feat: add grc20reg that works... today (#3135)

- [x] Switch to storing a `type XXX func() grc20.Token` instead of a
`grc20.Token` directly.
-  [x] Implement `grc20reg`.  
- [x] Add new tests in `gnovm/tests` to demonstrate the current VM's
management of the cross-realm feature and support potential changes in
#2743.
- [x] Create a demo in `atomicswap` or a similar application.
(#2510 (comment))
-  [x] Try using a `Token.Getter()` helper.  (Works! f99654e)
- [ ] Demonstrate how to manage "disappearing" functions during garbage
collection by checking if the function pointer is nil or non-resolvable.

Alternative to #2516  
NOT(!) depending on #2743

---------

Signed-off-by: moul <94029+moul@users.noreply.github.com>

examples/Makefile

@@ -45,7 +45,7 @@ test:
 
 .PHONY: lint
 lint:
-	go run ../gnovm/cmd/gno lint $(OFFICIAL_PACKAGES)
+	go run ../gnovm/cmd/gno lint -v $(OFFICIAL_PACKAGES)
 
 .PHONY: test.sync
 test.sync:

examples/gno.land/p/demo/grc/grc20/types.gno

@@ -39,11 +39,11 @@ type Teller interface {
 	//
 	// Returns an error if the operation failed.
 	//
-	// IMPORTANT: Beware that changing an allowance with this method brings the risk
-	// that someone may use both the old and the new allowance by unfortunate
-	// transaction ordering. One possible solution to mitigate this race
-	// condition is to first reduce the spender's allowance to 0 and set the
-	// desired value afterwards:
+	// IMPORTANT: Beware that changing an allowance with this method brings
+	// the risk that someone may use both the old and the new allowance by
+	// unfortunate transaction ordering. One possible solution to mitigate
+	// this race condition is to first reduce the spender's allowance to 0
+	// and set the desired value afterwards:
 	// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
 	Approve(spender std.Address, amount uint64) error
 
@@ -63,12 +63,23 @@ type Teller interface {
 // name, symbol, and decimals, as well as methods for interacting with the
 // ledger, including checking balances and allowances.
 type Token struct {
-	name     string         // Name of the token (e.g., "Dummy Token").
-	symbol   string         // Symbol of the token (e.g., "DUMMY").
-	decimals uint           // Number of decimal places used for the token's precision.
-	ledger   *PrivateLedger // Pointer to the PrivateLedger that manages balances and allowances.
+	// Name of the token (e.g., "Dummy Token").
+	name string
+	// Symbol of the token (e.g., "DUMMY").
+	symbol string
+	// Number of decimal places used for the token's precision.
+	decimals uint
+	// Pointer to the PrivateLedger that manages balances and allowances.
+	ledger *PrivateLedger
 }
 
+// TokenGetter is a function type that returns a Token pointer. This type allows
+// bypassing a limitation where we cannot directly pass Token pointers between
+// realms. Instead, we pass this function which can then be called to get the
+// Token pointer. For more details on this limitation and workaround, see:
+// https://github.com/gnolang/gno/pull/3135
+type TokenGetter func() *Token
+
 // PrivateLedger is a struct that holds the balances and allowances for the
 // token. It provides administrative functions for minting, burning,
 // transferring tokens, and managing allowances.
@@ -77,10 +88,14 @@ type Token struct {
 // information regarding token balances and allowances, and allows direct,
 // unrestricted access to all administrative functions.
 type PrivateLedger struct {
-	totalSupply uint64   // Total supply of the token managed by this ledger.
-	balances    avl.Tree // std.Address -> uint64
-	allowances  avl.Tree // owner.(std.Address)+":"+spender.(std.Address)) -> uint64
-	token       *Token   // Pointer to the associated Token struct
+	// Total supply of the token managed by this ledger.
+	totalSupply uint64
+	// std.Address -> uint64
+	balances avl.Tree
+	// owner.(std.Address)+":"+spender.(std.Address)) -> uint64
+	allowances avl.Tree
+	// Pointer to the associated Token struct
+	token *Token
 }
 
