gundo

vim/autoload/gundo.py

@@ -0,0 +1,577 @@
+# ============================================================================
+# File:        gundo.py
+# Description: vim global plugin to visualize your undo tree
+# Maintainer:  Steve Losh <steve@stevelosh.com>
+# License:     GPLv2+ -- look it up.
+# Notes:       Much of this code was thiefed from Mercurial, and the rest was
+#              heavily inspired by scratch.vim and histwin.vim.
+#
+# ============================================================================
+
+import difflib
+import itertools
+import sys
+import time
+import vim
+
+
+# Mercurial's graphlog code --------------------------------------------------------
+def asciiedges(seen, rev, parents):
+    """adds edge info to changelog DAG walk suitable for ascii()"""
+    if rev not in seen:
+        seen.append(rev)
+    nodeidx = seen.index(rev)
+
+    knownparents = []
+    newparents = []
+    for parent in parents:
+        if parent in seen:
+            knownparents.append(parent)
+        else:
+            newparents.append(parent)
+
+    ncols = len(seen)
+    seen[nodeidx:nodeidx + 1] = newparents
+    edges = [(nodeidx, seen.index(p)) for p in knownparents]
+
+    if len(newparents) > 0:
+        edges.append((nodeidx, nodeidx))
+    if len(newparents) > 1:
+        edges.append((nodeidx, nodeidx + 1))
+
+    nmorecols = len(seen) - ncols
+    return nodeidx, edges, ncols, nmorecols
+
+def get_nodeline_edges_tail(
+        node_index, p_node_index, n_columns, n_columns_diff, p_diff, fix_tail):
+    if fix_tail and n_columns_diff == p_diff and n_columns_diff != 0:
+        # Still going in the same non-vertical direction.
+        if n_columns_diff == -1:
+            start = max(node_index + 1, p_node_index)
+            tail = ["|", " "] * (start - node_index - 1)
+            tail.extend(["/", " "] * (n_columns - start))
+            return tail
+        else:
+            return ["\\", " "] * (n_columns - node_index - 1)
+    else:
+        return ["|", " "] * (n_columns - node_index - 1)
+
+def draw_edges(edges, nodeline, interline):
+    for (start, end) in edges:
+        if start == end + 1:
+            interline[2 * end + 1] = "/"
+        elif start == end - 1:
+            interline[2 * start + 1] = "\\"
+        elif start == end:
+            interline[2 * start] = "|"
+        else:
+            nodeline[2 * end] = "+"
+            if start > end:
+                (start, end) = (end, start)
+            for i in range(2 * start + 1, 2 * end):
+                if nodeline[i] != "+":
+                    nodeline[i] = "-"
+
+def fix_long_right_edges(edges):
+    for (i, (start, end)) in enumerate(edges):
+        if end > start:
+            edges[i] = (start, end + 1)
+
+def ascii(buf, state, type, char, text, coldata):
+    """prints an ASCII graph of the DAG
+
+    takes the following arguments (one call per node in the graph):
+
+      - Somewhere to keep the needed state in (init to asciistate())
+      - Column of the current node in the set of ongoing edges.
+      - Type indicator of node data == ASCIIDATA.
+      - Payload: (char, lines):
+        - Character to use as node's symbol.
+        - List of lines to display as the node's text.
+      - Edges; a list of (col, next_col) indicating the edges between
+        the current node and its parents.
+      - Number of columns (ongoing edges) in the current revision.
+      - The difference between the number of columns (ongoing edges)
+        in the next revision and the number of columns (ongoing edges)
+        in the current revision. That is: -1 means one column removed;
+        0 means no columns added or removed; 1 means one column added.
+    """
+
+    idx, edges, ncols, coldiff = coldata
+    assert -2 < coldiff < 2
+    if coldiff == -1:
+        # Transform
+        #
+        #     | | |        | | |
+        #     o | |  into  o---+
+        #     |X /         |/ /
+        #     | |          | |
+        fix_long_right_edges(edges)
+
+    # add_padding_line says whether to rewrite
+    #
+    #     | | | |        | | | |
+    #     | o---+  into  | o---+
+    #     |  / /         |   | |  # <--- padding line
+    #     o | |          |  / /
+    #                    o | |
+    add_padding_line = (len(text) > 2 and coldiff == -1 and
+                        [x for (x, y) in edges if x + 1 < y])
+
+    # fix_nodeline_tail says whether to rewrite
+    #
+    #     | | o | |        | | o | |
+    #     | | |/ /         | | |/ /
+    #     | o | |    into  | o / /   # <--- fixed nodeline tail
+    #     | |/ /           | |/ /
+    #     o | |            o | |
+    fix_nodeline_tail = len(text) <= 2 and not add_padding_line
+
+    # nodeline is the line containing the node character (typically o)
+    nodeline = ["|", " "] * idx
+    nodeline.extend([char, " "])
+
+    nodeline.extend(
+        get_nodeline_edges_tail(idx, state[1], ncols, coldiff,
+                                state[0], fix_nodeline_tail))
+
