Fix GetWordBeforeCursor

main.go

@@ -79,31 +79,33 @@ func main() {
 		}
 
 		// Display completions
-		out.SetColor("white", "teal")
+		if w := buffer.Document().GetWordBeforeCursor(); w != "" {
+			out.SetColor("white", "teal")
 
-		out.CursorDown(1)
+			out.CursorDown(1)
-		out.Write([]byte(" Foo "))
+			out.Write([]byte(" Foo "))
-		out.SetColor("white", "darkGray")
+			out.SetColor("white", "darkGray")
-		out.Write([]byte(" "))
+			out.Write([]byte(" "))
-		out.SetColor("white", "teal")
+			out.SetColor("white", "teal")
-		out.CursorBackward(len("foo") + 3)
+			out.CursorBackward(len("foo") + 3)
 
-		out.CursorDown(1)
+			out.CursorDown(1)
-		out.Write([]byte(" Hello "))
+			out.Write([]byte(" Hello "))
-		out.SetColor("white", "darkGray")
+			out.SetColor("white", "darkGray")
-		out.Write([]byte(" "))
+			out.Write([]byte(" "))
-		out.SetColor("white", "teal")
+			out.SetColor("white", "teal")
-		out.CursorBackward(len("Hello") + 3)
+			out.CursorBackward(len("Hello") + 3)
 
-		out.CursorDown(1)
+			out.CursorDown(1)
-		out.Write([]byte(" World "))
+			out.Write([]byte(" World "))
-		out.SetColor("white", "darkGray")
+			out.SetColor("white", "darkGray")
-		out.Write([]byte(" "))
+			out.Write([]byte(" "))
-		out.SetColor("white", "teal")
+			out.SetColor("white", "teal")
-		out.CursorBackward(len("World") + 3)
+			out.CursorBackward(len("World") + 3)
 
-		out.CursorUp(3)
+			out.CursorUp(3)
-		out.SetColor("default", "default")
+			out.SetColor("default", "default")
+		}
 
 		out.Flush()
 	}

prompt/buffer_test.go

@@ -32,9 +32,15 @@ func TestBuffer_CursorMovement(t *testing.T) {
 	b := NewBuffer()
 	b.InsertText("some_text", false, true)
 
-	b.CursorLeft(1)
+	if l := b.CursorLeft(1); l != 1 {
-	b.CursorLeft(2)
+		t.Errorf("Should be 1, but got %d", l)
-	b.CursorRight(1)
+	}
+	if l := b.CursorLeft(2); l != 2 {
+		t.Errorf("Should be 2, but got %d", l)
+	}
+	if l := b.CursorRight(1); l != 1 {
+		t.Errorf("Should be 1, but got %d", l)
+	}
 	b.InsertText("A", false, true)
 	if b.Text() != "some_teAxt" {
 		t.Errorf("Text should be %#v, got %#v", "some_teAxt", b.Text())

prompt/document.go

@@ -51,7 +51,7 @@ func (d *Document) FindStartOfPreviousWord() int {
 	// Reverse the text before the cursor, in order to do an efficient backwards search.
 	x := d.TextBeforeCursor()
 	l := len(x)
-	for i := l - 1; i > 0; i-- {
+	for i := l; i > 0; i-- {
 		if x[i-1:i] == " " {
 			return i
 		}

prompt/document_test.go

@@ -31,38 +31,89 @@ func TestDocument_TextBeforeCursor(t *testing.T) {
 }
 
 func TestDocument_TextAfterCursor(t *testing.T) {
-	d := &Document{
+	pattern := []struct{
-		Text:           "line 1\nline 2\nline 3\nline 4\n",
+		document *Document
-		CursorPosition: len("line 1\n" + "lin"),
+		expected string
+	} {
+		{
+			document: &Document{
+				Text:           "line 1\nline 2\nline 3\nline 4\n",
+				CursorPosition: len("line 1\n" + "lin"),
+			},
+			expected: "e 2\nline 3\nline 4\n",
+		},
+		{
+			document: &Document{
+				Text:           "",
+				CursorPosition: 0,
+			},
+			expected: "",
+		},
 	}
-	ac := d.TextAfterCursor()
+
-	ex := "e 2\nline 3\nline 4\n"
+	for _, p := range pattern {
-	if ac != ex {
+		ac := p.document.TextAfterCursor()
-		t.Errorf("Should be %#v, got %#v", ex, ac)
+		if ac != p.expected {
+			t.Errorf("Should be %#v, got %#v", p.expected, ac)
+		}
 	}
 }
 
 func TestDocument_GetWordBeforeCursor(t *testing.T) {
-	d := &Document{
+	pattern := []struct{
-		Text:           "apple bana",
+		document *Document
-		CursorPosition: len("apple bana"),
+		expected string
+	} {
+		{
+			document: &Document{
+				Text:           "apple bana",
+				CursorPosition: len("apple bana"),
+			},
+			expected: "bana",
+		},
+		{
+			document: &Document{
+				Text:           "apple ",
+				CursorPosition: len("apple "),
+			},
+			expected: "",
+		},
 	}
-	ac := d.GetWordBeforeCursor()
+
-	ex := "bana"
+	for _, p := range pattern {
-	if ac != ex {
+		ac := p.document.GetWordBeforeCursor()
-		t.Errorf("Should be %#v, got %#v", ex, ac)
+		if ac != p.expected {
+			t.Errorf("Should be %#v, got %#v", p.expected, ac)
+		}
 	}
 }
 
 func TestDocument_FindStartOfPreviousWord(t *testing.T) {
-	d := &Document{
+	pattern := []struct{
-		Text:           "apple bana",
+		document *Document
-		CursorPosition: len("apple bana"),
+		expected int
+	} {
+		{
+			document: &Document{
+				Text:           "apple bana",
+				CursorPosition: len("apple bana"),
+			},
+			expected: len("apple "),
+		},
+		{
+			document: &Document{
+				Text:           "apple ",
+				CursorPosition: len("apple "),
+			},
+			expected: len("apple "),
+		},
 	}
-	ac := d.FindStartOfPreviousWord()
+
-	ex := len("apple ")
+	for _, p := range pattern {
-	if ac != ex {
+		ac := p.document.FindStartOfPreviousWord()
-		t.Errorf("Should be %#v, got %#v", ex, ac)
+		if ac != p.expected {
+			t.Errorf("Should be %#v, got %#v", p.expected, ac)
+		}
 	}
 }
 

prompt/vt100_output.go

@@ -114,7 +114,7 @@ func (w *VT100Writer) CursorDown(n int) {
 
 func (w *VT100Writer) CursorForward(n int) {
 	if n < 0 {
-		w.CursorBackward(n)
+		w.CursorBackward(-n)
 		return
 	}
 	s := strconv.Itoa(n)
@@ -126,7 +126,7 @@ func (w *VT100Writer) CursorForward(n int) {
 
 func (w *VT100Writer) CursorBackward(n int) {
 	if n < 0 {
-		w.CursorForward(n)
+		w.CursorForward(-n)
 		return
 	}
 	s := strconv.Itoa(n)