add function_cache for performence gain

1 files changed, 32 insertions, 0 deletions

diff --git a/src/function_cache.rs b/src/function_cache.rs
new file mode 100644
index 0000000..d4beb16
--- /dev/null
+++ b/src/function_cache.rs
@@ -0,0 +1,32 @@
+use std::collections::HashMap;
+
+use crate::math::{
+    complex::Complex, context::Context, expression_function::ExpressionFunction,
+    function::{FunctionArgument, Function},
+};
+
+#[derive(Default)]
+pub struct FunctionCache {
+    func: ExpressionFunction,
+    cache: HashMap<Complex, Complex>,
+}
+
+impl FunctionCache {
+    pub fn new(func: ExpressionFunction) -> Self {
+        Self {
+            func,
+            cache: HashMap::new(),
+        }
+    }
+
+    pub fn eval(&mut self, x: Complex, ctx: &Context) -> Complex {
+        if self.cache.contains_key(&x) {
+            *self.cache.get(&x).unwrap()
+        } else {
+            let fargs = FunctionArgument::from_values(vec![x]);
+            let v = self.func.eval(&fargs, ctx).unwrap();
+            self.cache.insert(x, v);
+            v
+        }
+    }
+}