+    # shift_interline is the line containing the non-vertical
+    # edges between this entry and the next
+    shift_interline = ["|", " "] * idx
+    if coldiff == -1:
+        n_spaces = 1
+        edge_ch = "/"
+    elif coldiff == 0:
+        n_spaces = 2
+        edge_ch = "|"
+    else:
+        n_spaces = 3
+        edge_ch = "\\"
+    shift_interline.extend(n_spaces * [" "])
+    shift_interline.extend([edge_ch, " "] * (ncols - idx - 1))
+
+    # draw edges from the current node to its parents
+    draw_edges(edges, nodeline, shift_interline)
+
+    # lines is the list of all graph lines to print
+    lines = [nodeline]
+    if add_padding_line:
+        lines.append(get_padding_line(idx, ncols, edges))
+    lines.append(shift_interline)
+
+    # make sure that there are as many graph lines as there are
+    # log strings
+    while len(text) < len(lines):
+        text.append("")
+    if len(lines) < len(text):
+        extra_interline = ["|", " "] * (ncols + coldiff)
+        while len(lines) < len(text):
+            lines.append(extra_interline)
+
+    # print lines
+    indentation_level = max(ncols, ncols + coldiff)
+    for (line, logstr) in zip(lines, text):
+        ln = "%-*s %s" % (2 * indentation_level, "".join(line), logstr)
+        buf.write(ln.rstrip() + '\n')
+
+    # ... and start over
+    state[0] = coldiff
+    state[1] = idx
+
+def generate(dag, edgefn, current):
+    seen, state = [], [0, 0]
+    buf = Buffer()
+    for node, parents in list(dag):
+        if node.time:
+            age_label = age(int(node.time))
+        else:
+            age_label = 'Original'
+        line = '[%s] %s' % (node.n, age_label)
+        if node.n == current:
+            char = '@'
+        else:
+            char = 'o'
+        ascii(buf, state, 'C', char, [line], edgefn(seen, node, parents))
+    return buf.b
+
+
+# Mercurial age function -----------------------------------------------------------
+agescales = [("year", 3600 * 24 * 365),
+             ("month", 3600 * 24 * 30),
+             ("week", 3600 * 24 * 7),
+             ("day", 3600 * 24),
+             ("hour", 3600),
+             ("minute", 60),
+             ("second", 1)]
+
+def age(ts):
+    '''turn a timestamp into an age string.'''
+
+    def plural(t, c):
+        if c == 1:
+            return t
+        return t + "s"
+    def fmt(t, c):
+        return "%d %s" % (c, plural(t, c))
+
+    now = time.time()
+    then = ts
+    if then > now:
+        return 'in the future'
+
+    delta = max(1, int(now - then))
+    if delta > agescales[0][1] * 2:
+        return time.strftime('%Y-%m-%d', time.gmtime(float(ts)))
+
+    for t, s in agescales:
+        n = delta // s
+        if n >= 2 or s == 1:
+            return '%s ago' % fmt(t, n)
+
+
+# Python Vim utility functions -----------------------------------------------------
+normal = lambda s: vim.command('normal %s' % s)
+
+MISSING_BUFFER = "Cannot find Gundo's target buffer (%s)"
+MISSING_WINDOW = "Cannot find window (%s) for Gundo's target buffer (%s)"
+
+def _check_sanity():
+    '''Check to make sure we're not crazy.
+
+    Does the following things:
+
+        * Make sure the target buffer still exists.
+    '''
+    b = int(vim.eval('g:gundo_target_n'))
+
+    if not vim.eval('bufloaded(%d)' % b):
+        vim.command('echo "%s"' % (MISSING_BUFFER % b))
+        return False
+
+    w = int(vim.eval('bufwinnr(%d)' % b))
+    if w == -1:
+        vim.command('echo "%s"' % (MISSING_WINDOW % (w, b)))
+        return False
+
+    return True
+
+def _goto_window_for_buffer(b):
+    w = int(vim.eval('bufwinnr(%d)' % int(b)))
+    vim.command('%dwincmd w' % w)
+
+def _goto_window_for_buffer_name(bn):
+    b = vim.eval('bufnr("%s")' % bn)
+    return _goto_window_for_buffer(b)
+
+def _undo_to(n):
+    n = int(n)
+    if n == 0:
+        vim.command('silent earlier %s' % (int(vim.eval('&undolevels')) + 1))
+    else:
+        vim.command('silent undo %d' % n)
+
+
+INLINE_HELP = '''\
+" Gundo for %s (%d)
+" j/k  - move between undo states
+" p    - preview diff of selected and current states
+" <cr> - revert to selected state
+
+'''
+
+
+# Python undo tree data structures and functions -----------------------------------
+class Buffer(object):
+    def __init__(self):
+        self.b = ''
+
+    def write(self, s):
+        self.b += s
+
+class Node(object):
+    def __init__(self, n, parent, time, curhead):
+        self.n = int(n)
+        self.parent = parent
+        self.children = []
+        self.curhead = curhead
+        self.time = time
+
+def _make_nodes(alts, nodes, parent=None):
+    p = parent
+
+    for alt in alts:
+        curhead = 'curhead' in alt
+        node = Node(n=alt['seq'], parent=p, time=alt['time'], curhead=curhead)
+        nodes.append(node)
+        if alt.get('alt'):
+            _make_nodes(alt['alt'], nodes, p)
+        p = node
+
+def make_nodes():
+    ut = vim.eval('undotree()')
+    entries = ut['entries']
+
+    root = Node(0, None, False, 0)
+    nodes = []
+    _make_nodes(entries, nodes, root)
+    nodes.append(root)
