debug

main.go

@@ -3,15 +3,17 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"monkey/compiler"
 	"monkey/lexer"
+	"monkey/object"
 	"monkey/parser"
 	"monkey/repl"
 	"os"
 	"os/user"
 	"path"
+	"strings"
 )
 
 var (
@@ -37,6 +39,22 @@ func init() {
 	flag.StringVar(&engine, "e", "vm", "engine to use (eval or vm)")
 }
 
+// Indent indents a block of text with an indent string
+func Indent(text, indent string) string {
+	if text[len(text)-1:] == "\n" {
+		result := ""
+		for _, j := range strings.Split(text[:len(text)-1], "\n") {
+			result += indent + j + "\n"
+		}
+		return result
+	}
+	result := ""
+	for _, j := range strings.Split(strings.TrimRight(text, "\n"), "\n") {
+		result += indent + j + "\n"
+	}
+	return result[:len(result)-1]
+}
+
 func main() {
 	flag.Parse()
 
@@ -59,7 +77,7 @@ func main() {
 		f, err := os.Open(args[0])
 		defer f.Close()
 
-		b, err := ioutil.ReadAll(f)
+		b, err := io.ReadAll(f)
 		if err != nil {
 			log.Fatal(err)
 		}
@@ -79,7 +97,15 @@ func main() {
 		}
 
 		code := c.Bytecode()
-		fmt.Printf("%s\n", code.Instructions)
+		fmt.Printf("Main:\n%s\n", code.Instructions)
+
+		fmt.Print("Constants:\n")
+		for i, constant := range code.Constants {
+			fmt.Printf("%04d %s\n", i, constant.Inspect())
+			if fn, ok := constant.(*object.CompiledFunction); ok {
+				fmt.Printf("%s\n", Indent(fn.Instructions.String(), "     "))
+			}
+		}
 	} else {
 		opts := &repl.Options{
 			Debug:       debug,

repl/repl.go

@@ -126,6 +126,7 @@ func (r *REPL) Exec(f io.Reader) (state *VMState) {
 	state.constants = code.Constants
 
 	machine := vm.NewWithGlobalState(code, state.globals)
+	machine.Debug = r.opts.Debug
 	err = machine.Run()
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Woops! Executing bytecode failed:\n %s\n", err)
@@ -206,6 +207,7 @@ func (r *REPL) StartExecLoop(in io.Reader, out io.Writer, state *VMState) {
 		state.constants = code.Constants
 
 		machine := vm.NewWithGlobalState(code, state.globals)
+		machine.Debug = r.opts.Debug
 		err = machine.Run()
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Woops! Executing bytecode failed:\n %s\n", err)

vm/vm.go

@@ -2,9 +2,11 @@ package vm
 
 import (
 	"fmt"
+	"log"
 	"monkey/code"
 	"monkey/compiler"
 	"monkey/object"
+	"strings"
 )
 
 const StackSize = 2048
@@ -16,6 +18,8 @@ var True = &object.Boolean{Value: true}
 var False = &object.Boolean{Value: false}
 
 type VM struct {
+	Debug bool
+
 	constants []object.Object
 
 	stack []object.Object
@@ -77,6 +81,17 @@ func (vm *VM) Run() error {
 	var ins code.Instructions
 	var op code.Opcode
 
+	if vm.Debug {
+		log.Printf(
+			"%-20s %-20s\n",
+			strings.Split(ins[ip:].String(), "\n")[0],
+			fmt.Sprintf(
+				"[ip=%02d fp=%02d, sp=%02d]",
+				ip, vm.sp, vm.framesIndex-1,
+			),
+		)
+	}
+
 	for vm.currentFrame().ip < len(vm.currentFrame().Instructions())-1 {
 		vm.currentFrame().ip++