rpcclient: add CallAndExpandIterator to Invoker

And deprecate Client.InvokeAndPackIteratorResults.

pkg/rpcclient/helper.go

@@ -111,6 +111,9 @@ func topMapFromStack(st []stackitem.Item) (*stackitem.Map, error) {
 // retrieve iterator values via single `invokescript` JSON-RPC call. It returns
 // maxIteratorResultItems items at max which is set to
 // config.DefaultMaxIteratorResultItems by default.
+//
+// Deprecated: please use more convenient and powerful invoker.Invoker interface with
+// CallAndExpandIterator method. This method will be removed in future versions.
 func (c *Client) InvokeAndPackIteratorResults(contract util.Uint160, operation string, params []smartcontract.Parameter, signers []transaction.Signer, maxIteratorResultItems ...int) (*result.Invoke, error) {
 	max := config.DefaultMaxIteratorResultItems
 	if len(maxIteratorResultItems) != 0 {

pkg/rpcclient/invoker/invoker.go

@@ -1,6 +1,8 @@
 package invoker
 
 import (
+	"fmt"
+
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
@@ -125,6 +127,22 @@ func (v *Invoker) Call(contract util.Uint160, operation string, params ...interf
 	return v.client.InvokeFunction(contract, operation, ps, v.signers)
 }
 
+// CallAndExpandIterator creates a script containing a call of the specified method
+// of a contract with given parameters (similar to how Call operates). But then this
+// script contains additional code that expects that the result of the first call is
+// an iterator. This iterator is traversed extracting values from it and adding them
+// into an array until maxItems is reached or iterator has no more elements. The
+// result of the whole script is an array containing up to maxResultItems elements
+// from the iterator returned from the contract's method call. This script is executed
+// using regular JSON-API (according to the way Iterator is set up).
+func (v *Invoker) CallAndExpandIterator(contract util.Uint160, method string, maxItems int, params ...interface{}) (*result.Invoke, error) {
+	bytes, err := smartcontract.CreateCallAndUnwrapIteratorScript(contract, method, maxItems, params...)
+	if err != nil {
+		return nil, fmt.Errorf("iterator unwrapper script: %w", err)
+	}
+	return v.Run(bytes)
+}
+
 // Verify invokes contract's verify method in the verification context with
 // Invoker-specific signers and given witnesses and parameters.
 func (v *Invoker) Verify(contract util.Uint160, witnesses []transaction.Witness, params ...interface{}) (*result.Invoke, error) {

pkg/rpcclient/invoker/invoker_test.go

@@ -86,6 +86,13 @@ func TestInvoker(t *testing.T) {
 
 		_, err = inv.Call(util.Uint160{}, "method", make(map[int]int))
 		require.Error(t, err)
+
+		res, err = inv.CallAndExpandIterator(util.Uint160{}, "method", 10, 42)
+		require.NoError(t, err)
+		require.Equal(t, resExp, res)
+
+		_, err = inv.CallAndExpandIterator(util.Uint160{}, "method", 10, make(map[int]int))
+		require.Error(t, err)
 	}
 	t.Run("standard", func(t *testing.T) {
 		testInv(t, New(ri, nil))

pkg/rpcclient/native.go

@@ -7,12 +7,12 @@ import (
 	"fmt"
 
 	"github.com/google/uuid"
+	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
 	"github.com/nspcc-dev/neo-go/pkg/core/native/noderoles"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/nns"
-	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 )
 
@@ -118,12 +118,7 @@ func (c *Client) NNSGetAllRecords(nnsHash util.Uint160, name string) (uuid.UUID,
 // that no iterator session is used to retrieve values from iterator. Instead, unpacking
 // VM script is created and invoked via `invokescript` JSON-RPC call.
 func (c *Client) NNSUnpackedGetAllRecords(nnsHash util.Uint160, name string) ([]nns.RecordState, error) {
-	result, err := c.InvokeAndPackIteratorResults(nnsHash, "getAllRecords", []smartcontract.Parameter{
-		{
-			Type:  smartcontract.StringType,
-			Value: name,
-		},
-	}, nil)
+	result, err := c.reader.CallAndExpandIterator(nnsHash, "getAllRecords", config.DefaultMaxIteratorResultItems, name)
 	if err != nil {
 		return nil, err
 	}