+    nmap = dict((node.n, node) for node in nodes)
+    return nodes, nmap
+
+def changenr(nodes):
+    _curhead_l = list(itertools.dropwhile(lambda n: not n.curhead, nodes))
+    if _curhead_l:
+        current = _curhead_l[0].parent.n
+    else:
+        current = int(vim.eval('changenr()'))
+    return current
+
+
+# Gundo rendering ------------------------------------------------------------------
+
+# Rendering utility functions
+def _fmt_time(t):
+    return time.strftime('%Y-%m-%d %I:%M:%S %p', time.localtime(float(t)))
+
+def _output_preview_text(lines):
+    _goto_window_for_buffer_name('__Gundo_Preview__')
+    vim.command('setlocal modifiable')
+    vim.current.buffer[:] = lines
+    vim.command('setlocal nomodifiable')
+
+def _generate_preview_diff(current, node_before, node_after):
+    _goto_window_for_buffer(vim.eval('g:gundo_target_n'))
+
+    if not node_after.n:    # we're at the original file
+        before_lines = []
+
+        _undo_to(0)
+        after_lines = vim.current.buffer[:]
+
+        before_name = 'n/a'
+        before_time = ''
+        after_name = 'Original'
+        after_time = ''
+    elif not node_before.n: # we're at a pseudo-root state
+        _undo_to(0)
+        before_lines = vim.current.buffer[:]
+
+        _undo_to(node_after.n)
+        after_lines = vim.current.buffer[:]
+
+        before_name = 'Original'
+        before_time = ''
+        after_name = node_after.n
+        after_time = _fmt_time(node_after.time)
+    else:
+        _undo_to(node_before.n)
+        before_lines = vim.current.buffer[:]
+
+        _undo_to(node_after.n)
+        after_lines = vim.current.buffer[:]
+
+        before_name = node_before.n
+        before_time = _fmt_time(node_before.time)
+        after_name = node_after.n
+        after_time = _fmt_time(node_after.time)
+
+    _undo_to(current)
+
+    return list(difflib.unified_diff(before_lines, after_lines,
+                                     before_name, after_name,
+                                     before_time, after_time))
+
+def _generate_change_preview_diff(current, node_before, node_after):
+    _goto_window_for_buffer(vim.eval('g:gundo_target_n'))
+
+    _undo_to(node_before.n)
+    before_lines = vim.current.buffer[:]
+
+    _undo_to(node_after.n)
+    after_lines = vim.current.buffer[:]
+
+    before_name = node_before.n or 'Original'
+    before_time = node_before.time and _fmt_time(node_before.time) or ''
+    after_name = node_after.n or 'Original'
+    after_time = node_after.time and _fmt_time(node_after.time) or ''
+
+    _undo_to(current)
+
+    return list(difflib.unified_diff(before_lines, after_lines,
+                                     before_name, after_name,
+                                     before_time, after_time))
+
+def GundoRenderGraph():
+    if not _check_sanity():
+        return
+
+    nodes, nmap = make_nodes()
+
+    for node in nodes:
+        node.children = [n for n in nodes if n.parent == node]
+
+    def walk_nodes(nodes):
+        for node in nodes:
+            if node.parent:
+                yield (node, [node.parent])
+            else:
+                yield (node, [])
+
+    dag = sorted(nodes, key=lambda n: int(n.n), reverse=True)
+    current = changenr(nodes)
+
+    result = generate(walk_nodes(dag), asciiedges, current).rstrip().splitlines()
+    result = [' ' + l for l in result]
+
+    target = (vim.eval('g:gundo_target_f'), int(vim.eval('g:gundo_target_n')))
+
+    if int(vim.eval('g:gundo_help')):
+        header = (INLINE_HELP % target).splitlines()
+    else:
+        header = []
+
+    vim.command('call s:GundoOpenGraph()')
+    vim.command('setlocal modifiable')
+    vim.current.buffer[:] = (header + result)
+    vim.command('setlocal nomodifiable')
+
+    i = 1
+    for line in result:
+        try:
+            line.split('[')[0].index('@')
+            i += 1
+            break
+        except ValueError:
+            pass
+        i += 1
+    vim.command('%d' % (i+len(header)-1))
+
+def GundoRenderPreview():
+    if not _check_sanity():
+        return
+
+    target_state = vim.eval('s:GundoGetTargetState()')
+
+    # Check that there's an undo state. There may not be if we're talking about
+    # a buffer with no changes yet.
+    if target_state == None:
+        _goto_window_for_buffer_name('__Gundo__')
+        return
+    else:
+        target_state = int(target_state)
+
+    _goto_window_for_buffer(vim.eval('g:gundo_target_n'))
+
+    nodes, nmap = make_nodes()
+    current = changenr(nodes)
+
+    node_after = nmap[target_state]
+    node_before = node_after.parent
+
+    vim.command('call s:GundoOpenPreview()')
+    _output_preview_text(_generate_preview_diff(current, node_before, node_after))
+
+    _goto_window_for_buffer_name('__Gundo__')
+
+def GundoRenderChangePreview():
+    if not _check_sanity():
+        return
+
+    target_state = vim.eval('s:GundoGetTargetState()')
+
+    # Check that there's an undo state. There may not be if we're talking about
+    # a buffer with no changes yet.
