コグノスケ

A - B - C - D

A - B - C - D
|       |
E - F - G

Gitのバージョン

$ git --version
git version 1.7.10.4

自分のリポジトリを作る

$ mkdir git_test1
$ cd git_test1
$ git init
Initialized empty Git repository in /home/katsuhiro/git_test1/.git/

$ touch a
$ git add a
$ git commit

(...略...)

普通のコミットメッセージでコミット

$ touch file1
$ git add file1
$ git commit

----------------------------------------------------------------------
Add: Normal commit

Normal commit message.

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       new file:   file1
#
----------------------------------------------------------------------
".git/COMMIT_EDITMSG" [変換済] 12L, 297C書込み
[master 9ec38a3] Add: Normal commit
 0 files changed
 create mode 100644 file1

変なコミットメッセージでコミット

$ touch file2
$ git add file2
$ git commit

----------------------------------------------------------------------
Add: Abnormal commit

Abnormal commit message.

From 0000000000000000000000000000000000000000 Mon Jun 1 00:00:00 2000

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       new file:   file2
#
----------------------------------------------------------------------
".git/COMMIT_EDITMSG" [変換済] 14L, 372C書込み
[master c4e8588] Add: Abnormal commit
 0 files changed
 create mode 100644 file2

コミットログの確認

$ git log

commit c4e85884f643c0e8b107ad0f3e3b0c9fa917409b
Author: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Date:   Sat Jan 11 12:24:17 2014 +0900

    Add: Abnormal commit

    Abnormal commit message.

    From 0000000000000000000000000000000000000000 Mon Jun 1 00:00:00 2000

commit 9ec38a315e964241f69897728b11f2451eafd700
Author: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Date:   Sat Jan 11 12:22:49 2014 +0900

    Add: Normal commit

    Normal commit message.

commit f3e44926c8f50c557841a157fda89f3fab4aaab3
Author: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Date:   Sat Jan 11 12:22:21 2014 +0900

    Init.

パッチ作成

$ git format-patch f3e44926c8f50c557841a157fda89f3fab4aaab3
0001-Add-Normal-commit.patch
0002-Add-Abnormal-commit.patch

Normalの方のパッチ

From 9ec38a315e964241f69897728b11f2451eafd700 Mon Sep 17 00:00:00 2001
From: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Date: Sat, 11 Jan 2014 12:22:49 +0900
Subject: [PATCH 1/2] Add: Normal commit

Normal commit message.
---
 0 files changed
 create mode 100644 file1

diff --git a/file1 b/file1
new file mode 100644
index 0000000..e69de29
--
1.7.10.4

Abnormalの方のパッチ

From c4e85884f643c0e8b107ad0f3e3b0c9fa917409b Mon Sep 17 00:00:00 2001
From: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Date: Sat, 11 Jan 2014 12:24:17 +0900
Subject: [PATCH 2/2] Add: Abnormal commit

Abnormal commit message.

From 0000000000000000000000000000000000000000 Mon Jun 1 00:00:00 2000
---
 0 files changed
 create mode 100644 file2

diff --git a/file2 b/file2
new file mode 100644
index 0000000..e69de29
--
1.7.10.4

相手のリポジトリの作成

$ mkdir git_test2
$ cd git_test2
$ git init
Initialized empty Git repository in /home/katsuhiro/git_test2/.git/

パッチを受け取った

$ mv ../git_test1/000* ./

Normalのパッチ適用、成功

$ git am 0001-Add-Normal-commit.patch
Applying: Add: Normal commit
applying to an empty history

Abnormalのパッチ適用、失敗

$ git am 0002-Add-Abnormal-commit.patch
Patch is empty.  Was it split wrong?
If you would prefer to skip this patch, instead run "git am --skip".
To restore the original branch and stop patching run "git am --abort".

やりたいこと

（入力）
List(
  true, false, false, true, true, false, true, false,
  true, true, true, false, true, false, true, true
)

（出力）
List(154, 235)

foreachの場合

val a = List(
  true, false, false, true, true, false, true, false,
  true, true, true, false, true, false, true, true
)
var acc = 0
var p = 0
var b: List[Int] = List()

a.foreach { it =>
  acc <<= 1
  if (it) acc |= 1
  p += 1

  if (p >= 8) {
    b = b :+ acc
    acc = 0
    p = 0
  }
}

println(b)

mapの場合

object BooleanToByte {
  def apply(): (Boolean => Option[Int]) = {
    val o = new BooleanToByte()
    o.mapper
  }
}

class BooleanToByte() {
  private var v = 0
  private var p = 0

  def mapper(b: Boolean): Option[Int] = {
    v <<= 1
    if (b) v |= 1
    p += 1

    if (p >= 8) {
      val result = Some(v)
      v = 0
      p = 0
      result
    } else {
      None
    }
  }
}


val a = List(
  true, false, false, true, true, false, true, false,
  true, true, true, false, true, false, true, true
)

val b = a.map(BooleanToByte()).flatten

println(b)

iteratorの場合

val a = List(
  true, false, false, true, true, false, true, false,
  true, true, true, false, true, false, true, true
)
val it = a.iterator
var b: List[Int] = List()

while (it.hasNext) {
  var acc = 0
  var p = 0

  while (p < 8) {
    acc <<= 1
    if (it.next()) acc |= 1

    p += 1
  }
  b = b :+ acc
}

println(b)