example: "Exclude DEBUG, but keep [DEBUG] connect DB"
Such conditions are difficult to express clearly with grep.

chaf lets you write exclusion logic with logical expressions — a filter dedicated to exclusion.

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🖥️ Example Usage

## 🖥️ Example Usage

```bash
$ cat logs.txt
error: failed to connect
warn: deprecated API used
debug: retrying connection
info: connection established
warn: low disk space
error: timeout while waiting for response

# Lines containing "debug" or "warn" are excluded
$ chaf 'debug | warn' logs.txt
error: failed to connect
info: connection established
error: timeout while waiting for response

# Excludes:
# - Lines containing "debug"
# - Lines containing "warn" unless they also contain "API"
$ chaf 'debug | (warn & !API)' logs.txt
error: failed to connect
warn: deprecated API used
info: connection established
error: timeout while waiting for response
# Explanation:
# → "warn: low disk space" is excluded (no "API")
# → "warn: deprecated API used" is kept (contains "API")

# Invert mode: show only lines that match the condition
# Includes:
# - Lines containing "debug"
# - Lines containing "warn" unless they also contain "API"
$ chaf --invert 'debug | (warn & !API)' logs.txt
debug: retrying connection
warn: low disk space

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🚀 Installation

cargo install --git https://github.com/nakkiy/chaf

The chaf binary will be placed in:

$HOME/.cargo/bin/chaf

If your PATH doesn't include that directory, add it like so:

export PATH="$HOME/.cargo/bin:$PATH"

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✔ Command-Line Interface

chaf [OPTIONS] <QUERY> [FILE]

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📝 Query DSL (Logical Filter Language)

Syntax	Meaning
aaa & bbb	AND — match lines containing both aaa and bbb (exclude)
aaa | bbb	OR — match lines containing either aaa or bbb (exclude)
!aaa	NOT — match lines not containing aaa (exclude)
(aaa | bbb), (aaa & bbb)	Use parentheses to group and control precedence

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Operator Precedence

1. Parentheses "()"
2. NOT "!"
3. AND "&"
4. OR "|"

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🎛️ Available Options

Option	Description
--report, -r	Show summary: total lines, excluded lines, output lines
--invert, -i	Invert filter to show matching lines only (like grep)
--help, -h	Show help message
--version, -v	Show version information

Tip: You can redirect output to a file with > if needed.

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🙌 Contributing

Contributions for improvements or feature expansions are very welcome!
Feel free to open an issue or PR if you have any feedback or suggestions —
no matter how small, we'd love to hear from you.

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🔮 Planned Features

1. Wildcard support (*, ?) for more flexible pattern matching

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✅ License

This project is dual-licensed under:

• MIT License
  https://opensource.org/licenses/MIT
• Apache License 2.0
  https://www.apache.org/licenses/LICENSE-2.0

Use whichever license suits your needs.