From fab2213c25dba337d2196ae6cbbb55d9358b2a4c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 13 Nov 2016 10:21:54 +0530
Subject: [PATCH] More work on native streams

---
 generate-unicode-data.py |  57 +++++++
 kitty/boss.py            |   6 +-
 kitty/char_grid.py       |   9 +-
 kitty/charsets.c         |  30 ++++
 kitty/colors.c           |   2 +-
 kitty/config.py          |  13 +-
 kitty/cursor.c           |  75 +++++----
 kitty/data-types.c       |  13 +-
 kitty/data-types.h       |  78 ++++++++-
 kitty/line-buf.c         |  23 ++-
 kitty/line.c             |  73 ++++-----
 kitty/modes.h            |   2 +-
 kitty/parser.c           |  12 --
 kitty/savepoints.c       |  47 ++++++
 kitty/screen.c           | 334 ++++++++++++++++++++++++++++++++++++---
 kitty/screen.py          |   7 +-
 kitty/sprites.c          |   4 -
 kitty/tracker.c          |   7 +-
 kitty/unicode-data.h     |  11 ++
 kitty_tests/__init__.py  |  10 +-
 20 files changed, 652 insertions(+), 161 deletions(-)
 create mode 100644 generate-unicode-data.py
 create mode 100644 kitty/savepoints.c
 create mode 100644 kitty/unicode-data.h

diff --git a/generate-unicode-data.py b/generate-unicode-data.py
new file mode 100644
index 000000000..7c3233109
--- /dev/null
+++ b/generate-unicode-data.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
+
+import unicodedata
+import itertools
+import sys
+
+IGNORED_CATEGORIES = ('Cc', 'Cf', 'Cn', 'Cs')
+
+
+def ranges(i):
+    for a, b in itertools.groupby(enumerate(i), lambda r: r[1] - r[0]):
+        b = list(b)
+        yield b[0][1], b[-1][1]
+
+
+def generate_data(chars):
+    points, cranges = [], []
+    for l, r in ranges(chars):
+        if l == r:
+            points.append(l)
+        else:
+            cranges.append((l, r))
+    return points, cranges
+
+
+def generate_predicate(name, chars):
+    points, ranges = generate_data(chars)
+    ranges = ['(0x%s %s ch && ch <= 0x%s)' % (l, '<' if l == 0 else '<=', r) for l, r in ranges]
+    points = ['(ch == 0x%x)' % p for p in points]
+    return '''
+static inline bool %s(uint32_t ch) {
+    return %s || %s;
+}
+    ''' % (name, '||'.join(ranges), '||'.join(points))
+
+
+def main():
+    combining_chars = []
+    igchars = []
+    for c in map(chr, range(sys.maxunicode + 1)):
+        if unicodedata.category(c) in IGNORED_CATEGORIES:
+            igchars.append(ord(c))
+        if unicodedata.combining(c):
+            combining_chars.append(ord(c))
+
+    cc = generate_predicate('is_combining_char', combining_chars)
+    ig = generate_predicate('is_ignored_char', igchars)
+    with open('kitty/unicode-data.h', 'w') as f:
+        print('#pragma once', file=f)
+        print(cc, file=f)
+        print(ig, file=f)
+
+if __name__ == '__main__':
+    main()
+    # TODO: delete kitty/unicode.py alongwith kitty/screen.py
diff --git a/kitty/boss.py b/kitty/boss.py
index c2cb81526..e4fd8994e 100644
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -97,10 +97,10 @@ class Boss(Thread):
 
     def on_focus(self, window, focused):
         if focused:
-            if self.screen.enable_focus_tracking:
+            if self.screen.enable_focus_tracking():
                 self.write_to_child(b'\x1b[I')
         else:
-            if self.screen.enable_focus_tracking:
+            if self.screen.enable_focus_tracking():
                 self.write_to_child(b'\x1b[O')
 
     def on_mouse_button(self, window, button, action, mods):
@@ -110,7 +110,7 @@ class Boss(Thread):
                 # text = glfw.glfwGetClipboardString(window)
                 text = subprocess.check_output(['xsel'])
                 if text:
-                    if self.screen.in_bracketed_paste_mode:
+                    if self.screen.in_bracketed_paste_mode():
                         text = BRACKETED_PASTE_START.encode('ascii') + text + BRACKETED_PASTE_END.encode('ascii')
                     self.write_to_child(text)
 
diff --git a/kitty/char_grid.py b/kitty/char_grid.py
index 56a511b91..26af008bb 100644
--- a/kitty/char_grid.py
+++ b/kitty/char_grid.py
@@ -16,7 +16,8 @@ from .fast_data_types import (
     glBlendFunc, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, glClear,
     GL_COLOR_BUFFER_BIT, glClearColor, glViewport, glUniform2ui, glUniform4f,
     glUniform1i, glUniform2f, glDrawArraysInstanced, GL_TRIANGLE_FAN,
-    glEnable, glDisable, GL_BLEND, glDrawArrays, ColorProfile, REVERSE
+    glEnable, glDisable, GL_BLEND, glDrawArrays, ColorProfile, REVERSE,
+    CURSOR_BEAM, CURSOR_BLOCK, CURSOR_UNDERLINE
 )
 
 Size = namedtuple('Size', 'width height')
@@ -303,11 +304,11 @@ class CharGrid:
             col = cursor.color or self.default_cursor.color
             shape = cursor.shape or self.default_cursor.shape
             alpha = self.opts.cursor_opacity
-            if alpha < 1.0 and shape == 'block':
+            if alpha < 1.0 and shape == CURSOR_BLOCK:
                 glEnable(GL_BLEND)
-            right = left + (width(1.5) if shape == 'beam' else sg.dx)
+            right = left + (width(1.5) if shape == CURSOR_BEAM else sg.dx)
             bottom = top - sg.dy
-            if shape == 'underline':
+            if shape == CURSOR_UNDERLINE:
                 top = bottom + width(vert=False)
             glUniform4f(ul('color'), col[0], col[1], col[2], alpha)
             glUniform2f(ul('xpos'), left, right)
diff --git a/kitty/charsets.c b/kitty/charsets.c
index e7846513e..eca4419f3 100644
--- a/kitty/charsets.c
+++ b/kitty/charsets.c
@@ -166,3 +166,33 @@ uint16_t* translation_table(char which) {
     }
     return charset_translations[0];
 }
+
+// UTF-8 decode taken from: http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
+ 
+static const uint8_t utf8_data[] = {
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 00..1f
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 20..3f
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 40..5f
+  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 60..7f
+  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, // 80..9f
+  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, // a0..bf
+  8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // c0..df
+  0xa,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x4,0x3,0x3, // e0..ef
+  0xb,0x6,0x6,0x6,0x5,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8, // f0..ff
+  0x0,0x1,0x2,0x3,0x5,0x8,0x7,0x1,0x1,0x1,0x4,0x6,0x1,0x1,0x1,0x1, // s0..s0
+  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,1, // s1..s2
+  1,2,1,1,1,1,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1, // s3..s4
+  1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,3,1,1,1,1,1,1, // s5..s6
+  1,3,1,1,1,1,1,3,1,3,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // s7..s8
+};
+
+uint32_t decode_utf8(uint32_t* state, uint32_t* codep, uint8_t byte) {
+  uint32_t type = utf8_data[byte];
+
+  *codep = (*state != UTF8_ACCEPT) ?
+    (byte & 0x3fu) | (*codep << 6) :
+    (0xff >> type) & (byte);
+
+  *state = utf8_data[256 + *state*16 + type];
+  return *state;
+}
diff --git a/kitty/colors.c b/kitty/colors.c
index e4b8ea09d..0b209e3b1 100644
--- a/kitty/colors.c
+++ b/kitty/colors.c
@@ -63,7 +63,7 @@ new(PyTypeObject *type, PyObject UNUSED *args, PyObject UNUSED *kwds) {
 }
 
 static void
-dealloc(Cursor* self) {
+dealloc(ColorProfile* self) {
     Py_TYPE(self)->tp_free((PyObject*)self);
 }
 
diff --git a/kitty/config.py b/kitty/config.py
index ec393d4b8..50bef68c1 100644
--- a/kitty/config.py
+++ b/kitty/config.py
@@ -6,6 +6,7 @@ import re
 from collections import namedtuple
 from itertools import repeat
 
+from .fast_data_types import CURSOR_BLOCK, CURSOR_BEAM, CURSOR_UNDERLINE
 
 key_pat = re.compile(r'([a-zA-Z][a-zA-Z0-9_-]*)\s+(.+)$')
 # Color definitions  {{{
@@ -186,12 +187,14 @@ def to_font_size(x):
     return max(6, float(x))
 
 
+cshapes = {'block': CURSOR_BLOCK, 'beam': CURSOR_BEAM, 'underline': CURSOR_UNDERLINE}
+
+
 def to_cursor_shape(x):
-    shapes = 'block underline beam'
-    x = x.lower()
-    if x not in shapes.split():
-        raise ValueError('Invalid cursor shape: {} allowed values are {}'.format(x, shapes))
-    return x
+    try:
+        return cshapes[x.lower()]
+    except KeyError:
+        raise ValueError('Invalid cursor shape: {} allowed values are {}'.format(x, ', '.join(cshapes)))
 
 
 def to_bool(x):
diff --git a/kitty/cursor.c b/kitty/cursor.c
index 88219e512..a25950f3f 100644
--- a/kitty/cursor.c
+++ b/kitty/cursor.c
@@ -9,50 +9,30 @@
 
 #include <structmember.h>
 
-#define INIT_NONE(x) Py_INCREF(Py_None); x = Py_None;
-
 static PyObject *
 new(PyTypeObject *type, PyObject UNUSED *args, PyObject UNUSED *kwds) {
     Cursor *self;
 
     self = (Cursor *)type->tp_alloc(type, 0);
-    if (self != NULL) {
-        self->x = PyLong_FromLong(0);
-        if (self->x == NULL) { Py_CLEAR(self); return NULL; }
-        self->y = self->x; Py_INCREF(self->y);
-        INIT_NONE(self->shape);
-        INIT_NONE(self->blink);
-        INIT_NONE(self->color);
-        self->hidden = Py_False; Py_INCREF(Py_False);
-        self->bold = 0; self->italic = 0; self->reverse = 0; self->strikethrough = 0; self->decoration = 0;
-        self->fg = 0; self->bg = 0; self->decoration_fg = 0;
-    }
     return (PyObject*) self;
 }
 
 static void
 dealloc(Cursor* self) {
-    Py_CLEAR(self->shape);
-    Py_CLEAR(self->blink);
-    Py_CLEAR(self->color);
-    Py_CLEAR(self->hidden);
-    Py_CLEAR(self->x);
-    Py_CLEAR(self->y);
     Py_TYPE(self)->tp_free((PyObject*)self);
 }
 
 #define EQ(x) (a->x == b->x)
-#define PEQ(x) (PyObject_RichCompareBool(a->x, b->x, Py_EQ) == 1)
 static int __eq__(Cursor *a, Cursor *b) {
-    return EQ(bold) && EQ(italic) && EQ(strikethrough) && EQ(reverse) && EQ(decoration) && EQ(fg) && EQ(bg) && EQ(decoration_fg) && PEQ(x) && PEQ(y) && PEQ(shape) && PEQ(blink) && PEQ(color) && PEQ(hidden);
+    return EQ(bold) && EQ(italic) && EQ(strikethrough) && EQ(reverse) && EQ(decoration) && EQ(fg) && EQ(bg) && EQ(decoration_fg) && EQ(x) && EQ(y) && EQ(shape) && EQ(blink) && EQ(color) && EQ(hidden);
 }
 
