Added scope package

src/build/scope/Scope.go

@@ -0,0 +1,12 @@
+package scope
+
+import (
+	"git.akyoto.dev/cli/q/src/build/cpu"
+)
+
+// Scope represents an independent code block.
+type Scope struct {
+	Variables map[string]*Variable
+	InLoop    bool
+	cpu.State
+}

src/build/scope/Stack.go

@@ -0,0 +1,51 @@
+package scope
+
+import (
+	"git.akyoto.dev/cli/q/src/build/ast"
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+type Stack struct {
+	Scopes []*Scope
+}
+
+// CurrentScope returns the current scope.
+func (stack *Stack) CurrentScope() *Scope {
+	return stack.Scopes[len(stack.Scopes)-1]
+}
+
+// PopScope removes the scope at the top of the stack.
+func (stack *Stack) PopScope() {
+	stack.Scopes = stack.Scopes[:len(stack.Scopes)-1]
+}
+
+// PushScope pushes a new scope to the top of the stack.
+func (stack *Stack) PushScope(body ast.AST) *Scope {
+	s := &Scope{}
+
+	if len(stack.Scopes) > 0 {
+		lastScope := stack.Scopes[len(stack.Scopes)-1]
+		s.State = lastScope.State
+		s.Variables = make(map[string]*Variable, len(lastScope.Variables))
+		s.InLoop = lastScope.InLoop
+
+		for k, v := range lastScope.Variables {
+			count := ast.Count(body, token.Identifier, v.Name)
+
+			if count == 0 {
+				continue
+			}
+
+			s.Variables[k] = &Variable{
+				Name:     v.Name,
+				Register: v.Register,
+				Alive:    count,
+			}
+		}
+	} else {
+		s.Variables = map[string]*Variable{}
+	}
+
+	stack.Scopes = append(stack.Scopes, s)
+	return s
+}

src/build/scope/Variable.go

@@ -0,0 +1,13 @@
+package scope
+
+import (
+	"git.akyoto.dev/cli/q/src/build/cpu"
+)
+
+// Variable represents a named register.
+type Variable struct {
+	Scope    *Scope
+	Name     string
+	Register cpu.Register
+	Alive    int
+}