Add Storage Counter SC

Signed-off-by: Stanislav Bogatyrev <s.bogatyrev@yadro.com>

l3/storage/counter.go

@@ -0,0 +1,31 @@
+package counter
+
+import (
+	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
+	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
+)
+
+const itemKey = "Counter"
+
+func _deploy(_ interface{}, isUpdate bool) {
+	if !isUpdate {
+		ctx := storage.GetContext()
+		runtime.Notify("info", []byte("Counter not set in Storage. Setting to 0"))
+		itemValue := 0
+		storage.Put(ctx, itemKey, itemValue)
+		runtime.Notify("info", []byte("Counter in Storage is now initialised"))
+	}
+}
+
+func Main() interface{} {
+	ctx := storage.GetContext()
+	itemValue := storage.Get(ctx, itemKey)
+	runtime.Notify("info", []byte("Value read from Storage"))
+
+	runtime.Notify("info", []byte("Incrementing Counter by 1"))
+	itemValue = itemValue.(int) + 1
+
+	storage.Put(ctx, itemKey, itemValue)
+	runtime.Notify("info", []byte("New counter value written into Storage"))
+	return itemValue
+}

l3/storage/counter.yml

@@ -0,0 +1,8 @@
+name: "Storage Counter contract"
+sourceurl: https://git.frostfs.info/Web3N3/web3-course
+supportedstandards: []
+events:
+  - name: info
+    parameters:
+      - name: message
+        type: ByteString

l3/storage/go.mod

@@ -0,0 +1,5 @@
+module counter
+
+go 1.20
+
+require github.com/nspcc-dev/neo-go/pkg/interop v0.0.0-20231020160724-c3955f87d1b5

l3/storage/go.sum

@@ -0,0 +1,2 @@
+github.com/nspcc-dev/neo-go/pkg/interop v0.0.0-20231020160724-c3955f87d1b5 h1:09CpI5uwsxb1EeFPIKQRwwWlfCmDD/Dwwh01lPiQScM=
+github.com/nspcc-dev/neo-go/pkg/interop v0.0.0-20231020160724-c3955f87d1b5/go.mod h1:J/Mk6+nKeKSW4wygkZQFLQ6SkLOSGX5Ga0RuuuktEag=