1 files changed, 32 insertions, 18 deletions
diff --git a/tools/clang-format/clang-format.py b/tools/clang-format/clang-format.py
index d90c62a..f5a5756 100644
--- a/tools/clang-format/clang-format.py
+++ b/tools/clang-format/clang-format.py
@@ -17,31 +17,43 @@
 # It operates on the current, potentially unsaved buffer and does not create
 # or save any files. To revert a formatting, just undo.
 
-import vim
+import difflib
+import json
 import subprocess
+import sys
+import vim
 
 # Change this to the full path if clang-format is not on the path.
 binary = 'clang-format'
 
-# Change this to format according to other formatting styles (see 
-# clang-format -help)
-style = 'LLVM'
+# Change this to format according to other formatting styles. See the output of
+# 'clang-format --help' for a list of supported styles. The default looks for
+# a '.clang-format' or '_clang-format' file to indicate the style that should be
+# used.
+style = 'file'
 
 # Get the current text.
 buf = vim.current.buffer
-text = "\n".join(buf)
+text = '\n'.join(buf)
 
 # Determine range to format.
-offset = int(vim.eval('line2byte(' +
-                      str(vim.current.range.start + 1) + ')')) - 1
-length = int(vim.eval('line2byte(' +
-                      str(vim.current.range.end + 2) + ')')) - offset - 2
+cursor = int(vim.eval('line2byte(line("."))+col(".")')) - 2
+lines = '%s:%s' % (vim.current.range.start + 1, vim.current.range.end + 1)
+
+# Avoid flashing an ugly, ugly cmd prompt on Windows when invoking clang-format.
+startupinfo = None
+if sys.platform.startswith('win32'):
+  startupinfo = subprocess.STARTUPINFO()
+  startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
+  startupinfo.wShowWindow = subprocess.SW_HIDE
 
 # Call formatter.
-p = subprocess.Popen([binary, '-offset', str(offset), '-length', str(length),
-                      '-style', style],
+command = [binary, '-lines', lines, '-style', style, '-cursor', str(cursor)]
+if vim.current.buffer.name:
+  command.extend(['-assume-filename', vim.current.buffer.name])
+p = subprocess.Popen(command,
                      stdout=subprocess.PIPE, stderr=subprocess.PIPE,
-                     stdin=subprocess.PIPE)
+                     stdin=subprocess.PIPE, startupinfo=startupinfo)
 stdout, stderr = p.communicate(input=text)
 
 # If successful, replace buffer contents.
@@ -56,10 +68,12 @@ if stderr:
 if not stdout:
   print ('No output from clang-format (crashed?).\n' +
       'Please report to bugs.llvm.org.')
-elif stdout != text:
+else:
   lines = stdout.split('\n')
-  for i in range(min(len(buf), len(lines))):
-    buf[i] = lines[i]
-  for line in lines[len(buf):]:
-    buf.append(line)
-  del buf[len(lines):]
+  output = json.loads(lines[0])
+  lines = lines[1:]
+  sequence = difflib.SequenceMatcher(None, vim.current.buffer, lines)
+  for op in reversed(sequence.get_opcodes()):
+    if op[0] is not 'equal':
+      vim.current.buffer[op[1]:op[2]] = lines[op[3]:op[4]]
+  vim.command('goto %d' % (output['Cursor'] + 1))