Reorganize spec evaluation

src/eval/command/formula.rs

@@ -0,0 +1,84 @@
+use crate::files::commands::{self, Expr, Spanned, Time, Var};
+
+use super::super::command::CommandState;
+use super::super::delta::{Delta, DeltaStep};
+use super::super::Result;
+
+pub struct FormulaSpec {
+    // TODO Implement more efficient exprs and expr evaluation
+    pub start: Expr,
+    pub start_delta: Delta,
+    pub start_time: Option<Time>,
+    pub end_delta: Delta,
+}
+
+impl From<&commands::FormulaSpec> for FormulaSpec {
+    fn from(spec: &commands::FormulaSpec) -> Self {
+        let start: Expr = spec.start.as_ref().cloned().unwrap_or(Expr::Lit(1));
+
+        let start_delta: Delta = spec
+            .start_delta
+            .as_ref()
+            .map(|delta| delta.into())
+            .unwrap_or_default();
+
+        let mut end_delta: Delta = spec
+            .end_delta
+            .as_ref()
+            .map(|delta| delta.into())
+            .unwrap_or_default();
+        if let Some(time) = spec.end_time {
+            end_delta
+                .steps
+                .push(Spanned::new(time.span, DeltaStep::Time(time.value)));
+        }
+
+        Self {
+            start,
+            start_delta,
+            start_time: spec.start_time,
+            end_delta,
+        }
+    }
+}
+
+impl From<&commands::WeekdaySpec> for FormulaSpec {
+    fn from(spec: &commands::WeekdaySpec) -> Self {
+        let start = Expr::Eq(
+            Box::new(Expr::Var(Var::Weekday)),
+            Box::new(Expr::Var(spec.start.into())),
+        );
+
+        let mut end_delta = Delta::default();
+        if let Some(wd) = spec.end {
+            end_delta
+                .steps
+                .push(Spanned::new(wd.span, DeltaStep::Weekday(1, wd.value)));
+        }
+        if let Some(delta) = &spec.end_delta {
+            for step in &delta.0 {
+                end_delta
+                    .steps
+                    .push(Spanned::new(step.span, step.value.into()));
+            }
+        }
+        if let Some(time) = spec.end_time {
+            end_delta
+                .steps
+                .push(Spanned::new(time.span, DeltaStep::Time(time.value)));
+        }
+
+        Self {
+            start,
+            start_delta: Default::default(),
+            start_time: spec.start_time,
+            end_delta,
+        }
+    }
+}
+
+impl<'a> CommandState<'a> {
+    pub fn eval_formula_spec(&mut self, spec: FormulaSpec) -> Result<()> {
+        todo!()
+    }
+}