tsort: new applet
function old new delta tsort_main - 578 +578 .rodata 104884 104906 +22 applet_names 2759 2765 +6 applet_main 1596 1600 +4 packed_usage 34290 34288 -2 ------------------------------------------------------------------------------ (add/remove: 2/0 grow/shrink: 3/1 up/down: 610/-2) Total: 608 bytes Signed-off-by: David Leonard <d+busybox@adaptive-enterprises.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
David Leonard
Denys Vlasenko
parent
52a7bf6fa6
commit
4642cf5b38
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@ -0,0 +1,188 @@
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/* vi: set sw=4 ts=4: */
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/*
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* tsort implementation for busybox
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*
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* public domain -- David Leonard, 2022
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*/
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//config:config TSORT
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//config: bool "tsort (0.7 kb)"
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//config: default y
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//config: help
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//config: tsort performs a topological sort.
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//applet:IF_TSORT(APPLET(tsort, BB_DIR_USR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_TSORT) += tsort.o
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/* BB_AUDIT SUSv3 compliant */
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/* http://www.opengroup.org/onlinepubs/007904975/utilities/tsort.html */
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//usage:#define tsort_trivial_usage
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//usage: "[FILE]"
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//usage:#define tsort_full_usage "\n\n"
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//usage: "Topological sort"
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//usage:#define tsort_example_usage
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//usage: "$ echo -e \"a b\\nb c\" | tsort\n"
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//usage: "a\n"
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//usage: "b\n"
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//usage: "c\n"
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#include "libbb.h"
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#include "common_bufsiz.h"
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struct node {
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unsigned in_count;
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unsigned out_count;
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struct node **out;
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char name[1];
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};
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struct globals {
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struct node **nodes;
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unsigned nodes_len;
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};
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#define G (*(struct globals*)bb_common_bufsiz1)
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#define INIT_G() do { \
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setup_common_bufsiz(); \
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BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
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G.nodes = NULL; \
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G.nodes_len = 0; \
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} while (0)
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static struct node *
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get_node(const char *name)
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{
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struct node *n;
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unsigned a = 0;
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unsigned b = G.nodes_len;
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/* Binary search for name */
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while (a != b) {
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unsigned m = (a + b) / 2;
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int cmp = strcmp(name, G.nodes[m]->name);
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if (cmp == 0)
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return G.nodes[m]; /* found */
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if (cmp < 0) {
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b = m;
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} else {
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a = m + 1;
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}
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}
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/* Allocate new node */
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n = xzalloc(sizeof(*n) + strlen(name));
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//n->in_count = 0;
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//n->out_count = 0;
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//n->out = NULL;
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strcpy(n->name, name);
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/* Insert to maintain sort */
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G.nodes = xrealloc(G.nodes, (G.nodes_len + 1) * sizeof(*G.nodes));
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memmove(&G.nodes[a + 1], &G.nodes[a],
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(G.nodes_len - a) * sizeof(*G.nodes));
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G.nodes[a] = n;
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G.nodes_len++;
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return n;
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}
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static void
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add_edge(struct node *a, struct node *b)
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{
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a->out = xrealloc_vector(a->out, 6, a->out_count);
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a->out[a->out_count++] = b;
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b->in_count++;
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}
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int tsort_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int tsort_main(int argc UNUSED_PARAM, char **argv)
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{
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char *line;
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size_t linesz;
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ssize_t len;
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struct node *a;
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int cycles;
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INIT_G();
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if (argv[1]) {
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if (argv[2])
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bb_show_usage();
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if (NOT_LONE_DASH(argv[1])) {
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close(STDIN_FILENO); /* == 0 */
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xopen(argv[1], O_RDONLY); /* fd will be 0 */
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}
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}
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/* Read in words separated by <blank>s */
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a = NULL;
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line = NULL;
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linesz = 0;
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while ((len = getline(&line, &linesz, stdin)) != -1) {
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char *s = line;
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while (*(s = skip_whitespace(s)) != '\0') {
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struct node *b;
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char *word;
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word = s;
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s = skip_non_whitespace(s);
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if (*s)
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*s++ = '\0';
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/* Create nodes and edges for each word pair */
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b = get_node(word);
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if (!a) {
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a = b;
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} else {
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if (a != b)
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add_edge(a, b);
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a = NULL;
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}
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}
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}
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// Most other tools do not check for input read error (treat them as EOF)
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// die_if_ferror(in, input_filename);
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if (a)
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bb_simple_error_msg_and_die("odd input");
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free(line);
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/*
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* Kahn's algorithm:
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* - find a node that has no incoming edges, print and remove it
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* - repeat until the graph is empty
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* - if any nodes are left, they form cycles.
