config

commit b131e501e0f6ecb2914b3f82227f8ff88d6c0855
parent afbd66b19f91bd616c10a489a76c501f4f0390c4
Author: Jacob R. Edwards <n/a>
Date:   Wed, 28 Dec 2022 13:39:17 -0800

Add sr script

This script maintains a table of records (currently always lines)
from files. If the given name is prefixed with a plus ('+') it's
records are added to the table, if it's prefixed with minus ('-'),
records found in it are removed from the table.

At the end, all the records are printed out in the order they were
added to the table.

Diffstat:
A
local/bin/bin/sr
 | 
86
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 86 insertions(+), 0 deletions(-)
diff --git a/local/bin/bin/sr b/local/bin/bin/sr
@@ -0,0 +1,86 @@
+#!/bin/sh
+# Copyright 2022 Jacob R. Edwards
+# sr -- select records
+#
+# This script maintains a table of records (currently always lines)
+# from files. If the given name is prefixed with a plus ('+') it's
+# records are added to the table, if it's prefixed with minus ('-'),
+# records found in it are removed from the table.
+#
+# At the end, all the records are printed out in the order they were
+# added to the table. (If a record is already in the table, it is not
+# added again, so if the same record was obtained from both 'a' and
+# 'b' and it wasn't removed in between, it's position is depended 
+# solely upon 'a'.)
+
+
+awk 'function die(msg)
+{
+	status = msg
+	exit 1
+}
+
+function usage(msg)
+{
+	die(sprintf("%s\n%s", msg, "usage: sr (+|-)file [...]"));
+}
+
+function addx(x)
+{
+	if (! (x in t)) {
+		t[x] = count++;
+	}
+}
+
+function subx(x)
+{
+	if (x in t)
+		delete t[x];
+}
+
+function dofile(expr, _, op, file, n, line)
+{
+	op = substr(expr, 1, 1);
+	if (!match(op, "^[+-]$"))
+		usage(op ": Invalid operator");
+
+	file = substr(expr, 2);
+	if (!file)
+		file = "/dev/stdin"
+
+	while ((n = getline line < file) > 0)
+		op == "+" ? addx(line) : subx(line);
+	close(file)
+	if (n < 0)
+		die(file ": Unable to read file")
+}
+
+BEGIN {
+	keeporder = 1
+
+	if (ARGC == 1)
+		ARGV[ARGC++] = "+"
+
+	for (i = 1; i < ARGC; ++i)
+		dofile(ARGV[i]);
+
+	if (!keeporder) {
+		for (i in t)
+			print(i)
+		exit 0
+	}
+
+	for (i in t)
+		rt[t[i]] = i
+	for (i = 0; i < count; ++i)
+		if (i in rt)
+			print rt[i];
+	exit 0
+}
+
+END {
+	if (status) {
+		print "error: " status > "/dev/stderr"
+		exit 1
+	}
+}' "$@"