 #define BOOL(x) ((x) ? Py_True : Py_False)
 static PyObject *
 repr(Cursor *self) {
     return PyUnicode_FromFormat(
-        "Cursor(x=%R, y=%R, shape=%R, blink=%R, hidden=%R, color=%R, fg=#%08x, bg=#%08x, bold=%R, italic=%R, reverse=%R, strikethrough=%R, decoration=%d, decoration_fg=#%08x)",
-        self->x, self->y, self->shape, self->blink, self->hidden, self->color, self->fg, self->bg, BOOL(self->bold), BOOL(self->italic), BOOL(self->reverse), BOOL(self->strikethrough), self->decoration, self->decoration_fg
+        "Cursor(x=%u, y=%u, shape=%d, blink=%R, hidden=%R, color=#%08x, fg=#%08x, bg=#%08x, bold=%R, italic=%R, reverse=%R, strikethrough=%R, decoration=%d, decoration_fg=#%08x)",
+        self->x, self->y, self->shape, BOOL(self->blink), BOOL(self->hidden), self->color, self->fg, self->bg, BOOL(self->bold), BOOL(self->italic), BOOL(self->reverse), BOOL(self->strikethrough), self->decoration, self->decoration_fg
     );
 }
 
@@ -64,29 +44,39 @@ reset_display_attrs(Cursor *self) {
     Py_RETURN_NONE;
 }
 
+void cursor_reset(Cursor *self) {
+    self->x = 0; self->y = 0;
+    self->shape = 0; self->blink = false;
+    self->color = 0; self->hidden = false;
+}
+
 static PyObject*
-copy(Cursor *self, PyObject *args);
+copy(Cursor *self);
 #define copy_doc "Create a clone of this cursor"
 
+static PyObject* color_get(Cursor *self, void UNUSED *closure) { 
+    if (!(self->color & 0xFF)) { Py_RETURN_NONE; }
+    return Py_BuildValue("BBB", (self->color >> 24) & 0xFF, (self->color >> 16) & 0xFF, (self->color >> 8) & 0xFF);
+}
+
 // Boilerplate {{{
 
 BOOL_GETSET(Cursor, bold)
 BOOL_GETSET(Cursor, italic)
 BOOL_GETSET(Cursor, reverse)
 BOOL_GETSET(Cursor, strikethrough)
+BOOL_GETSET(Cursor, hidden)
+BOOL_GETSET(Cursor, blink)
 
 static PyMemberDef members[] = {
-    {"x", T_OBJECT_EX, offsetof(Cursor, x), 0, "x"},
-    {"y", T_OBJECT_EX, offsetof(Cursor, y), 0, "y"},
-    {"shape", T_OBJECT_EX, offsetof(Cursor, shape), 0, "shape"},
-    {"blink", T_OBJECT_EX, offsetof(Cursor, blink), 0, "blink"},
-    {"color", T_OBJECT_EX, offsetof(Cursor, color), 0, "color"},
-    {"hidden", T_OBJECT_EX, offsetof(Cursor, hidden), 0, "hidden"},
-
+    {"x", T_INT, offsetof(Cursor, x), 0, "x"},
+    {"y", T_INT, offsetof(Cursor, y), 0, "y"},
+    {"shape", T_UBYTE, offsetof(Cursor, shape), 0, "shape"},
+    {"color", T_ULONG, offsetof(Cursor, color), 0, "color"},
     {"decoration", T_UBYTE, offsetof(Cursor, decoration), 0, "decoration"},
-    {"fg", T_UINT, offsetof(Cursor, fg), 0, "fg"},
-    {"bg", T_UINT, offsetof(Cursor, bg), 0, "bg"},
-    {"decoration_fg", T_UINT, offsetof(Cursor, decoration_fg), 0, "decoration_fg"},
+    {"fg", T_ULONG, offsetof(Cursor, fg), 0, "fg"},
+    {"bg", T_ULONG, offsetof(Cursor, bg), 0, "bg"},
+    {"decoration_fg", T_ULONG, offsetof(Cursor, decoration_fg), 0, "decoration_fg"},
     {NULL}  /* Sentinel */
 };
 
@@ -95,6 +85,9 @@ static PyGetSetDef getseters[] = {
     GETSET(italic)
     GETSET(reverse)
     GETSET(strikethrough)
+    GETSET(hidden)
+    GETSET(blink)
+    {"color", (getter) color_get, NULL, "color", NULL},
     {NULL}  /* Sentinel */
 };
 
@@ -127,16 +120,20 @@ RICHCMP(Cursor)
 
 // }}}
  
-static PyObject*
-copy(Cursor *self, PyObject UNUSED *args) {
-#define CPY(x) ans->x = self->x; Py_XINCREF(self->x);
+Cursor*
+cursor_copy(Cursor *self) {
 #define CCY(x) ans->x = self->x;
     Cursor* ans;
     ans = alloc_cursor();
     if (ans == NULL) { PyErr_NoMemory(); return NULL; }
-    CPY(x); CPY(y); CPY(shape); CPY(blink); CPY(color); CPY(hidden);
+    CCY(x); CCY(y); CCY(shape); CCY(blink); CCY(color); CCY(hidden);
     CCY(bold); CCY(italic); CCY(strikethrough); CCY(reverse); CCY(decoration); CCY(fg); CCY(bg); CCY(decoration_fg); 
-    return (PyObject*)ans;
+    return ans;
+}
+
+static PyObject*
+copy(Cursor *self) {
+    return (PyObject*)cursor_copy(self);
 }
 
 Cursor *alloc_cursor() {
diff --git a/kitty/data-types.c b/kitty/data-types.c
index b7d1ad06c..271c100e8 100644
--- a/kitty/data-types.c
+++ b/kitty/data-types.c
@@ -6,16 +6,6 @@
  */
 
 #include "data-types.h"
-extern int init_LineBuf(PyObject *);
-extern int init_Cursor(PyObject *);
-extern int init_Line(PyObject *);
-extern int init_ColorProfile(PyObject *);
-extern int init_SpriteMap(PyObject *);
-extern int init_ChangeTracker(PyObject *);
-extern int init_Screen(PyObject *);
-extern PyObject* create_256_color_table();
-extern PyObject* parse_bytes_dump(PyObject UNUSED *self, PyObject *val);
-extern PyObject* parse_bytes(PyObject UNUSED *self, PyObject *val);
 #include "gl.h"
 #include "modes.h"
 
@@ -58,6 +48,9 @@ PyInit_fast_data_types(void) {
         PyModule_AddIntConstant(m, "DECORATION", DECORATION_SHIFT);
         PyModule_AddStringMacro(m, BRACKETED_PASTE_START);
         PyModule_AddStringMacro(m, BRACKETED_PASTE_END);
+        PyModule_AddIntMacro(m, CURSOR_BLOCK);
+        PyModule_AddIntMacro(m, CURSOR_BEAM);
+        PyModule_AddIntMacro(m, CURSOR_UNDERLINE);
     }
 
     return m;
diff --git a/kitty/data-types.h b/kitty/data-types.h
index edf831e18..4f2d1b08c 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -37,6 +37,12 @@ typedef unsigned int index_type;
 #define HAS_BG_MASK (0xFF << COL_SHIFT)
 #define CC_MASK 0xFFFF
 #define CC_SHIFT 16
+#define UTF8_ACCEPT 0
+#define UTF8_REJECT 1
+
+#define CURSOR_BLOCK 1
+#define CURSOR_BEAM 2
+#define CURSOR_UNDERLINE 3
 
 #define CURSOR_TO_ATTRS(c, w) \
     ((w) | (((c->decoration & 3) << DECORATION_SHIFT) | ((c->bold & 1) << BOLD_SHIFT) | \
@@ -119,6 +125,7 @@ typedef struct {
     bool continued;
     bool needs_free;
 } Line;
+PyTypeObject Line_Type;
 
 
 typedef struct {
@@ -136,17 +143,19 @@ typedef struct {
     decoration_type *decoration_fg;
     combining_type *combining_chars;
 } LineBuf;
+PyTypeObject LineBuf_Type;
 
 
 typedef struct {
     PyObject_HEAD
 
-    PyObject *x, *y, *shape, *blink, *hidden, *color;
-    bool bold, italic, reverse, strikethrough;
-    uint8_t decoration;
-    uint32_t fg, bg, decoration_fg;
+    bool bold, italic, reverse, strikethrough, blink, hidden;
+    int x, y;
+    uint8_t decoration, shape;
+    unsigned long fg, bg, decoration_fg, color;
 
 } Cursor;
+PyTypeObject Cursor_Type;
 
 
 typedef struct {
@@ -156,6 +165,7 @@ typedef struct {
     uint32_t ansi_color_table[120];
 
 } ColorProfile;
+PyTypeObject ColorProfile_Type;
 
 typedef struct SpritePosition SpritePosition;
 struct SpritePosition {
@@ -167,6 +177,7 @@ struct SpritePosition {
     bool filled;
     bool rendered;
 };
+PyTypeObject SpritePosition_Type;
 
 typedef struct {
     PyObject_HEAD
@@ -177,6 +188,7 @@ typedef struct {
     bool dirty;
 
 } SpriteMap;
+PyTypeObject SpriteMap_Type;
 
 typedef struct {
     PyObject_HEAD
@@ -190,12 +202,26 @@ typedef struct {
     bool *changed_cells;
     unsigned int history_line_added_count;
 } ChangeTracker;
+PyTypeObject ChangeTracker_Type;
 
 
 typedef struct {
-    bool LNM, IRM, DECTEM, DECSCNM, DECOM, DECAWM, DECCOLM;
+    bool mLNM, mIRM, mDECTCEM, mDECSCNM, mDECOM, mDECAWM, mDECCOLM, mBRACKETED_PASTE, mFOCUS_TRACKING;
 } ScreenModes;
+PyTypeObject ScreenModes_Type;
 
+typedef struct {
+    PyObject_HEAD
+
+    unsigned int current_charset;
+    uint16_t *g0_charset, *g1_charset;
+    uint32_t utf8_state;
+    Cursor *cursor;
+    bool mDECOM;
+    bool mDECAWM;
+
+} Savepoint;
+PyTypeObject Savepoint_Type;
 
 typedef struct {
     PyObject_HEAD
@@ -215,14 +241,56 @@ typedef struct {
     bool parser_has_pending_text;
 
 } Screen;
+PyTypeObject Screen_Type;
 
 Line* alloc_line();
 Cursor* alloc_cursor();
 LineBuf* alloc_linebuf();
 ChangeTracker* alloc_change_tracker();
+Savepoint* alloc_savepoint();
 