+    if target_state == None:
+        _goto_window_for_buffer_name('__Gundo__')
+        return
+    else:
+        target_state = int(target_state)
+
+    _goto_window_for_buffer(vim.eval('g:gundo_target_n'))
+
+    nodes, nmap = make_nodes()
+    current = changenr(nodes)
+
+    node_after = nmap[target_state]
+    node_before = nmap[current]
+
+    vim.command('call s:GundoOpenPreview()')
+    _output_preview_text(_generate_change_preview_diff(current, node_before, node_after))
+
+    _goto_window_for_buffer_name('__Gundo__')
+
+
+# Gundo undo/redo
+def GundoRevert():
+    if not _check_sanity():
+        return
+
+    target_n = int(vim.eval('s:GundoGetTargetState()'))
+    back = vim.eval('g:gundo_target_n')
+
+    _goto_window_for_buffer(back)
+    _undo_to(target_n)
+
+    vim.command('GundoRenderGraph')
+    _goto_window_for_buffer(back)
+
+    if int(vim.eval('g:gundo_close_on_revert')):
+        vim.command('GundoToggle')
+
+def GundoPlayTo():
+    if not _check_sanity():
+        return
+
+    target_n = int(vim.eval('s:GundoGetTargetState()'))
+    back = int(vim.eval('g:gundo_target_n'))
+
+    vim.command('echo "%s"' % back)
+
+    _goto_window_for_buffer(back)
+    normal('zR')
+
+    nodes, nmap = make_nodes()
+
+    start = nmap[changenr(nodes)]
+    end = nmap[target_n]
+
+    def _walk_branch(origin, dest):
+        rev = origin.n < dest.n
+
+        nodes = []
+        if origin.n > dest.n:
+            current, final = origin, dest
+        else:
+            current, final = dest, origin
+
+        while current.n >= final.n:
+            if current.n == final.n:
+                break
+            nodes.append(current)
+            current = current.parent
+        else:
+            return None
+        nodes.append(current)
+
+        if rev:
+            return reversed(nodes)
+        else:
+            return nodes
+
+    branch = _walk_branch(start, end)
+
+    if not branch:
+        vim.command('unsilent echo "No path to that node from here!"')
+        return
+
+    for node in branch:
+        _undo_to(node.n)
+        vim.command('GundoRenderGraph')
+        normal('zz')
+        _goto_window_for_buffer(back)
+        vim.command('redraw')
+        vim.command('sleep 60m')
+
+def initPythonModule():
+    if sys.version_info[:2] < (2, 4):
+        vim.command('let s:has_supported_python = 0')

vim/autoload/gundo.vim

@@ -0,0 +1,449 @@
+" ============================================================================
+" File:        gundo.vim
+" Description: vim global plugin to visualize your undo tree
+" Maintainer:  Steve Losh <steve@stevelosh.com>
+" License:     GPLv2+ -- look it up.
+" Notes:       Much of this code was thiefed from Mercurial, and the rest was
+"              heavily inspired by scratch.vim and histwin.vim.
+"
+" ============================================================================
+
+
+"{{{ Init
+
+if v:version < '703'"{{{
+    function! s:GundoDidNotLoad()
+        echohl WarningMsg|echomsg "Gundo unavailable: requires Vim 7.3+"|echohl None
+    endfunction
+    command! -nargs=0 GundoToggle call s:GundoDidNotLoad()
+    finish
+endif"}}}
+
+if !exists('g:gundo_width')"{{{
+    let g:gundo_width = 45
+endif"}}}
+if !exists('g:gundo_preview_height')"{{{
+    let g:gundo_preview_height = 15
+endif"}}}
+if !exists('g:gundo_preview_bottom')"{{{
+    let g:gundo_preview_bottom = 0
+endif"}}}
+if !exists('g:gundo_right')"{{{
+    let g:gundo_right = 0
+endif"}}}
+if !exists('g:gundo_help')"{{{
+    let g:gundo_help = 1
+endif"}}}
+if !exists("g:gundo_map_move_older")"{{{
+    let g:gundo_map_move_older = 'j'
+endif"}}}
+if !exists("g:gundo_map_move_newer")"{{{
+    let g:gundo_map_move_newer = 'k'
+endif"}}}
+if !exists("g:gundo_close_on_revert")"{{{
+    let g:gundo_close_on_revert = 0
+endif"}}}
+if !exists("g:gundo_prefer_python3")"{{{
+    let g:gundo_prefer_python3 = 0
+endif"}}}
+
+let s:has_supported_python = 0
+if g:gundo_prefer_python3 && has('python3')"{{{
+    let s:has_supported_python = 2
+elseif has('python')"
+    let s:has_supported_python = 1
+endif
+
+if !s:has_supported_python
+    function! s:GundoDidNotLoad()
+        echohl WarningMsg|echomsg "Gundo requires Vim to be compiled with Python 2.4+"|echohl None
+    endfunction
+    command! -nargs=0 GundoToggle call s:GundoDidNotLoad()
+    finish
+endif"}}}
+
+let s:plugin_path = escape(expand('<sfile>:p:h'), '\')
+"}}}
+
+"{{{ Gundo utility functions
+
+function! s:GundoGetTargetState()"{{{
+    let target_line = matchstr(getline("."), '\v\[[0-9]+\]')
+    return matchstr(target_line, '\v[0-9]+')
+endfunction"}}}
+
+function! s:GundoGoToWindowForBufferName(name)"{{{
+    if bufwinnr(bufnr(a:name)) != -1
+        exe bufwinnr(bufnr(a:name)) . "wincmd w"
+        return 1
+    else
+        return 0
+    endif
+endfunction"}}}
+
+function! s:GundoIsVisible()"{{{
+    if bufwinnr(bufnr("__Gundo__")) != -1 || bufwinnr(bufnr("__Gundo_Preview__")) != -1
+        return 1
+    else
+        return 0
+    endif
+endfunction"}}}
+
+function! s:GundoInlineHelpLength()"{{{
+    if g:gundo_help
+        return 6
+    else
+        return 0
+    endif
+endfunction"}}}
+
+"}}}
+
+"{{{ Gundo buffer settings
+
+function! s:GundoMapGraph()"{{{
+    exec 'nnoremap <script> <silent> <buffer> ' . g:gundo_map_move_older . " :call <sid>GundoMove(1)<CR>"
+    exec 'nnoremap <script> <silent> <buffer> ' . g:gundo_map_move_newer . " :call <sid>GundoMove(-1)<CR>"
+    nnoremap <script> <silent> <buffer> <CR>          :call <sid>GundoRevert()<CR>
+    nnoremap <script> <silent> <buffer> o             :call <sid>GundoRevert()<CR>
+    nnoremap <script> <silent> <buffer> <down>        :call <sid>GundoMove(1)<CR>
+    nnoremap <script> <silent> <buffer> <up>          :call <sid>GundoMove(-1)<CR>
+    nnoremap <script> <silent> <buffer> gg            gg:call <sid>GundoMove(1)<CR>
+    nnoremap <script> <silent> <buffer> P             :call <sid>GundoPlayTo()<CR>
