feat: improve fibonacci example

Author: 1995parham

fibonacci-1/src/fibonacci/dynamic.rs

@@ -0,0 +1,34 @@
+use crate::fibonacci::{Fibonacci, Iter};
+
+pub struct Dynamic {
+    data: Vec<i64>,
+}
+
+impl Dynamic {
+    pub fn new() -> Self {
+        return Dynamic { data: vec![1, 1] };
+    }
+}
+
+impl Fibonacci for Dynamic {
+    fn fibonacci(&mut self, n: usize) -> i64 {
+        match self.data.get(n) {
+            Some(v) => *v,
+            None => {
+                let v = self.fibonacci(n - 1) + self.fibonacci(n - 2);
+                self.data.insert(n, v);
+                v
+            }
+        }
+    }
+}
+
+impl<'a> IntoIterator for &'a mut Dynamic {
+    type Item = i64;
+
+    type IntoIter = Iter<'a, Dynamic>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Self::IntoIter{n: 0, generator: self}
+    }
+}

fibonacci-1/src/fibonacci/mod.rs

@@ -1,14 +1,30 @@
-use crate::fibonacci::rec::Recursive;
+use crate::fibonacci::{dynamic::Dynamic, rec::Recursive};
 
+mod dynamic;
 mod rec;
 
 pub trait Fibonacci {
-    fn fibonacci(&self, n: i32) -> i64;
+    fn fibonacci(&mut self, n: usize) -> i64;
+}
+
+pub struct Iter<'a, T: Fibonacci> {
+    n: usize,
+    generator: &'a mut T,
+}
+
+impl<'a, T: Fibonacci> Iterator for Iter<'a, T> {
+    type Item = i64;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.n += 1;
+        Some(self.generator.fibonacci(self.n - 1))
+    }
 }
 
 pub fn choose(name: &str) -> Box<dyn Fibonacci> {
     match name {
         "recursive" => Box::new(Recursive {}),
+        "dynamic" => Box::new(Dynamic::new()),
         _ => panic!("no such a fibonacci implementation named {}", name),
     }
 }

fibonacci-1/src/fibonacci/rec.rs

@@ -1,13 +1,23 @@
-use crate::fibonacci::Fibonacci;
+use crate::fibonacci::{Fibonacci, Iter};
 
 pub struct Recursive {}
 
 impl Fibonacci for Recursive {
-    fn fibonacci(&self, n: i32) -> i64 {
+    fn fibonacci(&mut self, n: usize) -> i64 {
         if n == 0 || n == 1 {
             1
         } else {
             self.fibonacci(n - 1) + self.fibonacci(n - 2)
         }
     }
 }
+
+impl<'a> IntoIterator for &'a mut Recursive {
+    type Item = i64;
+
+    type IntoIter = Iter<'a, Recursive>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Self::IntoIter{n: 0, generator: self}
+    }
+}

fibonacci-1/src/main.rs

@@ -3,7 +3,7 @@ use crate::fibonacci::choose;
 mod fibonacci;
 
 fn main() {
-    let r = choose("recursive");
+    let mut r = choose("dynamic");
 
     println!("{}", r.fibonacci(10));
 }