chore(crates): introduce new config crate for sprout configuration

crates/config/src/lib.rs

@@ -0,0 +1,97 @@
+//! Sprout configuration descriptions.
+//! This crate provides all the configuration structures for Sprout.
+
+use crate::actions::ActionDeclaration;
+use crate::drivers::DriverDeclaration;
+use crate::entries::EntryDeclaration;
+use crate::extractors::ExtractorDeclaration;
+use crate::generators::GeneratorDeclaration;
+use crate::phases::PhasesConfiguration;
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+
+pub mod actions;
+pub mod drivers;
+pub mod entries;
+pub mod extractors;
+pub mod generators;
+pub mod phases;
+
+/// This is the latest version of the sprout configuration format.
+/// This must be incremented when the configuration breaks compatibility.
+pub const LATEST_VERSION: u32 = 1;
+
+/// The default timeout for the boot menu in seconds.
+pub const DEFAULT_MENU_TIMEOUT_SECONDS: u64 = 10;
+
+/// The Sprout configuration format.
+#[derive(Serialize, Deserialize, Debug, Default, Clone)]
+pub struct RootConfiguration {
+    /// The version of the configuration. This should always be declared
+    /// and be the latest version that is supported. If not specified, it is assumed
+    /// the configuration is the latest version.
+    #[serde(default = "latest_version")]
+    pub version: u32,
+    /// Default options for Sprout.
+    #[serde(default)]
+    pub options: OptionsConfiguration,
+    /// Values to be inserted into the root sprout context.
+    #[serde(default)]
+    pub values: BTreeMap<String, String>,
+    /// Drivers to load.
+    /// These drivers provide extra functionality like filesystem support to Sprout.
+    /// Each driver has a name which uniquely identifies it inside Sprout.
+    #[serde(default)]
+    pub drivers: BTreeMap<String, DriverDeclaration>,
+    /// Declares the extractors that add values to the sprout context that are calculated
+    /// at runtime. Each extractor has a name which corresponds to the value it will set
+    /// inside the sprout context.
+    #[serde(default)]
+    pub extractors: BTreeMap<String, ExtractorDeclaration>,
+    /// Declares the actions that can execute operations for sprout.
+    /// Actions are executable modules in sprout that take in specific structured values.
+    /// Actions are responsible for ensuring that passed strings are stamped to replace values
+    /// at runtime.
+    /// Each action has a name that can be referenced by other base concepts like entries.
+    #[serde(default)]
+    pub actions: BTreeMap<String, ActionDeclaration>,
+    /// Declares the entries that are displayed on the boot menu. These entries are static
+    /// but can still use values from the sprout context.
+    #[serde(default)]
+    pub entries: BTreeMap<String, EntryDeclaration>,
+    /// Declares the generators that are used to generate entries at runtime.
+    /// Each generator has its own logic for generating entries, but generally they intake
+    /// a template entry and stamp that template entry over some values determined at runtime.
+    /// Each generator has an associated name used to differentiate it across sprout.
+    #[serde(default)]
+    pub generators: BTreeMap<String, GeneratorDeclaration>,
+    /// Configures the various phases of sprout. This allows you to hook into specific parts
+    /// of the boot process to execute actions, for example, you can show a boot splash during
+    /// the early phase.
+    #[serde(default)]
+    pub phases: PhasesConfiguration,
+}
+
+/// Options configuration for Sprout, used when the corresponding options are not specified.
+#[derive(Serialize, Deserialize, Debug, Default, Clone)]
+pub struct OptionsConfiguration {
+    /// The entry to boot without showing the boot menu.
+    /// If not specified, a boot menu is shown.
+    #[serde(rename = "default-entry", default)]
+    pub default_entry: Option<String>,
+    /// The timeout of the boot menu.
+    #[serde(rename = "menu-timeout", default = "default_menu_timeout")]
+    pub menu_timeout: u64,
+    /// Enables autoconfiguration of Sprout based on the environment.
+    #[serde(default)]
+    pub autoconfigure: bool,
+}
+
+/// Get the latest version of the Sprout configuration format.
+pub fn latest_version() -> u32 {
+    LATEST_VERSION
+}
+
+fn default_menu_timeout() -> u64 {
+    DEFAULT_MENU_TIMEOUT_SECONDS
+}