+    nnoremap <script> <silent> <buffer> p             :call <sid>GundoRenderChangePreview()<CR>
+    nnoremap <script> <silent> <buffer> q             :call <sid>GundoClose()<CR>
+    cabbrev  <script> <silent> <buffer> q             call <sid>GundoClose()
+    cabbrev  <script> <silent> <buffer> quit          call <sid>GundoClose()
+    nnoremap <script> <silent> <buffer> <2-LeftMouse> :call <sid>GundoMouseDoubleClick()<CR>
+endfunction"}}}
+
+function! s:GundoMapPreview()"{{{
+    nnoremap <script> <silent> <buffer> q     :call <sid>GundoClose()<CR>
+    cabbrev  <script> <silent> <buffer> q     call <sid>GundoClose()
+    cabbrev  <script> <silent> <buffer> quit  call <sid>GundoClose()
+endfunction"}}}
+
+function! s:GundoSettingsGraph()"{{{
+    setlocal buftype=nofile
+    setlocal bufhidden=hide
+    setlocal noswapfile
+    setlocal nobuflisted
+    setlocal nomodifiable
+    setlocal filetype=gundo
+    setlocal nolist
+    setlocal nonumber
+    setlocal norelativenumber
+    setlocal nowrap
+    call s:GundoSyntaxGraph()
+    call s:GundoMapGraph()
+endfunction"}}}
+
+function! s:GundoSettingsPreview()"{{{
+    setlocal buftype=nofile
+    setlocal bufhidden=hide
+    setlocal noswapfile
+    setlocal nobuflisted
+    setlocal nomodifiable
+    setlocal filetype=diff
+    setlocal nonumber
+    setlocal norelativenumber
+    setlocal nowrap
+    setlocal foldlevel=20
+    setlocal foldmethod=diff
+    call s:GundoMapPreview()
+endfunction"}}}
+
+function! s:GundoSyntaxGraph()"{{{
+    let b:current_syntax = 'gundo'
+
+    syn match GundoCurrentLocation '@'
+    syn match GundoHelp '\v^".*$'
+    syn match GundoNumberField '\v\[[0-9]+\]'
+    syn match GundoNumber '\v[0-9]+' contained containedin=GundoNumberField
+
+    hi def link GundoCurrentLocation Keyword
+    hi def link GundoHelp Comment
+    hi def link GundoNumberField Comment
+    hi def link GundoNumber Identifier
+endfunction"}}}
+
+"}}}
+
+"{{{ Gundo buffer/window management
+
+function! s:GundoResizeBuffers(backto)"{{{
+    call s:GundoGoToWindowForBufferName('__Gundo__')
+    exe "vertical resize " . g:gundo_width
+
+    call s:GundoGoToWindowForBufferName('__Gundo_Preview__')
+    exe "resize " . g:gundo_preview_height
+
+    exe a:backto . "wincmd w"
+endfunction"}}}
+
+function! s:GundoOpenGraph()"{{{
+    let existing_gundo_buffer = bufnr("__Gundo__")
+
+    if existing_gundo_buffer == -1
+        call s:GundoGoToWindowForBufferName('__Gundo_Preview__')
+        exe "new __Gundo__"
+        if g:gundo_preview_bottom
+            if g:gundo_right
+                wincmd L
+            else
+                wincmd H
+            endif
+        endif
+        call s:GundoResizeBuffers(winnr())
+    else
+        let existing_gundo_window = bufwinnr(existing_gundo_buffer)
+
+        if existing_gundo_window != -1
+            if winnr() != existing_gundo_window
+                exe existing_gundo_window . "wincmd w"
+            endif
+        else
+            call s:GundoGoToWindowForBufferName('__Gundo_Preview__')
+            if g:gundo_preview_bottom
+                if g:gundo_right
+                    exe "botright vsplit +buffer" . existing_gundo_buffer
+                else
+                    exe "topleft vsplit +buffer" . existing_gundo_buffer
+                endif
+            else
+                exe "split +buffer" . existing_gundo_buffer
+            endif
+            call s:GundoResizeBuffers(winnr())
+        endif
+    endif
+    if exists("g:gundo_tree_statusline")
+        let &l:statusline = g:gundo_tree_statusline
+    endif
+endfunction"}}}
+
+function! s:GundoOpenPreview()"{{{
+    let existing_preview_buffer = bufnr("__Gundo_Preview__")
+
+    if existing_preview_buffer == -1
+        if g:gundo_preview_bottom
+            exe "botright new __Gundo_Preview__"
+        else
+            if g:gundo_right
+                exe "botright vnew __Gundo_Preview__"
+            else
+                exe "topleft vnew __Gundo_Preview__"
+            endif
+        endif
+    else
+        let existing_preview_window = bufwinnr(existing_preview_buffer)
+
+        if existing_preview_window != -1
+            if winnr() != existing_preview_window
+                exe existing_preview_window . "wincmd w"
+            endif
+        else
+            if g:gundo_preview_bottom
+                exe "botright split +buffer" . existing_preview_buffer
+            else
+                if g:gundo_right
+                    exe "botright vsplit +buffer" . existing_preview_buffer
+                else
+                    exe "topleft vsplit +buffer" . existing_preview_buffer
+                endif
+            endif
+        endif
+    endif
+    if exists("g:gundo_preview_statusline")
+        let &l:statusline = g:gundo_preview_statusline
+    endif
+endfunction"}}}
+
+function! s:GundoClose()"{{{
+    if s:GundoGoToWindowForBufferName('__Gundo__')
+        quit
+    endif
+
+    if s:GundoGoToWindowForBufferName('__Gundo_Preview__')
+        quit
+    endif
+
+    exe bufwinnr(g:gundo_target_n) . "wincmd w"
+endfunction"}}}
+
+function! s:GundoOpen()"{{{
+    if !exists('g:gundo_py_loaded')
+        if s:has_supported_python == 2 && g:gundo_prefer_python3
+            exe 'py3file ' . s:plugin_path . '/gundo.py'
+            python3 initPythonModule()
+        else
+            exe 'pyfile ' . s:plugin_path . '/gundo.py'
+            python initPythonModule()
+        endif
+
+        if !s:has_supported_python
+            function! s:GundoDidNotLoad()
+                echohl WarningMsg|echomsg "Gundo unavailable: requires Vim 7.3+"|echohl None
+            endfunction
+            command! -nargs=0 GundoToggle call s:GundoDidNotLoad()
+            call s:GundoDidNotLoad()
+            return
+        endif"
+
+        let g:gundo_py_loaded = 1
+    endif
+
+    " Save `splitbelow` value and set it to default to avoid problems with
+    " positioning new windows.