 var (

examples/gno.land/r/demo/bar20/bar20.gno

@@ -9,6 +9,7 @@ import (
 
 	"gno.land/p/demo/grc/grc20"
 	"gno.land/p/demo/ufmt"
+	"gno.land/r/demo/grc20reg"
 )
 
 var (
@@ -17,7 +18,8 @@ var (
 )
 
 func init() {
-	// XXX: grc20reg.Register(Token, "")
+	getter := func() *grc20.Token { return Token }
+	grc20reg.Register(getter, "")
 }
 
 func Faucet() string {

examples/gno.land/r/demo/bar20/gno.mod

@@ -5,4 +5,5 @@ require (
 	gno.land/p/demo/testutils v0.0.0-latest
 	gno.land/p/demo/ufmt v0.0.0-latest
 	gno.land/p/demo/urequire v0.0.0-latest
+	gno.land/r/demo/grc20reg v0.0.0-latest
 )

examples/gno.land/r/demo/foo20/foo20.gno

@@ -10,6 +10,7 @@ import (
 	"gno.land/p/demo/ownable"
 	"gno.land/p/demo/ufmt"
 	pusers "gno.land/p/demo/users"
+	"gno.land/r/demo/grc20reg"
 	"gno.land/r/demo/users"
 )
 
@@ -21,7 +22,8 @@ var (
 
 func init() {
 	privateLedger.Mint(owner.Owner(), 1_000_000*10_000) // @privateLedgeristrator (1M)
-	// XXX: grc20reg.Register(Token, "")
+	getter := func() *grc20.Token { return Token }
+	grc20reg.Register(getter, "")
 }
 
 func TotalSupply() uint64 {

examples/gno.land/r/demo/foo20/gno.mod

@@ -7,5 +7,6 @@ require (
 	gno.land/p/demo/uassert v0.0.0-latest
 	gno.land/p/demo/ufmt v0.0.0-latest
 	gno.land/p/demo/users v0.0.0-latest
+	gno.land/r/demo/grc20reg v0.0.0-latest
 	gno.land/r/demo/users v0.0.0-latest
 )

examples/gno.land/r/demo/grc20factory/gno.mod

@@ -7,4 +7,5 @@ require (
 	gno.land/p/demo/testutils v0.0.0-latest
 	gno.land/p/demo/uassert v0.0.0-latest
 	gno.land/p/demo/ufmt v0.0.0-latest
+	gno.land/r/demo/grc20reg v0.0.0-latest
 )

examples/gno.land/r/demo/grc20factory/grc20factory.gno

@@ -8,6 +8,7 @@ import (
 	"gno.land/p/demo/grc/grc20"
 	"gno.land/p/demo/ownable"
 	"gno.land/p/demo/ufmt"
+	"gno.land/r/demo/grc20reg"
 )
 
 var instances avl.Tree // symbol -> instance
@@ -42,7 +43,8 @@ func NewWithAdmin(name, symbol string, decimals uint, initialMint, faucet uint64
 		faucet: faucet,
 	}
 	instances.Set(symbol, &inst)
-	// XXX: grc20reg.Register(token, symbol)
+	getter := func() *grc20.Token { return token }
+	grc20reg.Register(getter, symbol)
 }
 
 func (inst instance) Token() *grc20.Token {

examples/gno.land/r/demo/grc20reg/gno.mod

@@ -0,0 +1,9 @@
+module gno.land/r/demo/grc20reg
+
+require (
+	gno.land/p/demo/avl v0.0.0-latest
+	gno.land/p/demo/fqname v0.0.0-latest
+	gno.land/p/demo/grc/grc20 v0.0.0-latest
+	gno.land/p/demo/ufmt v0.0.0-latest
+	gno.land/p/demo/urequire v0.0.0-latest
+)

