Merge pull request #83 from skx/allow-raw-line-for-if

Allow omitting GOTO for IF-tests.

eval/eval.go

@@ -136,6 +136,11 @@ func New(stream *tokenizer.Tokenizer) (*Interpreter, error) {
 	//
 	t.fns = make(map[string]userFunction)
 
+	//
+	// The previous token we've seen, if any.
+	//
+	var prevToken token.Token
+
 	//
 	// Save the tokens that our program consists of, one by one,
 	// until we hit the end.
@@ -169,9 +174,29 @@ func New(stream *tokenizer.Tokenizer) (*Interpreter, error) {
 			// sequential.  Or at least going-backwards.
 		}
 
+		//
+		// If the previous token was a "THEN" or "ELSE", and the
+		// current token is an integer then we add in the implicit
+		// GOTO.
+		//
+		// This allows the following two programs to be identical:
+		//
+		//   IF 1 < 2 THEN 300 ELSE 400
+		//
+		//   IF 1 < 2 THEN GOTO 300 ELSE GOTO 400
+		//
+		if prevToken.Type == token.THEN || prevToken.Type == token.ELSE {
+			if tok.Type == token.INT {
+				t.program = append(t.program,
+					token.Token{Type: token.GOTO, Literal: "GOTO"})
+			}
+		}
+
 		// Regardless append the token to our array
 		t.program = append(t.program, tok)
 
+		// Continue - recording the previous token too.
+		prevToken = tok
 		offset++
 	}
 

eval/eval_test.go

@@ -862,6 +862,72 @@ func TestIF(t *testing.T) {
 		t.Errorf("The error we found was not what we expected: %s", err.Error())
 	}
 
+	//
+	// Now some simple tests of "GOTO" in IF
+	//
+	// The first with a `GOTO` token, the second without.
+	//
+	test1 := `
+10 IF 2 < 10 THEN GOTO 40
+20 LET a = 3
+30 END
+40 LET a = 33
+50 END
+`
+	test2 := `
+10 IF 2 < 10 THEN 40 ELSE 99
+20 LET a = 2
+30 END
+40 LET a = 313
+50 END
+`
+	//
+	// test1
+	//
+	e, err = FromString(test1)
+	if err != nil {
+		t.Errorf("Failed to parse program")
+	}
+
+	err = e.Run()
+	if err != nil {
+		t.Errorf("Didn't expect a runtime-error, received one %s", err.Error())
+	}
+	cur := e.GetVariable("a")
+	if cur.Type() == object.ERROR {
+		t.Errorf("Variable 'a' does not exist for %s", test1)
+	}
+	if cur.Type() != object.NUMBER {
+		t.Errorf("Variable 'a' had wrong type: %s", cur.String())
+	}
+	out := cur.(*object.NumberObject).Value
+	if out != 33 {
+		t.Errorf("Expected 'a' to be %d, got %f", 33, out)
+	}
+
+	//
+	// test2
+	//
+	e, err = FromString(test2)
+	if err != nil {
+		t.Errorf("Failed to parse program")
+	}
+
+	err = e.Run()
+	if err != nil {
+		t.Errorf("Didn't expect a runtime-error, received one %s", err.Error())
+	}
+	cur = e.GetVariable("a")
+	if cur.Type() == object.ERROR {
+		t.Errorf("Variable 'a' does not exist for %s", test2)
+	}
+	if cur.Type() != object.NUMBER {
+		t.Errorf("Variable 'a' had wrong type: %s", cur.String())
+	}
+	out = cur.(*object.NumberObject).Value
+	if out != 313 {
+		t.Errorf("Expected 'a' to be %d, got %f", 313, out)
+	}
 }
 
 // TestINPUT performs testing of our INPUT implementation.