Merge pull request #795 from nspcc-dev/feature/find_storage_example

examples: expand storage smartcontract with find() usage example

examples/storage/storage.go

@@ -1,6 +1,7 @@
 package storagecontract
 
 import (
+	"github.com/nspcc-dev/neo-go/pkg/interop/iterator"
 	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
 )
 
@@ -33,7 +34,20 @@ func Main(operation string, args []interface{}) interface{} {
 		return true
 	}
 
-	// TODO: storage.Find()
+	// Returns an array of key-value pairs with key that matched the passed value
+	if operation == "find" {
+		if checkArgs(args, 1) {
+			value := args[0].([]byte)
+			iter := storage.Find(ctx, value)
+			result := []string{}
+			for iterator.Next(iter) {
+				val := iterator.Value(iter)
+				key := iterator.Key(iter)
+				result = append(result, key.(string)+":"+val.(string))
+			}
+			return result
+		}
+	}
 
 	return false
 }

pkg/compiler/syscall.go

@@ -86,6 +86,8 @@ var syscalls = map[string]map[string]string{
 		"Create": "Neo.Iterator.Create",
 		"Key":    "Neo.Iterator.Key",
 		"Keys":   "Neo.Iterator.Keys",
+		"Next":   "Neo.Iterator.Next",
+		"Value":  "Neo.Iterator.Value",
 		"Values": "Neo.Iterator.Values",
 	},
 }

pkg/interop/iterator/iterator.go

@@ -22,6 +22,17 @@ func Keys(it Iterator) []interface{} {
 	return nil
 }
 
+// Next advances the iterator, return true if it is was successful
+// and false otherwise.
+func Next(it Iterator) bool {
+	return true
+}
+
+// Value returns the current iterator value.
+func Value(it Iterator) interface{} {
+	return nil
+}
+
 // Values returns the iterator values.
 func Values(it Iterator) []interface{} {
 	return nil