Added bounds checks for Combobox.InsertBefore() and Combobox.Delete().

combobox.go

@@ -53,31 +53,49 @@ func (c *Combobox) Append(what ...string) (err error) {
 	return nil
 }
 
-// InsertBefore inserts a new item in the Combobox before the item at the given position. (TODO action if before is out of bounds)
+// InsertBefore inserts a new item in the Combobox before the item at the given position. It panics if the given index is out of bounds.
 func (c *Combobox) InsertBefore(what string, before int) (err error) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
+	var m []string
+
 	if c.created {
+		if before < 0 || before >= c.sysData.len() {
+			goto badrange
+		}
 		return c.sysData.insertBefore(what, before)
 	}
-	m := make([]string, 0, len(c.initItems) + 1)
+	if before < 0 || before >= len(c.initItems) {
+		goto badrange
+	}
+	m = make([]string, 0, len(c.initItems) + 1)
 	m = append(m, c.initItems[:before]...)
 	m = append(m, what)
 	c.initItems = append(m, c.initItems[before:]...)
 	return nil
+badrange:
+	panic(fmt.Errorf("index %d out of range in Combobox.InsertBefore()", before))
 }
 
-// Delete removes the given item from the Combobox. (TODO action if index is out of bounds)
+// Delete removes the given item from the Combobox. It panics if the given index is out of bounds.
 func (c *Combobox) Delete(index int) error {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
 	if c.created {
+		if index < 0 || index >= c.sysData.len() {
+			goto badrange
+		}
 		return c.sysData.delete(index)
 	}
+	if index < 0 || index >= len(c.initItems) {
+		goto badrange
+	}
 	c.initItems = append(c.initItems[:index], c.initItems[index + 1:]...)
 	return nil
+badrange:
+	panic(fmt.Errorf("index %d out of range in Combobox.Delete()", index))
 }
 
 // Selection returns the current selection.

test/main.go

@@ -37,6 +37,35 @@ func gridWindow() (*Window, error) {
 
 var macCrashTest = flag.Bool("maccrash", false, "attempt crash on Mac OS X on deleting too far (debug lack of panic on 32-bit)")
 
+func invalidTest(c *Combobox, l *Listbox) {
+	x := func(what string ) {
+		if j := recover(); j == nil {
+			MsgBoxError("test", "%s: no panic", what)
+			panic("invalid test fail")
+		} else {
+			println("got", j.(error).Error())
+		}
+	}
+
+	func() {
+		defer x("Combobox.InsertBefore < 0"); c.InsertBefore("xxx", -5); panic(nil)
+	}()
+	func() {
+		defer x("Combobox.InsertBefore > len"); c.InsertBefore("xxx", c.Len() + 5); panic(nil)
+	}()
+	func() {
+		defer x("Combobox.Delete < 0"); c.Delete(-5); panic(nil)
+	}()
+	func() {
+		defer x("Listbox.Delete > len"); c.Delete(c.Len() + 5); panic(nil)
+	}()
+	// TODO
+	_ = l
+	MsgBox("test", "all working as intended")
+}
+
+var invalidBefore = flag.Bool("invalid", false, "run invalid test before opening window")
+
 func myMain() {
 	w := NewWindow("Main Window", 320, 240)
 	w.Closing = Event()
@@ -56,7 +85,8 @@ func myMain() {
 	prog := 0
 	incButton := NewButton("Inc")
 	decButton := NewButton("Dec")
-	sincdec := NewHorizontalStack(incButton, decButton)
+	invalidButton := NewButton("Run Invalid Test")
+	sincdec := NewHorizontalStack(incButton, decButton, invalidButton)
 	password := NewPasswordEdit()
 	s0 := NewVerticalStack(s2, c, cb1, cb2, e, s3, pbar, sincdec, Space(), password)
 	s0.SetStretchy(8)
@@ -79,6 +109,9 @@ func myMain() {
 	s := NewHorizontalStack(s1, s0)
 	s.SetStretchy(0)
 	s.SetStretchy(1)
+	if *invalidBefore {
+		invalidTest(cb1, lb1)
+	}
 	err := w.Open(s)
 	if err != nil {
 		panic(err)
@@ -146,6 +179,8 @@ mainloop:
 				prog = 0
 			}
 			pbar.SetProgress(prog)
+		case <-invalidButton.Clicked:
+			invalidTest(cb1, lb1)
 		}
 	}
 	w.Hide()