🙃

src/evaluator.rs

@@ -1,8 +1,10 @@
+use crate::cell::{Cell, CellRef};
 use crate::parser::*;
 use crate::tokenizer::Literal;
+use std::collections::HashMap;
 use std::fmt;
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub enum Eval {
     Literal(Literal),
     Expr(Expr),
@@ -17,25 +19,70 @@ impl fmt::Display for Eval {
     }
 }
 
-pub fn _evaluate(expr: &mut Expr) -> Result<Eval, String> {
-    let res = match expr {
-        Expr::Literal(lit) => Eval::Literal(lit.clone()),
-        Expr::Infix { op, lhs, rhs } => {
-            let lval = _evaluate(lhs)?;
-            let rval = _evaluate(rhs)?;
+pub struct Evaluator {
+    cells: HashMap<CellRef, Cell>,
+}
 
-            match op {
-                InfixOp::ADD => eval_add(&lval, &rval)?,
-                InfixOp::SUB => eval_sub(&lval, &rval)?,
-                InfixOp::MUL => eval_mul(&lval, &rval)?,
-                InfixOp::DIV => eval_div(&lval, &rval)?,
-                _ => return Err(format!("Evaluation error: Unsupported operator {:?}", op)),
-            }
+impl Evaluator {
+    pub fn new() -> Evaluator {
+        return Evaluator {
+            cells: HashMap::new(),
+        };
+    }
+
+    pub fn set_cell(&mut self, cell_ref: CellRef, raw_val: String) -> Result<(), String> {
+        if self.cells.contains_key(&cell_ref) && self.cells[&cell_ref].raw() == raw_val {
+            return Ok(());
         }
-        it => return Err(format!("Evaluation error: Unsupported expression {:?}", it)),
-    };
 
-    Ok(res)
+        let mut eval: Option<Eval> = None;
+        if let Some(c) = raw_val.chars().nth(0)
+            && c == '='
+        {
+            if let Ok(e) = self.evaluate(raw_val[1..].to_owned()) {
+                eval = Some(e);
+            };
+        }
+
+        self.cells.insert(cell_ref, Cell::new(eval, raw_val));
+        Ok(())
+    }
+
+    pub fn get_cell(&mut self, cell_ref: CellRef) -> Result<(String, Option<Eval>), String> {
+        if !self.cells.contains_key(&cell_ref) {
+            return Err(format!("Cell at {:?} not found.", cell_ref));
+        }
+
+        let cell = &self.cells[&cell_ref];
+
+        Ok((cell.raw(), cell.eval()))
+    }
+
+    pub fn evaluate(&self, str: String) -> Result<Eval, String> {
+        let mut expr = parse(&str)?;
+        self.evaluate_expr(&mut expr)
+    }
+
+    fn evaluate_expr(&self, expr: &mut Expr) -> Result<Eval, String> {
+        let res = match expr {
+            Expr::Literal(lit) => Eval::Literal(lit.clone()),
+            Expr::Infix { op, lhs, rhs } => {
+                let lval = self.evaluate_expr(lhs)?;
+                let rval = self.evaluate_expr(rhs)?;
+
+                match op {
+                    InfixOp::ADD => eval_add(&lval, &rval)?,
+                    InfixOp::SUB => eval_sub(&lval, &rval)?,
+                    InfixOp::MUL => eval_mul(&lval, &rval)?,
+                    InfixOp::DIV => eval_div(&lval, &rval)?,
+                    _ => return Err(format!("Evaluation error: Unsupported operator {:?}", op)),
+                }
+            }
+            it => return Err(format!("Evaluation error: Unsupported expression {:?}", it)),
+        };
+
+        Ok(res)
+    }
 }
 
 fn eval_add(lval: &Eval, rval: &Eval) -> Result<Eval, String> {
@@ -59,16 +106,43 @@ fn eval_add(lval: &Eval, rval: &Eval) -> Result<Eval, String> {
 }
 
 fn eval_sub(lval: &Eval, rval: &Eval) -> Result<Eval, String> {
-    Err("Todo.".to_string())
+    match (lval, rval) {
+        (Eval::Literal(a), Eval::Literal(b)) => {
+            if let Some(res) = eval_numeric_infix(a, b, |x, y| x - y, |x, y| x - y) {
+                return Ok(Eval::Literal(res));
+            }
+
+            Err("Evaluation error: expected string or numeric types for SUB function.".to_string())
+        }
+        _ => return Err("Evalutation error: expected literals for SUB function.".to_string()),
+    }
 }
 fn eval_mul(lval: &Eval, rval: &Eval) -> Result<Eval, String> {
-    Err("Todo.".to_string())
+    match (lval, rval) {
+        (Eval::Literal(a), Eval::Literal(b)) => {
+            if let Some(res) = eval_numeric_infix(a, b, |x, y| x * y, |x, y| x * y) {
+                return Ok(Eval::Literal(res));
+            }
+
+            Err("Evaluation error: expected string or numeric types for MUL function.".to_string())
+        }
+        _ => return Err("Evalutation error: expected literals for MUL function.".to_string()),
+    }
 }
 fn eval_div(lval: &Eval, rval: &Eval) -> Result<Eval, String> {
-    Err("Todo.".to_string())
+    match (lval, rval) {
+        (Eval::Literal(a), Eval::Literal(b)) => {
+            if let Some(res) = eval_numeric_infix(a, b, |x, y| x / y, |x, y| x / y) {
+                return Ok(Eval::Literal(res));
+            }
+
+            Err("Evaluation error: expected string or numeric types for DIV function.".to_string())
+        }
+        _ => return Err("Evalutation error: expected literals for DIV function.".to_string()),
+    }
 }
 
-pub fn eval_numeric_infix<FInt, FDouble>(
+fn eval_numeric_infix<FInt, FDouble>(
     lhs: &Literal,
     rhs: &Literal,
     int_op: FInt,