Implement proper errors for expression evaluation

... the hard way

src/files/commands.rs

@@ -201,49 +201,35 @@ impl Var {
     }
 }
 
-impl From<Weekday> for Var {
-    fn from(wd: Weekday) -> Self {
-        match wd {
-            Weekday::Monday => Self::Monday,
-            Weekday::Tuesday => Self::Tuesday,
-            Weekday::Wednesday => Self::Wednesday,
-            Weekday::Thursday => Self::Thursday,
-            Weekday::Friday => Self::Friday,
-            Weekday::Saturday => Self::Saturday,
-            Weekday::Sunday => Self::Sunday,
-        }
-    }
-}
-
 #[derive(Debug, Clone)]
 pub enum Expr {
     Lit(i64),
     Var(Var),
-    Paren(Box<Expr>),
+    Paren(Box<Spanned<Expr>>),
     // Integer-y operations
-    Neg(Box<Expr>),
-    Add(Box<Expr>, Box<Expr>),
-    Sub(Box<Expr>, Box<Expr>),
-    Mul(Box<Expr>, Box<Expr>),
-    Div(Box<Expr>, Box<Expr>),
-    Mod(Box<Expr>, Box<Expr>),
+    Neg(Box<Spanned<Expr>>),
+    Add(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Sub(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Mul(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Div(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Mod(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
     // Comparisons
-    Eq(Box<Expr>, Box<Expr>),
-    Neq(Box<Expr>, Box<Expr>),
-    Lt(Box<Expr>, Box<Expr>),
-    Lte(Box<Expr>, Box<Expr>),
-    Gt(Box<Expr>, Box<Expr>),
-    Gte(Box<Expr>, Box<Expr>),
+    Eq(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Neq(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Lt(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Lte(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Gt(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Gte(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
     // Boolean-y operations
-    Not(Box<Expr>),
-    And(Box<Expr>, Box<Expr>),
-    Or(Box<Expr>, Box<Expr>),
-    Xor(Box<Expr>, Box<Expr>),
+    Not(Box<Spanned<Expr>>),
+    And(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Or(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    Xor(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
 }
 
 #[derive(Debug)]
 pub struct FormulaSpec {
-    pub start: Option<Expr>, // None: *
+    pub start: Option<Spanned<Expr>>, // None: *
     pub start_delta: Option<Delta>,
     pub start_time: Option<Time>,
     pub end_delta: Option<Delta>,