 #define left_shift_line(line, at, num) \
     for(index_type __i__ = (at); __i__ < (line)->xnum - (num); __i__++) { \
         COPY_CELL(line, __i__ + (num), line, __i__) \
     } \
     if ((((line)->chars[(at)] >> ATTRS_SHIFT) & WIDTH_MASK) != 1) (line)->chars[(at)] = (1 << ATTRS_SHIFT) | 32;
+
+
+// Global functions 
+int init_LineBuf(PyObject *);
+int init_Cursor(PyObject *);
+int init_Line(PyObject *);
+int init_ColorProfile(PyObject *);
+int init_SpriteMap(PyObject *);
+int init_ChangeTracker(PyObject *);
+int init_Screen(PyObject *);
+PyObject* create_256_color_table();
+PyObject* parse_bytes_dump(PyObject UNUSED *, PyObject *);
+PyObject* parse_bytes(PyObject UNUSED *, PyObject *);
+uint16_t* translation_table(char);
+uint32_t decode_utf8(uint32_t*, uint32_t*, uint8_t byte);
+void linebuf_init_line(LineBuf *, index_type);
+void line_set_char(Line *, unsigned int , uint32_t , unsigned int , Cursor *);
+void line_right_shift(Line *, unsigned int , unsigned int );
+void line_add_combining_char(Line *, uint32_t , unsigned int );
+void cursor_reset(Cursor*);
+void linebuf_set_attribute(LineBuf *, unsigned int , unsigned int );
+Cursor* cursor_copy(Cursor*);
+void linebuf_clear(LineBuf *);
+bool screen_restore_cursor(Screen *);
+bool screen_save_cursor(Screen *);
+bool screen_cursor_position(Screen*, unsigned int, unsigned int);
+bool screen_erase_in_display(Screen *, unsigned int, bool);
+bool screen_draw(Screen *screen, uint8_t *buf, unsigned int buflen);
+bool update_cell_range_data(SpriteMap *, Line *, unsigned int, unsigned int, ColorProfile *, const uint32_t, const uint32_t, unsigned int *);
+uint32_t to_color(ColorProfile *, uint32_t, uint32_t);
+PyObject* line_text_at(char_type, combining_type);
+void linebuf_init_line(LineBuf *, index_type);
+#define DECLARE_CH_SCREEN_HANDLER(name) bool screen_##name(Screen *screen, uint8_t ch);
+DECLARE_CH_SCREEN_HANDLER(bell)
+DECLARE_CH_SCREEN_HANDLER(backspace)
+DECLARE_CH_SCREEN_HANDLER(tab)
+DECLARE_CH_SCREEN_HANDLER(linefeed)
+DECLARE_CH_SCREEN_HANDLER(carriage_return)
+DECLARE_CH_SCREEN_HANDLER(shift_out)
+DECLARE_CH_SCREEN_HANDLER(shift_in)
diff --git a/kitty/line-buf.c b/kitty/line-buf.c
index b351c2185..b7dd0e36f 100644
--- a/kitty/line-buf.c
+++ b/kitty/line-buf.c
@@ -7,7 +7,6 @@
 
 #include "data-types.h"
 #include <structmember.h>
-extern PyTypeObject Line_Type;
 
 static inline void
 clear_chars_to_space(LineBuf* linebuf, index_type y) {
@@ -15,15 +14,19 @@ clear_chars_to_space(LineBuf* linebuf, index_type y) {
     for (index_type i = 0; i < linebuf->xnum; i++) chars[i] = (1 << ATTRS_SHIFT) | 32;
 }
 
-static PyObject*
-clear(LineBuf *self) {
-#define clear_doc "Clear all lines in this LineBuf"
+void linebuf_clear(LineBuf *self) {
     memset(self->buf, 0, self->block_size * CELL_SIZE);
     memset(self->continued_map, 0, self->ynum * sizeof(bool));
     for (index_type i = 0; i < self->ynum; i++) {
         clear_chars_to_space(self, i);
         self->line_map[i] = i;
     }
+}
+
+static PyObject*
+clear(LineBuf *self) {
+#define clear_doc "Clear all lines in this LineBuf"
+    linebuf_clear(self);
     Py_RETURN_NONE;
 }
 
@@ -110,16 +113,20 @@ line(LineBuf *self, PyObject *y) {
     return (PyObject*)self->line;
 }
 
+void linebuf_set_attribute(LineBuf *self, unsigned int shift, unsigned int val) {
+    char_type mask;
+    for (index_type y = 0; y < self->ynum; y++) {
+        SET_ATTRIBUTE(self->chars + y * self->xnum, shift, val);
+    }
+}
+
 static PyObject*
 set_attribute(LineBuf *self, PyObject *args) {
 #define set_attribute_doc "set_attribute(which, val) -> Set the attribute on all cells in the line."
     unsigned int shift, val;
-    char_type mask;
     if (!PyArg_ParseTuple(args, "II", &shift, &val)) return NULL;
     if (shift < DECORATION_SHIFT || shift > STRIKE_SHIFT) { PyErr_SetString(PyExc_ValueError, "Unknown attribute"); return NULL; }
-    for (index_type y = 0; y < self->ynum; y++) {
-        SET_ATTRIBUTE(self->chars + y * self->xnum, shift, val);
-    }
+    linebuf_set_attribute(self, shift, val);
     Py_RETURN_NONE;
 }
 
diff --git a/kitty/line.c b/kitty/line.c
index 65db254f5..94be0007b 100644
--- a/kitty/line.c
+++ b/kitty/line.c
@@ -6,7 +6,6 @@
  */
 
 #include "data-types.h"
-extern PyTypeObject Cursor_Type;
 
 static PyObject *
 new(PyTypeObject UNUSED *type, PyObject UNUSED *args, PyObject UNUSED *kwds) {
@@ -108,6 +107,12 @@ basic_cell_data(Line *self, PyObject *val) {
     return Py_BuildValue("IBK", (unsigned int)(ch & CHAR_MASK), (unsigned char)(ch >> ATTRS_SHIFT), (unsigned long long)self->colors[x]);
 }
 
+void line_add_combining_char(Line *self, uint32_t ch, unsigned int x) {
+    combining_type c = self->combining_chars[x];
+    if (c & CC_MASK) self->combining_chars[x] = (c & CC_MASK) | ( (ch & CC_MASK) << CC_SHIFT );
+    else self->combining_chars[x] = ch & CC_MASK;
+}
+
 static PyObject*
 add_combining_char(Line* self, PyObject *args) {
 #define add_combining_char_doc "add_combining_char(x, ch) -> Add the specified character as a combining char to the specified cell."
@@ -118,9 +123,7 @@ add_combining_char(Line* self, PyObject *args) {
         PyErr_SetString(PyExc_ValueError, "Column index out of bounds");
         return NULL;
     }
-    combining_type c = self->combining_chars[x];
-    if (c & CC_MASK) self->combining_chars[x] = (c & CC_MASK) | ( (new_char & CC_MASK) << CC_SHIFT );
-    else self->combining_chars[x] = new_char & CC_MASK;
+    line_add_combining_char(self, new_char, x);
     Py_RETURN_NONE;
 }
 
@@ -134,7 +137,6 @@ set_text(Line* self, PyObject *args) {
     Cursor *cursor;
     int kind;
     void *buf;
-    unsigned long x;
 
     if (!PyArg_ParseTuple(args, "UnnO!", &src, &offset, &sz, &Cursor_Type, &cursor)) return NULL;
     if (PyUnicode_READY(src) != 0) {
@@ -148,12 +150,11 @@ set_text(Line* self, PyObject *args) {
         PyErr_SetString(PyExc_ValueError, "Out of bounds offset/sz");
         return NULL;
     }
-    x = PyLong_AsUnsignedLong(cursor->x);
     attrs = CURSOR_TO_ATTRS(cursor, 1);
     color_type col = (cursor->fg & COL_MASK) | ((color_type)(cursor->bg & COL_MASK) << COL_SHIFT);
     decoration_type dfg = cursor->decoration_fg & COL_MASK;
 
-    for (index_type i = x; offset < limit && i < self->xnum; i++, offset++) {
+    for (index_type i = cursor->x; offset < limit && i < self->xnum; i++, offset++) {
         self->chars[i] = (PyUnicode_READ(kind, buf, offset) & CHAR_MASK) | attrs;
         self->colors[i] = col;
         self->decoration_fg[i] = dfg;
@@ -166,23 +167,16 @@ set_text(Line* self, PyObject *args) {
 static PyObject*
 cursor_from(Line* self, PyObject *args) {
 #define cursor_from_doc "cursor_from(x, y=0) -> Create a cursor object based on the formatting attributes at the specified x position. The y value of the cursor is set as specified."
-    unsigned long x, y = 0;
-    PyObject *xo, *yo;
+    unsigned int x, y = 0;
     Cursor* ans;
-    if (!PyArg_ParseTuple(args, "k|k", &x, &y)) return NULL;
+    if (!PyArg_ParseTuple(args, "I|I", &x, &y)) return NULL;
     if (x >= self->xnum) {
         PyErr_SetString(PyExc_ValueError, "Out of bounds x");
         return NULL;
     }
     ans = alloc_cursor();
     if (ans == NULL) { PyErr_NoMemory(); return NULL; }
-    xo = PyLong_FromUnsignedLong(x); yo = PyLong_FromUnsignedLong(y);
-    if (xo == NULL || yo == NULL) {
-        Py_CLEAR(ans); Py_CLEAR(xo); Py_CLEAR(yo);
-        PyErr_NoMemory(); return NULL;
-    }
-    Py_CLEAR(ans->x); Py_CLEAR(ans->y);
-    ans->x = xo; ans->y = yo;
+    ans->x = x; ans->y = y;
     char_type attrs = self->chars[x] >> ATTRS_SHIFT;
     ATTRS_TO_CURSOR(attrs, ans);
     COLORS_TO_CURSOR(self->colors[x], ans);
@@ -228,6 +222,15 @@ apply_cursor(Line* self, PyObject *args) {
     Py_RETURN_NONE;
 }
 
+void line_right_shift(Line *self, unsigned int at, unsigned int num) {
+    for(index_type i = self->xnum - 1; i >= at + num; i--) {
+        COPY_SELF_CELL(i - num, i)
+    }
+    // Check if a wide character was split at the right edge
+    char_type w = (self->chars[self->xnum - 1] >> ATTRS_SHIFT) & 3;
+    if (w != 1) self->chars[self->xnum - 1] = (1 << ATTRS_SHIFT) | 32;
+}
+
 static PyObject*
 right_shift(Line *self, PyObject *args) {
 #define right_shift_doc "right_shift(at, num) -> ..."
@@ -238,12 +241,7 @@ right_shift(Line *self, PyObject *args) {
         return NULL;
     }
     if (num > 0) {
-        for(index_type i = self->xnum - 1; i >= at + num; i--) {
-            COPY_SELF_CELL(i - num, i)
-        }
-        // Check if a wide character was split at the right edge
-        char_type w = (self->chars[self->xnum - 1] >> ATTRS_SHIFT) & 3;
-        if (w != 1) self->chars[self->xnum - 1] = (1 << ATTRS_SHIFT) | 32;
+        line_right_shift(self, at, num);
     }
     Py_RETURN_NONE;
 }
@@ -261,20 +259,8 @@ left_shift(Line *self, PyObject *args) {
     Py_RETURN_NONE;
 }
  
-static PyObject*
-set_char(Line *self, PyObject *args) {
-#define set_char_doc "set_char(at, ch, width=1, cursor=None) -> Set the character at the specified cell. If cursor is not None, also set attributes from that cursor."
-    unsigned int at, width=1;
-    int ch;
-    Cursor *cursor = NULL;
+void line_set_char(Line *self, unsigned int at, uint32_t ch, unsigned int width, Cursor *cursor) {
     char_type attrs;
-
-    if (!PyArg_ParseTuple(args, "IC|IO!", &at, &ch, &width, &Cursor_Type, &cursor)) return NULL;
-    if (at >= self->xnum) {
-        PyErr_SetString(PyExc_ValueError, "Out of bounds");
-        return NULL;
-    }
-
     if (cursor == NULL) {
         attrs = (((self->chars[at] >> ATTRS_SHIFT) & ~3) | (width & 3)) << ATTRS_SHIFT;
     } else {
@@ -284,6 +270,21 @@ set_char(Line *self, PyObject *args) {
     }
     self->chars[at] = (ch & CHAR_MASK) | attrs;
     self->combining_chars[at] = 0;
+}
+
+static PyObject*
+set_char(Line *self, PyObject *args) {
+#define set_char_doc "set_char(at, ch, width=1, cursor=None) -> Set the character at the specified cell. If cursor is not None, also set attributes from that cursor."
+    unsigned int at, width=1;
+    int ch;
+    Cursor *cursor = NULL;
+
+    if (!PyArg_ParseTuple(args, "IC|IO!", &at, &ch, &width, &Cursor_Type, &cursor)) return NULL;
+    if (at >= self->xnum) {
+        PyErr_SetString(PyExc_ValueError, "Out of bounds");
+        return NULL;
+    }
+    line_set_char(self, at, ch, width, cursor);
     Py_RETURN_NONE;
 }
 
diff --git a/kitty/modes.h b/kitty/modes.h
index 4b2b04530..d54813afe 100644
--- a/kitty/modes.h
+++ b/kitty/modes.h
@@ -18,7 +18,7 @@
    right margin are lost. Otherwise, new display characters replace
    old display characters at the cursor position. 
 */
-#define IRM
+#define IRM 4
 
