Add matrix_map and keymap/layers config proc-macro

[HaoboGu]

Now defining keymap and layout in Rust code is cumbersome. An approach is to reuse the matrix_map and layers parsing, add a proc-macro for defining keymap in Rust code, like:

// keymap.rs

const KEYMAP: [[[KeyAction; COL]; ROW]; NUM_LAYER] = keymap! {
    matrix_map: "
        (0,0) (0,1) (0,2)
        (1,0) (1,1) (1,2)
    ",

    layers: [
        {
            layer: 0,
            name: "base_layer",
            layout: "
                A B C
                D E F
            "
        },
        {
            layer: 1,
            name: "fn_layer",
            layout: "
                F1 F2 F3
                F4 F5 F6
            "
        }
    ]
}

// Alternative
const KEYMAP: [[[KeyAction; COL]; ROW]; NUM_LAYER] = keymap! {
    matrix_map: "
        (0,0) (0,1) (0,2)
        (1,0) (1,1) (1,2)
    "

    layer(layer = 0, name = "base_layer"): "
        A B C
        D E F
    "

    layer(layer = 1, name = "fn_layer"): "
        F1 F2 F3
        F4 F5 F6
    "
}

[hitsmaxft]

Personally, i perfer generating this part from a keyboard toml file

Since programming matrix map or keymap is rarely needed

[HaoboGu]

Personally, i perfer generating this part from a keyboard toml file

Since programming matrix map or keymap is rarely needed

That's out-of-the-scope of this issue. Projects using Rust code doesn't need keyboard.toml

[hitsmaxft]

Personally, i perfer generating this part from a keyboard toml file
Since programming matrix map or keymap is rarely needed

That's out-of-the-scope of this issue. Projects using Rust code doesn't need keyboard.toml

Yep, but what i means isn' t a complete keyboard.toml, but a file that provides martrix_map and keymap parts.
I think is would be easier for maintaining.
But if this still needs code generation? I don't know if parsing while bootstrap device will cause to much

[HaoboGu]

Yep, but what i means isn' t a complete keyboard.toml, but a file that provides martrix_map and keymap parts.
I think is would be easier for maintaining.

The proc-macro uses in Rust code will reuse the code of parsing matrix_map and layers in keyboard.toml, so it doesn't increase much maintenance work -- just provide an extra API configuring keymap for Rust code users.

But if this still needs code generation? I don't know if parsing while bootstrap device will cause to much

All the work will be done at the compile-time, there's no cost on keyboard.