Add and replace []string buffer with ropes

ui/buffer/rope_test.go

@@ -34,14 +34,52 @@ func TestRopeBounds(t *testing.T) {
 		t.Fail()
 	}
 
+	if len := buf.RunesInLineWithDelim(4); len != 0 {
+		t.Errorf("Expected 0 runes in line 5, found %v", len)
+		t.Fail()
+	}
+
 	line, col := buf.ClampLineCol(15, 5) // Should become last line, first column
 	if line != 4 && col != 0 {
 		t.Errorf("Expected to clamp line col to 4,0 got %v,%v", line, col)
 		t.Fail()
 	}
 
+	line, col = buf.ClampLineCol(4, -1)
+	if line != 4 && col != 0 {
+		t.Errorf("Expected to clamp line col to 4,0 got %v,%v", line, col)
+		t.Fail()
+	}
+
+	line, col = buf.ClampLineCol(2, 5) // Should be third line, pointing at the newline char
+	if line != 2 && col != 5 {
+		t.Errorf("Expected to clamp line, col to 2,5 got %v,%v", line, col)
+		t.Fail()
+	}
+
 	if line := string(buf.Line(2)); line != "\tsome\n" {
 		t.Errorf("Expected line 3 to equal \"\\tsome\", got %#v", line)
 		t.Fail()
 	}
+
+	if line := string(buf.Line(4)); line != "" {
+		t.Errorf("Got %#v", line)
+		t.Fail()
+	}
+}
+
+func TestRopeCount(t *testing.T) {
+	var buf Buffer = NewRopeBuffer([]byte("\t\tlot of\n\ttabs"))
+
+	tabsAtOf := buf.Count(0, 0, 0, 7, []byte{'\t'})
+	if tabsAtOf != 2 {
+		t.Errorf("Expected 2 tabs before 'of', got %#v", tabsAtOf)
+		t.Fail()
+	}
+
+	tabs := buf.Count(0, 0, 0, 0, []byte{'\t'})
+	if tabs != 0 {
+		t.Errorf("Expected no tabs at column zero, got %v", tabs)
+		t.Fail()
+	}
 }