Merge pull request #2217 from nspcc-dev/compiler-overload

compiler: allow to overload methods in manifest

cli/contract_test.go

@@ -647,6 +647,22 @@ func TestCompileExamples(t *testing.T) {
 				"--config", path.Join(examplePath, info.Name(), cfgName),
 			}
 			e.Run(t, opts...)
+
+			if info.Name() == "storage" {
+				rawM, err := ioutil.ReadFile(manifestF)
+				require.NoError(t, err)
+
+				m := new(manifest.Manifest)
+				require.NoError(t, json.Unmarshal(rawM, m))
+
+				require.Nil(t, m.ABI.GetMethod("getDefault", 0))
+				require.NotNil(t, m.ABI.GetMethod("get", 0))
+				require.NotNil(t, m.ABI.GetMethod("get", 1))
+
+				require.Nil(t, m.ABI.GetMethod("putDefault", 1))
+				require.NotNil(t, m.ABI.GetMethod("put", 1))
+				require.NotNil(t, m.ABI.GetMethod("put", 2))
+			}
 		})
 	}
 

cli/smartcontract/smart_contract.go

@@ -498,6 +498,7 @@ func contractCompile(ctx *cli.Context) error {
 			o.Permissions[i] = manifest.Permission(conf.Permissions[i])
 		}
 		o.SafeMethods = conf.SafeMethods
+		o.Overloads = conf.Overloads
 	}
 
 	result, err := compiler.CompileAndSave(src, o)
@@ -740,6 +741,7 @@ type ProjectConfig struct {
 	SupportedStandards []string
 	Events             []manifest.Event
 	Permissions        []permission
+	Overloads          map[string]string `yaml:"overloads,omitempty"`
 }
 
 func inspect(ctx *cli.Context) error {

docs/compiler.md

@@ -233,6 +233,7 @@ Configuration file contains following options:
 | `supportedstandards` | List of standards this contract implements. For example, `NEP-11` or `NEP-17` token standard. This will enable additional checks in compiler. The check can be disabled with `--no-standards` flag. | `["NEP-17"]`
 | `events` | Notifications emitted by this contract. | See [Events](#Events). |
 | `permissions` | Foreign calls allowed for this contract. | See [Permissions](#Permissions). |
+| `overloads` | Custom method names for this contract. | See [Overloads](#Overloads). |
 
 ##### Events
 Each event must have a name and 0 or more parameters. Parameters are specified using their name and type.
@@ -318,6 +319,28 @@ Using either constant or literal for contract hash and method will allow compile
 to perform more extensive analysis.
 This check can be disabled with `--no-permissions` flag.
 
+##### Overloads
+NeoVM allows a contract to have multiple methods with the same name
+but different parameters number. Go lacks this feature but this can be circumvented
+with `overloads` section. Essentially it is a mapping from default contract method names
+to the new ones.
+```
+- overloads:
+    oldName1: newName
+    oldName2: newName
+```
+Because the use-case for this is to provide multiple implementations with the same ABI name,
+`newName` is required to be already present in the compiled contract.
+
+As an example consider [`NEP-11` standard](https://github.com/neo-project/proposals/blob/master/nep-11.mediawiki#transfer).
+It requires divisible NFT contract to have 2 `transfer` methods. To achieve this we might implement
+`Tranfer` and `TransferDivisible` and specify emitted name in config:
+```
+- overloads:
+    transferDivisible:transfer
+```
+
+
 #### Manifest file
 Any contract can be included in a group identified by a public key which is used in [permissions](#Permissions).
 This is achieved with `manifest add-group` command.

examples/storage/storage.go

@@ -8,6 +8,9 @@ import (
 // ctx holds storage context for contract methods
 var ctx storage.Context
 
+// defaultKey represents the default key.
+var defaultKey = []byte("default")
+
 // init inits storage context before any other contract method is called
 func init() {
 	ctx = storage.GetContext()
@@ -19,11 +22,22 @@ func Put(key, value []byte) []byte {
 	return key
 }
 
+// PutDefault puts value to the default key.
+func PutDefault(value []byte) []byte {
+	storage.Put(ctx, defaultKey, value)
+	return defaultKey
+}
+
 // Get returns the value at passed key.
 func Get(key []byte) interface{} {
 	return storage.Get(ctx, key)
 }
 