+    let saved_splitbelow = &splitbelow
+    let &splitbelow = 0
+
+    call s:GundoOpenPreview()
+    exe bufwinnr(g:gundo_target_n) . "wincmd w"
+
+    call s:GundoRenderGraph()
+    call s:GundoRenderPreview()
+
+    " Restore `splitbelow` value.
+    let &splitbelow = saved_splitbelow
+endfunction"}}}
+
+function! s:GundoToggle()"{{{
+    if s:GundoIsVisible()
+        call s:GundoClose()
+    else
+        let g:gundo_target_n = bufnr('')
+        let g:gundo_target_f = @%
+        call s:GundoOpen()
+    endif
+endfunction"}}}
+
+function! s:GundoShow()"{{{
+    call s:GundoOpen()
+endfunction"}}}
+
+function! s:GundoHide()"{{{
+    call s:GundoClose()
+endfunction"}}}
+
+"}}}
+
+"{{{ Gundo mouse handling
+
+function! s:GundoMouseDoubleClick()"{{{
+    let start_line = getline('.')
+
+    if stridx(start_line, '[') == -1
+        return
+    else
+        call s:GundoRevert()
+    endif
+endfunction"}}}
+
+"}}}
+
+"{{{ Gundo movement
+
+function! s:GundoMove(direction) range"{{{
+    let start_line = getline('.')
+    if v:count1 == 0
+        let move_count = 1
+    else
+        let move_count = v:count1
+    endif
+    let distance = 2 * move_count
+
+    " If we're in between two nodes we move by one less to get back on track.
+    if stridx(start_line, '[') == -1
+        let distance = distance - 1
+    endif
+
+    let target_n = line('.') + (distance * a:direction)
+
+    " Bound the movement to the graph.
+    if target_n <= s:GundoInlineHelpLength() - 1
+        call cursor(s:GundoInlineHelpLength(), 0)
+    else
+        call cursor(target_n, 0)
+    endif
+
+    let line = getline('.')
+
+    " Move to the node, whether it's an @ or an o
+    let idx1 = stridx(line, '@')
+    let idx2 = stridx(line, 'o')
+    if idx1 != -1
+        call cursor(0, idx1 + 1)
+    else
+        call cursor(0, idx2 + 1)
+    endif
+
+    call s:GundoRenderPreview()
+endfunction"}}}
+
+"}}}
+
+"{{{ Gundo rendering
+
+function! s:GundoRenderGraph()"{{{
+    if s:has_supported_python == 2 && g:gundo_prefer_python3
+        python3 GundoRenderGraph()
+    else
+        python GundoRenderGraph()
+    endif
+endfunction"}}}
+
+function! s:GundoRenderPreview()"{{{
+    if s:has_supported_python == 2 && g:gundo_prefer_python3
+        python3 GundoRenderPreview()
+    else
+        python GundoRenderPreview()
+    endif
+endfunction"}}}
+
+function! s:GundoRenderChangePreview()"{{{
+    if s:has_supported_python == 2 && g:gundo_prefer_python3
+        python3 GundoRenderChangePreview()
+    else
+        python GundoRenderChangePreview()
+    endif
+endfunction"}}}
+
+"}}}
+
+"{{{ Gundo undo/redo
+
+function! s:GundoRevert()"{{{
+    if s:has_supported_python == 2 && g:gundo_prefer_python3
+        python3 GundoRevert()
+    else
+        python GundoRevert()
+    endif
+endfunction"}}}
+
+function! s:GundoPlayTo()"{{{
+    if s:has_supported_python == 2 && g:gundo_prefer_python3
+        python3 GundoPlayTo()
+    else
+        python GundoPlayTo()
+    endif
+endfunction"}}}
+
+"}}}
+
+"{{{ Misc
+
+function! gundo#GundoToggle()"{{{
+    call s:GundoToggle()
+endfunction"}}}
+
+function! gundo#GundoRenderGraph()"{{{
+    call s:GundoRenderGraph()
+endfunction"}}}
+
+augroup GundoAug
+    autocmd!
