basic: add minimalistic table formatter

We have plenty of code in our codebase that outputs tables to the
console, and all is homegrown and awful. Let's replace it with a generic
implementation that can do automatically what the old implementations
did manually.

Features:

1. Ellipsation (for fields overly long) and alignment (for
   fields overly short)

2. Sorting of rows

3. automatically copies formatting from the same cell in the row above

4. Heavy use of varargs to make putting together tables easy

5. can expand and compress tables, with weights

6. Has a minimal understanding of unicode wide characters in order to
   match unicode strings to character cell terminals.

7. Columns can be reordered and individually turned off.

8. pretty printing for various data types

And more.

1 files changed, 139 insertions, 0 deletions

diff --git a/src/test/test-format-table.c b/src/test/test-format-table.c
new file mode 100644
index 000000000..6c5ae9f87
--- /dev/null
+++ b/src/test/test-format-table.c
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+//#include "alloc-util.h"
+//#include "format-table.h"
+//#include "string-util.h"
+//#include "time-util.h"
+
+int main(int argc, char *argv[]) {
+
+        _cleanup_(table_unrefp) Table *t = NULL;
+        _cleanup_free_ char *formatted = NULL;
+
+        assert_se(setenv("COLUMNS", "40", 1) >= 0);
+
+        assert_se(t = table_new("ONE", "TWO", "THREE"));
+
+        assert_se(table_set_align_percent(t, TABLE_HEADER_CELL(2), 100) >= 0);
+
+        assert_se(table_add_many(t,
+                                 TABLE_STRING, "xxx",
+                                 TABLE_STRING, "yyy",
+                                 TABLE_BOOLEAN, true) >= 0);
+
+        assert_se(table_add_many(t,
+                                 TABLE_STRING, "a long field",
+                                 TABLE_STRING, "yyy",
+                                 TABLE_BOOLEAN, false) >= 0);
+
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "ONE          TWO THREE\n"
+                        "xxx          yyy   yes\n"
+                        "a long field yyy    no\n"));
+
+        formatted = mfree(formatted);
+
+        table_set_width(t, 40);
+
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "ONE                TWO             THREE\n"
+                        "xxx                yyy               yes\n"
+                        "a long field       yyy                no\n"));
+
+        formatted = mfree(formatted);
+
+        table_set_width(t, 12);
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "ONE TWO THR…\n"
+                        "xxx yyy  yes\n"
+                        "a … yyy   no\n"));
+
+        formatted = mfree(formatted);
+
+        table_set_width(t, 5);
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "… … …\n"
+                        "… … …\n"
+                        "… … …\n"));
+
+        formatted = mfree(formatted);
+
+        table_set_width(t, 3);
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "… … …\n"
+                        "… … …\n"
+                        "… … …\n"));
+
+        formatted = mfree(formatted);
+
+        table_set_width(t, (size_t) -1);
+        assert_se(table_set_sort(t, (size_t) 0, (size_t) 2, (size_t) -1) >= 0);
+
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "ONE          TWO THREE\n"
+                        "a long field yyy    no\n"
+                        "xxx          yyy   yes\n"));
+
+        formatted = mfree(formatted);
+
+        table_set_header(t, false);
+
+        assert_se(table_add_many(t,
+                                 TABLE_STRING, "fäää",
+                                 TABLE_STRING, "uuu",
+                                 TABLE_BOOLEAN, true) >= 0);
+
+        assert_se(table_add_many(t,
+                                 TABLE_STRING, "fäää",
+                                 TABLE_STRING, "zzz",
+                                 TABLE_BOOLEAN, false) >= 0);
+
+        assert_se(table_add_many(t,
+                                 TABLE_EMPTY,
+                                 TABLE_SIZE, (uint64_t) 4711,
+                                 TABLE_TIMESPAN, (usec_t) 5*USEC_PER_MINUTE) >= 0);
+
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "a long field yyy    no\n"
+                        "fäää         zzz    no\n"
+                        "fäää         uuu   yes\n"
+                        "xxx          yyy   yes\n"
+                        "             4.6K 5min\n"));
+
+        formatted = mfree(formatted);
+
+        assert_se(table_set_display(t, (size_t) 2, (size_t) 0, (size_t) 2, (size_t) 0, (size_t) 0, (size_t) -1) >= 0);
+
+        assert_se(table_format(t, &formatted) >= 0);
+        printf("%s\n", formatted);
+
+        assert_se(streq(formatted,
+                        "  no a long f…   no a long f… a long fi…\n"
+                        "  no fäää        no fäää      fäää      \n"
+                        " yes fäää       yes fäää      fäää      \n"
+                        " yes xxx        yes xxx       xxx       \n"
+                        "5min           5min                     \n"));
+
+        return 0;
+}