+// GetDefault returns the value at the default key.
+func GetDefault() interface{} {
+	return storage.Get(ctx, defaultKey)
+}
+
 // Delete deletes the value at passed key.
 func Delete(key []byte) bool {
 	storage.Delete(ctx, key)

examples/storage/storage.yml

@@ -2,3 +2,6 @@ name: "Storage example"
 sourceurl: https://github.com/nspcc-dev/neo-go/
 supportedstandards: []
 events: []
+overloads:
+  getDefault: get
+  putDefault: put

pkg/compiler/compiler.go

@@ -64,6 +64,10 @@ type Options struct {
 	// SafeMethods contains list of methods which will be marked as safe in manifest.
 	SafeMethods []string
 
+	// Overloads contains mapping from compiled method name to the name emitted in manifest.
+	// It can be used to provide method overloads as Go doesn't have such capability.
+	Overloads map[string]string
+
 	// Permissions is a list of permissions for every contract method.
 	Permissions []manifest.Permission
 }

pkg/compiler/debug.go

@@ -446,5 +446,21 @@ func (di *DebugInfo) ConvertToManifest(o *Options) (*manifest.Manifest, error) {
 		result.ABI.Events = make([]manifest.Event, 0)
 	}
 	result.Permissions = o.Permissions
+	for name, emitName := range o.Overloads {
+		m := result.ABI.GetMethod(name, -1)
+		if m == nil {
+			return nil, fmt.Errorf("overload for method %s was provided but it wasn't found", name)
+		}
+		if result.ABI.GetMethod(emitName, -1) == nil {
+			return nil, fmt.Errorf("overload with target method %s was provided but it wasn't found", emitName)
+		}
+
+		realM := result.ABI.GetMethod(emitName, len(m.Parameters))
+		if realM != nil {
+			return nil, fmt.Errorf("conflict overload for %s: "+
+				"multiple methods with the same number of parameters", name)
+		}
+		m.Name = emitName
+	}
 	return result, nil
 }

pkg/compiler/debug_test.go

@@ -2,6 +2,7 @@ package compiler
 
 import (
 	"encoding/json"
+	"strings"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/internal/testserdes"
@@ -361,3 +362,52 @@ func TestDebugInfo_MarshalJSON(t *testing.T) {
 
 	testserdes.MarshalUnmarshalJSON(t, d, new(DebugInfo))
 }
+
+func TestManifestOverload(t *testing.T) {
+	src := `package foo
+	func Main() int {
+		return 1
+	}
+	func Add3() int {
+		return Add3Aux(0)
+	}
+	func Add3Aux(a int) int {
+		return a + 3
+	}
+	func Add3Aux2(b int) int {
+		return b + 3
+	}
+	func Add4() int {
+		return 4
+	}`
+
+	_, di, err := CompileWithDebugInfo("foo", strings.NewReader(src))
+	require.NoError(t, err)
+
+	m, err := di.ConvertToManifest(&Options{Overloads: map[string]string{"add3Aux": "add3"}})
+	require.NoError(t, err)
+	require.NoError(t, m.ABI.IsValid())
+	require.NotNil(t, m.ABI.GetMethod("add3", 0))
+	require.NotNil(t, m.ABI.GetMethod("add3", 1))
+	require.Nil(t, m.ABI.GetMethod("add3Aux", 1))
+
+	t.Run("missing method", func(t *testing.T) {
+		_, err := di.ConvertToManifest(&Options{Overloads: map[string]string{"miss": "add3"}})
+		require.Error(t, err)
+	})
+	t.Run("parameter conflict", func(t *testing.T) {
+		_, err := di.ConvertToManifest(&Options{Overloads: map[string]string{"add4": "add3"}})
+		require.Error(t, err)
+	})
+	t.Run("parameter conflict, overload", func(t *testing.T) {
+		_, err := di.ConvertToManifest(&Options{Overloads: map[string]string{
+			"add3Aux":  "add3",
+			"add3Aux2": "add3",
+		}})
+		require.Error(t, err)
+	})
+	t.Run("missing target method", func(t *testing.T) {
+		_, err := di.ConvertToManifest(&Options{Overloads: map[string]string{"add4": "add5"}})
+		require.Error(t, err)
+	})
+}