[PATCH] feat: add Elixir to supported userdiff languages

["Łukasz Niemier" <lukasz@niemier.pl>]

---
 t/t4018-diff-funcname    | 115 +++++++++++++++++++++++++++++++++++++++
 t/t4018-diff-funcname.sh |   1 +
 t/t4018/elixir-function  |   5 ++
 t/t4018/elixir-module    |   9 +++
 userdiff.c               |   7 +++
 5 files changed, 137 insertions(+)
 create mode 100755 t/t4018-diff-funcname
 create mode 100644 t/t4018/elixir-function
 create mode 100644 t/t4018/elixir-module

diff --git a/t/t4018-diff-funcname b/t/t4018-diff-funcname
new file mode 100755
index 0000000000..194310377e
--- /dev/null
+++ b/t/t4018-diff-funcname
@@ -0,0 +1,115 @@
+#!/bin/sh
+#
+# Copyright (c) 2007 Johannes E. Schindelin
+#
+
+test_description='Test custom diff function name patterns'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	# a non-trivial custom pattern
+	git config diff.custom1.funcname "!static
+!String
+[^ 	].*s.*" &&
+
+	# a custom pattern which matches to end of line
+	git config diff.custom2.funcname "......Beer\$" &&
+
+	# alternation in pattern
+	git config diff.custom3.funcname "Beer$" &&
+	git config diff.custom3.xfuncname "^[ 	]*((public|static).*)$" &&
+
+	# for regexp compilation tests
+	echo A >A.java &&
+	echo B >B.java
+'
+
+diffpatterns="
+	ada
+	bibtex
+	cpp
+	csharp
+	css
+	elixir
+	dts
+	fortran
+	fountain
+	golang
+	html
+	java
+	matlab
+	objc
+	pascal
+	perl
+	php
+	python
+	ruby
+	rust
+	tex
+	custom1
+	custom2
+	custom3
+"
+
+for p in $diffpatterns
+do
+	test_expect_success "builtin $p pattern compiles" '
+		echo "*.java diff=$p" >.gitattributes &&
+		test_expect_code 1 git diff --no-index \
+			A.java B.java 2>msg &&
+		test_i18ngrep ! fatal msg &&
+		test_i18ngrep ! error msg
+	'
+	test_expect_success "builtin $p wordRegex pattern compiles" '
+		echo "*.java diff=$p" >.gitattributes &&
+		test_expect_code 1 git diff --no-index --word-diff \
+			A.java B.java 2>msg &&
+		test_i18ngrep ! fatal msg &&
+		test_i18ngrep ! error msg
+	'
+done
+
+test_expect_success 'last regexp must not be negated' '
+	echo "*.java diff=java" >.gitattributes &&
+	test_config diff.java.funcname "!static" &&
+	test_expect_code 128 git diff --no-index A.java B.java 2>msg &&
+	test_i18ngrep ": Last expression must not be negated:" msg
+'
+
+test_expect_success 'setup hunk header tests' '
+	for i in $diffpatterns
+	do
+		echo "$i-* diff=$i"
+	done > .gitattributes &&
+
+	# add all test files to the index
+	(
+		cd "$TEST_DIRECTORY"/t4018 &&
+		git --git-dir="$TRASH_DIRECTORY/.git" add .
+	) &&
+
+	# place modified files in the worktree
+	for i in $(git ls-files)
+	do
+		sed -e "s/ChangeMe/IWasChanged/" <"$TEST_DIRECTORY/t4018/$i" >"$i" || return 1
+	done
+'
+
+# check each individual file
+for i in $(git ls-files)
+do
+	if grep broken "$i" >/dev/null 2>&1
+	then
+		result=failure
+	else
+		result=success
+	fi
+	test_expect_$result "hunk header: $i" "
+		test_when_finished 'cat actual' &&	# for debugging only
+		git diff -U1 $i >actual &&
+		grep '@@ .* @@.*RIGHT' actual
+	"
+done
+
+test_done
diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index 6f5ef0035e..194310377e 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -31,6 +31,7 @@ diffpatterns="
 	cpp
 	csharp
 	css
+	elixir
 	dts
 	fortran
 	fountain
diff --git a/t/t4018/elixir-function b/t/t4018/elixir-function
new file mode 100644
index 0000000000..d452f495a7
--- /dev/null
+++ b/t/t4018/elixir-function
@@ -0,0 +1,5 @@
+def function(RIGHT, arg) do
+  # comment
+  # comment
+  ChangeMe
+end
diff --git a/t/t4018/elixir-module b/t/t4018/elixir-module
new file mode 100644
index 0000000000..91a4e7aa20
--- /dev/null
+++ b/t/t4018/elixir-module
@@ -0,0 +1,9 @@
+defmodule RIGHT do
+  @moduledoc """
+  Foo bar
+  """
+
+  def ChangeMe(a) where is_map(a) do
+    a
+  end
+end
diff --git a/userdiff.c b/userdiff.c
index e187d356f6..31fff34e1e 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -32,6 +32,13 @@ PATTERNS("dts",
 	 /* Property names and math operators */
 	 "[a-zA-Z0-9,._+?#-]+"
 	 "|[-+*/%&^|!~]|>>|<<|&&|\\|\\|"),
+PATTERNS("elixir",
+	 "^[ \t]*((def(macro|module|impl|guard|protocol)?p?|test)[ \t].*)$",
+	 "[a-zA-Z0-9_.]+"
+	 "|:[a-zA-Z0-9@_]+"
+	 "|:'a-zA-Z0-9@_]+'"
+	 "|:\"[a-zA-Z0-9@_]+\""
+	 "|@[a-zA-Z0-9_]+"),
 IPATTERN("fortran",
 	 "!^([C*]|[ \t]*!)\n"
 	 "!^[ \t]*MODULE[ \t]+PROCEDURE[ \t]\n"
-- 
2.23.0