Derive macros for rcman settings library.

This crate provides #[derive(SettingsSchema)] for automatically generating settings schema implementations from Rust structs. It translates strongly-typed native Rust definitions directly into runtime rcman::SettingMetadata, preventing bugs and ensuring absolute schema correctness via compile-time semantic validation.

Features

Native Type Binding: Automatically translates String, PathBuf, integers, floats, bool, and Vec<T> into their corresponding rcman::SettingType.
Strict Verification: The macro prevents contradictory constraints at compile time (e.g. min > max or options on bool).
Dynamic UI Metadata: Every unknown attribute literal (e.g., label = "Server") is automatically injected into the schema as customizable metadata.
#[cfg] Forwarding: Safely obeys macro feature flags attached to struct fields.

Usage

use rcman::DeriveSettingsSchema as SettingsSchema;
use serde::{Serialize, Deserialize};

#[derive(SettingsSchema, Default, Serialize, Deserialize)]
#[schema(category = "network")] // Required: sets the root prefix for the UI
struct NetworkSettings {
    #[setting(rename = "server-auth-port")]
    pub port: u16,

    #[setting(rename = "enable_tls")]
    pub tls: bool,

    #[setting(rename = "server-url")]
    pub url: String,
    
    pub roles: Vec<String>,
}

fn main() {}

Attribute Reference

Container Attributes (`#[schema(...)]`)

Apply these directly to the struct.

Attribute	Description	Required	Example
`category`	The root grouping prefix used for all fields.	Yes	`#[schema(category = "general")]`

Field Attributes (`#[setting(...)]`)

Apply these to individual struct fields.

Attribute	Type Mapping	Description	Example
`rename`	All	Overrides the field name when constructing the schema key (`category.rename`)	`#[setting(rename = "App-Theme")]`
`skip`	All	Silently ignores the field; it will not appear in the settings schema	`#[setting(skip)]`
`secret`	All	Asserts the field contains sensitive data, diverting it to the OS Keychain backing	`#[setting(secret)]`
`category`	All	Overrides the container `category` specifically for this single field	`#[setting(category = "overridden")]`
`nested`	Structs	Extracts the schema from an inner struct and flattens it upward	`#[setting(nested)]`
`min`	Number	Sets a numeric minimum constraint (must be `<= max`)	`#[setting(min = 1.0)]`
`max`	Number	Sets a numeric maximum constraint (must be `>= min`)	`#[setting(max = 100.0)]`
`step`	Number	Defines valid increment stepping	`#[setting(step = 5.0)]`
`pattern`	Text	Enforces standard Regex validation string	`#[setting(pattern = "^[a-z]+$")]`
`options`	Text/Num	Enforces strict dropdown alternatives mappings	`#[setting(options(("val", "Label")))]`

Dynamic Metadata

Any key = value assignment in #[setting(...)] that isn't functionally reserved above is transparently forwarded into the resulting SettingMetadata map for your UI components to access dynamically.

use rcman::DeriveSettingsSchema as SettingsSchema;
use serde::{Serialize, Deserialize};

#[derive(SettingsSchema, Default, Serialize, Deserialize)]
#[schema(category = "network")]
struct ServerSettings {
    #[setting(
        min = 1024,                  // 1. Reserved constraint
        label = "Server Port",       // 2. -> .meta_str("label", "Server Port")
        order = 1,                   // 3. -> .meta_num("order", 1)
        advanced = false             // 4. -> .meta_bool("advanced", false)
    )]
    pub port: u16,
}

fn main() {}

Panics

This macro performs completely safe compile-time error reporting (yielding syn::Error) returning targeted IDE-friendly error underlines instead of panicking. It blocks:

Setting min/max/step on non-numeric types (bool, Vec, String).
Setting pattern on non-Text types (bool, Vec, i32).
Unknown/Unsupported types missing #[setting(skip)] (e.g. Duration or HashMap) so that you never accidentally leak invalid config metadata to the UI.

rcman-derive 0.1.6