sourceafIocConfig::ConfigProvider.fan

** Implement to provide a new source of config properties.
** Instances should be contributed to 'ConfigSource':
** 
** pre>
** @Contribute { serviceType=ConfigSource# }
** Void contributeConfigSource(Configuration config) {
**     config["appConfig"] = ConfigProvider(`myConfig.props`.toFile)
** }
** <pre
** 
** Should you wish to use them for ordering your own providers, the default provider IDs that IocConfig contribute are:
**
**  - 'afIocConfig.factoryDefaults'
**  - 'afIocConfig.envVars'
**  - 'afIocConfig.configFile'
**  - 'afIocConfig.applicationDefaults'
** 
** See 'IocConfigModule' source for details.
**  
@Js
const mixin ConfigProvider {

    ** Returns the config properties.
    abstract Str:Obj config()
    
    ** Returns a simple 'ConfigProvider' implementation that returns properties from the given config file.
    ** May be used like a ctor:
    ** 
    **   syntax: fantom
    **   configProvider := ConfigProvider(`myConfig.props`.toFile)
    ** 
    ** An Err is thrown if 'checked' is 'true' and the file does not exist. 
    static new fromProps(File file, Bool checked := true) {
        if (file.exists.not)
            return !checked ? SimpleConfigProvider([:]) : (null ?: throw IOErr("File not found: ${file.normalize.osPath}"))
        return SimpleConfigProvider(file.readProps)
    }

    ** Returns a simple 'ConfigProvider' implementation that returns the given properties.
    ** May be used like a ctor:
    ** 
    **   syntax: fantom
    **   configProvider := ConfigProvider(["name":"value"])
    static new fromMap(Str:Obj map) {
        SimpleConfigProvider(map)
    }
    
    @NoDoc
    override Str toStr() {
        config.toStr
    }
}

@Js
internal const class SimpleConfigProvider : ConfigProvider {
    override const Str:Obj config
    
    new make(Str:Obj config) {
        this.config = config
    }
}