userdiff: add built-in pattern for CSS

CSS is widely used, motivating it being included as a built-in pattern.

It must be noted that the word_regex for CSS (i.e. the regex defining
what is a word in the language) does not consider '.' and '#' characters
(in CSS selectors) to be part of the word. This behavior is documented
by the test t/t4018/css-rule.
The logic behind this behavior is the following: identifiers in CSS
selectors are identifiers in a HTML/XML document. Therefore, the '.'/'#'
character are not part of the identifier, but an indicator of the nature
of the identifier in HTML/XML (class or id). Diffing ".class1" and
".class2" must show that the class name is changed, but we still are
selecting a class.

Logic behind the "pattern" regex is:
    1. reject lines ending with a colon/semicolon (properties)
    2. if a line begins with a name in column 1, pick the whole line

Credits to Johannes Sixt (j6t@kdbg.org) for the pattern regex and most
of the tests.

Signed-off-by: William Duclot <william.duclot@ensimag.grenoble-inp.fr>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Reviewed-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

8 files changed, 38 insertions, 0 deletions

diff --git a/t/t4018/css-brace-in-col-1 b/t/t4018/css-brace-in-col-1
new file mode 100644
index 0000000000..7831577506
--- /dev/null
+++ b/t/t4018/css-brace-in-col-1
@@ -0,0 +1,5 @@
+RIGHT label.control-label
+{
+    margin-top: 10px!important;
+    border : 10px ChangeMe #C6C6C6;
+}
diff --git a/t/t4018/css-colon-eol b/t/t4018/css-colon-eol
new file mode 100644
index 0000000000..5a30553d29
--- /dev/null
+++ b/t/t4018/css-colon-eol
@@ -0,0 +1,4 @@
+RIGHT h1 {
+color:
+ChangeMe;
+}
diff --git a/t/t4018/css-colon-selector b/t/t4018/css-colon-selector
new file mode 100644
index 0000000000..c6d71fb42d
--- /dev/null
+++ b/t/t4018/css-colon-selector
@@ -0,0 +1,5 @@
+RIGHT a:hover {
+    margin-top:
+    10px!important;
+    border : 10px ChangeMe #C6C6C6;
+}
diff --git a/t/t4018/css-common b/t/t4018/css-common
new file mode 100644
index 0000000000..84ed754b33
--- /dev/null
+++ b/t/t4018/css-common
@@ -0,0 +1,4 @@
+RIGHT label.control-label {
+    margin-top: 10px!important;
+    border : 10px ChangeMe #C6C6C6;
+}
diff --git a/t/t4018/css-long-selector-list b/t/t4018/css-long-selector-list
new file mode 100644
index 0000000000..7ccd25d9ed
--- /dev/null
+++ b/t/t4018/css-long-selector-list
@@ -0,0 +1,6 @@
+p.header,
+label.control-label,
+div ul#RIGHT {
+    margin-top: 10px!important;
+    border : 10px ChangeMe #C6C6C6;
+}
diff --git a/t/t4018/css-prop-sans-indent b/t/t4018/css-prop-sans-indent
new file mode 100644
index 0000000000..a9e3c86b3c
--- /dev/null
+++ b/t/t4018/css-prop-sans-indent
@@ -0,0 +1,5 @@
+RIGHT, label.control-label {
+margin-top: 10px!important;
+padding: 0;
+border : 10px ChangeMe #C6C6C6;
+}
diff --git a/t/t4018/css-short-selector-list b/t/t4018/css-short-selector-list
new file mode 100644
index 0000000000..6a0bdee336
--- /dev/null
+++ b/t/t4018/css-short-selector-list
@@ -0,0 +1,4 @@
+label.control, div ul#RIGHT {
+    margin-top: 10px!important;
+    border : 10px ChangeMe #C6C6C6;
+}
diff --git a/t/t4018/css-trailing-space b/t/t4018/css-trailing-space
new file mode 100644
index 0000000000..32b5606c70
--- /dev/null
+++ b/t/t4018/css-trailing-space
@@ -0,0 +1,5 @@
+RIGHT label.control-label {
+    margin:10px;   
+    padding:10px;
+    border : 10px ChangeMe #C6C6C6;
+}