--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/streamlet-examples/__relpipe_in_filesystem_script_cloc	Sun Jan 12 01:21:22 2020 +0100
@@ -0,0 +1,78 @@
+#!/bin/bash
+
+# Relational pipes
+# Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, version 3 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+# This streamlet counts lines of code of given files. It calls the tool cloc.
+#
+# With no options, these attributes are provided: language, code, comment, blank
+# Specific attributes can be selected using options – e.g. --option 'attribute' 'code'
+# or --option "attribute" "total" (sum of code, comment and blank lines, hidden by default).
+#
+# Optional prefix can be added to attribute names: --option 'prefix' 'my_prefix_'
+
+
+. "$(dirname $0)/streamlet-common.sh"
+
+processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES_METADATA() {
+	clocFields=()
+
+	for (( i=0; i<${#optionNames[@]}; i++)); do
+		if [[ "x${optionNames[$i]}" == "xattribute" ]]; then
+			if [[ "${optionValues[$i]}" =~ ^(language|blank|comment|code)$ ]]; then
+				clocFields+=("${optionValues[$i]}");
+			else
+				echo "Unsupported attribute: ${optionValues[$i]}" >&2
+			fi
+		elif [[ "x${optionNames[$i]}" == "xprefix" ]]; then
+			clocPrefix="${optionValues[$i]}";
+		else
+			echo "Unsupported option: ${optionNames[$i]}" >&2
+		fi
+	done
+
+	if [[ -z "$clocFields" ]]; then
+		clocFields=( "language" "code" "comment" "blank" ); # + "total"
+	fi
+
+	for (( i=0; i<${#clocFields[@]}; i++)); do
+		if [[ "x${clocFields[$i]}" == "xlanguage" ]]; then local type="string"; else local type="integer"; fi
+		send OUTPUT_ATTRIBUTE_METADATA "${outputAttributeAliases[$i]-$clocPrefix${clocFields[$i]}}"    "$type"
+	done
+
+	send WAITING_FOR_INPUT_ATTRIBUTES
+}
+
+processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES() {
+	local language files blank comment code total;
+	
+	[[ -d "$currentFile" ]] || read_nullbyte language files blank comment code total < <( cloc "$currentFile" | perl -ne 'if (/(.*?)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)/) { print "$1\0$2\0$3\0$4\0$5\0"; print $3 + $4 + $5; print "\0"; }' );
+
+	for (( i=0; i<${#clocFields[@]}; i++)); do
+		value="${!clocFields[$i]}";
+
+		if [[ "x$files" == "x1" ]]; then                                isNull="false";
+		elif [[ "x${clocFields[$i]}" == "xlanguage" ]]; then value="";  isNull="true";
+		else                                                 value="0"; isNull="true"; fi
+
+		send OUTPUT_ATTRIBUTE "$value"    "$isNull";
+	done
+	
+	send WAITING_FOR_INPUT_ATTRIBUTES;
+}
+
+initialize
+processMessages