[PATCH v2] userdiff: add support for R programming language

[Rodrigo Carvalho <rodrigorsdc@gmail.com>]

The patch appends userdiff.c file in order to support R programming
language function header. This will be useful for those who use Git
for versioning .R files.

Also, add three userdiff tests for R programming language
files. These files define simple function and nested function,
with and without indentation.

Signed-off-by: Rodrigo Carvalho <rodrigorsdc@gmail.com>
---
Changes in v2:
- Add support for function defined by '='
- Replace word regex to '[^ \t']
- Add new test that handles with nested function

 t/t4018/r-indent        |  6 ++++++
 t/t4018/r-indent-nested | 10 ++++++++++
 t/t4018/r-noindent      |  6 ++++++
 userdiff.c              |  4 ++++
 4 files changed, 26 insertions(+)
 create mode 100644 t/t4018/r-indent
 create mode 100644 t/t4018/r-indent-nested
 create mode 100644 t/t4018/r-noindent

diff --git a/t/t4018/r-indent b/t/t4018/r-indent
new file mode 100644
index 0000000000..9df440f2a4
--- /dev/null
+++ b/t/t4018/r-indent
@@ -0,0 +1,6 @@
+RIGHT <- function(a, b) {
+    c = mean(a, b)
+    d = c + 2
+    ChangeMe()
+    return (d)
+}
diff --git a/t/t4018/r-indent-nested b/t/t4018/r-indent-nested
new file mode 100644
index 0000000000..30412e6c79
--- /dev/null
+++ b/t/t4018/r-indent-nested
@@ -0,0 +1,10 @@
+LEFT = function(a, b) {
+    c = mean(a, b)
+    RIGHT = function(d, e) {
+        f = var(d, e)
+        g = f + 1
+        ChangeMe()
+        return (g)
+    }
+    return (RIGHT(2, 3))
+}
diff --git a/t/t4018/r-noindent b/t/t4018/r-noindent
new file mode 100644
index 0000000000..6d9b01ffe3
--- /dev/null
+++ b/t/t4018/r-noindent
@@ -0,0 +1,6 @@
+RIGHT <- function(a, b) {
+c = mean(a, b)
+d = c + 2
+ChangeMe()
+return (c)
+}
diff --git a/userdiff.c b/userdiff.c
index da75625020..64e5005682 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -317,6 +317,10 @@ PATTERNS("python",
 	 "|[-+0-9.e]+[jJlL]?|0[xX]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]=|//=?|<<=?|>>=?|\\*\\*=?"),
 	 /* -- */
+PATTERNS("r",
+	"^[ \t]*([a-zA-z][a-zA-Z0-9_.]*[ \t]*(<-|=)[ \t]*function.*)$",
+	/* -- */
+	"[^ \t]+"),
 PATTERNS("ruby",
 	 "^[ \t]*((class|module|def)[ \t].*)$",
 	 /* -- */
-- 
2.43.0