abstract flags, implement comments as words, fix some bugs

builtins.go

@@ -9,9 +9,9 @@ type Builtins struct{}
 var ErrExit = fmt.Errorf("exit requested")
 
 // Colon sets the COMPILE/IMMEDIATE flag to COMPILE
-func (b *Builtins) Colon(f *bool) func() error {
+func (b *Builtins) Colon(c *Context) func() error {
 	return func() error {
-		*f = false
+		c.Flags.SetFlag("Immediate", false)
 		return nil
 	}
 }
@@ -20,7 +20,26 @@ func (b *Builtins) Colon(f *bool) func() error {
 func (b *Builtins) Semicolon(c *Context) func() error {
 	return func() error {
 		c.Dictionary.AddWord(c.Words[0], nil, c.Words[1:], false)
-		c.Immediate = true
+		c.Words = []string{}
+		c.Flags.SetFlag("Immediate", true)
+		return nil
+	}
+}
+
+// OpenComment puts the parser into an "ignore" mode
+func (b *Builtins) OpenComment(c *Context) func() error {
+	return func() error {
+		c.Flags.SetFlag("Comment", true)
+		c.Flags.SetFlag("Immediate", false)
+		return nil
+	}
+}
+
+// CloseComment resumes parsing
+func (b *Builtins) CloseComment(c *Context) func() error {
+	return func() error {
+		c.Flags.SetFlag("Comment", false)
+		c.Flags.SetFlag("Immediate", false)
 		return nil
 	}
 }
@@ -303,6 +322,16 @@ func (b *Builtins) Words(d Dictionary) func() error {
 	}
 }
 
+// Flags outputs a list of all flags
+func (b *Builtins) Flags(c Context) func() error {
+	return func() error {
+		for n := range c.Flags {
+			fmt.Printf("%s %v\n", n, c.Flags.GetFlag(n))
+		}
+		return nil
+	}
+}
+
 // Emit outputs the UTF-8 rune for the int on the top of the stack
 func (b *Builtins) Emit(s *Stack) func() error {
 	return func() error {
@@ -443,14 +472,6 @@ func (b *Builtins) I(s *Stack, r *Stack) func() error {
 	}
 }
 
-// CR prints a newline to standard out
-func (b *Builtins) CR() func() error {
-	return func() error {
-		fmt.Print("\n")
-		return nil
-	}
-}
-
 // Quit exits the repl
 func (b *Builtins) Quit() func() error {
 	return func() error {

eval.go

@@ -6,12 +6,12 @@ import (
 	"strings"
 )
 
-// Context is a set of Dictionary + Stacks representing a runtime environment
+// Context is a set of Dictionary + Stacks + Flags representing a runtime environment
 type Context struct {
 	Dictionary Dictionary
 	Stack      *Stack
 	RStack     *Stack
-	Immediate  bool
+	Flags      Flags
 	Words      []string
 }
 
@@ -19,38 +19,29 @@ type Context struct {
 func (c *Context) Eval(line string) error {
 	// state
 	var word []byte
-	var comment bool
 
 	for i := 0; i < len(line); i = i + 1 {
 		switch line[i] {
-		case '(', ')': // comments
+		case ' ':
+			sword := strings.TrimSpace(string(word))
 			if len(word) == 0 {
-				if line[i] == '(' {
-					comment = true
-					continue
-				}
-				comment = false
+				// empty space, just continue...
 				continue
-			} else {
-				word = append(word, line[i])
 			}
-		case ' ':
-			sword := strings.TrimSpace(string(word))
-			if !c.Immediate { // continue building our subroutine if we're not in immediate mode...
-				if len(word) != 0 { // don't add empty words to our list
-					// Was that a word we know?
-					w, _ := c.Dictionary.GetWord(sword)
-					// check if it's an IMMEDIATE mode toggle word
-					c.Immediate = w.Immediate
-					if !c.Immediate {
-						c.Words = append(c.Words, sword)
-						word = []byte{}
-						continue
-					}
-				}
+			// Is this a word we know?
+			w, _ := c.Dictionary.GetWord(sword)
+			// check if it's an IMMEDIATE mode toggle word
+			if !c.Flags.GetFlag("Immediate") {
+				c.Flags.SetFlag("Immediate", w.Immediate)
 			}
-			if len(word) == 0 || comment {
-				// empty space, just continue...
+
+			if !c.Flags.GetFlag("Immediate") && !c.Flags.GetFlag("Comment") {
+				c.Words = append(c.Words, sword)
+				word = []byte{}
+				continue
+			}
+			if !c.Flags.GetFlag("Immediate") && c.Flags.GetFlag("Comment") {
+				word = []byte{}
 				continue
 			}
 