+    autocmd BufNewFile __Gundo__ call s:GundoSettingsGraph()
+    autocmd BufNewFile __Gundo_Preview__ call s:GundoSettingsPreview()
+augroup END
+
+"}}}

vim/doc/gundo.txt

@@ -0,0 +1,270 @@
+*gundo.txt*   Graph your undo tree so you can actually USE it.
+
+Making Vim's undo tree usable by humans.
+
+==============================================================================
+CONTENTS                                                      *Gundo-contents*
+
+    1. Intro .......................... |GundoIntro|
+    2. Usage .......................... |GundoUsage|
+    3. Configuration .................. |GundoConfig|
+        3.1 gundo_width ............... |gundo_width|
+        3.2 gundo_preview_height ...... |gundo_preview_height|
+        3.3 gundo_preview_bottom ...... |gundo_preview_bottom|
+        3.4 gundo_right ............... |gundo_right|
+        3.5 gundo_help ................ |gundo_help|
+        3.6 gundo_disable ............. |gundo_disable|
+        3.7 gundo_map_move_older ...... |gundo_map_move_older|
+            gundo_map_move_newer ...... |gundo_map_move_newer|
+        3.8 gundo_close_on_revert ..... |gundo_close_on_revert|
+        3.9 gundo_preview_statusline .. |gundo_preview_statusline|
+            gundo_tree_statusline ..... |gundo_tree_statusline|
+    4. License ........................ |GundoLicense|
+    5. Bugs ........................... |GundoBugs|
+    6. Contributing ................... |GundoContributing|
+    7. Changelog ...................... |GundoChangelog|
+    8. Credits ........................ |GundoCredits|
+
+==============================================================================
+1. Intro                                                          *GundoIntro*
+
+You know that Vim lets you undo changes like any text editor. What you might
+not know is that it doesn't just keep a list of your changes -- it keeps
+a goddamed |:undo-tree| of them.
+
+Say you make a change (call it X), undo that change, and then make another
+change (call it Y). With most editors, change X is now gone forever. With Vim
+you can get it back.
+
+The problem is that trying to do this in the real world is painful. Vim gives
+you an |:undolist| command that shows you the leaves of the tree. Good luck
+finding the change you want in that list.
+
+Gundo is a plugin to make browsing this ridiculously powerful undo tree less
+painful.
+
+==============================================================================
+2. Usage                                                          *GundoUsage*
+
+We'll get to the technical details later, but if you're a human the first
+thing you need to do is add a mapping to your |:vimrc| to toggle the undo
+graph: >
+
+    nnoremap <F5> :GundoToggle<CR>
+
+Change the mapped key to suit your taste. We'll stick with F5 because that's
+what the author uses.
+
+Now you can press F5 to toggle the undo graph and preview pane, which will
+look something like this: >
+
+      Undo graph                          File
+    +-----------------------------------+------------------------------------+
+    | " Gundo for something.txt [1]     |one                                 |
+    | " j/k  - move between undo states |two                                 |
+    | " <cr> - revert to that state     |three                               |
+    |                                   |five                                |
+    | @  [5] 3 hours ago                |                                    |
+    | |                                 |                                    |
+    | | o  [4] 4 hours ago              |                                    |
+    | | |                               |                                    |
+    | o |  [3] 4 hours ago              |                                    |
+    | | |                               |                                    |
+    | o |  [2] 4 hours ago              |                                    |
+    | |/                                |                                    |
+    | o  [1] 4 hours ago                |                                    |
+    | |                                 |                                    |
+    | o  [0] Original                   |                                    |
+    +-----------------------------------+                                    |
+    | --- 3 2010-10-12 06:27:35 PM      |                                    |
+    | +++ 5 2010-10-12 07:38:37 PM      |                                    |
+    | @@ -1,3 +1,4                      |                                    |
+    |  one                              |                                    |
+    |  two                              |                                    |
+    |  three                            |                                    |
+    | +five                             |                                    |
+    +-----------------------------------+------------------------------------+
+      Preview pane
+
+Your current position in the undo tree is marked with an '@' character. Other
+nodes are marked with an 'o' character.
+
+When you toggle open the graph Gundo will put your cursor on your current
+position in the tree. You can move up and down the graph with the j and
+k keys.
+
+You can move to the top of the graph (the newest state) with gg and to the
+bottom of the graph (the oldest state) with G.
+
+As you move between undo states the preview pane will show you a unified diff
+of the change that state made.
+
+Pressing enter on a state (or double clicking on it) will revert the contents
+of the file to match that state.
+
+You can use p on a state to make the preview window show the diff between
+your current state and the selected state, instead of a preview of what the
+selected state changed.
+
+Pressing P while on a state will initiate "play to" mode targeted at that
+state. This will replay all the changes between your current state and the
+target, with a slight pause after each change. It's mostly useless, but can be
+fun to watch and see where your editing lags -- that might be a good place to
+define a new mapping to speed up your editing.
+
+Pressing q while in the undo graph will close it.  You can also just press your
+toggle mapping key.
+
+==============================================================================
+3. Configuration                                                 *GundoConfig*
+
+You can tweak the behavior of Gundo by setting a few variables in your :vimrc
+file. For example: >
+
+    let g:gundo_width = 60
+    let g:gundo_preview_height = 40
+    let g:gundo_right = 1
+
+------------------------------------------------------------------------------
+3.1 g:gundo_width                                                *gundo_width*
+
+Set the horizontal width of the Gundo graph (and preview).
+
+Default: 45
+
+------------------------------------------------------------------------------
+3.2 g:gundo_preview_height                              *gundo_preview_height*
+
+Set the vertical height of the Gundo preview.
+
+Default: 15
+
+------------------------------------------------------------------------------
+3.3 g:gundo_preview_bottom                              *gundo_preview_bottom*
+
+Force the preview window below current windows instead of below the graph.
