feat: add std.PrevRealm (gnolang#667)

Co-authored-by: Antonio Navarro Perez <antnavper@gmail.com>
Co-authored-by: Thomas Bruyelle <thomasbruyelle@hey.com>
Co-authored-by: Manfred Touron <94029+moul@users.noreply.github.com>

examples/gno.land/p/demo/tests/subtests/subtests.gno

@@ -0,0 +1,17 @@
+package subtests
+
+import (
+	"std"
+)
+
+func CurrentRealmPath() string {
+	return std.CurrentRealmPath()
+}
+
+func GetPrevRealm() std.Realm {
+	return std.PrevRealm()
+}
+
+func Exec(fn func()) {
+	fn()
+}

examples/gno.land/p/demo/tests/tests.gno

@@ -3,7 +3,9 @@ package tests
 import (
 	"std"
 
+	psubtests "gno.land/p/demo/tests/subtests"
 	"gno.land/r/demo/tests"
+	rtests "gno.land/r/demo/tests"
 )
 
 // IncCounter demonstrates that it's possible to call a realm function from
@@ -51,3 +53,20 @@ func ModifyTestRealmObject2b() {
 func ModifyTestRealmObject2c() {
 	SomeValue3.Field = "modified"
 }
+
+func GetPrevRealm() std.Realm {
+	return std.PrevRealm()
+}
+
+func GetPSubtestsPrevRealm() std.Realm {
+	return psubtests.GetPrevRealm()
+}
+
+func GetRTestsGetPrevRealm() std.Realm {
+	return rtests.GetPrevRealm()
+}
+
+// Warning: unsafe pattern.
+func Exec(fn func()) {
+	fn()
+}

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

@@ -0,0 +1,17 @@
+package subtests
+
+import (
+	"std"
+)
+
+func CurrentRealmPath() string {
+	return std.CurrentRealmPath()
+}
+
+func GetPrevRealm() std.Realm {
+	return std.PrevRealm()
+}
+
+func Exec(fn func()) {
+	fn()
+}

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

@@ -1,6 +1,10 @@
 package tests
 
-import "std"
+import (
+	"std"
+
+	"gno.land/r/demo/tests/subtests"
+)
 
 var counter int
 
@@ -69,3 +73,15 @@ func ModTestNodes() {
 func PrintTestNodes() {
 	println(gTestNode2.Child.Name)
 }
+
+func GetPrevRealm() std.Realm {
+	return std.PrevRealm()
+}
+
+func GetPSubtestsPrevRealm() std.Realm {
+	return subtests.GetPrevRealm()
+}
+
+func Exec(fn func()) {
+	fn()
+}

gnovm/pkg/gnolang/frame.go

@@ -1,6 +1,8 @@
 package gnolang
 
-import "fmt"
+import (
+	"fmt"
+)
 
 //----------------------------------------
 // (runtime) Frame

gnovm/stdlibs/frame.go

@@ -0,0 +1,20 @@
+package stdlibs
+
+import "github.com/gnolang/gno/tm2/pkg/crypto"
+
+type Realm struct {
+	addr    crypto.Bech32Address
+	pkgPath string
+}
+
+func (r Realm) Addr() crypto.Bech32Address {
+	return r.addr
+}
+
+func (r Realm) PkgPath() string {
+	return r.pkgPath
+}
+
+func (r Realm) IsUser() bool {
+	return r.pkgPath == ""
+}

gnovm/stdlibs/std/frame.gno

@@ -0,0 +1,18 @@
+package std
+
+type Realm struct {
+	addr    Address
+	pkgPath string
+}
+
+func (r Realm) Addr() Address {
+	return r.addr
+}
+
+func (r Realm) PkgPath() string {
+	return r.pkgPath
+}
+
+func (r Realm) IsUser() bool {
+	return r.pkgPath == ""
+}

