[pacman-dev] [PATCH] VerbosePkgLists: format table lines in i18n-compatible way

[Dan McGee]

This had the unfortunate implementation detail that depended on the
strings having 1 byte == 1 column hold true. As we know, this is not at
all the case once you move past the base ASCII character set.

Reimplement this whole thing so it doesn't depend on format strings at
all. Instead, simply calculate the max column widths, and then when
displaying each row add the correct amount of padding using UTF-8 safe
string length functions.

Before:

名字        旧版本新版本  净变化 下载大小

libgee                0.6.2.1-1  0.60 MiB    0.10 MiB
libsocialweb          0.25.19-2  1.92 MiB    0.23 MiB
folks                 0.6.3.2-1  1.38 MiB    0.25 MiB

After:

名字          旧版本  新版本     净变化    下载大小

libgee                0.6.2.1-1  0.60 MiB  0.10 MiB
libsocialweb          0.25.19-2  1.92 MiB  0.23 MiB
folks                 0.6.3.2-1  1.38 MiB  0.25 MiB

Signed-off-by: Dan McGee <dan at archlinux.org>
---

Given the scope of this change, I'd rather wait for 4.0.1 to land this so it
gets at least a little testing in -git first and doesn't cause segfaults.

Note this also removes the two extra spaces in the final column because we
weren't good about padding between columns, instead we had padding on every
column.

Lesson to be learned here: don't use exotic format strings.

 src/pacman/util.c |   89 ++++++++++++++++++++++++++++-------------------------
 1 files changed, 47 insertions(+), 42 deletions(-)

diff --git a/src/pacman/util.c b/src/pacman/util.c
index 79fb54d..ee8fe3f 100644
--- a/src/pacman/util.c
+++ b/src/pacman/util.c
@@ -488,34 +488,47 @@ void string_display(const char *title, const char *string)
 }
 
 static void table_print_line(const alpm_list_t *line,
-		const alpm_list_t *formats)
+		size_t colcount, size_t *widths)
 {
-	const alpm_list_t *curformat = formats;
-	const alpm_list_t *curcell = line;
+	size_t i;
+	const alpm_list_t *curcell;
 
-	while(curcell && curformat) {
-		printf(alpm_list_getdata(curformat), alpm_list_getdata(curcell));
-		curcell = alpm_list_next(curcell);
-		curformat = alpm_list_next(curformat);
+	for(i = 0, curcell = line; curcell && i < colcount;
+			i++, curcell = alpm_list_next(curcell)) {
+		const char *value = curcell->data;
+		size_t len = string_length(value);
+		/* silly printf requires padding size to be an int */
+		int padding = (int)widths[i] - (int)len;
+		if(padding < 0) {
+			padding = 0;
+		}
+		/* left-align all but the last column */
+		if(i + 1 < colcount) {
+			printf("%s%*s", value, padding, "");
+		} else {
+			printf("%*s%s", padding, "", value);
+		}
 	}
 
 	printf("\n");
 }
 
-/* creates format strings by checking max cell lengths in cols */
-static alpm_list_t *table_create_format(const alpm_list_t *header,
-		const alpm_list_t *rows)
+/* find the max string width of each column */
+static size_t table_calc_widths(const alpm_list_t *header,
+		const alpm_list_t *rows, size_t totalcols, size_t **widths)
 {
-	alpm_list_t *formats = NULL;
 	const alpm_list_t *i;
 	const unsigned short padding = 2;
-	size_t curcol, totalcols, totalwidth = 0;
+	size_t curcol, totalwidth = 0;
 	size_t *colwidths;
 
-	totalcols = alpm_list_count(header);
+	if(totalcols <= 0) {
+		return 0;
+	}
+
 	colwidths = malloc(totalcols * sizeof(size_t));
 	if(!colwidths) {
-		return NULL;
+		return 0;
 	}
 	/* header determines column count and initial values of longest_strs */
 	for(i = header, curcol = 0; i; i = alpm_list_next(i), curcol++) {
@@ -536,30 +549,16 @@ static alpm_list_t *table_create_format(const alpm_list_t *header,
 		}
 	}
 
-	/* now use the column width info to generate format strings */
-	for(curcol = 0; curcol < totalcols; curcol++) {
-		const char *display;
-		char *formatstr;
-		size_t colwidth = colwidths[curcol] + padding;
-		totalwidth += colwidth;
-
-		/* right align the last column for a cleaner table display */
-		display = (curcol + 1 < totalcols) ? "%%-%ds" : "%%%ds";
-		pm_asprintf(&formatstr, display, colwidth);
-
-		formats = alpm_list_add(formats, formatstr);
-	}
-
-	free(colwidths);
-
-	/* return NULL if terminal is not wide enough */
-	if(totalwidth > getcols()) {
-		fprintf(stderr, _("insufficient columns available for table display\n"));
-		FREELIST(formats);
-		return NULL;
+	for(i = header, curcol = 0; i; i = alpm_list_next(i), curcol++) {
+		/* pad everything but the last column */
+		if(curcol + 1 < totalcols) {
+			colwidths[curcol] += padding;
+		}
+		totalwidth += colwidths[curcol];
 	}
 
-	return formats;
+	*widths = colwidths;
+	return totalwidth;
 }
 
 /** Displays the list in table format
@@ -576,14 +575,20 @@ int table_display(const char *title, const alpm_list_t *header,
 		const alpm_list_t *rows)
 {
 	const alpm_list_t *i;
-	alpm_list_t *formats;
+	size_t *widths = NULL, totalcols, totalwidth;
 
 	if(rows == NULL || header == NULL) {
 		return 0;
 	}
 
-	formats = table_create_format(header, rows);
-	if(formats == NULL) {
+	totalcols = alpm_list_count(header);
+	totalwidth = table_calc_widths(header, rows, totalcols, &widths);
+	/* return -1 if terminal is not wide enough */
+	if(totalwidth > getcols()) {
+		fprintf(stderr, _("insufficient columns available for table display\n"));
+		return -1;
+	}
+	if(!totalwidth || !widths) {
 		return -1;
 	}
 
@@ -591,14 +596,14 @@ int table_display(const char *title, const alpm_list_t *header,
 		printf("%s\n\n", title);
 	}
 
-	table_print_line(header, formats);
+	table_print_line(header, totalcols, widths);
 	printf("\n");
 
 	for(i = rows; i; i = alpm_list_next(i)) {
-		table_print_line(alpm_list_getdata(i), formats);
+		table_print_line(alpm_list_getdata(i), totalcols, widths);
 	}
 
-	FREELIST(formats);
+	free(widths);
 	return 0;
 }
 
-- 
1.7.7