Commit cherry-picking

Hi!

I often use darcs, and one feature I miss when I use git is the ability to do cherry-picking on what I'm about to commit.

It allows me to do small changes to the code when I'm working on something else, and don't do ugly commits.

I know the proper way to do this would be to have different branches and all. But that means I have to switch between branches to do quick fixes, which is an expensive operation in human terms, because I have to stop thinking about the code and switch branches and so on.

So I wrote two small scripts to do that: git-pcp and git-commit-cp. The former acts as a helper to the later. Both are attached.

git-pcp takes a diff file, and produces two files: one with the hunks to apply, and another one with the ones to skip. It asks the user to select, for each hunk, where to put it.

git-commit-cp is the command to use, which calls git-pcp to do the cherrypicking, and then applies the corresponding patches.

The implementation of git-pcp should be better (the diff parsing is not as strong as it should be, although it works for most cases; and the user interaction sucks, because I don't like UI =), so it's working but it needs some improvements.

I wanted to ask you if this was an acceptable command to add to git, and if you had any recommendations or thoughts about the implementation.

Thanks a lot,
		Alberto

PS: Is there a way of telling git-diff how many context lines to use?

#!/usr/bin/env python

""" Patch Cherry-Picking

This scripts takes a patch and asks you which chunks you want to apply. Then it creates two output files: one with the ones to apply, and one with the ones to skip.

Note that the output patches are NOT fixed, you might want to run them through rediff (although git-commit-cp does not need to). """

import sys

# # Classes and main data structures #

class Diff:
	def __init__(self):
		self.parts = []

	def append(self, part):
		self.parts.append(part)

	def __str__(self):
		s = ''.join((str(i) for i in self.parts))
		return s

	def __eq__(self, other):
		if self.parts == other.parts:
			return True
		return False

class File:
	def __init__(self, fname):
		self.fname = fname
		self.parts = []

	def append(self, part):
		self.parts.append(part)

	def __str__(self):
		s = ''.join((str(i) for i in self.parts))
		return s

	def __eq__(self, other):
		if self.parts == other.parts:
			return True
		return False

class Hunk:
	def __init__(self):
		self.parts = []

	def append(self, line):
		self.parts.append(line)

	def __str__(self):
		s = ''.join(self.parts)
		return s

	def __eq__(self, other):
		if self.parts == other.parts:
			return True
		return False

# # Diff parsing #

def startswithany(l, *starts):
	for s in starts:
		if l.startswith(s):
			return True
	return False

def parse(fd):
	diff = Diff()
	file = None
	hunk = None
	current = diff
	trailing = []

	for line in fd:
		if line.startswith('+++ '):
			unused, fname = line.strip().split(' ', 1)
			if hunk:
				file.append(hunk)
				hunk = Hunk()
			if file:
				diff.append(file)
			file = File(fname)
			for i in trailing:
				file.append(i)
			file.append(line)
			trailing = []

		elif line.startswith('@@ '):
			if hunk:
				file.append(hunk)
			hunk = Hunk()
			hunk.append(line)

		elif startswithany(line, '+', '-', ' ') \
				and not line.startswith('---'):
			if hunk:
				hunk.append(line)
			else:
				trailing.append(line)

		else:
			if hunk:
				file.append(hunk)
				hunk = None
			trailing.append(line)

	if hunk:
		file.append(hunk)
	if file:
		if trailing:
			for i in trailing:
				file.append(i)
		trailing = []
		diff.append(file)
	if trailing:
		for i in trailing:
			diff.append(i)
	return diff

# # Cherry-picking #

def cherrypick(original, toapply, toskip):
	for part in original.parts:
		if isinstance(part, File):
			print '+++ ', part.fname
			happly, hskip = select_parts(part.parts)
			print

			if happly:
				f = File(part.fname)
				for i in happly:
					f.append(i)
				toapply.append(f)

			if hskip:
				f = File(part.fname)
				for i in hskip:
					f.append(i)
				toskip.append(f)
		else:
			toapply.append(part)
			toskip.append(part)

def ask(prompt, valid_options, default = None, help = ()):

	while True:
		r = raw_input(prompt)
		if not r:
			if default:
				r = default
			else:
				continue

		if r in valid_options:
			return r
		elif help and r == help[0]:
			print help[1]
		else:
			print " -- Unknown option"

def select_parts(parts):
	happly = []
	hskip = []

	for h in parts:
		if not isinstance(h, Hunk):
			# we don't care about lines
			happly.append(h)
			hskip.append(h)
			continue

		sys.stdout.write(str(h))
		print
		r = ask("* Include in commit? [y/n/Y/N/?] ", 'ynYN',
			help = ('?', 'Help not implemented') )

		if r == 'y':
			happly.append(h)
		elif r == 'n':
			hskip.append(h)
		elif r == 'Y':
			return (parts, [])
		elif r == 'N':
			return ([], parts)

	# if we don't have any chunks, skip everything
	if len( [h for h in happly if isinstance(h, Hunk)] ) == 0:
		hskip = []
	if len( [h for h in hskip if isinstance(h, Hunk)] ) == 0:
		hskip = []

	return (happly, hskip)

# # Main #

if __name__ == '__main__':
	if len(sys.argv) != 4:
		print "Usage: pccp diff_file to_apply to_skip"
		sys.exit(1)

	fin, fapply, fskip = sys.argv[1:4]

	original = parse(open(fin))
	toapply = Diff()
	toskip = Diff()
	cherrypick(original, toapply, toskip)

	open(fapply, 'w').write(str(toapply))
	open(fskip, 'w').write(str(toskip))

#!/bin/bash

set -e SUBDIRECTORY_OK=Yes . git-sh-setup require_work_tree cd_to_toplevel

TMPB=`mktemp -t git-commit-cp.XXXXXX` || exit 1 ORIGINAL="$TMPB-original" TOAPPLY="$TMPB-apply" TOSKIP="$TMPB-skip"

function cleanup() {
	rm $TMPB $ORIGINAL $TOAPPLY $TOSKIP
}

git-diff --full-index HEAD > $ORIGINAL

git-pcp $ORIGINAL $TOAPPLY $TOSKIP

if [ ! -s $TOAPPLY ]; then
	echo "* Nothing to commit!"
	cleanup
	exit 1
fi

if [ -s $TOSKIP ]; then
	git-apply -R $TOSKIP;
fi

git-commit -a "$@"

if [ -s $TOSKIP ]; then
	git-apply --index $TOSKIP;
fi

cleanup exit 0