gnovm/stdlibs/stdlibs.go

@@ -17,6 +17,7 @@ func InjectNativeMappings(store gno.Store) {
 	store.AddGo2GnoMapping(reflect.TypeOf(crypto.Bech32Address("")), "std", "Address")
 	store.AddGo2GnoMapping(reflect.TypeOf(std.Coins{}), "std", "Coins")
 	store.AddGo2GnoMapping(reflect.TypeOf(std.Coin{}), "std", "Coin")
+	store.AddGo2GnoMapping(reflect.TypeOf(Realm{}), "std", "Realm")
 }
 
 func InjectPackage(store gno.Store, pn *gno.PackageNode) {
@@ -262,6 +263,61 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 				m.PushValue(res0)
 			},
 		)
+		pn.DefineNative("PrevRealm",
+			gno.Flds( // params
+			),
+			gno.Flds( // results
+				"", "Realm",
+			),
+			func(m *gno.Machine) {
+				var (
+					ctx = m.Context.(ExecContext)
+					// Default lastCaller is OrigCaller, the signer of the tx
+					lastCaller  = ctx.OrigCaller
+					lastPkgPath = ""
+				)
+
+				for i := m.NumFrames() - 1; i > 0; i-- {
+					fr := m.Frames[i]
+					if fr.LastPackage == nil || !fr.LastPackage.IsRealm() {
+						// Ignore non-realm frame
+						continue
+					}
+					pkgPath := fr.LastPackage.PkgPath
+					// The first realm we encounter will be the one calling
+					// this function; to get the calling realm determine the first frame
+					// where fr.LastPackage changes.
+					if lastPkgPath == "" {
+						lastPkgPath = pkgPath
+					} else if lastPkgPath == pkgPath {
+						continue
+					} else {
+						lastCaller = fr.LastPackage.GetPkgAddr().Bech32()
+						lastPkgPath = pkgPath
+						break
+					}
+				}
+
+				// Empty the pkgPath if we return a user
+				if ctx.OrigCaller == lastCaller {
+					lastPkgPath = ""
+				}
+
+				// Return the result
+				res0 := gno.Go2GnoValue(
+					m.Alloc,
+					m.Store,
+					reflect.ValueOf(Realm{
+						addr:    lastCaller,
+						pkgPath: lastPkgPath,
+					}),
+				)
+
+				realmT := store.GetType(gno.DeclaredTypeID("std", "Realm"))
+				res0.T = realmT
+				m.PushValue(res0)
+			},
+		)
 		pn.DefineNative("GetOrigPkgAddr",
 			gno.Flds( // params
 			),

gnovm/stdlibs/stdshim/frame.gno

@@ -0,0 +1,18 @@
+package std
+
+type Realm struct {
+	addr    Address
+	pkgPath string
+}
+
+func (r Realm) Addr() Address {
+	return r.addr
+}
+
+func (r Realm) PkgPath() string {
+	return r.pkgPath
+}
+
+func (r Realm) IsUser() bool {
+	return r.pkgPath == ""
+}

gnovm/stdlibs/stdshim/stdshim.gno

@@ -36,6 +36,14 @@ func GetOrigSend() Coins {
 	return Coins{}
 }
 
+func PrevRealm() Realm {
+	panic(shimWarn)
+	return Realm{
+		addr:    Address(""),
+		pkgPath: "",
+	}
+}
+
 func GetOrigCaller() Address {
 	panic(shimWarn)
 	return Address("")

gnovm/tests/file.go

@@ -13,13 +13,12 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/pmezard/go-difflib/difflib"
-
 	gno "github.com/gnolang/gno/gnovm/pkg/gnolang"
 	"github.com/gnolang/gno/gnovm/stdlibs"
 	"github.com/gnolang/gno/tm2/pkg/crypto"
 	osm "github.com/gnolang/gno/tm2/pkg/os"
 	"github.com/gnolang/gno/tm2/pkg/std"
+	"github.com/pmezard/go-difflib/difflib"
 )
 
 type loggerFunc func(args ...interface{})