 
 // Private modes.
diff --git a/kitty/parser.c b/kitty/parser.c
index fdd268aed..fd3209f84 100644
--- a/kitty/parser.c
+++ b/kitty/parser.c
@@ -8,24 +8,12 @@
 #include "data-types.h"
 #include "control-codes.h"
 
-extern PyTypeObject Screen_Type;
-
 #define NORMAL_STATE 0
 #define ESC_STATE 1
 #define CSI_STATE 2
 #define OSC_STATE 3
 #define DCS_STATE 4
 
-#define DECLARE_CH_SCREEN_HANDLER(name) extern bool screen_##name(Screen *screen, uint8_t ch);
-DECLARE_CH_SCREEN_HANDLER(bell)
-DECLARE_CH_SCREEN_HANDLER(backspace)
-DECLARE_CH_SCREEN_HANDLER(tab)
-DECLARE_CH_SCREEN_HANDLER(linefeed)
-DECLARE_CH_SCREEN_HANDLER(carriage_return)
-DECLARE_CH_SCREEN_HANDLER(shift_out)
-DECLARE_CH_SCREEN_HANDLER(shift_in)
-extern bool screen_draw(Screen *screen, uint8_t *buf, unsigned int buflen);
-
 // Parse text {{{
 static inline bool
 read_text(Screen *screen, uint8_t *buf, unsigned int buflen, unsigned int *pos) {
diff --git a/kitty/savepoints.c b/kitty/savepoints.c
new file mode 100644
index 000000000..e5182e578
--- /dev/null
+++ b/kitty/savepoints.c
@@ -0,0 +1,47 @@
+/*
+ * savepoints.c
+ * Copyright (C) 2016 Kovid Goyal <kovid at kovidgoyal.net>
+ *
+ * Distributed under terms of the GPL3 license.
+ */
+
+#include "data-types.h"
+
+static PyObject *
+new(PyTypeObject *type, PyObject UNUSED *args, PyObject UNUSED *kwds) {
+    Savepoint *self;
+    self = (Savepoint *)type->tp_alloc(type, 0);
+    return (PyObject*) self;
+}
+
+static void
+dealloc(Savepoint* self) {
+    Py_TYPE(self)->tp_free((PyObject*)self);
+}
+
+
+// Boilerplate {{{
+
+static PyMethodDef methods[] = {
+    {NULL}  /* Sentinel */
+};
+
+
+PyTypeObject Savepoint_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    .tp_name = "fast_data_types.Savepoint",
+    .tp_basicsize = sizeof(Savepoint),
+    .tp_dealloc = (destructor)dealloc, 
+    .tp_flags = Py_TPFLAGS_DEFAULT,        
+    .tp_doc = "Savepoint",
+    .tp_methods = methods,
+    .tp_new = new,                
+};
+
+INIT_TYPE(Savepoint)
+
+Savepoint *alloc_savepoint() {
+    return (Savepoint*)new(&Savepoint_Type, NULL, NULL);
+}
+
+// }}}
diff --git a/kitty/screen.c b/kitty/screen.c
index d35835832..812229be7 100644
--- a/kitty/screen.c
+++ b/kitty/screen.c
@@ -6,19 +6,27 @@
  */
 
 #include "data-types.h"
+#include <structmember.h>
+#include "unicode-data.h"
+#include "tracker.h"
+#include "modes.h"
 
-static const ScreenModes empty_modes = {0};
+static const ScreenModes empty_modes = {0, .mDECAWM=true, .mDECTCEM=true};
 
+// Constructor/destructor {{{
 static PyObject*
 new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     Screen *self;
     PyObject *callbacks = Py_None;
-    if (!PyArg_ParseTuple(args, "|O", &callbacks)) return NULL;
+    unsigned int columns, lines;
+    if (!PyArg_ParseTuple(args, "|OII", &callbacks, &lines, &columns)) return NULL;
 
     self = (Screen *)type->tp_alloc(type, 0);
     if (self != NULL) {
         self->current_charset = 2;
-        self->columns = 80; self->lines=24;
+        self->g0_charset = translation_table('B');
+        self->g1_charset = translation_table('0');
+        self->columns = columns; self->lines = lines;
         self->modes = empty_modes;
         self->utf8_state = 0;
         self->margin_top = 0; self->margin_bottom = self->lines - 1;
@@ -42,60 +50,349 @@ dealloc(Screen* self) {
     Py_CLEAR(self->cursor); Py_CLEAR(self->main_linebuf); Py_CLEAR(self->alt_linebuf);
     Py_CLEAR(self->main_savepoints); Py_CLEAR(self->alt_savepoints); Py_CLEAR(self->change_tracker);
     Py_TYPE(self)->tp_free((PyObject*)self);
-}
+} // }}}
 
-bool screen_bell(Screen UNUSED *scr, uint8_t ch) {
+bool screen_bell(Screen UNUSED *self, uint8_t ch) {  // {{{
     FILE *f = fopen("/dev/tty", "w");
     if (f != NULL) {
         fwrite(&ch, 1, 1, f);
         fclose(f);
     }
     return true;
-}
+} // }}}
 
-bool screen_draw(Screen UNUSED *scr, uint8_t UNUSED ch) {
+
+bool screen_linefeed(Screen UNUSED *self, uint8_t UNUSED ch) {
     // TODO: Implement this
     return true;
 }
 
-bool screen_backspace(Screen UNUSED *scr, uint8_t UNUSED ch) {
-    // TODO: Implement this
-    return true;
-}
-
-bool screen_tab(Screen UNUSED *scr, uint8_t UNUSED ch) {
+bool screen_carriage_return(Screen UNUSED *self, uint8_t UNUSED ch) {
     // TODO: Implement this
     return true;
 }
 
 
-bool screen_linefeed(Screen UNUSED *scr, uint8_t UNUSED ch) {
+// Draw text {{{
+
+static inline int safe_wcwidth(uint32_t ch) {
+    int ans = wcwidth(ch);
+    if (ans < 0) ans = 1;
+    return MIN(2, ans);
+}
+
+static inline bool
+draw_codepoint(Screen UNUSED *self, uint32_t ch) {
+    if (is_ignored_char(ch)) return true;
+    int char_width = safe_wcwidth(ch);
+    int space_left_in_line = self->columns - self->cursor->x;
+    if (space_left_in_line < char_width) {
+        if (self->modes.mDECAWM) {
+            if (!screen_carriage_return(self, 13)) return false;
+            if (!screen_linefeed(self, 10)) return false;
+            self->linebuf->continued_map[self->cursor->y] = true;
+        } else {
+            self->cursor->x = self->columns - char_width;
+        }
+    }
+    if (char_width > 0) {
+        unsigned int cx = self->cursor->x;
+        linebuf_init_line(self->linebuf, self->cursor->y);
+        if (self->modes.mIRM) {
+            line_right_shift(self->linebuf->line, self->cursor->x, char_width);
+        }
+        line_set_char(self->linebuf->line, self->cursor->x, ch, char_width, self->cursor);
+        self->cursor->x++;
+        if (char_width == 2) {
+            line_set_char(self->linebuf->line, self->cursor->x, 0, 0, self->cursor);
+            self->cursor->x++;
+        }
+        unsigned int right = self->modes.mIRM ? self->columns - 1 : MIN((unsigned int)(MAX(self->cursor->x, 1) - 1), self->columns - 1);
+        tracker_update_cell_range(self->change_tracker, self->cursor->y, cx, right);
+    } else if (is_combining_char(ch)) {
+        if (self->cursor->x > 0) {
+            linebuf_init_line(self->linebuf, self->cursor->y);
+            line_add_combining_char(self->linebuf->line, ch, self->cursor->x - 1);
+            tracker_update_cell_range(self->change_tracker, self->cursor->y, self->cursor->x - 1, self->cursor->x - 1);
+        } else if (self->cursor->y > 0) {
+            linebuf_init_line(self->linebuf, self->cursor->y - 1);
+            line_add_combining_char(self->linebuf->line, ch, self->columns - 1);
+            tracker_update_cell_range(self->change_tracker, self->cursor->y - 1, self->columns - 1, self->columns - 1);
+        }
+    }
+    return true;
+}
+
+static inline bool 
+screen_draw_utf8(Screen *self, uint8_t *buf, unsigned int buflen) {
+    uint32_t prev = UTF8_ACCEPT, codepoint = 0;
+    for (unsigned int i = 0; i < buflen; i++, prev = self->utf8_state) {
+        switch (decode_utf8(&self->utf8_state, &codepoint, buf[i])) {
+            case UTF8_ACCEPT:
+                if (!draw_codepoint(self, codepoint)) return false;
+                break;
+            case UTF8_REJECT:
+                self->utf8_state = UTF8_ACCEPT;
+                if (prev != UTF8_ACCEPT) i--;
+                break;
+        }
+    }
+    return true;
+}
+
+static inline bool 
+screen_draw_charset(Screen *self, unsigned short *table, uint8_t *buf, unsigned int buflen) {
+    for (unsigned int i = 0; i < buflen; i++) {
+        if (!draw_codepoint(self, table[buf[i]])) return false;
+    }
+    return true;
+}
+
+bool screen_draw(Screen *self, uint8_t *buf, unsigned int buflen) {
+    switch(self->current_charset) {
+        case 0:
+            return screen_draw_charset(self, self->g0_charset, buf, buflen);
+            break;
+        case 1:
+            return screen_draw_charset(self, self->g1_charset, buf, buflen);
+            break;
+        default:
+            return screen_draw_utf8(self, buf, buflen); break;
+    }
+}
+// }}}
+
+bool screen_backspace(Screen UNUSED *self, uint8_t UNUSED ch) {
     // TODO: Implement this
     return true;
 }
 
-bool screen_carriage_return(Screen UNUSED *scr, uint8_t UNUSED ch) {
+bool screen_tab(Screen UNUSED *self, uint8_t UNUSED ch) {
     // TODO: Implement this
     return true;
 }
 
-bool screen_shift_out(Screen UNUSED *scr, uint8_t UNUSED ch) {
+bool screen_shift_out(Screen UNUSED *self, uint8_t UNUSED ch) {
     // TODO: Implement this
     return true;
 }
 
-bool screen_shift_in(Screen UNUSED *scr, uint8_t UNUSED ch) {
+bool screen_shift_in(Screen UNUSED *self, uint8_t UNUSED ch) {
     // TODO: Implement this
     return true;
 }
 
