From bee75360420ec1b62210c444ac39f5cd1cda65ed Mon Sep 17 00:00:00 2001
From: Aotokitsuruya <contact@aotoki.me>
Date: Wed, 22 May 2024 22:35:18 +0800
Subject: [PATCH] Implement minimal rest parameter feature

---
 array.go                | 38 ++++++++++++++++++++++++++++++++++++++
 class.go                |  2 ++
 features/method.feature |  1 -
 init.go                 |  4 ++++
 mruby.go                |  1 +
 presym.go               |  2 ++
 proc.go                 | 12 ++++++++++++
 vm.go                   | 19 ++++++++++++++++++-
 8 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 array.go

diff --git a/array.go b/array.go
new file mode 100644
index 0000000..ec152c4
--- /dev/null
+++ b/array.go
@@ -0,0 +1,38 @@
+package mruby
+
+func initArray(mrb *State) (err error) {
+	mrb.ArrayClass, err = mrb.DefineClassId(_ArrayClass(mrb), mrb.ObjectClass)
+	if err != nil {
+		return err
+	}
+
+	mrb.DefineMethodId(mrb.ArrayClass, _join(mrb), arrayJoin)
+
+	return nil
+}
+
+func arrayJoin(mrb *State, self Value) Value {
+	argv := mrb.GetArgv()
+
+	elem, ok := self.([]Value)
+	if !ok {
+		return nil
+	}
+
+	ret := ""
+	elemLen := len(elem)
+	for i, v := range elem {
+		v, ok := v.(string)
+		if !ok {
+			continue
+		}
+
+		ret += v
+		hasNext := elemLen > i+1
+		if hasNext {
+			ret += argv[0].(string)
+		}
+	}
+
+	return ret
+}
diff --git a/class.go b/class.go
index c16c647..e157b46 100644
--- a/class.go
+++ b/class.go
@@ -41,6 +41,8 @@ func (mrb *State) Class(v Value) RClass {
 	switch v := v.(type) {
 	case RObject:
 		return v.Class()
+	case []Value:
+		return mrb.ArrayClass
 	case bool:
 		if v {
 			return mrb.TrueClass
diff --git a/features/method.feature b/features/method.feature
index afda085..102e3ae 100644
--- a/features/method.feature
+++ b/features/method.feature
@@ -48,7 +48,6 @@ Feature: Method
       """
     Then there should return string "Hello, Ruby! I love Ruby"
 
-  @wip
   Scenario: I can call the method with rest arguments
     When I execute ruby code:
       """
diff --git a/init.go b/init.go
index d5840ae..6457b93 100644
--- a/init.go
+++ b/init.go
@@ -13,5 +13,9 @@ func initCore(mrb *State) (err error) {
 		return
 	}
 
+	if err = initArray(mrb); err != nil {
+		return
+	}
+
 	return
 }
diff --git a/mruby.go b/mruby.go
index dcba331..114e102 100644
--- a/mruby.go
+++ b/mruby.go
@@ -21,6 +21,7 @@ type State struct {
 	ClassClass   RClass
 	FalseClass   RClass
 	TrueClass    RClass
+	ArrayClass   RClass
 	KernelModule RClass
 
 	topSelf RObject
diff --git a/presym.go b/presym.go
index ebc0bcf..38a0681 100644
--- a/presym.go
+++ b/presym.go
@@ -19,5 +19,7 @@ var (
 	_Kernel      = predefineSymbol("Kernel")
 	_TrueClass   = predefineSymbol("TrueClass")
 	_FalseClass  = predefineSymbol("FalseClass")
+	_ArrayClass  = predefineSymbol("Array")
+	_join        = predefineSymbol("join")
 	_raise       = predefineSymbol("raise")
 )
diff --git a/proc.go b/proc.go
index aa024ce..62dec4d 100644
--- a/proc.go
+++ b/proc.go
@@ -2,6 +2,18 @@ package mruby
 
 import "github.com/elct9620/mruby-go/insn"
 
+func AspecReq(n int) int {
+	return (((n) >> 18) & 0x1f)
+}
+
+func AspecOpt(n int) int {
+	return (((n) >> 13) & 0x1f)
+}
+
+func AspecRest(n int) int {
+	return (((n) >> 12) & 0x1)
+}
+
 type RProc interface {
 	IsGoFunction() bool
 	Body() any
diff --git a/vm.go b/vm.go
index 61f125f..ee30a34 100644
--- a/vm.go
+++ b/vm.go
@@ -198,7 +198,24 @@ func (mrb *State) VmExec(proc RProc, code *insn.Sequence) (ret Value, err error)
 			ctx.Set(0, method.Call(mrb, recv))
 			mrb.callinfoPop()
 		case op.Enter:
-			_ = code.ReadW()
+			a := code.ReadW()
+			a = append([]byte{0x00}, a...)
+			aspec := int(binary.BigEndian.Uint32(a))
+
+			req := AspecReq(aspec)
+			opt := AspecOpt(aspec)
+			rest := AspecRest(aspec)
+
+			if rest > 0 {
+				values := make([]Value, 0)
+				argv := mrb.GetArgv()
+				for i := 0; i < len(argv); i++ {
+					values = append(values, argv[i])
+				}
+
+				ctx.Set(req+opt+1, values)
+			}
+
 			ctx.SetSequenceCursor(code.Cursor())
 		case op.EQ:
 			a := code.ReadB()