examples/gno.land/r/demo/grc20reg/grc20reg.gno

@@ -0,0 +1,76 @@
+package grc20reg
+
+import (
+	"std"
+
+	"gno.land/p/demo/avl"
+	"gno.land/p/demo/fqname"
+	"gno.land/p/demo/grc/grc20"
+	"gno.land/p/demo/ufmt"
+)
+
+var registry = avl.NewTree() // rlmPath[.slug] -> TokenGetter (slug is optional)
+
+func Register(tokenGetter grc20.TokenGetter, slug string) {
+	rlmPath := std.PrevRealm().PkgPath()
+	key := fqname.Construct(rlmPath, slug)
+	registry.Set(key, tokenGetter)
+	std.Emit(
+		registerEvent,
+		"pkgpath", rlmPath,
+		"slug", slug,
+	)
+}
+
+func Get(key string) grc20.TokenGetter {
+	tokenGetter, ok := registry.Get(key)
+	if !ok {
+		return nil
+	}
+	return tokenGetter.(grc20.TokenGetter)
+}
+
+func MustGet(key string) grc20.TokenGetter {
+	tokenGetter := Get(key)
+	if tokenGetter == nil {
+		panic("unknown token: " + key)
+	}
+	return tokenGetter
+}
+
+func Render(path string) string {
+	switch {
+	case path == "": // home
+		// TODO: add pagination
+		s := ""
+		count := 0
+		registry.Iterate("", "", func(key string, tokenI interface{}) bool {
+			count++
+			tokenGetter := tokenI.(grc20.TokenGetter)
+			token := tokenGetter()
+			rlmPath, slug := fqname.Parse(key)
+			rlmLink := fqname.RenderLink(rlmPath, slug)
+			infoLink := "/r/demo/grc20reg:" + key
+			s += ufmt.Sprintf("- **%s** - %s - [info](%s)\n", token.GetName(), rlmLink, infoLink)
+			return false
+		})
+		if count == 0 {
+			return "No registered token."
+		}
+		return s
+	default: // specific token
+		key := path
+		tokenGetter := MustGet(key)
+		token := tokenGetter()
+		rlmPath, slug := fqname.Parse(key)
+		rlmLink := fqname.RenderLink(rlmPath, slug)
+		s := ufmt.Sprintf("# %s\n", token.GetName())
+		s += ufmt.Sprintf("- symbol: **%s**\n", token.GetSymbol())
+		s += ufmt.Sprintf("- realm: %s\n", rlmLink)
+		s += ufmt.Sprintf("- decimals: %d\n", token.GetDecimals())
+		s += ufmt.Sprintf("- total supply: %d\n", token.TotalSupply())
+		return s
+	}
+}
+
+const registerEvent = "register"

examples/gno.land/r/demo/grc20reg/grc20reg_test.gno

@@ -0,0 +1,59 @@
+package grc20reg
+
+import (
+	"std"
+	"strings"
+	"testing"
+
+	"gno.land/p/demo/grc/grc20"
+	"gno.land/p/demo/urequire"
+)
+
+func TestRegistry(t *testing.T) {
+	std.TestSetRealm(std.NewCodeRealm("gno.land/r/demo/foo"))
+	realmAddr := std.CurrentRealm().PkgPath()
+	token, ledger := grc20.NewToken("TestToken", "TST", 4)
+	ledger.Mint(std.CurrentRealm().Addr(), 1234567)
+	tokenGetter := func() *grc20.Token { return token }
+	// register
+	Register(tokenGetter, "")
+	regTokenGetter := Get(realmAddr)
+	regToken := regTokenGetter()
+	urequire.True(t, regToken != nil, "expected to find a token") // fixme: use urequire.NotNil
+	urequire.Equal(t, regToken.GetSymbol(), "TST")
+
+	expected := `- **TestToken** - [gno.land/r/demo/foo](/r/demo/foo) - [info](/r/demo/grc20reg:gno.land/r/demo/foo)
+`
+	got := Render("")
+	urequire.True(t, strings.Contains(got, expected))
+	// 404
+	invalidToken := Get("0xdeadbeef")
+	urequire.True(t, invalidToken == nil)
+
+	// register with a slug
+	Register(tokenGetter, "mySlug")
+	regTokenGetter = Get(realmAddr + ".mySlug")
+	regToken = regTokenGetter()
+	urequire.True(t, regToken != nil, "expected to find a token") // fixme: use urequire.NotNil
+	urequire.Equal(t, regToken.GetSymbol(), "TST")
+
+	// override
+	Register(tokenGetter, "")
+	regTokenGetter = Get(realmAddr + "")
+	regToken = regTokenGetter()
+	urequire.True(t, regToken != nil, "expected to find a token") // fixme: use urequire.NotNil
+	urequire.Equal(t, regToken.GetSymbol(), "TST")
+
+	got = Render("")
+	urequire.True(t, strings.Contains(got, `- **TestToken** - [gno.land/r/demo/foo](/r/demo/foo) - [info](/r/demo/grc20reg:gno.land/r/demo/foo)`))
+	urequire.True(t, strings.Contains(got, `- **TestToken** - [gno.land/r/demo/foo](/r/demo/foo).mySlug - [info](/r/demo/grc20reg:gno.land/r/demo/foo.mySlug)`))
+
+	expected = `# TestToken
+- symbol: **TST**
+- realm: [gno.land/r/demo/foo](/r/demo/foo).mySlug
+- decimals: 4
+- total supply: 1234567
+`
+	got = Render("gno.land/r/demo/foo.mySlug")
+	urequire.Equal(t, expected, got)
+}