@@ -63,7 +54,7 @@ func (c *Context) Eval(line string) error {
 			}
 
 			// it wasn't a number. Is it a word we know?
-			w, err := c.Dictionary.GetWord(sword)
+			w, err = c.Dictionary.GetWord(sword)
 			if err != nil {
 				return fmt.Errorf("could not parse %s; %v", w.Name, err)
 			}
@@ -78,9 +69,7 @@ func (c *Context) Eval(line string) error {
 			}
 			word = []byte{}
 		default:
-			if !comment {
-				word = append(word, line[i])
-			}
+			word = append(word, line[i])
 		}
 	}
 

flags.go

@@ -0,0 +1,12 @@
+package main
+
+// Flags is a simple map of strings to boolean flag fields
+type Flags map[string]bool
+
+func (f Flags) GetFlag(s string) bool {
+	return f[s]
+}
+
+func (f Flags) SetFlag(s string, b bool) {
+	f[s] = b
+}

main.go

@@ -18,14 +18,20 @@ func main() {
 		Dictionary: dict,
 		Stack:      &stack,
 		RStack:     &rstack,
-		Immediate:  true,
-		Words:      []string{},
+		Flags: Flags{
+			"Immediate": true,
+			"Comment":   false,
+		},
+		Words: []string{},
 	}
 
 	b := &Builtins{}
 	// word definitions
-	dict.AddWord(":", b.Colon(&c.Immediate), nil, false)
+	dict.AddWord(":", b.Colon(&c), nil, false)
 	dict.AddWord(";", b.Semicolon(&c), nil, true)
+	// comments
+	dict.AddWord("(", b.OpenComment(&c), nil, true)
+	dict.AddWord(")", b.CloseComment(&c), nil, true)
 	// math
 	dict.AddWord("+", b.Add(&stack), nil, false)
 	dict.AddWord("-", b.Sub(&stack), nil, false)
@@ -34,7 +40,7 @@ func main() {
 	// output
 	dict.AddWord(".", b.Print(&stack), nil, false)
 	dict.AddWord("EMIT", b.Emit(&stack), nil, false)
-	dict.AddWord("CR", b.CR(), nil, false)
+	dict.AddWord("CR", nil, []string{"10", "EMIT"}, false) // emit a newline
 	// logic
 	dict.AddWord("=", b.Eq(&stack), nil, false)
 	dict.AddWord("0=", nil, []string{"0", "="}, false)
@@ -53,6 +59,7 @@ func main() {
 	dict.AddWord("ROT", b.Rot(&stack), nil, false)
 	// debugging
 	dict.AddWord("WORDS", b.Words(dict), nil, false)
+	dict.AddWord("FLAGS", b.Flags(c), nil, false)
 	dict.AddWord(".S", b.Debug(&stack), nil, false)
 	dict.AddWord(".R", b.Debug(&rstack), nil, false)
 	dict.AddWord("R>", b.RFrom(&stack, &rstack), nil, false)
@@ -66,11 +73,15 @@ func main() {
 	dict.AddWord("BYE", b.Quit(), nil, false)
 
 	reader := bufio.NewReader(os.Stdin)
-	fmt.Print("prosper")
+	fmt.Print("prosper\n")
 
 	// read loop
 	for {
-		fmt.Print("\n> ")
+		if c.Flags["Immediate"] {
+			fmt.Print("> ")
+		} else {
+			fmt.Print("    ")
+		}
 
 		line, err := reader.ReadString('\n')
 		if err != nil {
@@ -83,9 +94,9 @@ func main() {
 			fmt.Printf("bye\n")
 			os.Exit(0)
 		} else if err != nil {
-			fmt.Printf("error in evaluation: %v", err)
-		} else {
-			fmt.Print("ok")
+			fmt.Printf("error in evaluation: %v\n", err)
+		} else if c.Flags["Immediate"] {
+			fmt.Print("ok\n")
 		}
 	}
 }