A simple naive hashmap implementation.

hashmap/impl.go

@@ -0,0 +1,52 @@
+package hashmap
+
+
+import (
+  "hash/crc32"
+)
+
+const (
+  BucketCount = 256
+)
+
+type HashNode struct {
+  key string
+  val any
+}
+
+type HashBucket struct {
+  contents []HashNode
+}
+
+type Hashmap struct {
+  buckets [BucketCount]HashBucket
+}
+
+func New() *Hashmap {
+  hmap := new(Hashmap)
+  return hmap
+}
+
+func (hmap *Hashmap) Hash(key string) uint32 {
+  return crc32.ChecksumIEEE([]byte(key)) % BucketCount
+}
+
+func (hmap *Hashmap) Add(key string, val any) {
+  id := hmap.Hash(key)
+  the_bucket := &hmap.buckets[id]
+  node := HashNode{key, val}
+  the_bucket.contents = append(the_bucket.contents, node)
+}
+
+func (hmap *Hashmap) Get(key string) any {
+  id := hmap.Hash(key)
+  the_bucket := &hmap.buckets[id]
+
+  for _, node := range the_bucket.contents {
+    if node.key == key {
+      return node.val
+    }
+  }
+
+  return nil
+}

tests/hashmap_test.go

@@ -0,0 +1,27 @@
+package tests
+
+import (
+  "testing"
+  "github.com/stretchr/testify/assert"
+  "MY/dsa/hashmap"
+)
+
+func TestHashmap(t *testing.T) {
+  hmap := hashmap.New()
+
+  hmap.Add("zed", 100)
+  hmap.Add("joe", "That Thing")
+  hmap.Add("mary", 300.10)
+
+  val := hmap.Get("zed")
+  assert.Equal(t, val, 100, "bad zed")
+
+  val2 := hmap.Get("joe")
+  assert.Equal(t, val2, "That Thing", "bad joe")
+
+  val3 := hmap.Get("mary")
+  assert.Equal(t, val3, 300.10, "bad mary")
+
+  val4 := hmap.Get("nothere")
+  assert.Equal(t, val4, nil, "bad missing")
+}