turn slopes map into a vec to have multiple slopes for same variable, struct Compiler

src/compiler.rs

@@ -7,7 +7,7 @@ use std::{
 
 use derive_new::new;
 use derive_wrapper::{AsRef, From};
-use fasteval::{Compiler, EvalNamespace, Evaler, Instruction, Slab};
+use fasteval::{Compiler as _, EvalNamespace, Evaler, Instruction, Slab};
 use lazy_static::lazy_static;
 use thiserror::Error;
 
@@ -204,13 +204,13 @@ impl Type for Slope<'_> {
 
 impl Token for Slope<'_> {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
-        context.slopes.insert(self.0.0, self.0.1.clone());
+        context.slopes.push((self.0.0, self.0.1.clone()));
         context = self
             .1
             .0
             .iter()
             .try_fold(context, |context, t| t.apply(context))?;
-        context.slopes.remove(&self.0.0);
+        context.slopes.pop();
         Ok(context)
     }
 }
@@ -231,7 +231,6 @@ impl Clone for Expression {
     }
 }
 
-#[cfg(test)]
 impl PartialEq for Expression {
     fn eq(&self, other: &Self) -> bool {
         format!("{self:?}") == format!("{other:?}")
@@ -254,13 +253,16 @@ impl FromStr for Expression {
     }
 }
 
-#[derive(Clone)]
+#[derive(Clone, new)]
 #[cfg_attr(test, derive(Debug, PartialEq))]
 pub struct Context {
+    #[new(default)]
     pub result: Vec<f64>,
+    #[new(into_iter = "(char, f64)")]
     pub variables: HashMap<char, f64>,
     pub instrument: Expression,
-    pub slopes: HashMap<char, Expression>,
+    #[new(into_iter = "(char, Expression)")]
+    pub slopes: Vec<(char, Expression)>,
 }
 
 #[derive(Debug, Error)]
@@ -282,9 +284,19 @@ pub enum CompilerError {
 }
 
 impl Context {
-    pub fn current_length(&self) -> Result<f64, CompilerError> {
-        self.eval(self.get_slope('l').map_err(CompilerError::from)?)
-            .map_err(Into::into)
+    pub fn current_length(&mut self) -> Result<f64, CompilerError> {
+        *self = self
+            .get_slopes_for('L')
+            .map_err(CompilerError::from)?
+            .iter()
+            .try_fold(
+                self.clone(),
+                |mut acc, slope| -> Result<Context, CompilerError> {
+                    *acc.get_mut('L')? = self.eval(slope).map_err(Into::<CompilerError>::into)?;
+                    Ok(acc)
+                },
+            )?;
+        Ok(*self.get('L')?)
     }
 
     pub fn get(&self, name: char) -> Result<&f64, VariableNotFoundError> {
@@ -297,8 +309,17 @@ impl Context {
             .ok_or(VariableNotFoundError(name))
     }
 
-    pub fn get_slope(&self, name: char) -> Result<&Expression, SlopeNotFoundError> {
-        self.slopes.get(&name).ok_or(SlopeNotFoundError(name))
+    pub fn get_slopes_for(&self, var: char) -> Result<Vec<&Expression>, SlopeNotFoundError> {
+        let result: Vec<&Expression> = self
+            .slopes
+            .iter()
+            .filter_map(|(c, e)| (c == &var).then_some(e))
+            .collect();
+        if result.is_empty() {
+            return Err(SlopeNotFoundError(var));
+        } else {
+            Ok(result)
+        }
     }
 
     fn tick(&mut self) -> Result<(), CompilerError> {
@@ -383,15 +404,56 @@ impl Context {
             Ok(vec![0.0; (*self.get('t')? - curr_t) as usize])
         }
     }
+
+    pub fn finalize(self) -> Vec<f64> {
+        self.result
+    }
+}
+
+#[derive(From)]
+struct Compiler(Context);
+
+impl Compiler {
+    fn step(self, token: impl Token) -> Result<Self, CompilerError> {
+        token.apply(self.0).map(Into::into)
+    }
+    fn compile_all<'a>(
+        self,
+        tokens: impl IntoIterator<Item = impl Token>,
+    ) -> Result<Vec<f64>, CompilerError> {
+        tokens
+            .into_iter()
+            .try_fold(self, |acc, token| acc.step(token))
+            .map(|c| c.0)
+            .map(Context::finalize)
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use crate::compiler::Expression;
 
+    use super::Context;
+
     #[test]
     fn expression_is_clone() {
         let expr: Expression = "1 + 5 / x".parse().unwrap();
         assert_eq!(expr, expr.clone());
     }
+
+    fn context_generator() -> Context {
+        Context::new(
+            [
+                ('a', 5.0),
+                ('t', 0.0),
+                ('n', 0.0),
+                ('N', 12.0),
+                ('L', 0.0),
+                ('l', 4.0),
+                ('T', 60.0),
+            ],
+            "sin(2*PI*(442+442*((n+1)/N))*t)".parse().unwrap(),
+            [('L', "2^(2-log_2(l))*(60/T)")].map(|(c, e)| (c, e.parse().unwrap())),
+        )
+    }
 }