lib/fold: Add text fold utility

We want to fold help text into the ncurses UI, so add a little module to
split text into lines.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

5 files changed, 232 insertions, 1 deletions

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 1c19e11..f6009cf 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -20,6 +20,8 @@ AM_CFLAGS = $(DEFAULT_CFLAGS)
 noinst_LTLIBRARIES = libpbcore.la
 
 libpbcore_la_SOURCES = \
+	fold/fold.h \
+	fold/fold.c \
 	log/log.h \
 	log/log.c \
 	list/list.c \
diff --git a/lib/fold/fold.c b/lib/fold/fold.c
new file mode 100644
index 0000000..ec10c8c
--- /dev/null
+++ b/lib/fold/fold.c
@@ -0,0 +1,44 @@
+
+#include "fold/fold.h"
+
+void fold_text(const char *text,
+		int linelen,
+		int line_cb(void *arg, const char *start, int len),
+		void *arg)
+{
+	const char *start, *end, *sep;
+	int rc = 0;
+
+	start = end = sep = text;
+
+	while (!rc) {
+
+		if (*end == '\n') {
+			rc = line_cb(arg, start, end - start);
+			start = sep = ++end;
+
+		} else if (*end == '\0') {
+			line_cb(arg, start, end - start);
+			rc = 1;
+
+		} else if (end - start >= linelen - 1) {
+			if (sep != start) {
+				/* split on a previous word boundary, if
+				 * possible */
+				rc = line_cb(arg, start, sep - start);
+				start = end = ++sep;
+			} else {
+				/* otherwise, break the word */
+				end++;
+				rc = line_cb(arg, start, end - start);
+				start = sep = end;
+			}
+
+		} else {
+			end++;
+			/* record our last separator */
+			if (*end == ' ')
+				sep = end;
+		}
+	}
+}
diff --git a/lib/fold/fold.h b/lib/fold/fold.h
new file mode 100644
index 0000000..834fcf2
--- /dev/null
+++ b/lib/fold/fold.h
@@ -0,0 +1,27 @@
+/*
+ *  Copyright (C) 2013 IBM Corporation
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef FOLD_H
+#define FOLD_H
+
+void fold_text(const char *text,
+		int linelen,
+		int line_cb(void *arg, const char *start, int len),
+		void *arg);
+
+#endif /* FOLD_H */
+
diff --git a/test/lib/Makefile.am b/test/lib/Makefile.am
index ae6027f..ed570af 100644
--- a/test/lib/Makefile.am
+++ b/test/lib/Makefile.am
@@ -31,7 +31,8 @@ check_PROGRAMS = list-test \
 	test-process-async \
 	test-process-async-stdout \
 	test-process-parent-stdout \
-	test-process-both
+	test-process-both \
+	test-fold
 
 TESTS = $(check_PROGRAMS)
 
diff --git a/test/lib/test-fold.c b/test/lib/test-fold.c
new file mode 100644
index 0000000..1f58fdf
--- /dev/null
+++ b/test/lib/test-fold.c
@@ -0,0 +1,157 @@
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include <fold/fold.h>
+#include <list/list.h>
+#include <talloc/talloc.h>
+
+struct line {
+	const char		*buf;
+	unsigned int		len;
+	struct list_item	list;
+};
+
+struct ctx {
+	struct list		lines;
+};
+
+struct test {
+	const char	*in;
+	unsigned int	linelen;
+	const char	*out[];
+};
+
+/* split on newline boundaries, no actual folding */
+struct test test_split = {
+	.in	= "Lorem ipsum dolor\nsit amet,\nconsectetuer\n",
+	.linelen = 20,
+	.out = {
+		"Lorem ipsum dolor",
+		"sit amet,",
+		"consectetuer",
+		"",
+		NULL,
+	},
+};
+
+/* fold a long line */
+struct test test_fold_line = {
+	.in = "Lorem ipsum dolor sit amet, consectetuer adipiscing "
+		"elit, sed diam nonummy nibh euismod tincidunt ut "
+		"laoreet dolore magna aliquam erat volutpat.",
+	.linelen = 20,
+	.out = {
+		"Lorem ipsum dolor",
+		"sit amet,",
+		"consectetuer",
+		"adipiscing elit,",
+		"sed diam nonummy",
+		"nibh euismod",
+		"tincidunt ut",
+		"laoreet dolore",
+		"magna aliquam erat",
+		"volutpat.",
+		NULL
+	},
+};
+
+/* break a word */
+struct test test_break = {
+	.in = "Lorem ipsum dolor sit amet, consectetuer",
+	.linelen = 10,
+	.out = {
+		"Lorem",
+		"ipsum",
+		"dolor sit",
+		"amet,",
+		"consectetu",
+		"er",
+		NULL
+	},
+};
+
+static struct test *tests[] = {
+	&test_split, &test_fold_line, &test_break,
+};
+
+static void __attribute__((noreturn)) fail(struct ctx *ctx,
+		struct test *test, const char *msg)
+{
+	struct line *line;
+	int i;
+
+	fprintf(stderr, "%s\n", msg);
+	fprintf(stderr, "input:\n%s\n", test->in);
+
+	fprintf(stderr, "expected:\n");
+	for (i = 0; test->out[i]; i++)
+		fprintf(stderr, "  '%s'\n", test->out[i]);
+
+	fprintf(stderr, "actual:\n");
+	list_for_each_entry(&ctx->lines, line, list) {
+		char *buf = talloc_strndup(ctx, line->buf, line->len);
+		fprintf(stderr, "  '%s'\n", buf);
+		talloc_free(buf);
+	}
+
+	exit(EXIT_FAILURE);
+}
+
+static int fold_line_cb(void *arg, const char *start, int len)
+{
+	struct ctx *ctx = arg;
+	struct line *line;
+
+	line = talloc(ctx, struct line);
+	line->buf = start;
+	line->len = len;
+	list_add_tail(&ctx->lines, &line->list);
+
+	return 0;
+}
+
+static void run_test(struct test *test)
+{
+	struct line *line;
+	struct ctx *ctx;
+	int i;
+
+	ctx = talloc(NULL, struct ctx);
+	list_init(&ctx->lines);
+	fold_text(test->in, test->linelen, fold_line_cb, ctx);
+
+	i = 0;
+	list_for_each_entry(&ctx->lines, line, list) {
+		if (!test->out[i])
+			fail(ctx, test,
+				"fold_text returned more lines than expected");
+
+		if (line->len > test->linelen)
+			fail(ctx, test, "line too long");
+
+		if (line->len != strlen(test->out[i]))
+			fail(ctx, test, "line lengths differ");
+
+		if (strncmp(line->buf, test->out[i], line->len))
+			fail(ctx, test, "line data differs");
+
+		i++;
+	}
+
+	if (test->out[i])
+		fail(ctx, test, "fold_text returned fewer lines than expected");
+
+	talloc_free(ctx);
+}
+
+int main(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(tests); i++)
+		run_test(tests[i]);
+
+	return EXIT_SUCCESS;
+}