+This gives the preview window more space to show the unified diff.
+
+Example:
+
+   +--------+            +--------+
+   !g!      !            !      !g!
+   !g!      !     or     !      !g!
+   !g!______!            !______!g!
+   !g!pppppp!            !pppppp!g!
+   +--------+            +--------+
+
+Default: 0
+
+------------------------------------------------------------------------------
+3.4 g:gundo_right                                                *gundo_right*
+
+Set this to 1 to make the Gundo graph (and preview) open on the right side
+instead of the left.
+
+Default: 0 (off, open on the left side)
+
+------------------------------------------------------------------------------
+3.5 g:gundo_help                                                  *gundo_help*
+
+Set this to 0 to disable the help text in the Gundo graph window.
+
+Default: 1 (show the help)
+
+------------------------------------------------------------------------------
+3.6 g:gundo_disable                                            *gundo_disable*
+
+Set this to 1 to disable Gundo entirely.
+
+Useful if you use the same ~/.vim folder on multiple machines, and some of
+them may not have Python support.
+
+Default: 0 (Gundo is enabled as usual)
+
+------------------------------------------------------------------------------
+3.7 g:gundo_map_move_older, g:gundo_map_move_newer      *gundo_map_move_older*
+                                                        *gundo_map_move_newer*
+
+These options let you change the keys that navigate the undo graph. This is
+useful if you use a Dvorak keyboard and have changed your movement keys.
+
+Default: gundo_map_move_older = "j"
+         gundo_map_move_newer = "k"
+
+------------------------------------------------------------------------------
+3.8 g:gundo_close_on_revert                            *gundo_close_on_revert*
+
+Set this to 1 to automatically close the Gundo windows when reverting.
+
+Default: 0 (windows do not automatically close)
+
+------------------------------------------------------------------------------
+3.9 g:gundo_preview_statusline                      *gundo_preview_statusline*
+    g:gundo_tree_statusline                            *gundo_tree_statusline*
+
+Set these to a string to display it as the status line for each Gundo window.
+
+Default: unset (windows use the default statusline)
+
+==============================================================================
+4. License                                                      *GundoLicense*
+
+GPLv2+. Look it up.
+
+==============================================================================
+5. Bugs                                                            *GundoBugs*
+
+If you find a bug please post it on the issue tracker:
+http://bitbucket.org/sjl/gundo.vim/issues?status=new&status=open
+
+==============================================================================
+6. Contributing                                            *GundoContributing*
+
+Think you can make this plugin better? Awesome. Fork it on BitBucket or GitHub
+and send a pull request.
+
+BitBucket: http://bitbucket.org/sjl/gundo.vim/
+GitHub: http://github.com/sjl/gundo.vim/
+
+==============================================================================
+7. Changelog                                                  *GundoChangelog*
+
+v2.3.0
+    * Add statusline configuration.
+v2.2.2
+    * More performance improvements.
+v2.2.1
+    * Refactoring and performance improvements.
+v2.2.0
+    * Add the g:gundo_close_on_revert setting.
+    * Fix a bug with the splitbelow setting.
+v2.1.1
+    * Fix a bug with the movement key mappings.
+v2.1.0
+    * Warnings about having an incompatible Vim and/or Python installation
+      are now deferred until the first time you try to use Gundo, instead
+      of being displayed on launch.
+    * The <j> and <k> mappings are now configurable with
+      g:gundo_map_move_older and g:gundo_map_move_newer.
+    * The o, <Up> and <Down> keys are now mapped in the Gundo pane.
+    * Improve and add several unit tests for Gundo.
+v2.0.0
+    * Make GundoToggle close the Gundo windows if they're visible but not the
+      current window, instead of moving to them.
+    * Add the g:gundo_help setting.
+    * Add the g:gundo_disable setting.
+    * Add the 'p' mapping to preview the result of reverting to the selected
+      state.
+    * Fix movement commands with counts in the graph.
+v1.0.0
+    * Initial stable release.
+
+==============================================================================
+8. Credits                                                      *GundoCredits*
+
+The graphing code was all taken from Mercurial, hence the GPLv2+ license.
+
+The plugin was heavily inspired by histwin.vim, and the code for scratch.vim
+helped the author get started.
+
+==============================================================================

vim/plugin/gundo.vim

@@ -0,0 +1,24 @@
+" ============================================================================
+" File:        gundo.vim
+" Description: vim global plugin to visualize your undo tree
+" Maintainer:  Steve Losh <steve@stevelosh.com>
+" License:     GPLv2+ -- look it up.
+" Notes:       Much of this code was thiefed from Mercurial, and the rest was
+"              heavily inspired by scratch.vim and histwin.vim.
+"
+" ============================================================================
+
+
+"{{{ Init
+if !exists('g:gundo_debug') && (exists('g:gundo_disable') || exists('loaded_gundo') || &cp)"{{{
+    finish
+endif
+let loaded_gundo = 1"}}}
+"}}}
+
+"{{{ Misc
+command! -nargs=0 GundoToggle call gundo#GundoToggle()
+command! -nargs=0 GundoShow call gundo#GundoShow()
+command! -nargs=0 GundoHide call gundo#GundoHide()
+command! -nargs=0 GundoRenderGraph call gundo#GundoRenderGraph()
+"}}}

vimrc

@@ -38,6 +38,7 @@ map <C-h> :AS<CR>
 vmap P "_dP
 inoremap <C-d> <C-t>
 inoremap <C-a> <C-d>
+nnoremap U :GundoToggle<CR>
 
 filetype plugin indent on
 syntax on