fix(eval): allow expressions in functions

added:
- pass context to function calls
fixed:
- functions not evaluating expressions inside their params

src/math/context.rs

@@ -2,7 +2,7 @@ use std::collections::HashMap;
 
 use crate::math::{lexer, parser, types::Expression};
 
-type FunctionCallback = Box<dyn Fn(Vec<Expression>) -> Expression>;
+type FunctionCallback = Box<dyn Fn(&Context, Vec<Expression>) -> Expression>;
 
 pub struct Context {
     variables: HashMap<String, Expression>,
@@ -26,7 +26,7 @@ impl Context {
 
     pub fn register_function<F>(&mut self, name: &str, callback: F)
     where
-        F: Fn(Vec<Expression>) -> Expression + 'static,
+        F: Fn(&Context, Vec<Expression>) -> Expression + 'static,
     {
         self.functions.insert(name.to_owned(), Box::new(callback));
     }
@@ -38,7 +38,7 @@ impl Context {
         }
 
         let func = func.unwrap();
-        func(params)
+        func(self, params)
     }
 
     pub fn get_variable(&self, name: &str) -> Option<&Expression> {

src/math/functions.rs

@@ -2,45 +2,91 @@ use crate::math::context::Context;
 use crate::math::types::Expression;
 use rust_decimal::Decimal;
 use rust_decimal::MathematicalOps;
+use rust_decimal::RoundingStrategy;
+use rust_decimal::dec;
 use rust_decimal::prelude::ToPrimitive;
 
 impl Context {
     pub fn register_builtin_functions(&mut self) {
-        self.register_function("abs", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| d.abs())
+        self.register_function("abs", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| d.abs())
         });
-        self.register_function("sqrt", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| d.abs().sqrt().unwrap())
+        self.register_function("sqrt", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| {
+                d.abs().sqrt().unwrap()
+            })
         });
-        self.register_function("sin", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| d.sin())
+        self.register_function("sin", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| d.sin())
         });
-        self.register_function("cos", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| d.cos())
+        self.register_function("cos", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| d.cos())
         });
-        self.register_function("tan", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| d.tan())
+        self.register_function("tan", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| d.tan())
         });
-        self.register_function("asin", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| map_f64(&d, |f| f.asin()))
+        self.register_function("asin", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| {
+                map_f64(&d, |f| f.asin())
+            })
         });
-        self.register_function("acos", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| map_f64(&d, |f| f.acos()))
+        self.register_function("acos", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| {
+                map_f64(&d, |f| f.acos())
+            })
         });
-        self.register_function("atan", |params: Vec<Expression>| {
-            map_decimal(&params[0], |d| map_f64(&d, |f| f.atan()))
+        self.register_function("atan", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| {
+                map_f64(&d, |f| f.atan())
+            })
+        });
+        self.register_function("round", |ctx, params: Vec<Expression>| {
+            let decimal = if params.len() == 2 {
+                if let Some(d) = get_decimal(&params[1]) {
+                    d
+                } else {
+                    dec!(0)
+                }
+            } else {
+                dec!(0)
+            }
+            .to_u32()
+            .expect("unable to parse decimal number");
+
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| {
+                d.round_dp_with_strategy(decimal, RoundingStrategy::MidpointAwayFromZero)
+            })
+        });
+        self.register_function("floor", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| d.floor())
+        });
+        self.register_function("ceil", |ctx, params: Vec<Expression>| {
+            map_decimal(&ctx.eval_expr(params[0].clone()), |d| d.ceil())
         });
     }
 }
 
-fn map_decimal(expr: &Expression, f: fn(Decimal) -> Decimal) -> Expression {
+fn get_decimal(expr: &Expression) -> Option<Decimal> {
+    match expr {
+        Expression::Number(d) => Some(*d),
+        _ => None,
+    }
+}
+
+fn map_decimal<F>(expr: &Expression, f: F) -> Expression
+where
+    F: Fn(Decimal) -> Decimal,
+{
     match expr {
         Expression::Number(d) => Expression::Number(f(*d)),
         _ => panic!("expected decimal"),
     }
 }
 
-fn map_f64(decimal: &Decimal, f: fn(f64) -> f64) -> Decimal {
+fn map_f64<F>(decimal: &Decimal, f: F) -> Decimal
+where
+    F: Fn(f64) -> f64,
+{
     let num = decimal.to_f64().expect("unable to unwrap decimal");
     let num = f(num);
     Decimal::from_f64_retain(num).expect("unable to wrap decimal")

src/math/mod.rs

@@ -1,5 +1,3 @@
-use crate::math::types::Expression;
-
 #[cfg(test)]
 mod tests;