Macro chart 

macro_rules! chart {
    (&$ds:expr) => { ... };
    ($ds:expr) => { ... };
    ($( $(&)? $col:ident ),+ $(,)?) => { ... };
    (@parse_col $res:ident, &$name:ident) => { ... };
    (@parse_col $res:ident, $name:ident) => { ... };
}

A convenience macro to initialize a [Chart] with data.

The chart! macro supports two primary usage patterns:

1. Direct Variable Mapping (Auto-Stringify)

Pass one or more local variables. The macro will automatically use the variable names as column names in the underlying [Dataset].

let x = vec![1.0, 2.0, 3.0];
let y = vec![10.0, 20.0, 30.0];

// This creates a Dataset with columns "x" and "y"
chart!(x, y)?
    .mark_point()?
    .encode((alt::x("x"), alt::y("y")))?
    .save("out.svg")?;

2. Existing Dataset

Pass a pre-constructed [Dataset] directly into the macro.

let ds = get_data_from_source()?;
chart!(ds)?
    .mark_line()?
    .encode((alt::x("x"), alt::y("y")))?
    .save("out.svg")?;

Errors

Returns [ChartonError::Data] if the provided variables have inconsistent row lengths when building a new dataset.

Panics

The macro itself does not panic, but it propagates errors via the ? operator.