examples/gno.land/r/demo/tests/crossrealm/crossrealm.gno

@@ -27,3 +27,31 @@ func Make1() *p_crossrealm.Container {
 		B: local,
 	}
 }
+
+type Fooer interface{ Foo() }
+
+var fooer Fooer
+
+func SetFooer(f Fooer) Fooer {
+	fooer = f
+	return fooer
+}
+
+func GetFooer() Fooer { return fooer }
+
+func CallFooerFoo() { fooer.Foo() }
+
+type FooerGetter func() Fooer
+
+var fooerGetter FooerGetter
+
+func SetFooerGetter(fg FooerGetter) FooerGetter {
+	fooerGetter = fg
+	return fg
+}
+
+func GetFooerGetter() FooerGetter {
+	return fooerGetter
+}
+
+func CallFooerGetterFoo() { fooerGetter().Foo() }

examples/gno.land/r/demo/tests/crossrealm_b/crossrealm.gno

@@ -0,0 +1,25 @@
+package crossrealm_b
+
+import (
+	"std"
+
+	"gno.land/r/demo/tests/crossrealm"
+)
+
+type fooer struct {
+	s string
+}
+
+func (f *fooer) SetS(newVal string) {
+	f.s = newVal
+}
+
+func (f *fooer) Foo() {
+	println("hello " + f.s + " cur=" + std.CurrentRealm().PkgPath() + " prev=" + std.PrevRealm().PkgPath())
+}
+
+var (
+	Fooer              = &fooer{s: "A"}
+	FooerGetter        = func() crossrealm.Fooer { return Fooer }
+	FooerGetterBuilder = func() crossrealm.FooerGetter { return func() crossrealm.Fooer { return Fooer } }
+)

examples/gno.land/r/demo/tests/crossrealm_b/gno.mod

@@ -0,0 +1,3 @@
+module gno.land/r/demo/tests/crossrealm_b
+
+require gno.land/r/demo/tests/crossrealm v0.0.0-latest

examples/gno.land/r/demo/tests/tests.gno

@@ -50,6 +50,8 @@ type TestRealmObject struct {
 	Field string
 }
 
+var TestRealmObjectValue TestRealmObject
+
 func ModifyTestRealmObject(t *TestRealmObject) {
 	t.Field += "_modified"
 }

examples/gno.land/r/demo/wugnot/gno.mod

@@ -4,5 +4,6 @@ require (
 	gno.land/p/demo/grc/grc20 v0.0.0-latest
 	gno.land/p/demo/ufmt v0.0.0-latest
 	gno.land/p/demo/users v0.0.0-latest
+	gno.land/r/demo/grc20reg v0.0.0-latest
 	gno.land/r/demo/users v0.0.0-latest
 )

examples/gno.land/r/demo/wugnot/wugnot.gno

@@ -7,6 +7,7 @@ import (
 	"gno.land/p/demo/grc/grc20"
 	"gno.land/p/demo/ufmt"
 	pusers "gno.land/p/demo/users"
+	"gno.land/r/demo/grc20reg"
 	"gno.land/r/demo/users"
 )
 
@@ -18,7 +19,8 @@ const (
 )
 
 func init() {
-	// XXX: grc20reg.Register(Token, "")
+	getter := func() *grc20.Token { return Token }
+	grc20reg.Register(getter, "")
 }
 
 func Deposit() {