userdiff: add Octave

Octave pattern is almost the same as matlab, except
that '%%%' and '##' can also be used to begin code sections,
in addition to '%%' that is understood by both. Octave
pattern is merged into Matlab pattern. Test cases for
the hunk header patterns of matlab and octave under
t/t4018 are added.

Signed-off-by: Boxuan Li <liboxuan@connect.hku.hk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/gitattributes.txt

@@ -819,7 +819,7 @@ patterns are available:
 
 - `java` suitable for source code in the Java language.
 
-- `matlab` suitable for source code in the MATLAB language.
+- `matlab` suitable for source code in the MATLAB and Octave language.
 
 - `objc` suitable for source code in the Objective-C language.
 

t/t4018/matlab-class-definition

@@ -0,0 +1,5 @@
+classdef RIGHT
+    properties
+        ChangeMe
+    end
+end

t/t4018/matlab-function

@@ -0,0 +1,4 @@
+function y = RIGHT()
+x = 5;
+y = ChangeMe + x;
+end

t/t4018/matlab-octave-section-1

@@ -0,0 +1,3 @@
+%%% RIGHT section
+# this is octave script
+ChangeMe = 1;

t/t4018/matlab-octave-section-2

@@ -0,0 +1,3 @@
+## RIGHT section
+# this is octave script
+ChangeMe = 1;

t/t4018/matlab-section

@@ -0,0 +1,3 @@
+%% RIGHT section
+% this is understood by both matlab and octave
+ChangeMe = 1;

userdiff.c

@@ -58,7 +58,10 @@ PATTERNS("java",
 	 "|[-+*/<>%&^|=!]="
 	 "|--|\\+\\+|<<=?|>>>?=?|&&|\\|\\|"),
 PATTERNS("matlab",
-	 "^[[:space:]]*((classdef|function)[[:space:]].*)$|^%%[[:space:]].*$",
+	 /* Octave pattern is mostly the same as matlab, except that '%%%' and
+	  * '##' can also be used to begin code sections, in addition to '%%'
+	  * that is understood by both. */
+	 "^[[:space:]]*((classdef|function)[[:space:]].*)$|^(%%%?|##)[[:space:]].*$",
 	 "[a-zA-Z_][a-zA-Z0-9_]*|[-+0-9.e]+|[=~<>]=|\\.[*/\\^']|\\|\\||&&"),
 PATTERNS("objc",
 	 /* Negate C statements that can look like functions */