pkg/rpcclient/nep11.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/google/uuid"
+	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
 	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
@@ -101,12 +102,7 @@ func (c *Client) NEP11TokensOf(tokenHash util.Uint160, owner util.Uint160) (uuid
 // is used to retrieve values from iterator. Instead, unpacking VM script is created and invoked via
 // `invokescript` JSON-RPC call.
 func (c *Client) NEP11UnpackedTokensOf(tokenHash util.Uint160, owner util.Uint160) ([][]byte, error) {
-	result, err := c.InvokeAndPackIteratorResults(tokenHash, "tokensOf", []smartcontract.Parameter{
-		{
-			Type:  smartcontract.Hash160Type,
-			Value: owner,
-		},
-	}, nil)
+	result, err := c.reader.CallAndExpandIterator(tokenHash, "tokensOf", config.DefaultMaxIteratorResultItems, owner)
 	if err != nil {
 		return nil, err
 	}
@@ -194,12 +190,7 @@ func (c *Client) NEP11DOwnerOf(tokenHash util.Uint160, tokenID []byte) (uuid.UUI
 // iterator session is used to retrieve values from iterator. Instead, unpacking VM
 // script is created and invoked via `invokescript` JSON-RPC call.
 func (c *Client) NEP11DUnpackedOwnerOf(tokenHash util.Uint160, tokenID []byte) ([]util.Uint160, error) {
-	result, err := c.InvokeAndPackIteratorResults(tokenHash, "ownerOf", []smartcontract.Parameter{
-		{
-			Type:  smartcontract.ByteArrayType,
-			Value: tokenID,
-		},
-	}, nil)
+	result, err := c.reader.CallAndExpandIterator(tokenHash, "ownerOf", config.DefaultMaxIteratorResultItems, tokenID)
 	if err != nil {
 		return nil, err
 	}
@@ -261,7 +252,7 @@ func (c *Client) NEP11Tokens(tokenHash util.Uint160) (uuid.UUID, result.Iterator
 // iterator session is used to retrieve values from iterator. Instead, unpacking
 // VM script is created and invoked via `invokescript` JSON-RPC call.
 func (c *Client) NEP11UnpackedTokens(tokenHash util.Uint160) ([][]byte, error) {
-	result, err := c.InvokeAndPackIteratorResults(tokenHash, "tokens", []smartcontract.Parameter{}, nil)
+	result, err := c.reader.CallAndExpandIterator(tokenHash, "tokens", config.DefaultMaxIteratorResultItems)
 	if err != nil {
 		return nil, err
 	}

pkg/services/rpcsrv/client_test.go

@@ -1280,7 +1280,7 @@ func TestClient_InvokeAndPackIteratorResults(t *testing.T) {
 	require.NoError(t, err)
 
 	t.Run("default max items constraint", func(t *testing.T) {
-		res, err := c.InvokeAndPackIteratorResults(storageHash, "iterateOverValues", []smartcontract.Parameter{}, nil)
+		res, err := c.InvokeAndPackIteratorResults(storageHash, "iterateOverValues", []smartcontract.Parameter{}, nil) //nolint:staticcheck // SA1019: c.InvokeAndPackIteratorResults is deprecated
 		require.NoError(t, err)
 		require.Equal(t, vmstate.Halt.String(), res.State)
 		require.Equal(t, 1, len(res.Stack))
@@ -1296,7 +1296,7 @@ func TestClient_InvokeAndPackIteratorResults(t *testing.T) {
 	})
 	t.Run("custom max items constraint", func(t *testing.T) {
 		max := 123
-		res, err := c.InvokeAndPackIteratorResults(storageHash, "iterateOverValues", []smartcontract.Parameter{}, nil, max)
+		res, err := c.InvokeAndPackIteratorResults(storageHash, "iterateOverValues", []smartcontract.Parameter{}, nil, max) //nolint:staticcheck // SA1019: c.InvokeAndPackIteratorResults is deprecated
 		require.NoError(t, err)
 		require.Equal(t, vmstate.Halt.String(), res.State)
 		require.Equal(t, 1, len(res.Stack))