+bool screen_toggle_screen_buffer(Screen *self) {
+    if (!screen_save_cursor(self)) return false;
+    if (self->linebuf == self->main_linebuf) {
+        self->linebuf = self->alt_linebuf;
+        self->savepoints = self->alt_savepoints;
+    } else {
+        self->linebuf = self->main_linebuf;
+        self->savepoints = self->main_savepoints;
+    }
+    screen_restore_cursor(self);
+    tracker_update_screen(self->change_tracker);
+    return true;
+}
+
+
+// Modes {{{
+
+static inline void set_mode_from_const(Screen *self, int mode, bool val) {
+    switch(mode) {
+        case LNM: 
+            self->modes.mLNM = val; break;
+        case IRM: 
+            self->modes.mIRM = val; break;
+        case DECTCEM: 
+            self->modes.mDECTCEM = val; break;
+        case DECSCNM: 
+            self->modes.mDECSCNM = val; break;
+        case DECOM: 
+            self->modes.mDECOM = val; break;
+        case DECAWM: 
+            self->modes.mDECAWM = val; break;
+        case DECCOLM: 
+            self->modes.mDECCOLM = val; break;
+        case BRACKETED_PASTE: 
+            self->modes.mBRACKETED_PASTE = val; break;
+        case FOCUS_TRACKING: 
+            self->modes.mFOCUS_TRACKING = val; break;
+    }
+}
+
+bool screen_set_mode(Screen *self, int mode) {
+    if (mode == DECCOLM) {
+        // When DECCOLM mode is set, the screen is erased and the cursor
+        // moves to the home position.
+        if (!screen_erase_in_display(self, 2, false)) return false;
+        if (!screen_cursor_position(self, 1, 1)) return false;
+    }
+    // According to `vttest`, DECOM should also home the cursor, see
+    // vttest/main.c:303.
+    if (mode == DECOM) { if (!screen_cursor_position(self, 1, 1)) return false; }
+
+    if (mode == DECSCNM) {
+        // Mark all displayed characters as reverse.
+        linebuf_set_attribute(self->linebuf, REVERSE_SHIFT, 1);
+        tracker_update_screen(self->change_tracker);
+        self->cursor->reverse = true;
+        tracker_cursor_changed(self->change_tracker);
+    }
+
+    if (mode == DECTCEM && self->cursor->hidden) {
+        self->cursor->hidden = false;
+        tracker_cursor_changed(self->change_tracker);
+    }
+
+    if (mode == ALTERNATE_SCREEN && self->linebuf == self->main_linebuf) { 
+        if (!screen_toggle_screen_buffer(self)) return false;
+    }
+    set_mode_from_const(self, mode, true);
+    return true;
+}
+
+static PyObject*
+in_bracketed_paste_mode(Screen *self) {
+#define in_bracketed_paste_mode_doc ""
+    PyObject *ans = self->modes.mBRACKETED_PASTE ? Py_True : Py_False;
+    Py_INCREF(ans);
+    return ans;
+}
+
+static PyObject*
+enable_focus_tracking(Screen *self) {
+#define enable_focus_tracking_doc ""
+    PyObject *ans = self->modes.mFOCUS_TRACKING ? Py_True : Py_False;
+    Py_INCREF(ans);
+    return ans;
+}
+
+bool screen_reset_mode(Screen *self, int mode) {
+    if (mode == DECCOLM) {
+        // When DECCOLM mode is set, the screen is erased and the cursor
+        // moves to the home position.
+        if (!screen_erase_in_display(self, 2, false)) return false;
+        if (!screen_cursor_position(self, 1, 1)) return false;
+    }
+    // According to `vttest`, DECOM should also home the cursor, see
+    // vttest/main.c:303.
+    if (mode == DECOM) { if (!screen_cursor_position(self, 1, 1)) return false; }
+
+    if (mode == DECSCNM) {
+        // Mark all displayed characters as reverse.
+        linebuf_set_attribute(self->linebuf, REVERSE_SHIFT, 0);
+        tracker_update_screen(self->change_tracker);
+        self->cursor->reverse = false;
+        tracker_cursor_changed(self->change_tracker);
+    }
+
+    if (mode == DECTCEM && !self->cursor->hidden) {
+        self->cursor->hidden = true;
+        tracker_cursor_changed(self->change_tracker);
+    }
+
+    if (mode == ALTERNATE_SCREEN && self->linebuf != self->main_linebuf) { 
+        if (!screen_toggle_screen_buffer(self)) return false;
+    }
+ 
+    set_mode_from_const(self, mode, false);
+    return true;
+}
+// }}}
+
+// Cursor {{{
+bool screen_save_cursor(Screen *self) {
+    Savepoint *sp = alloc_savepoint();
+    if (sp == NULL) return false;
+    sp->cursor = cursor_copy(self->cursor);
+    if (sp->cursor == NULL) { Py_CLEAR(sp); return NULL; }
+    sp->g0_charset = self->g0_charset;
+    sp->g1_charset = self->g1_charset;
+    sp->current_charset = self->current_charset;
+    sp->mDECOM = self->modes.mDECOM;
+    sp->mDECAWM = self->modes.mDECAWM;
+    sp->utf8_state = self->utf8_state;
+    bool ret = PyList_Append(self->savepoints, (PyObject*)sp) == 0;
+    Py_CLEAR(sp);
+    return ret;
+}
+
+bool screen_restore_cursor(Screen *self) {
+    Py_ssize_t sz = PyList_GET_SIZE(self->savepoints);
+    if (sz > 0) {
+        Savepoint *sp = (Savepoint*)PyList_GET_ITEM(self->savepoints, sz - 1);
+        self->g0_charset = sp->g0_charset;
+        self->g1_charset = sp->g1_charset;
+        self->current_charset = sp->current_charset;
+        self->utf8_state = sp->utf8_state;
+        if (sp->mDECOM) screen_set_mode(self, DECOM);
+        if (sp->mDECAWM) screen_set_mode(self, DECAWM);
+        PyList_SetSlice(self->savepoints, sz-1, sz, NULL);
+    } else {
+        screen_cursor_position(self, 1, 1);
+        tracker_cursor_changed(self->change_tracker);
+        screen_reset_mode(self, DECOM);
+    }
+    return true;
+}
+
+bool screen_cursor_position(Screen UNUSED *self, unsigned int UNUSED line, unsigned int UNUSED column) {
+    return true; // TODO: Implement this
+}
+
+// }}}
+
+// Editing {{{
+bool screen_erase_in_display(Screen UNUSED *self, unsigned int UNUSED how, bool UNUSED private) {
+    return true; // TODO: Implement this
+}
+// }}}
+
+bool screen_reset(Screen *self) {
+    if (self->linebuf == self->alt_linebuf) {if (!screen_toggle_screen_buffer(self)) return false; }
+    linebuf_clear(self->linebuf);
+    // TODO: Implement this
+    return true;
+}
+
+static PyObject*
+line(Screen *self, PyObject *val) {
+#define line_doc ""
+    unsigned long y = PyLong_AsUnsignedLong(val);
+    if (y >= self->lines) { PyErr_SetString(PyExc_IndexError, "Out of bounds"); return NULL; }
+    linebuf_init_line(self->linebuf, y);
+    Py_INCREF(self->linebuf->line);
+    return (PyObject*) self->linebuf->line;
+}
+
+static PyObject*
+draw(Screen *self, PyObject *args) {
+#define draw_doc ""
+    Py_buffer pybuf;
+    if(!PyArg_ParseTuple(args, "y*", &pybuf)) return NULL;
+    if (!screen_draw(self, pybuf.buf, pybuf.len)) return NULL;
+    Py_RETURN_NONE;
+}
+ 
 // Boilerplate {{{
 
 static PyMethodDef methods[] = {
+    METHOD(line, METH_O)
+    METHOD(draw, METH_VARARGS)
+    METHOD(enable_focus_tracking, METH_NOARGS)
+    METHOD(in_bracketed_paste_mode, METH_NOARGS)
+
     {NULL}  /* Sentinel */
 };
 
-
+static PyMemberDef members[] = {
+    {"cursor", T_OBJECT_EX, offsetof(Screen, cursor), 0, "cursor"},
+    {"linebuf", T_OBJECT_EX, offsetof(Screen, linebuf), 0, "linebuf"},
+    {NULL}
+};
+ 
 PyTypeObject Screen_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     .tp_name = "fast_data_types.Screen",
@@ -104,6 +401,7 @@ PyTypeObject Screen_Type = {
     .tp_flags = Py_TPFLAGS_DEFAULT,        
     .tp_doc = "Screen",
     .tp_methods = methods,
+    .tp_members = members,
     .tp_new = new,                
 };
 
diff --git a/kitty/screen.py b/kitty/screen.py
index c4615195e..6f87f2925 100644
--- a/kitty/screen.py
+++ b/kitty/screen.py
@@ -11,7 +11,7 @@ from typing import Sequence
 from pyte import charsets as cs, graphics as g, modes as mo
 from .utils import wcwidth, is_simple_string, sanitize_title
 from .unicode import ignore_pat
-from .fast_data_types import LineBuf, REVERSE, Cursor, ChangeTracker
+from .fast_data_types import LineBuf, REVERSE, Cursor, ChangeTracker, CURSOR_BEAM, CURSOR_BLOCK, CURSOR_UNDERLINE
 
 
 #: A container for screen's scroll margins.
@@ -251,11 +251,9 @@ class Screen:
         if mo.ALTERNATE_SCREEN in self.mode and self.linebuf is self.main_linebuf:
             self.toggle_screen_buffer()
 
-    @property
     def in_bracketed_paste_mode(self):
         return mo.BRACKETED_PASTE in self.mode
 
-    @property
     def enable_focus_tracking(self):
         return mo.FOCUS_TRACKING in self.mode
 
@@ -302,7 +300,6 @@ class Screen:
                          from ``b"B0UK"``, otherwise ignored.
         :param str mode: if ``"("`` ``G0`` charset is defined, if
                          ``")"`` -- we operate on ``G1``.
-
         .. warning:: User-defined charsets are currently not supported.
         """
         if code in cs.MAPS:
@@ -984,7 +981,7 @@ class Screen:
             shape = blink = None
             if mode > 0:
                 blink = bool(mode % 2)
-                shape = 'block' if mode < 3 else 'underline' if mode < 5 else 'beam' if mode < 7 else None
+                shape = CURSOR_BLOCK if mode < 3 else CURSOR_UNDERLINE if mode < 5 else CURSOR_BEAM if mode < 7 else None
             if shape != self.cursor.shape or blink != self.cursor.blink:
                 self.cursor.shape, self.cursor.blink = shape, blink
                 self.cursor_changed()
diff --git a/kitty/sprites.c b/kitty/sprites.c
index 477a491eb..3e658219e 100644
--- a/kitty/sprites.c
+++ b/kitty/sprites.c
@@ -7,10 +7,6 @@
 
 #include "data-types.h"
 #include <structmember.h>
-extern PyTypeObject Line_Type;
-extern PyTypeObject ColorProfile_Type;
-extern uint32_t to_color(ColorProfile *, uint32_t, uint32_t);
-extern PyObject* line_text_at(char_type, combining_type);
 
 static PyObject*
 new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
diff --git a/kitty/tracker.c b/kitty/tracker.c
index 0986e00d0..b4338c21a 100644
--- a/kitty/tracker.c
+++ b/kitty/tracker.c
@@ -7,11 +7,6 @@
 
 #include "data-types.h"
 #include "tracker.h"
-extern PyTypeObject SpriteMap_Type;
-extern PyTypeObject ColorProfile_Type;
-extern PyTypeObject LineBuf_Type;
-extern bool update_cell_range_data(SpriteMap *, Line *, unsigned int, unsigned int, ColorProfile *, const uint32_t, const uint32_t, unsigned int *);
-extern void linebuf_init_line(LineBuf *, index_type);
 
 #define RESET_STATE_VARS(self) \
     self->screen_changed = false; self->cursor_changed = false; self->dirty = false; self->history_line_added_count = 0; 
@@ -273,7 +268,7 @@ static PyMethodDef methods[] = {
 };
 
