Add a better version of join.

bash.sh

@@ -53,14 +53,34 @@ array_filter() {
 #
 # Join array elements with a string.
 #
-# $1: String separator
-# $@: Array elements
+# $1: String default, used in case array to join is empty
+# $2: String separator, has to be a single element
+# $@: Array elements, empty elements will be skipped
 #
-array_join() {
-    local sep=$1; shift
-    IFS=$sep eval 'echo "$*"'
+
+join() {
+    local -a args
+    local default
+    local ifs
+    local IFS
+
+    default="$1"; shift
+
+    ifs="$1"; shift
+
+    [ "${#ifs}" -gt 1 ] && exit 1
+
+    # read into array, ifs is still a space
+    read -r -a args <<< "$*"
+
+    IFS="$ifs"
+    # args will be unbound if no more arguments were passed in
+    # check for that, use default if necessary
+    # otherwise dump the string with overwritten ifs
+    [ -z "${args-}" ] && echo "$default" || echo "${args[*]}"
 }
 
+
 ################
 # Benchmarking #
 ################

test-bash.sh

@@ -44,6 +44,70 @@ test_resolve_symlinks() {
     [ "$(resolve_symlinks /tmp/1/2/foo)" == "/tmp/foo" ]
 }
 
+test_join_standard() {
+    local result
+
+    result=$(join "def" - 1 2 3)
+
+    [ "$result" == "1-2-3" ]
+}
+
+test_join_one() {
+    local result
+
+    result=$(join "def" - 1)
+
+    [ "$result" == "1" ]
+}
+
+test_join_spaces() {
+    local result
+
+    result=$(join "def" - 1 '' '' 3)
+
+    [ "$result" == "1-3" ]
+}
+
+test_join_more_spaces() {
+    local result
+
+    result=$(join "def" - 1   3)
+
+    [ "$result" == "1-3" ]
+}
+
+test_join_other_delimeter() {
+    local result
+
+    result=$(join "def" "b" 1   3)
+
+    [ "$result" == "1b3" ]
+}
+
+test_join_invalid_delimeter() {
+    local result
+
+    result=$(join "def" "bb" 1   3)
+
+    [ "$?" == 1 ]
+}
+
+test_join_no_delimeter() {
+    local result
+
+    result=$(join "def")
+
+    [ "$result" == "def" ]
+}
+
+test_join_default() {
+    local result
+
+    result=$(join "def" - '' '')
+
+    [ "$result" == "def" ]
+}
+
 tests() {
     local ret=0
     local test_log="/tmp/${0##*/}.test.log"