Added RopeBuffer Buffer implementation

ui/buffer/rope_test.go

@@ -0,0 +1,47 @@
+package buffer
+
+import "testing"
+
+func TestRopeInserting(t *testing.T) {
+	var buf Buffer = NewRopeBuffer([]byte("some"))
+	buf.Insert(0, 4, []byte(" text")) // Insert " text" after "some"
+	buf.Insert(0, 0, []byte("with\n\t"))
+	// "with\n\tsome text"
+
+	buf.Remove(0, 4, 1, 5) // Delete from line 0, col 4, to line 1, col 6 "\n\tsome "
+
+	if str := string(buf.Bytes()); str != "withtext" {
+		t.Errorf("string does not match \"withtext\", got %#v", str)
+		t.Fail()
+	}
+}
+
+func TestRopeBounds(t *testing.T) {
+	var buf Buffer = NewRopeBuffer([]byte("this\nis (は)\n\tsome\ntext\n"))
+	//this
+	//is (は)
+	//	some
+	//text
+	//
+
+	if buf.Lines() != 5 {
+		t.Errorf("Expected buf.Lines() == 5")
+		t.Fail()
+	}
+
+	if len := buf.RunesInLine(1); len != 6 { // "is" in English and in japanese
+		t.Errorf("Expected 6 runes in line 2, 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()
+	}
+
+	if line := string(buf.Line(2)); line != "\tsome\n" {
+		t.Errorf("Expected line 3 to equal \"\\tsome\", got %#v", line)
+		t.Fail()
+	}
+}