deboog-derive 0.3.0

# deboog

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Derive macro for extended debug formatting.

Currently allows skipping fields and masking field values using various strategies, with more to follow.

## Basic usage

Skip serializing a field:

```rust
use deboog::Deboog;

#[derive(Deboog)]
struct Data {
    shown: i32,
    #[deboog(skip)]
    skipped: i32,
}

assert_eq!(
    format!("{:?}", Data { shown: 123, skipped: 234 }),
    r#"Data { shown: 123 }"#
);
```

Also works with tuple structs:

```rust
use deboog::Deboog;

#[derive(Deboog)]
struct Data(i32, #[deboog(skip)] i32);

assert_eq!(
    format!("{:?}", Data(123, 234)),
    r#"Data(123)"#
);
```

And in enums too:

```rust
use deboog::Deboog;

#[derive(Deboog)]
enum Data {
    One,
    Two {
        shown: i32,
        #[deboog(skip)]
        skipped: i32,
    },
}

assert_eq!(
    format!("{:?}", Data::Two { shown: 123, skipped: 234 }),
    r#"Two { shown: 123 }"#
);
```

## Masking

Mask a field:

```rust
use deboog::Deboog;

#[derive(Deboog)]
struct Data {
    unmasked: i32,
    #[deboog(mask = "all")]
    masked: i32,
}

assert_eq!(
    format!("{:?}", Data { unmasked: 123, masked: 23456 }),
    r#"Data { unmasked: 123, masked: ***** }"#
);
```

Mask a credit card number or a similar value:

```rust
use deboog::Deboog;

#[derive(Deboog)]
struct Data {
    unmasked: &'static str,
    #[deboog(mask = "pan")]
    masked: &'static str,
}

assert_eq!(
    format!("{:?}", Data { unmasked: "1111222233334444", masked: "1111222233334444" }),
    r#"Data { unmasked: "1111222233334444", masked: "111122******4444" }"#
);
```

In case you need to hide real field length:

```rust
use deboog::Deboog;

#[derive(Deboog)]
struct Data {
    unmasked: i32,
    #[deboog(mask = "hidden")]
    masked: i32,
}

assert_eq!(
    format!("{:?}", Data { unmasked: 123, masked: 23456 }),
    r#"Data { unmasked: 123, masked: *** }"#
);
```

## Type support

Support for masking for custom field types can be implemented using [`field::DeboogField`] trait:

```rust
use deboog::{Deboog, DeboogField, MaskType};

#[derive(Deboog)]
struct What;

impl DeboogField for What {
    fn fmt_masked(&self, f: &mut std::fmt::Formatter<'_>, _mask_type: MaskType) -> std::fmt::Result {
        write!(f, "WHAT?")
    }
}

#[derive(Deboog)]
struct Data {
    unmasked: What,
    #[deboog(mask = "all")]
    masked: What,
}

assert_eq!(
    format!("{:?}", Data { unmasked: What, masked: What }),
    r#"Data { unmasked: What, masked: WHAT? }"#
);
```

## Optional features

List of feature flags supported by this crate:

- `chrono`: support date/time types from chrono library.

## Version history

See [change log](CHANGELOG.md).

## License

Licensed under either of [Apache License, Version 2.0](LICENSE-APACHE) or
[MIT license](LICENSE-MIT) at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall
be dual licensed as above, without any additional terms or conditions.