update CrossVMMetadataViews & add to go lib

Author: sisyphusSmiling

contracts/CrossVMMetadataViews.cdc

@@ -0,0 +1,63 @@
+import "EVM"
+
+/// This contract implements views originally proposed in FLIP-318 supporting NFT collections
+/// with project-defined implementations across both Cadence & EVM.
+///
+access(all) contract CrossVMMetadataViews {
+
+    /// An enum denoting a VM. For now, there are only two VMs on Flow, but this enum could be
+    /// expanded in the event other VMs are supported on the network.
+    ///
+    access(all) enum VM : UInt8 {
+        access(all) case Cadence
+        access(all) case EVM
+    }
+
+    /// View resolved at contract & resource level pointing to the associated EVM implementation.
+    /// NOTE: This view alone is not sufficient to validate an association across Cadence & EVM!
+    /// Both the Cadence Type/contract *and* the EVM contract should point to each other, with the
+    /// EVM pointer being facilitated by ICrossVM.sol contract interface methods. For more
+    /// information and context, see FLIP-318: https://github.com/onflow/flips/issues/318
+    ///
+    access(all) struct EVMPointer {
+        /// The associated Cadence Type
+        access(all) let cadenceType: Type
+        /// The defining Cadence contract address
+        access(all) let cadenceContractAddress: Address
+        /// The associated EVM contract address
+        access(all) let evmContractAddress: EVM.EVMAddress
+        /// Whether the asset is Cadence- or EVM-native. Native here meaning the VM in which the
+        /// asset is distributed.
+        access(all) let nativeVM: VM
+
+        init(
+            cadenceType: Type,
+            cadenceContractAddress: Address,
+            evmContractAddress: EVM.EVMAddress,
+            nativeVM: VM
+        ) {
+            self.cadenceType = cadenceType
+            self.cadenceContractAddress = cadenceContractAddress
+            self.evmContractAddress = evmContractAddress
+            self.nativeVM = nativeVM
+        }
+    }
+
+    /// View resolved at resource level denoting any metadata to be passed to the associated EVM
+    /// contract at the time of / bridging. This optional view would allow EVM side metadata to be
+    /// updated based on current Cadence state. If the / view is not supported, no bytes will be
+    /// passed into EVM when bridging.
+    ///
+    access(all) struct EVMBytesMetadata {
+        /// Returns the bytes to be passed to the EVM contract on `fulfillToEVM` call, allowing the
+        /// EVM contract to update / the metadata associated with the NFT. The corresponding Solidity
+        /// `bytes` type allows the implementer greater / flexibility by enabling them to pass
+        /// arbitrary data between VMs.
+        access(all) let bytes: EVM.EVMBytes?
+
+        init(bytes: EVM.EVMBytes?) {
+            self.bytes = bytes
+        }
+    }
+
+}

lib/go/contracts/contracts.go

@@ -14,27 +14,30 @@ import (
 )
 
 var (
-	placeholderNonFungibleToken    = regexp.MustCompile(`"NonFungibleToken"`)
-	nonFungibleTokenImport         = "NonFungibleToken from "
-	placeholderMetadataViews       = regexp.MustCompile(`"MetadataViews"`)
-	metadataViewsImport            = "MetadataViews from "
-	placeholderFungibleToken       = regexp.MustCompile(`"FungibleToken"`)
-	fungibleTokenImport            = "FungibleToken from "
-	placeholderResolver            = regexp.MustCompile(`"ViewResolver"`)
-	viewResolverImport             = "ViewResolver from "
-	placeholderUniversalCollection = regexp.MustCompile(`"UniversalCollection"`)
-	universalCollectionImport      = "UniversalCollection from "
+	placeholderNonFungibleToken     = regexp.MustCompile(`"NonFungibleToken"`)
+	nonFungibleTokenImport          = "NonFungibleToken from "
+	placeholderMetadataViews        = regexp.MustCompile(`"MetadataViews"`)
+	metadataViewsImport             = "MetadataViews from "
+	placeholderFungibleToken        = regexp.MustCompile(`"FungibleToken"`)
+	fungibleTokenImport             = "FungibleToken from "
+	placeholderResolver             = regexp.MustCompile(`"ViewResolver"`)
+	viewResolverImport              = "ViewResolver from "
+	placeholderUniversalCollection  = regexp.MustCompile(`"UniversalCollection"`)
+	universalCollectionImport       = "UniversalCollection from "
+	placeholderCrossVMMetadataViews = regexp.MustCompile(`"CrossVMMetadataViews"`)
+	crossVMMetadataViewsImport      = "CrossVMMetadataViews from "
 )
 
 const (
-	filenameNonFungibleToken    = "NonFungibleToken.cdc"
-	filenameExampleNFT          = "ExampleNFT.cdc"
-	filenameMetadataViews       = "MetadataViews.cdc"
-	filenameNFTMetadataViews    = "NFTMetadataViews.cdc"
-	filenameViewResolver        = "ViewResolver.cdc"
-	filenameUniversalCollection = "UniversalCollection.cdc"
-	filenameBasicNFT            = "BasicNFT.cdc"
-	filenameFungibleToken       = "utility/FungibleToken.cdc"
+	filenameNonFungibleToken     = "NonFungibleToken.cdc"
+	filenameExampleNFT           = "ExampleNFT.cdc"
+	filenameMetadataViews        = "MetadataViews.cdc"
+	filenameCrossVMMetadataViews = "CrossVMMetadataViews.cdc"
+	filenameNFTMetadataViews     = "NFTMetadataViews.cdc"
+	filenameViewResolver         = "ViewResolver.cdc"
+	filenameUniversalCollection  = "UniversalCollection.cdc"
+	filenameBasicNFT             = "BasicNFT.cdc"
+	filenameFungibleToken        = "utility/FungibleToken.cdc"
 )
 
 func withHexPrefix(address string) string {
@@ -84,6 +87,14 @@ func ViewResolver() []byte {
 	return []byte(code)
 }
 
+func CrossVMMetadataViews(evmAddress string) []byte {
+	code := assets.MustAssetString(filenameCrossVMMetadataViews)
+
+	code = placeholderFungibleToken.ReplaceAllString(code, fungibleTokenImport+withHexPrefix(evmAddress))
+
+	return []byte(code)
+}
+
 func UniversalCollection(nftAddress, resolverAddress, metadataAddress flow.Address) []byte {
 	code := assets.MustAssetString(filenameUniversalCollection)
 	code = placeholderMetadataViews.ReplaceAllString(code, metadataViewsImport+withHexPrefix(metadataAddress.String()))

lib/go/contracts/contracts_test.go

@@ -35,3 +35,8 @@ func TestMetadataViewsContract(t *testing.T) {
 	contract := contracts.MetadataViews(addrA, addrA, addrA)
 	assert.NotNil(t, contract)
 }
+
+func TestCrossVMMetadataViewsContract(t *testing.T) {
+	contract := contracts.CrossVMMetadataViews(addrA)
+	assert.NotNil(t, contract)
+}