feat(_comp_split): add a function to split a string into an array

bash_completion

@@ -390,6 +390,56 @@ _comp_expand_glob()
     return 0
 }
 
+# Split a string and assign to an array.  This function basically performs
+# `IFS=<sep>; <array_name>=(<text>)` but properly handles saving/restoring the
+# state of `IFS` and the shell option `noglob`.  A naive splitting by
+# `arr=(...)` suffers from unexpected IFS and pathname expansions, so one
+# should prefer this function to such naive splitting.
+# @param $1 array_name  The array name
+#   The array name should not start with an underscores "_", which is
+#   internally used.  The array name should not be either "IFS" or
+#   "OPT{IND,ARG,ERR}".
+# @param $2 text        The string to split
+# OPTIONS
+#   -a      Append to the array
+#   -F sep  Set a set of separator characters (used as IFS).  The default
+#           separator is $' \t\n'
+#   -l      The same as -F $'\n'
+_comp_split()
+{
+    local _assign='=' IFS=$' \t\n'
+
+    local OPTIND=1 OPTARG='' OPTERR=0 _opt
+    while getopts ':alF:' _opt "$@"; do
+        case $_opt in
+            a) _assign='+=' ;;
+            l) IFS=$'\n' ;;
+            F) IFS=$OPTARG ;;
+            *)
+                echo "bash_completion: $FUNCNAME: usage error" >&2
+                return 2
+                ;;
+        esac
+    done
+    shift "$((OPTIND - 1))"
+    if (($# != 2)); then
+        printf '%s\n' "bash_completion: $FUNCNAME: unexpected number of arguments." >&2
+        printf '%s\n' "usage: $FUNCNAME [-a] [-F SEP] ARRAY_NAME TEXT" >&2
+        return 2
+    elif [[ $1 == @(*[^_a-zA-Z0-9]*|[0-9]*|''|_*|IFS|OPTIND|OPTARG|OPTERR) ]]; then
+        printf '%s\n' "bash_completion: $FUNCNAME: invalid array name '$1'." >&2
+        return 2
+    fi
+
+    local _original_opts=$SHELLOPTS
+    set -o noglob
+
+    eval "$1$_assign(\$2)"
+
+    [[ :$_original_opts: == *:noglob:* ]] || set +o noglob
+    return 0
+}
+
 # Check if the argument looks like a path.
 # @param $1 thing to check
 # @return True (0) if it does, False (> 0) otherwise

test/t/unit/Makefile.am

@@ -22,6 +22,7 @@ EXTRA_DIST = \
 	test_unit_pnames.py \
 	test_unit_quote.py \
 	test_unit_quote_readline.py \
+	test_unit_split.py \
 	test_unit_tilde.py \
 	test_unit_unlocal.py \
 	test_unit_variables.py \

test/t/unit/test_unit_split.py

@@ -0,0 +1,90 @@
+import pytest
+
+from conftest import assert_bash_exec, bash_env_saved
+
+
+@pytest.mark.bashcomp(
+    cmd=None, ignore_env=r"^\+declare -f (dump_array|__tester)$"
+)
+class TestUtilSplit:
+    @pytest.fixture
+    def functions(self, bash):
+        assert_bash_exec(
+            bash, "dump_array() { printf '<%s>' \"${arr[@]}\"; echo; }"
+        )
+        assert_bash_exec(
+            bash,
+            '__tester() { local -a arr=(00); _comp_split "${@:1:$#-1}" arr "${@:$#}"; dump_array; }',
+        )
+
+    def test_1(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester '12 34 56'", want_output=True
+        )
+        assert output.strip() == "<12><34><56>"
+
+    def test_2(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester $'12\\n34\\n56'", want_output=True
+        )
+        assert output.strip() == "<12><34><56>"
+
+    def test_3(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester '12:34:56'", want_output=True
+        )
+        assert output.strip() == "<12:34:56>"
+
+    def test_option_F_1(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester -F : '12:34:56'", want_output=True
+        )
+        assert output.strip() == "<12><34><56>"
+
+    def test_option_F_2(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester -F : '12 34 56'", want_output=True
+        )
+        assert output.strip() == "<12 34 56>"
+
+    def test_option_l_1(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester -l $'12\\n34\\n56'", want_output=True
+        )
+        assert output.strip() == "<12><34><56>"
+
+    def test_option_l_2(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester -l '12 34 56'", want_output=True
+        )
+        assert output.strip() == "<12 34 56>"
+
+    def test_option_a_1(self, bash, functions):
+        output = assert_bash_exec(
+            bash, "__tester -aF : '12:34:56'", want_output=True
+        )
+        assert output.strip() == "<00><12><34><56>"
+
+    def test_protect_from_failglob(self, bash, functions):
+        with bash_env_saved(bash) as bash_env:
+            bash_env.shopt("failglob", True)
+            output = assert_bash_exec(
+                bash, "__tester -F '*' '12*34*56'", want_output=True
+            )
+            assert output.strip() == "<12><34><56>"
+
+    def test_protect_from_nullglob(self, bash, functions):
+        with bash_env_saved(bash) as bash_env:
+            bash_env.shopt("nullglob", True)
+            output = assert_bash_exec(
+                bash, "__tester -F '*' '12*34*56'", want_output=True
+            )
+            assert output.strip() == "<12><34><56>"
+
+    def test_protect_from_IFS(self, bash, functions):
+        with bash_env_saved(bash) as bash_env:
+            bash_env.write_variable("IFS", "34")
+            output = assert_bash_exec(
+                bash, "__tester '12 34 56'", want_output=True
+            )
+            assert output.strip() == "<12><34><56>"