From 3837b26ee097fb461a76d6d17e050df35c0bff2a Mon Sep 17 00:00:00 2001
From: Valentin Lab <valentin.lab@kalysto.org>
Date: Wed, 4 Feb 2015 19:07:55 +0700
Subject: [PATCH] new: added ``udiff`` to get unified diffs of strings.

---
 README.rst               | 17 +++++++++++++++++
 src/kids/txt/__init__.py |  1 +
 src/kids/txt/diff.py     | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 src/kids/txt/diff.py

diff --git a/README.rst b/README.rst
index 0d95121..f7022cb 100644
--- a/README.rst
+++ b/README.rst
@@ -33,6 +33,7 @@ using ``kids.txt``:
 - You'll have a ``indent`` / ``dedent`` / ``shorten`` command also in python 2.
 - You'll be able to ``wrap`` text keeping the paragraph separated.
 - minor helper like ``ucfirst`` function.
+- produce unified diffs between 2 strings easily with ``udiff``.
 
 
 Installation
@@ -134,6 +135,22 @@ replace the last 2 characters by a '..' to indicate truncation::
     'sup..'
 
 
+udiff
+-----
+
+Shows the unified diff between to text::
+
+    >>> print(txt.udiff('a\n\nc', 'b\n\nc'))
+    --- None
+    +++ None
+    @@ -1,3 +1,3 @@
+    -a
+    +b
+    <BLANKLINE>
+     c
+    <BLANKLINE>
+
+
 Contributing
 ============
 
diff --git a/src/kids/txt/__init__.py b/src/kids/txt/__init__.py
index adeb8a2..85661db 100644
--- a/src/kids/txt/__init__.py
+++ b/src/kids/txt/__init__.py
@@ -1,3 +1,4 @@
 # Package placeholder
 
 from .txt import indent, dedent, paragraph_wrap, ucfirst, shorten
+from .diff import udiff
diff --git a/src/kids/txt/diff.py b/src/kids/txt/diff.py
new file mode 100644
index 0000000..86490f5
--- /dev/null
+++ b/src/kids/txt/diff.py
@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+
+import difflib
+
+
+def udiff(a, b, fa=None, fb=None):
+    r"""Returns a classical unified diff between two given strings.
+
+    Straightforward to use::
+
+        >>> print(udiff('a\n\nc', 'b\n\nc'))
+        --- None
+        +++ None
+        @@ -1,3 +1,3 @@
+        -a
+        +b
+        <BLANKLINE>
+         c
+        <BLANKLINE>
+
+    Note that if the input texts do not ends with a new line, it'll be
+    added automatically, so::
+
+        >>> udiff('a', 'b') == udiff('a\n', 'b') == udiff('a', 'b\n')
+        True
+
+
+    """
+    if not a.endswith("\n"):
+        a += "\n"
+    if not b.endswith("\n"):
+        b += "\n"
+    return "".join(
+        difflib.unified_diff(
+            a.splitlines(1), b.splitlines(1),
+            fa, fb))