refactor how repl works

repl.go

@@ -0,0 +1,191 @@
+package monkey
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"golang.org/x/term"
+
+	"monkey/internal/compiler"
+	"monkey/internal/object"
+	"monkey/internal/parser"
+	"monkey/internal/vm"
+)
+
+// Package repl implements the Read-Eval-Print-Loop or interactive console
+// by lexing, parsing and evaluating the input in the interpreter
+
+func VmREPL() error {
+	var state = vm.NewVMState()
+
+	initState, err := term.MakeRaw(0)
+	if err != nil {
+		fmt.Println(err)
+		return fmt.Errorf("error opening terminal: %w", err)
+	}
+	defer term.Restore(0, initState)
+
+	t := term.NewTerminal(os.Stdin, ">>> ")
+	t.AutoCompleteCallback = autoComplete
+	object.Stdout = t
+
+	PrintVersionInfo(t)
+	for {
+		input, err := t.ReadLine()
+		check(t, initState, err)
+
+		input = strings.TrimRight(input, " ")
+		if len(input) > 0 && input[len(input)-1] == '{' {
+			input, err = acceptUntil(t, input, "\n\n")
+			check(t, initState, err)
+		}
+
+		res, errs := parser.Parse("<stdin>", input)
+		if len(errs) != 0 {
+			for _, e := range errs {
+				fmt.Fprintln(t, e)
+			}
+			continue
+		}
+
+		c := compiler.NewWithState(state.Symbols, &state.Constants)
+		if err := c.Compile(res); err != nil {
+			fmt.Fprintln(t, err)
+			continue
+		}
+
+		mvm := vm.NewWithState("<stdin>", c.Bytecode(), state)
+		if err := mvm.Run(); err != nil {
+			fmt.Fprintf(t, "runtime error: %v\n", err)
+			continue
+		}
+
+		if val := mvm.LastPoppedStackElem(); val.Type() != object.NULL_OBJ {
+			fmt.Fprintln(t, val.Inspect())
+		}
+	}
+}
+
+func autoComplete(line string, pos int, key rune) (newLine string, newPos int, ok bool) {
+	if key == '\t' {
+		return line + "    ", pos + 4, true
+	}
+	return
+}
+
+func check(t *term.Terminal, initState *term.State, err error) {
+	if err != nil {
+		// Quit without error on Ctrl^D.
+		if err != io.EOF {
+			fmt.Fprintln(t, err)
+		}
+		term.Restore(0, initState)
+		fmt.Println()
+		os.Exit(0)
+	}
+}
+
+func acceptUntil(t *term.Terminal, start, end string) (string, error) {
+	var buf strings.Builder
+
+	buf.WriteString(start)
+	buf.WriteRune('\n')
+	t.SetPrompt("... ")
+	defer t.SetPrompt(">>> ")
+
+	for {
+		line, err := t.ReadLine()
+		if err != nil {
+			return "", err
+		}
+
+		line = strings.TrimRight(line, " ")
+		buf.WriteString(line)
+		buf.WriteRune('\n')
+
+		if s := buf.String(); len(s) > len(end) && s[len(s)-len(end):] == end {
+			break
+		}
+	}
+
+	return buf.String(), nil
+}
+
+func SimpleVmREPL() {
+	var (
+		state  = vm.NewVMState()
+		reader = bufio.NewReader(os.Stdin)
+	)
+
+	PrintVersionInfo(os.Stdout)
+	for {
+		fmt.Print(">>> ")
+		input, err := reader.ReadString('\n')
+		simpleCheck(err)
+
+		input = strings.TrimRight(input, " \n")
+		if len(input) > 0 && input[len(input)-1] == '{' {
+			input, err = simpleAcceptUntil(reader, input, "\n\n")
+			simpleCheck(err)
+		}
+
+		res, errs := parser.Parse("<stdin>", input)
+		if len(errs) != 0 {
+			for _, e := range errs {
+				fmt.Println(e)
+			}
+			continue
+		}
+
+		c := compiler.NewWithState(state.Symbols, &state.Constants)
+		c.SetFileInfo("<stdin>", input)
+		if err := c.Compile(res); err != nil {
+			fmt.Println(err)
+			continue
+		}
+		mvm := vm.NewWithState("<stdin>", c.Bytecode(), state)
+
+		if err := mvm.Run(); err != nil {
+			fmt.Printf("runtime error: %v\n", err)
+			continue
+		}
+
+		if val := mvm.LastPoppedStackElem(); val.Type() != object.NULL_OBJ {
+			fmt.Println(val.Inspect())
+		}
+	}
+}
+
+func simpleCheck(err error) {
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(0)
+	}
+}
+
+func simpleAcceptUntil(r *bufio.Reader, start, end string) (string, error) {
+	var buf strings.Builder
+
+	buf.WriteString(start)
+	buf.WriteRune('\n')
+	for {
+		fmt.Print("... ")
+		line, err := r.ReadString('\n')
+		if err != nil {
+			return "", err
+		}
+
+		line = strings.TrimRight(line, " \n")
+		buf.WriteString(line)
+		buf.WriteRune('\n')
+
+		if s := buf.String(); len(s) > len(end) && s[len(s)-len(end):] == end {
+			break
+		}
+	}
+
+	return buf.String(), nil
+}