 
-static PyTypeObject ChangeTracker_Type = {
+PyTypeObject ChangeTracker_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     .tp_name = "fast_data_types.ChangeTracker",
     .tp_basicsize = sizeof(ChangeTracker),
diff --git a/kitty/unicode-data.h b/kitty/unicode-data.h
new file mode 100644
index 000000000..3deab3a95
--- /dev/null
+++ b/kitty/unicode-data.h
@@ -0,0 +1,11 @@
+#pragma once
+
+static inline bool is_combining_char(uint32_t ch) {
+    return (0x768 <= ch && ch <= 0x846)||(0x848 <= ch && ch <= 0x879)||(0x1155 <= ch && ch <= 0x1159)||(0x1425 <= ch && ch <= 0x1469)||(0x1473 <= ch && ch <= 0x1474)||(0x1476 <= ch && ch <= 0x1477)||(0x1552 <= ch && ch <= 0x1562)||(0x1611 <= ch && ch <= 0x1631)||(0x1750 <= ch && ch <= 0x1756)||(0x1759 <= ch && ch <= 0x1764)||(0x1767 <= ch && ch <= 0x1768)||(0x1770 <= ch && ch <= 0x1773)||(0x1840 <= ch && ch <= 0x1866)||(0x2027 <= ch && ch <= 0x2035)||(0x2070 <= ch && ch <= 0x2073)||(0x2075 <= ch && ch <= 0x2083)||(0x2085 <= ch && ch <= 0x2087)||(0x2089 <= ch && ch <= 0x2093)||(0x2137 <= ch && ch <= 0x2139)||(0x2275 <= ch && ch <= 0x2303)||(0x2385 <= ch && ch <= 0x2388)||(0x3157 <= ch && ch <= 0x3158)||(0x3640 <= ch && ch <= 0x3642)||(0x3656 <= ch && ch <= 0x3659)||(0x3768 <= ch && ch <= 0x3769)||(0x3784 <= ch && ch <= 0x3787)||(0x3864 <= ch && ch <= 0x3865)||(0x3953 <= ch && ch <= 0x3954)||(0x3962 <= ch && ch <= 0x3965)||(0x3970 <= ch && ch <= 0x3972)||(0x3974 <= ch && ch <= 0x3975)||(0x4153 <= ch && ch <= 0x4154)||(0x4957 <= ch && ch <= 0x4959)||(0x6457 <= ch && ch <= 0x6459)||(0x6679 <= ch && ch <= 0x6680)||(0x6773 <= ch && ch <= 0x6780)||(0x6832 <= ch && ch <= 0x6845)||(0x7019 <= ch && ch <= 0x7027)||(0x7082 <= ch && ch <= 0x7083)||(0x7154 <= ch && ch <= 0x7155)||(0x7376 <= ch && ch <= 0x7378)||(0x7380 <= ch && ch <= 0x7392)||(0x7394 <= ch && ch <= 0x7400)||(0x7416 <= ch && ch <= 0x7417)||(0x7616 <= ch && ch <= 0x7669)||(0x7676 <= ch && ch <= 0x7679)||(0x8400 <= ch && ch <= 0x8412)||(0x8421 <= ch && ch <= 0x8432)||(0x11503 <= ch && ch <= 0x11505)||(0x11744 <= ch && ch <= 0x11775)||(0x12330 <= ch && ch <= 0x12335)||(0x12441 <= ch && ch <= 0x12442)||(0x42612 <= ch && ch <= 0x42621)||(0x42654 <= ch && ch <= 0x42655)||(0x42736 <= ch && ch <= 0x42737)||(0x43232 <= ch && ch <= 0x43249)||(0x43307 <= ch && ch <= 0x43309)||(0x43698 <= ch && ch <= 0x43700)||(0x43703 <= ch && ch <= 0x43704)||(0x43710 <= ch && ch <= 0x43711)||(0x65056 <= ch && ch <= 0x65071)||(0x66422 <= ch && ch <= 0x66426)||(0x68152 <= ch && ch <= 0x68154)||(0x68325 <= ch && ch <= 0x68326)||(0x69817 <= ch && ch <= 0x69818)||(0x69888 <= ch && ch <= 0x69890)||(0x69939 <= ch && ch <= 0x69940)||(0x70197 <= ch && ch <= 0x70198)||(0x70377 <= ch && ch <= 0x70378)||(0x70502 <= ch && ch <= 0x70508)||(0x70512 <= ch && ch <= 0x70516)||(0x70850 <= ch && ch <= 0x70851)||(0x71103 <= ch && ch <= 0x71104)||(0x71350 <= ch && ch <= 0x71351)||(0x92912 <= ch && ch <= 0x92916)||(0x92976 <= ch && ch <= 0x92982)||(0x119141 <= ch && ch <= 0x119145)||(0x119149 <= ch && ch <= 0x119154)||(0x119163 <= ch && ch <= 0x119170)||(0x119173 <= ch && ch <= 0x119179)||(0x119210 <= ch && ch <= 0x119213)||(0x119362 <= ch && ch <= 0x119364)||(0x125136 <= ch && ch <= 0x125142) || (ch == 0x5bf)||(ch == 0x5c7)||(ch == 0x670)||(ch == 0x711)||(ch == 0x93c)||(ch == 0x94d)||(ch == 0x9bc)||(ch == 0x9cd)||(ch == 0xa3c)||(ch == 0xa4d)||(ch == 0xabc)||(ch == 0xacd)||(ch == 0xb3c)||(ch == 0xb4d)||(ch == 0xbcd)||(ch == 0xc4d)||(ch == 0xcbc)||(ch == 0xccd)||(ch == 0xd4d)||(ch == 0xdca)||(ch == 0xf35)||(ch == 0xf37)||(ch == 0xf39)||(ch == 0xf74)||(ch == 0xf80)||(ch == 0xfc6)||(ch == 0x1037)||(ch == 0x108d)||(ch == 0x1714)||(ch == 0x1734)||(ch == 0x17d2)||(ch == 0x17dd)||(ch == 0x18a9)||(ch == 0x1a60)||(ch == 0x1a7f)||(ch == 0x1b34)||(ch == 0x1b44)||(ch == 0x1be6)||(ch == 0x1c37)||(ch == 0x1ced)||(ch == 0x1cf4)||(ch == 0x20e1)||(ch == 0x2d7f)||(ch == 0xa66f)||(ch == 0xa806)||(ch == 0xa8c4)||(ch == 0xa953)||(ch == 0xa9b3)||(ch == 0xa9c0)||(ch == 0xaab0)||(ch == 0xaac1)||(ch == 0xaaf6)||(ch == 0xabed)||(ch == 0xfb1e)||(ch == 0x101fd)||(ch == 0x102e0)||(ch == 0x10a0d)||(ch == 0x10a0f)||(ch == 0x10a3f)||(ch == 0x11046)||(ch == 0x1107f)||(ch == 0x11173)||(ch == 0x111c0)||(ch == 0x111ca)||(ch == 0x1133c)||(ch == 0x1134d)||(ch == 0x1163f)||(ch == 0x1172b)||(ch == 0x1bc9e);
+}
+    
+
+static inline bool is_ignored_char(uint32_t ch) {
+    return (0x0 < ch && ch <= 0x31)||(0x127 <= ch && ch <= 0x159)||(0x888 <= ch && ch <= 0x889)||(0x896 <= ch && ch <= 0x899)||(0x1367 <= ch && ch <= 0x1368)||(0x1419 <= ch && ch <= 0x1420)||(0x1480 <= ch && ch <= 0x1487)||(0x1515 <= ch && ch <= 0x1519)||(0x1525 <= ch && ch <= 0x1541)||(0x1564 <= ch && ch <= 0x1565)||(0x1806 <= ch && ch <= 0x1807)||(0x1867 <= ch && ch <= 0x1868)||(0x1970 <= ch && ch <= 0x1983)||(0x2043 <= ch && ch <= 0x2047)||(0x2094 <= ch && ch <= 0x2095)||(0x2140 <= ch && ch <= 0x2141)||(0x2143 <= ch && ch <= 0x2207)||(0x2229 <= ch && ch <= 0x2274)||(0x2445 <= ch && ch <= 0x2446)||(0x2449 <= ch && ch <= 0x2450)||(0x2483 <= ch && ch <= 0x2485)||(0x2490 <= ch && ch <= 0x2491)||(0x2501 <= ch && ch <= 0x2502)||(0x2505 <= ch && ch <= 0x2506)||(0x2511 <= ch && ch <= 0x2518)||(0x2520 <= ch && ch <= 0x2523)||(0x2532 <= ch && ch <= 0x2533)||(0x2556 <= ch && ch <= 0x2560)||(0x2571 <= ch && ch <= 0x2574)||(0x2577 <= ch && ch <= 0x2578)||(0x2618 <= ch && ch <= 0x2619)||(0x2627 <= ch && ch <= 0x2630)||(0x2633 <= ch && ch <= 0x2634)||(0x2638 <= ch && ch <= 0x2640)||(0x2642 <= ch && ch <= 0x2648)||(0x2655 <= ch && ch <= 0x2661)||(0x2678 <= ch && ch <= 0x2688)||(0x2746 <= ch && ch <= 0x2747)||(0x2766 <= ch && ch <= 0x2767)||(0x2769 <= ch && ch <= 0x2783)||(0x2788 <= ch && ch <= 0x2789)||(0x2802 <= ch && ch <= 0x2808)||(0x2810 <= ch && ch <= 0x2816)||(0x2829 <= ch && ch <= 0x2830)||(0x2833 <= ch && ch <= 0x2834)||(0x2874 <= ch && ch <= 0x2875)||(0x2885 <= ch && ch <= 0x2886)||(0x2889 <= ch && ch <= 0x2890)||(0x2894 <= ch && ch <= 0x2901)||(0x2904 <= ch && ch <= 0x2907)||(0x2916 <= ch && ch <= 0x2917)||(0x2936 <= ch && ch <= 0x2945)||(0x2955 <= ch && ch <= 0x2957)||(0x2966 <= ch && ch <= 0x2968)||(0x2976 <= ch && ch <= 0x2978)||(0x2981 <= ch && ch <= 0x2983)||(0x2987 <= ch && ch <= 0x2989)||(0x3002 <= ch && ch <= 0x3005)||(0x3011 <= ch && ch <= 0x3013)||(0x3022 <= ch && ch <= 0x3023)||(0x3025 <= ch && ch <= 0x3030)||(0x3032 <= ch && ch <= 0x3045)||(0x3067 <= ch && ch <= 0x3071)||(0x3130 <= ch && ch <= 0x3132)||(0x3150 <= ch && ch <= 0x3156)||(0x3163 <= ch && ch <= 0x3167)||(0x3172 <= ch && ch <= 0x3173)||(0x3184 <= ch && ch <= 0x3191)||(0x3258 <= ch && ch <= 0x3259)||(0x3278 <= ch && ch <= 0x3284)||(0x3287 <= ch && ch <= 0x3293)||(0x3300 <= ch && ch <= 0x3301)||(0x3315 <= ch && ch <= 0x3328)||(0x3387 <= ch && ch <= 0x3388)||(0x3407 <= ch && ch <= 0x3414)||(0x3416 <= ch && ch <= 0x3422)||(0x3428 <= ch && ch <= 0x3429)||(0x3446 <= ch && ch <= 0x3448)||(0x3456 <= ch && ch <= 0x3457)||(0x3479 <= ch && ch <= 0x3481)||(0x3518 <= ch && ch <= 0x3519)||(0x3527 <= ch && ch <= 0x3529)||(0x3531 <= ch && ch <= 0x3534)||(0x3552 <= ch && ch <= 0x3557)||(0x3568 <= ch && ch <= 0x3569)||(0x3573 <= ch && ch <= 0x3584)||(0x3643 <= ch && ch <= 0x3646)||(0x3676 <= ch && ch <= 0x3712)||(0x3717 <= ch && ch <= 0x3718)||(0x3723 <= ch && ch <= 0x3724)||(0x3726 <= ch && ch <= 0x3731)||(0x3752 <= ch && ch <= 0x3753)||(0x3774 <= ch && ch <= 0x3775)||(0x3790 <= ch && ch <= 0x3791)||(0x3802 <= ch && ch <= 0x3803)||(0x3808 <= ch && ch <= 0x3839)||(0x3949 <= ch && ch <= 