Globals to compiler

compiler/compiler.go

@@ -18,6 +18,8 @@ type Compiler struct {
 
 	lastInstruction     EmittedInstruction
 	previousInstruction EmittedInstruction
+
+	symbolTable *SymbolTable
 }
 
 func New() *Compiler {
@@ -26,6 +28,7 @@ func New() *Compiler {
 		constants:           []object.Object{},
 		lastInstruction:     EmittedInstruction{},
 		previousInstruction: EmittedInstruction{},
+		symbolTable:         NewSymbolTable(),
 	}
 }
 
@@ -164,6 +167,22 @@ func (c *Compiler) Compile(node ast.Node) error {
 			}
 		}
 
+	case *ast.LetStatement:
+		err := c.Compile(node.Value)
+		if err != nil {
+			return err
+		}
+		symbol := c.symbolTable.Define(node.Name.Value)
+		c.emit(code.OpSetGlobal, symbol.Index)
+
+	case *ast.Identifier:
+		symbol, ok := c.symbolTable.Resolve(node.Value)
+		if !ok {
+			return fmt.Errorf("undefined varible %s", node.Value)
+		}
+
+		c.emit(code.OpGetGlobal, symbol.Index)
+
 	}
 
 	return nil