libsmartcols: cleanup and extend padding functionality

LIBSMARTCOLS_DEBUG_PADDING=on in the next examples forces libsmartcols
print '.' as a padding char. See line "ffff" in the exmaples.

* default output is to fill all except last cell

	$ LIBSMARTCOLS_DEBUG_PADDING=on ./sample-scols-fromfile --nlines 10  --width 80 --column tests/ts/libsmartcols/files/col-name --column tests/ts/libsmartcols/files/col-number --column tests/ts/libsmartcols/files/col-string --column tests/ts/libsmartcols/files/col-string tests/ts/libsmartcols/files/data-string tests/ts/libsmartcols/files/data-number tests/ts/libsmartcols/files/data-string-empty tests/ts/libsmartcols/files/data-string-empty 2> /dev/null
	NAME.. ......NUM STRINGS STRINGS
	aaaa.. ........0 aaaa... aaaa
	bbb... ......100 bbb.... bbb
	ccccc. .......21 ccccc.. ccccc
	dddddd ........3 dddddd. dddddd
	ee.... ......411 ee..... ee
	ffff.. .....5111 .......
	gggggg 678993321 gggggg. gggggg
	hhh... ..7666666 hhh.... hhh

* scols_table_enable_minout() minimizes output for tailing empty cells, example:

	$ LIBSMARTCOLS_DEBUG_PADDING=on ./sample-scols-fromfile --nlines 10 --minout  --width 80 --column tests/ts/libsmartcols/files/col-name --column tests/ts/libsmartcols/files/col-number --column tests/ts/libsmartcols/files/col-string --column tests/ts/libsmartcols/files/col-string tests/ts/libsmartcols/files/data-string tests/ts/libsmartcols/files/data-number tests/ts/libsmartcols/files/data-string-empty tests/ts/libsmartcols/files/data-string-empty 2> /dev/null
	NAME.. ......NUM STRINGS STRINGS
	aaaa.. ........0 aaaa... aaaa
	bbb... ......100 bbb.... bbb
	ccccc. .......21 ccccc.. ccccc
	dddddd ........3 dddddd. dddddd
	ee.... ......411 ee..... ee
	ffff.. .....5111
	gggggg 678993321 gggggg. gggggg
	hhh... ..7666666 hhh.... hhh

* cleanup up scols_table_enable_maxout() use, example:

	$ LIBSMARTCOLS_DEBUG_PADDING=on ./sample-scols-fromfile --nlines 10 --maxout  --width 80 --column tests/ts/libsmartcols/files/col-name --column tests/ts/libsmartcols/files/col-number --column tests/ts/libsmartcols/files/col-string --column tests/ts/libsmartcols/files/col-string tests/ts/libsmartcols/files/data-string tests/ts/libsmartcols/files/data-number tests/ts/libsmartcols/files/data-string-empty tests/ts/libsmartcols/files/data-string-empty 2> /dev/null
	NAME.............. ..................NUM STRINGS............ STRINGS............
	aaaa.............. ....................0 aaaa............... aaaa...............
	bbb............... ..................100 bbb................ bbb................
	ccccc............. ...................21 ccccc.............. ccccc..............
	dddddd............ ....................3 dddddd............. dddddd.............
	ee................ ..................411 ee................. ee.................
	ffff.............. .................5111 ................... ...................
	gggggg............ ............678993321 gggggg............. gggggg.............
	hhh............... ..............7666666 hhh................ hhh................

Note that we cannot make scols_table_enable_minout() default because
for example "column --table" is pretty commonly used with non-blank
columns separator and in this case all cells has to be filled.

	$ echo -e "aa,b,ccc\na,,\naaa,bbb,ccc" |  column --table --separator ',' --output-separator '|'
	aa |b  |ccc
	a  |   |
	aaa|bbb|ccc

Addresses: https://github.com/karelzak/util-linux/issues/826
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 66 insertions, 2 deletions

diff --git a/libsmartcols/src/table.c b/libsmartcols/src/table.c
index 944c1e593..e14c82b1b 100644
--- a/libsmartcols/src/table.c
+++ b/libsmartcols/src/table.c
@@ -475,6 +475,33 @@ int scols_table_next_column(struct libscols_table *tb,
 }
 
 /**
+ * scols_table_set_columns_iter:
+ * @tb: tab pointer
+ * @itr: iterator
+ * @cl: tab entry
+ *
+ * Sets @iter to the position of @cl in the file @tb.
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int scols_table_set_columns_iter(
+			struct libscols_table *tb,
+			struct libscols_iter *itr,
+			struct libscols_column *cl)
+{
+	if (!tb || !itr || !cl)
+		return -EINVAL;
+
+	if (cl->table != tb)
+		return -EINVAL;
+
+	SCOLS_ITER_INIT(itr, &tb->tb_columns);
+	itr->p = &cl->cl_columns;
+
+	return 0;
+}
+
+/**
  * scols_table_get_ncols:
  * @tb: table
  *
@@ -1133,20 +1160,46 @@ int scols_table_enable_header_repeat(struct libscols_table *tb, int enable)
  * @enable: 1 or 0
  *
  * The extra space after last column is ignored by default. The output
- * maximization use the extra space for all columns.
+ * maximization add padding for all columns.
+ *
+ * This setting is mutually exclusive to cols_table_enable_minout().
  *
  * Returns: 0 on success, negative number in case of an error.
  */
 int scols_table_enable_maxout(struct libscols_table *tb, int enable)
 {
-	if (!tb)
+	if (!tb || tb->minout)
 		return -EINVAL;
+
 	DBG(TAB, ul_debugobj(tb, "maxout: %s", enable ? "ENABLE" : "DISABLE"));
 	tb->maxout = enable ? 1 : 0;
 	return 0;
 }
 
 /**
+ * scols_table_enable_minout:
+ * @tb: table
+ * @enable: 1 or 0
+ *
+ * Force library to terminate line after last column with data. The extra
+ * padding is not added to the empty cells at the end of the line. The default is fill
+ * tailing empty cells except the last line cell.
+ *
+ * This setting is mutually exclusive to cols_table_enable_maxout().
+ *
+ * Returns: 0 on success, negative number in case of an error.
+ */
+int scols_table_enable_minout(struct libscols_table *tb, int enable)
+{
+	if (!tb || tb->maxout)
+		return -EINVAL;
+
+	DBG(TAB, ul_debugobj(tb, "minout: %s", enable ? "ENABLE" : "DISABLE"));
+	tb->minout = enable ? 1 : 0;
+	return 0;
+}
+
+/**
  * scols_table_enable_nowrap:
  * @tb: table
  * @enable: 1 or 0
@@ -1316,6 +1369,17 @@ int scols_table_is_maxout(const struct libscols_table *tb)
 }
 
 /**
+ * scols_table_is_minout
+ * @tb: table
+ *
+ * Returns: 1 if output minimization is enabled or 0
+ */
+int scols_table_is_minout(const struct libscols_table *tb)
+{
+	return tb->minout;
+}
+
+/**
  * scols_table_is_tree:
  * @tb: table
  *