0x3952)||(0x4059 <= ch && ch <= 0x4095)||(0x4296 <= ch && ch <= 0x4300)||(0x4302 <= ch && ch <= 0x4303)||(0x4686 <= ch && ch <= 0x4687)||(0x4702 <= ch && ch <= 0x4703)||(0x4750 <= ch && ch <= 0x4751)||(0x4790 <= ch && ch <= 0x4791)||(0x4806 <= ch && ch <= 0x4807)||(0x4886 <= ch && ch <= 0x4887)||(0x4955 <= ch && ch <= 0x4956)||(0x4989 <= ch && ch <= 0x4991)||(0x5018 <= ch && ch <= 0x5023)||(0x5110 <= ch && ch <= 0x5111)||(0x5118 <= ch && ch <= 0x5119)||(0x5789 <= ch && ch <= 0x5791)||(0x5881 <= ch && ch <= 0x5887)||(0x5909 <= ch && ch <= 0x5919)||(0x5943 <= ch && ch <= 0x5951)||(0x5972 <= ch && ch <= 0x5983)||(0x6004 <= ch && ch <= 0x6015)||(0x6110 <= ch && ch <= 0x6111)||(0x6122 <= ch && ch <= 0x6127)||(0x6138 <= ch && ch <= 0x6143)||(0x6158 <= ch && ch <= 0x6159)||(0x6170 <= ch && ch <= 0x6175)||(0x6264 <= ch && ch <= 0x6271)||(0x6315 <= ch && ch <= 0x6319)||(0x6390 <= ch && ch <= 0x6399)||(0x6444 <= ch && ch <= 0x6447)||(0x6460 <= ch && ch <= 0x6463)||(0x6465 <= ch && ch <= 0x6467)||(0x6510 <= ch && ch <= 0x6511)||(0x6517 <= ch && ch <= 0x6527)||(0x6572 <= ch && ch <= 0x6575)||(0x6602 <= ch && ch <= 0x6607)||(0x6619 <= ch && ch <= 0x6621)||(0x6684 <= ch && ch <= 0x6685)||(0x6781 <= ch && ch <= 0x6782)||(0x6794 <= ch && ch <= 0x6799)||(0x6810 <= ch && ch <= 0x6815)||(0x6830 <= ch && ch <= 0x6831)||(0x6847 <= ch && ch <= 0x6911)||(0x6988 <= ch && ch <= 0x6991)||(0x7037 <= ch && ch <= 0x7039)||(0x7156 <= ch && ch <= 0x7163)||(0x7224 <= ch && ch <= 0x7226)||(0x7242 <= ch && ch <= 0x7244)||(0x7296 <= ch && ch <= 0x7359)||(0x7368 <= ch && ch <= 0x7375)||(0x7418 <= ch && ch <= 0x7423)||(0x7670 <= ch && ch <= 0x7675)||(0x7958 <= ch && ch <= 0x7959)||(0x7966 <= ch && ch <= 0x7967)||(0x8006 <= ch && ch <= 0x8007)||(0x8014 <= ch && ch <= 0x8015)||(0x8062 <= ch && ch <= 0x8063)||(0x8148 <= ch && ch <= 0x8149)||(0x8176 <= ch && ch <= 0x8177)||(0x8203 <= ch && ch <= 0x8207)||(0x8234 <= ch && ch <= 0x8238)||(0x8288 <= ch && ch <= 0x8303)||(0x8306 <= ch && ch <= 0x8307)||(0x8349 <= ch && ch <= 0x8351)||(0x8383 <= ch && ch <= 0x8399)||(0x8433 <= ch && ch <= 0x8447)||(0x8588 <= ch && ch <= 0x8591)||(0x9211 <= ch && ch <= 0x9215)||(0x9255 <= ch && ch <= 0x9279)||(0x9291 <= ch && ch <= 0x9311)||(0x11124 <= ch && ch <= 0x11125)||(0x11158 <= ch && ch <= 0x11159)||(0x11194 <= ch && ch <= 0x11196)||(0x11218 <= ch && ch <= 0x11243)||(0x11248 <= ch && ch <= 0x11263)||(0x11508 <= ch && ch <= 0x11512)||(0x11560 <= ch && ch <= 0x11564)||(0x11566 <= ch && ch <= 0x11567)||(0x11624 <= ch && ch <= 0x11630)||(0x11633 <= ch && ch <= 0x11646)||(0x11671 <= ch && ch <= 0x11679)||(0x11843 <= ch && ch <= 0x11903)||(0x12020 <= ch && ch <= 0x12031)||(0x12246 <= ch && ch <= 0x12271)||(0x12284 <= ch && ch <= 0x12287)||(0x12439 <= ch && ch <= 0x12440)||(0x12544 <= ch && ch <= 0x12548)||(0x12590 <= ch && ch <= 0x12592)||(0x12731 <= ch && ch <= 0x12735)||(0x12772 <= ch && ch <= 0x12783)||(0x19894 <= ch && ch <= 0x19903)||(0x40918 <= ch && ch <= 0x40959)||(0x42125 <= ch && ch <= 0x42127)||(0x42183 <= ch && ch <= 0x42191)||(0x42540 <= ch && ch <= 0x42559)||(0x42744 <= ch && ch <= 0x42751)||(0x42926 <= ch && ch <= 0x42927)||(0x42936 <= ch && ch <= 0x42998)||(0x43052 <= ch && ch <= 0x43055)||(0x43066 <= ch && ch <= 0x43071)||(0x43128 <= ch && ch <= 0x43135)||(0x43205 <= ch && ch <= 0x43213)||(0x43226 <= ch && ch <= 0x43231)||(0x43262 <= ch && ch <= 0x43263)||(0x43348 <= ch && ch <= 0x43358)||(0x43389 <= ch && ch <= 0x43391)||(0x43482 <= ch && ch <= 0x43485)||(0x43575 <= ch && ch <= 0x43583)||(0x43598 <= ch && ch <= 0x43599)||(0x43610 <= ch && ch <= 0x43611)||(0x43715 <= ch && ch <= 0x43738)||(0x43767 <= ch && ch <= 0x43776)||(0x43783 <= ch && ch <= 0x43784)||(0x43791 <= ch && ch <= 0x43792)||(0x43799 <= ch && ch <= 0x43807)||(0x43878 <= ch && ch <= 0x43887)||(0x44014 <= ch && ch <= 0x44015)||(0x44026 <= ch && ch <= 0x44031)||(0x55204 <= ch && ch <= 0x55215)||(0x55239 <= ch && ch <= 0x55242)||(0x55292 <= ch && ch <= 0x57343)||(0x64110 <= ch && ch <= 0x64111)||(0x64218 <= ch && ch <= 0x64255)||(0x64263 <= ch && ch <= 0x64274)||(0x64280 <= ch && ch <= 0x64284)||(0x64450 <= ch && ch <= 0x64466)||(0x64832 <= ch && ch <= 0x64847)||(0x64912 <= ch && ch <= 0x64913)||(0x64968 <= ch && ch <= 0x65007)||(0x65022 <= ch && ch <= 0x65023)||(0x65050 <= ch && ch <= 0x65055)||(0x65132 <= ch && ch <= 0x65135)||(0x65277 <= ch && ch <= 0x65280)||(0x65471 <= ch && ch <= 0x65473)||(0x65480 <= ch && ch <= 0x65481)||(0x65488 <= ch && ch <= 0x65489)||(0x65496 <= ch && ch <= 0x65497)||(0x65501 <= ch && ch <= 0x65503)||(0x65519 <= ch && ch <= 0x65531)||(0x65534 <= ch && ch <= 0x65535)||(0x65614 <= ch && ch <= 0x65615)||(0x65630 <= ch && ch <= 0x65663)||(0x65787 <= ch && ch <= 0x65791)||(0x65795 <= ch && ch <= 0x65798)||(0x65844 <= ch && ch <= 0x65846)||(0x65933 <= ch && ch <= 0x65935)||(0x65948 <= ch && ch <= 0x65951)||(0x65953 <= ch && ch <= 0x65999)||(0x66046 <= ch && ch <= 0x66175)||(0x66205 <= ch && ch <= 0x66207)||(0x66257 <= ch && ch <= 0x66271)||(0x66300 <= ch && ch <= 0x66303)||(0x66340 <= ch && ch <= 0x66351)||(0x66379 <= ch && ch <= 0x66383)||(0x66427 <= ch && ch <= 0x66431)||(0x66500 <= ch && ch <= 0x66503)||(0x66518 <= ch && ch <= 0x66559)||(0x66718 <= ch && ch <= 0x66719)||(0x66730 <= ch && ch <= 0x66815)||(0x66856 <= ch && ch <= 0x66863)||(0x66916 <= ch && ch <= 0x66926)||(0x66928 <= ch && ch <= 0x67071)||(0x67383 <= ch && ch <= 0x67391)||(0x67414 <= ch && ch <= 0x67423)||(0x67432 <= ch && ch <= 0x67583)||(0x67590 <= ch && ch <= 0x67591)||(0x67641 <= ch && ch <= 0x67643)||(0x67645 <= ch && ch <= 0x67646)||(0x67743 <= ch && ch <= 0x67750)||(0x67760 <= ch && ch <= 0x67807)||(0x67830 <= ch && ch <= 0x67834)||(0x67868 <= ch && ch <= 0x67870)||(0x67898 <= ch && ch <= 0x67902)||(0x67904 <= ch && ch <= 0x67967)||(0x68024 <= ch && ch <= 0x68027)||(0x68048 <= ch && ch <= 0x68049)||(0x68103 <= ch && ch <= 0x68107)||(0x68148 <= ch && ch <= 0x68151)||(0x68155 <= ch && ch <= 0x68158)||(0x68168 <= ch && ch <= 0x68175)||(0x68185 <= ch && ch <= 0x68191)||(0x68256 <= ch && ch <= 0x68287)||(0x68327 <= ch && ch <= 0x68330)||(0x68343 <= ch && ch <= 0x68351)||(0x68406 <= ch && ch <= 0x68408)||(0x68438 <= ch && ch <= 0x68439)||(0x68467 <= ch && ch <= 0x68471)||(0x68498 <= ch && ch <= 0x68504)||(0x68509 <= ch && ch <= 0x68520)||(0x68528 <= ch && ch <= 0x68607)||(0x68681 <= ch && ch <= 0x68735)||(0x68787 <= ch && ch <= 0x68799)||(0x68851 <= ch && ch <= 0x68857)||(0x68864 <= ch && ch <= 0x69215)||(0x69247 <= ch && ch <= 0x69631)||(0x69710 <= ch && ch <= 0x69713)||(0x69744 <= ch && ch <= 0x69758)||(0x69826 <= ch && ch <= 0x69839)||(0x69865 <= ch && ch <= 0x69871)||(0x69882 <= ch && ch <= 0x69887)||(0x69956 <= ch && ch <= 0x69967)||(0x70007 <= ch && ch <= 0x70015)||(0x70094 <= ch && ch <= 0x70095)||(0x70133 <= ch && ch <= 0x70143)||(0x70206 <= ch && ch <= 0x70271)||(0x70314 <= ch && ch <= 0x70319)||(0x70379 <= ch && ch <= 0x70383)||(0x70394 <= ch && ch <= 0x70399)||(0x70413 <= ch && ch <= 0x70414)||(0x70417 <= ch && ch <= 0x70418)||(0x70458 <= ch && ch <= 0x70459)||(0x70469 <= ch && ch <= 0x70470)||(0x70473 <= ch && ch <= 0x70474)||(0x70478 <= ch && ch <= 0x70479)||(0x70481 <= ch && ch <= 0x70486)||(0x70488 <= ch && ch <= 0x70492)||(0x70500 <= ch && ch <= 0x70501)||(0x70509 <= ch && ch <= 0x70511)||(0x70517 <= ch && ch <= 0x70783)||(0x70856 <= ch && ch <= 0x70863)||(0x70874 <= ch && ch <= 0x71039)||(0x71094 <= ch && ch <= 0x71095)||(0x71134 <= ch && ch <= 0x71167)||(0x71237 <= ch && ch <= 