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*/
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cycles = 0;
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while (G.nodes_len) {
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struct node *n;
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unsigned i;
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/* Search for first node with no incoming edges */
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for (i = 0; i < G.nodes_len; i++) {
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if (!G.nodes[i]->in_count)
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break;
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}
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if (i == G.nodes_len) {
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/* Must be a cycle; arbitraily break it at node 0 */
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cycles++;
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i = 0;
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#ifndef TINY
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bb_error_msg("cycle at %s", G.nodes[i]->name);
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#endif
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}
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/* Remove the node (need no longer maintain sort) */
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n = G.nodes[i];
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G.nodes[i] = G.nodes[--G.nodes_len];
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/* And remove its outgoing edges */
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for (i = 0; i < n->out_count; i++)
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n->out[i]->in_count--;
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free(n->out);
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puts(n->name);
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free(n);
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}
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free(G.nodes);
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fflush_stdout_and_exit(cycles ? 1 : 0);
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}
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@ -24,7 +24,7 @@ POSIX Tools not supported:
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gencat, getconf, iconv, join, link, locale, localedef, lp, m4,
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mailx, newgrp, nl, pathchk, pax, pr, qalter, qdel, qhold, qmove,
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qmsg, qrerun, qrls, qselect, qsig, qstat, qsub, tabs, talk, tput,
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tsort, unlink, uucp, uustat, uux
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unlink, uucp, uustat, uux
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POSIX Tools not supported (DEVELOPMENT):
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admin, cflow, ctags, cxref, delta, fort77, get, lex, make, nm, prs, rmdel,
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@ -0,0 +1,110 @@
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#!/bin/sh
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# SUSv3 compliant sort tests.
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# Public Domain, David Leonard 2022
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. ./testing.sh
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# name cmd expected ./input stdin
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testing "" "tsort" "a\n" "" "a a\n"
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testing "" "tsort -" "a\n" "" "a a\n"
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testing "" "tsort input" "a\n" "a a\n" ""
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testing "tsort input (w/o eol)" "tsort input" "a\n" "a a" ""
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testing "" "tsort /dev/null" "" "" ""
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testing "tsort empty" tsort "" "" ""
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testing "tsort blank" tsort "" "" "\n"
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testing "tsort blanks" tsort "" "" "\n\n \t\n "
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# simple inputs having exactly one solution
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testing "tsort 1-edge" tsort "a\nb\n" "" "a b\n"
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testing "tsort 2-edge" tsort "a\nb\nc\n" "" "a b b c\n"
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# The following test helper accommodates future variable output because, as
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# tsort is allowed to emit any total ordering that satisfies its input,
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# should the implementation changes, these tests will remain valid.
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#
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# The idea is to verify that:
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# - each input word is present EXACTLY ONCE in tsort's output
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# - for each input pair 'a b', the occurrence of 'a' APPEARS BEFORE 'b'
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# - the exit code is 0
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tsort_test () {
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fail=
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name="$1"; shift
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args="$*"
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if [ $VERBOSE ]; then
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echo "============"
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echo "echo \"$args\" | tsort >actual"
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fi
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echo "$args" | tsort >actual
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ec=$?
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if [ $ec -ne 0 ]; then
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fail "tsort exit $ec, expected 0"
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fi
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while [ $# -ne 0 ]; do
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a=$1; shift
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b=$1; shift
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aline=$(grep -nxF "$a" <actual | cut -d: -f1)
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bline=$(grep -nxF "$b" <actual | cut -d: -f1)
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case $aline in
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"") fail "word $a missing from output ($args)";;
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*" "*) fail "word $a duplicated ($args)";;
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esac
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case $bline in
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"") fail "word $b missing from output ($args)";;
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*" "*) fail "word $b duplicated ($args)";;
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esac
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if [ $aline -gt $bline ]; then
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fail "$a appears after $b ($args)"
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fi
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done
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if [ $fail ] && [ $VERBOSE ]; then
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echo "exit $ec, actual:"
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cat actual
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fi
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rm actual
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report "$name"
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}
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# Test that erroneous input causes an unsuccessful exit code
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# we don't test the output error message
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tsort_test_err () {
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fail=
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name="$1"; shift
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echo "$*" | tsort >/dev/null 2>/dev/null
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ec=$?
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if [ $ec -eq 0 ]; then
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fail "$name: unexpected exit 0 ($*)"
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fi
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report "$name"
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}
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fail () {
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[ $VERBOSE ] && echo "ERROR: $*"
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fail=1
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}
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report () {
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if [ $fail ]; then
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FAILCOUNT=$(($FAILCOUNT + 1))
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echo "FAIL: $*"
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else
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echo "PASS: $*"
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fi
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}
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tsort_test "tsort empty2"
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tsort_test "tsort singleton" a a
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tsort_test "tsort simple" a b b c
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tsort_test "tsort 2singleton" a a b b
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tsort_test "tsort medium" a b a b b c
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tsort_test "tsort std.example" a b c c d e g g f g e f h h
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tsort_test "tsort prefixes" a aa aa aaa aaaa aaaaa a aaaaa
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tsort_test_err "tsort odd" a
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tsort_test_err "tsort odd2" a b c
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tsort_test_err "tsort cycle" a b b a
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exit $FAILCOUNT
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