From 44af84b6a7e13e43c1f55694b66dfdea2d0cd308 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Delgado?=
 <48872887+Alvarodb@users.noreply.github.com>
Date: Wed, 1 May 2024 06:04:21 -0600
Subject: [PATCH] feat(MemcpyEnterScope): enters a new scope for the memory
 copy operaton with a specified length (#372)

* feat(MemcpyEnterScope): enters a new scope for the memory copy operation with a specified length

* fix: addressing review comments

* adding unit test for memcpy hint

* fix lint issue plus and rename hint code to memcpyEnterScopeCode

* rename hint to newMemcpyEnterScopeHint

* fix: memcpy hint as new hint

* fix order of codes
---
 pkg/hintrunner/zero/hintcode.go             |  7 +++---
 pkg/hintrunner/zero/zerohint.go             |  2 ++
 pkg/hintrunner/zero/zerohint_memcpy.go      | 23 ++++++++++++++++++
 pkg/hintrunner/zero/zerohint_memcpy_test.go | 27 +++++++++++++++++++++
 4 files changed, 56 insertions(+), 3 deletions(-)
 create mode 100644 pkg/hintrunner/zero/zerohint_memcpy_test.go

diff --git a/pkg/hintrunner/zero/hintcode.go b/pkg/hintrunner/zero/hintcode.go
index 71a6fca2..7bb2d717 100644
--- a/pkg/hintrunner/zero/hintcode.go
+++ b/pkg/hintrunner/zero/hintcode.go
@@ -84,7 +84,8 @@ const (
 	// ------ Dictionaries hints related code ------
 
 	// ------ Other hints related code ------
-	allocSegmentCode string = "memory[ap] = segments.add()"
-	vmEnterScopeCode string = "vm_enter_scope()"
-	vmExitScopeCode  string = "vm_exit_scope()"
+	allocSegmentCode     string = "memory[ap] = segments.add()"
+	memcpyEnterScopeCode string = "vm_enter_scope({'n': ids.len})"
+	vmEnterScopeCode     string = "vm_enter_scope()"
+	vmExitScopeCode      string = "vm_exit_scope()"
 )
diff --git a/pkg/hintrunner/zero/zerohint.go b/pkg/hintrunner/zero/zerohint.go
index 35ebdd7d..878e3994 100644
--- a/pkg/hintrunner/zero/zerohint.go
+++ b/pkg/hintrunner/zero/zerohint.go
@@ -147,6 +147,8 @@ func GetHintFromCode(program *zero.ZeroProgram, rawHint zero.Hint, hintPC uint64
 		return createAllocSegmentHinter(resolver)
 	case vmEnterScopeCode:
 		return createVMEnterScopeHinter(resolver)
+	case memcpyEnterScopeCode:
+		return createMemcpyEnterScopeHinter(resolver)
 	case vmExitScopeCode:
 		return createVMExitScopeHinter(resolver)
 	case testAssignCode:
diff --git a/pkg/hintrunner/zero/zerohint_memcpy.go b/pkg/hintrunner/zero/zerohint_memcpy.go
index 31c5fc87..bef67555 100644
--- a/pkg/hintrunner/zero/zerohint_memcpy.go
+++ b/pkg/hintrunner/zero/zerohint_memcpy.go
@@ -20,6 +20,29 @@ func createVMEnterScopeHinter(resolver hintReferenceResolver) (hinter.Hinter, er
 	}, nil
 }
 
+func newMemcpyEnterScopeHint(len hinter.ResOperander) hinter.Hinter {
+	return &GenericZeroHinter{
+		Name: "MemcpyEnterScope",
+		Op: func(vm *VM.VirtualMachine, ctx *hinter.HintRunnerContext) error {
+			//>  vm_enter_scope({'n': ids.len})
+			len, err := hinter.ResolveAsFelt(vm, len)
+			if err != nil {
+				return err
+			}
+			ctx.ScopeManager.EnterScope(map[string]any{"n": len})
+			return nil
+		},
+	}
+}
+
+func createMemcpyEnterScopeHinter(resolver hintReferenceResolver) (hinter.Hinter, error) {
+	len, err := resolver.GetResOperander("len")
+	if err != nil {
+		return nil, err
+	}
+	return newMemcpyEnterScopeHint(len), nil
+}
+
 func createVMExitScopeHinter(resolver hintReferenceResolver) (hinter.Hinter, error) {
 	return &GenericZeroHinter{
 		Name: "VMExitScope",
diff --git a/pkg/hintrunner/zero/zerohint_memcpy_test.go b/pkg/hintrunner/zero/zerohint_memcpy_test.go
new file mode 100644
index 00000000..0c2da90a
--- /dev/null
+++ b/pkg/hintrunner/zero/zerohint_memcpy_test.go
@@ -0,0 +1,27 @@
+package zero
+
+import (
+	"testing"
+
+	"github.com/NethermindEth/cairo-vm-go/pkg/hintrunner/hinter"
+)
+
+func TestZeroHintMemcpy(t *testing.T) {
+
+	runHinterTests(t, map[string][]hintTestCase{
+		"MemcpyEnterScope": {
+			{
+				operanders: []*hintOperander{
+					{Name: "len", Kind: apRelative, Value: feltUint64(1)},
+				},
+				ctxInit: func(ctx *hinter.HintRunnerContext) {
+					hinter.InitializeScopeManager(ctx, map[string]any{})
+				},
+				makeHinter: func(ctx *hintTestContext) hinter.Hinter {
+					return newMemcpyEnterScopeHint(ctx.operanders["len"])
+				},
+				check: varValueInScopeEquals("n", feltUint64(1)),
+			},
+		},
+	})
+}