Initial commit.

.gitignore

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+/target
+.idea

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "rust-hash-map"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "rust-hash-map"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

src/main.rs

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+struct HashMap<'a, K: PartialEq, V> {
+    table: Vec<Option<Vec<(&'a K, &'a V)>>>,
+    hash_fn: fn(&K) -> usize,
+}
+
+impl<'a, K: PartialEq, V> HashMap<'a, K, V> {
+    fn new(capacity: usize, hash_fn: fn(&K) -> usize) -> Self {
+        HashMap {
+            table: Vec::with_capacity(capacity),
+            hash_fn,
+        }
+    }
+
+    fn put(&mut self, k: &'a K, v: &'a V) {
+        let hash = (self.hash_fn)(&k);
+        let target_index = hash % self.table.capacity();
+        match self.table[target_index].take() {
+            None => {
+                let new_container = vec![(k, v)];
+                self.table.insert(target_index, Some(new_container));
+            },
+            Some(mut container) => {
+                container.push((k, v));
+                self.table.insert(target_index, Some(container));
+            }
+        }
+    }
+
+    fn get(&mut self, k: &K) -> Option<&V> {
+        let hash = (self.hash_fn)(&k);
+        let target_index = hash % self.table.capacity();
+        let container_opt = self.table[target_index].take();
+        if container_opt.is_none() {
+            None
+        } else {
+            let container = container_opt.unwrap();
+            for item in container.iter() {
+                if item.0 == k {
+                    let result = Some(item.1);
+                    self.table[target_index] = Some(container);
+                    return result;
+                }
+            }
+            self.table[target_index] = Some(container);
+            None
+        }
+    }
+}
+
+#[cfg(test)]
+mod hash_map_tests {
+    use super::*;
+
+    #[test]
+    fn simple_put_and_get() {
+        let jesse = String::from("Jesse");
+        let brault = String::from("Brault");
+        let mut map: HashMap<String, String> = HashMap::new(8, |s| s.len());
+        map.put(&jesse, &brault);
+        assert_eq!(map.get(&jesse), Some(&brault));
+    }
+}
+
+fn main() {
+    println!("Hello, world!");
+}