0x71247)||(0x71258 <= ch && ch <= 0x71295)||(0x71352 <= ch && ch <= 0x71359)||(0x71370 <= ch && ch <= 0x71423)||(0x71450 <= ch && ch <= 0x71452)||(0x71468 <= ch && ch <= 0x71471)||(0x71488 <= ch && ch <= 0x71839)||(0x71923 <= ch && ch <= 0x71934)||(0x71936 <= ch && ch <= 0x72383)||(0x72441 <= ch && ch <= 0x73727)||(0x74650 <= ch && ch <= 0x74751)||(0x74869 <= ch && ch <= 0x74879)||(0x75076 <= ch && ch <= 0x77823)||(0x78895 <= ch && ch <= 0x82943)||(0x83527 <= ch && ch <= 0x92159)||(0x92729 <= ch && ch <= 0x92735)||(0x92778 <= ch && ch <= 0x92781)||(0x92784 <= ch && ch <= 0x92879)||(0x92910 <= ch && ch <= 0x92911)||(0x92918 <= ch && ch <= 0x92927)||(0x92998 <= ch && ch <= 0x93007)||(0x93048 <= ch && ch <= 0x93052)||(0x93072 <= ch && ch <= 0x93951)||(0x94021 <= ch && ch <= 0x94031)||(0x94079 <= ch && ch <= 0x94094)||(0x94112 <= ch && ch <= 0x110591)||(0x110594 <= ch && ch <= 0x113663)||(0x113771 <= ch && ch <= 0x113775)||(0x113789 <= ch && ch <= 0x113791)||(0x113801 <= ch && ch <= 0x113807)||(0x113818 <= ch && ch <= 0x113819)||(0x113824 <= ch && ch <= 0x118783)||(0x119030 <= ch && ch <= 0x119039)||(0x119079 <= ch && ch <= 0x119080)||(0x119155 <= ch && ch <= 0x119162)||(0x119273 <= ch && ch <= 0x119295)||(0x119366 <= ch && ch <= 0x119551)||(0x119639 <= ch && ch <= 0x119647)||(0x119666 <= ch && ch <= 0x119807)||(0x119968 <= ch && ch <= 0x119969)||(0x119971 <= ch && ch <= 0x119972)||(0x119975 <= ch && ch <= 0x119976)||(0x120075 <= ch && ch <= 0x120076)||(0x120135 <= ch && ch <= 0x120137)||(0x120486 <= ch && ch <= 0x120487)||(0x120780 <= ch && ch <= 0x120781)||(0x121484 <= ch && ch <= 0x121498)||(0x121520 <= ch && ch <= 0x124927)||(0x125125 <= ch && ch <= 0x125126)||(0x125143 <= ch && ch <= 0x126463)||(0x126501 <= ch && ch <= 0x126502)||(0x126524 <= ch && ch <= 0x126529)||(0x126531 <= ch && ch <= 0x126534)||(0x126549 <= ch && ch <= 0x126550)||(0x126565 <= ch && ch <= 0x126566)||(0x126620 <= ch && ch <= 0x126624)||(0x126652 <= ch && ch <= 0x126703)||(0x126706 <= ch && ch <= 0x126975)||(0x127020 <= ch && ch <= 0x127023)||(0x127124 <= ch && ch <= 0x127135)||(0x127151 <= ch && ch <= 0x127152)||(0x127222 <= ch && ch <= 0x127231)||(0x127245 <= ch && ch <= 0x127247)||(0x127340 <= ch && ch <= 0x127343)||(0x127387 <= ch && ch <= 0x127461)||(0x127491 <= ch && ch <= 0x127503)||(0x127547 <= ch && ch <= 0x127551)||(0x127561 <= ch && ch <= 0x127567)||(0x127570 <= ch && ch <= 0x127743)||(0x128721 <= ch && ch <= 0x128735)||(0x128749 <= ch && ch <= 0x128751)||(0x128756 <= ch && ch <= 0x128767)||(0x128884 <= ch && ch <= 0x128895)||(0x128981 <= ch && ch <= 0x129023)||(0x129036 <= ch && ch <= 0x129039)||(0x129096 <= ch && ch <= 0x129103)||(0x129114 <= ch && ch <= 0x129119)||(0x129160 <= ch && ch <= 0x129167)||(0x129198 <= ch && ch <= 0x129295)||(0x129305 <= ch && ch <= 0x129407)||(0x129413 <= ch && ch <= 0x129471)||(0x129473 <= ch && ch <= 0x131071)||(0x173783 <= ch && ch <= 0x173823)||(0x177973 <= ch && ch <= 0x177983)||(0x178206 <= ch && ch <= 0x178207)||(0x183970 <= ch && ch <= 0x194559)||(0x195102 <= ch && ch <= 0x917759)||(0x918000 <= ch && ch <= 0x983039)||(0x1048574 <= ch && ch <= 0x1048575)||(0x1114110 <= ch && ch <= 0x1114111) || (ch == 0xad)||(ch == 0x38b)||(ch == 0x38d)||(ch == 0x3a2)||(ch == 0x530)||(ch == 0x560)||(ch == 0x588)||(ch == 0x590)||(ch == 0x6dd)||(ch == 0x83f)||(ch == 0x984)||(ch == 0x9a9)||(ch == 0x9b1)||(ch == 0x9de)||(ch == 0xa04)||(ch == 0xa29)||(ch == 0xa31)||(ch == 0xa34)||(ch == 0xa37)||(ch == 0xa3d)||(ch == 0xa5d)||(ch == 0xa84)||(ch == 0xa8e)||(ch == 0xa92)||(ch == 0xaa9)||(ch == 0xab1)||(ch == 0xab4)||(ch == 0xac6)||(ch == 0xaca)||(ch == 0xb04)||(ch == 0xb29)||(ch == 0xb31)||(ch == 0xb34)||(ch == 0xb5e)||(ch == 0xb84)||(ch == 0xb91)||(ch == 0xb9b)||(ch == 0xb9d)||(ch == 0xbc9)||(ch == 0xc04)||(ch == 0xc0d)||(ch == 0xc11)||(ch == 0xc29)||(ch == 0xc45)||(ch == 0xc49)||(ch == 0xc57)||(ch == 0xc80)||(ch == 0xc84)||(ch == 0xc8d)||(ch == 0xc91)||(ch == 0xca9)||(ch == 0xcb4)||(ch == 0xcc5)||(ch == 0xcc9)||(ch == 0xcdf)||(ch == 0xcf0)||(ch == 0xd04)||(ch == 0xd0d)||(ch == 0xd11)||(ch == 0xd45)||(ch == 0xd49)||(ch == 0xd84)||(ch == 0xdb2)||(ch == 0xdbc)||(ch == 0xdd5)||(ch == 0xdd7)||(ch == 0xe83)||(ch == 0xe89)||(ch == 0xe98)||(ch == 0xea0)||(ch == 0xea4)||(ch == 0xea6)||(ch == 0xeac)||(ch == 0xeba)||(ch == 0xec5)||(ch == 0xec7)||(ch == 0xf48)||(ch == 0xf98)||(ch == 0xfbd)||(ch == 0xfcd)||(ch == 0x10c6)||(ch == 0x1249)||(ch == 0x1257)||(ch == 0x1259)||(ch == 0x1289)||(ch == 0x12b1)||(ch == 0x12bf)||(ch == 0x12c1)||(ch == 0x12d7)||(ch == 0x1311)||(ch == 0x170d)||(ch == 0x176d)||(ch == 0x1771)||(ch == 0x191f)||(ch == 0x1a5f)||(ch == 0x1cf7)||(ch == 0x1f58)||(ch == 0x1f5a)||(ch == 0x1f5c)||(ch == 0x1f5e)||(ch == 0x1fb5)||(ch == 0x1fc5)||(ch == 0x1fdc)||(ch == 0x1ff5)||(ch == 0x1fff)||(ch == 0x208f)||(ch == 0x2bc9)||(ch == 0x2c2f)||(ch == 0x2c5f)||(ch == 0x2d26)||(ch == 0x2da7)||(ch == 0x2daf)||(ch == 0x2db7)||(ch == 0x2dbf)||(ch == 0x2dc7)||(ch == 0x2dcf)||(ch == 0x2dd7)||(ch == 0x2ddf)||(ch == 0x2e9a)||(ch == 0x3040)||(ch == 0x318f)||(ch == 0x321f)||(ch == 0x32ff)||(ch == 0xa9ce)||(ch == 0xa9ff)||(ch == 0xab27)||(ch == 0xab2f)||(ch == 0xfb37)||(ch == 0xfb3d)||(ch == 0xfb3f)||(ch == 0xfb42)||(ch == 0xfb45)||(ch == 0xfe53)||(ch == 0xfe67)||(ch == 0xfe75)||(ch == 0xffe7)||(ch == 0x1000c)||(ch == 0x10027)||(ch == 0x1003b)||(ch == 0x1003e)||(ch == 0x1039e)||(ch == 0x10809)||(ch == 0x10836)||(ch == 0x10856)||(ch == 0x108f3)||(ch == 0x10a04)||(ch == 0x10a14)||(ch == 0x10a18)||(ch == 0x110bd)||(ch == 0x11135)||(ch == 0x111e0)||(ch == 0x11212)||(ch == 0x11287)||(ch == 0x11289)||(ch == 0x1128e)||(ch == 0x1129e)||(ch == 0x11304)||(ch == 0x11329)||(ch == 0x11331)||(ch == 0x11334)||(ch == 0x1246f)||(ch == 0x16a5f)||(ch == 0x16b5a)||(ch == 0x16b62)||(ch == 0x1d455)||(ch == 0x1d49d)||(ch == 0x1d4ad)||(ch == 0x1d4ba)||(ch == 0x1d4bc)||(ch == 0x1d4c4)||(ch == 0x1d506)||(ch == 0x1d515)||(ch == 0x1d51d)||(ch == 0x1d53a)||(ch == 0x1d53f)||(ch == 0x1d545)||(ch == 0x1d551)||(ch == 0x1daa0)||(ch == 0x1ee04)||(ch == 0x1ee20)||(ch == 0x1ee23)||(ch == 0x1ee28)||(ch == 0x1ee33)||(ch == 0x1ee38)||(ch == 0x1ee3a)||(ch == 0x1ee48)||(ch == 0x1ee4a)||(ch == 0x1ee4c)||(ch == 0x1ee50)||(ch == 0x1ee53)||(ch == 0x1ee58)||(ch == 0x1ee5a)||(ch == 0x1ee5c)||(ch == 0x1ee5e)||(ch == 0x1ee60)||(ch == 0x1ee63)||(ch == 0x1ee6b)||(ch == 0x1ee73)||(ch == 0x1ee78)||(ch == 0x1ee7d)||(ch == 0x1ee7f)||(ch == 0x1ee8a)||(ch == 0x1eea4)||(ch == 0x1eeaa)||(ch == 0x1f0c0)||(ch == 0x1f0d0)||(ch == 0x1f12f)||(ch == 0x1f57a)||(ch == 0x1f5a4);
+}
+    
diff --git a/kitty_tests/__init__.py b/kitty_tests/__init__.py
index e1949d568..64ebda3d7 100644
--- a/kitty_tests/__init__.py
+++ b/kitty_tests/__init__.py
@@ -4,8 +4,8 @@
 
 from unittest import TestCase
 
-from kitty.screen import Screen
-from kitty.fast_data_types import LineBuf, Cursor
+from kitty.screen import Screen as S
+from kitty.fast_data_types import LineBuf, Cursor, Screen
 
 
 def filled_line_buf(ynum=5, xnum=5, cursor=Cursor()):
@@ -31,8 +31,10 @@ class BaseTest(TestCase):
     ae = TestCase.assertEqual
 
     def create_screen(self, cols=5, lines=5, history_size=5):
-        s = Screen(history_size, columns=cols, lines=lines)
-        return s
+        return S(history_size, columns=cols, lines=lines)
+
+    def create_screen2(self, cols=5, lines=5, history_size=5):
+        return Screen(history_size, None, lines, cols)
 
     def assertEqualAttributes(self, c1, c2):
         x1, y1, c1.x, c1.y = c1.x, c1.y, 0, 0