begin documenting some functions and align error messages

src/phases.rs

@@ -0,0 +1,38 @@
+use crate::actions;
+use crate::context::SproutContext;
+use anyhow::Context;
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+use std::rc::Rc;
+
+#[derive(Serialize, Deserialize, Default, Clone)]
+pub struct PhasesConfiguration {
+    #[serde(default)]
+    pub early: Vec<PhaseConfiguration>,
+    #[serde(default)]
+    pub startup: Vec<PhaseConfiguration>,
+    #[serde(default)]
+    pub late: Vec<PhaseConfiguration>,
+}
+
+#[derive(Serialize, Deserialize, Default, Clone)]
+pub struct PhaseConfiguration {
+    #[serde(default)]
+    pub actions: Vec<String>,
+    #[serde(default)]
+    pub values: BTreeMap<String, String>,
+}
+
+pub fn phase(context: Rc<SproutContext>, phase: &[PhaseConfiguration]) -> anyhow::Result<()> {
+    for item in phase {
+        let mut context = context.fork();
+        context.insert(&item.values);
+        let context = context.freeze();
+
+        for action in item.actions.iter() {
+            actions::execute(context.clone(), action)
+                .context(format!("unable to execute action '{}'", action))?;
+        }
+    }
+    Ok(())
+}