1 files changed, 117 insertions, 0 deletions
diff --git a/term_tab.c b/term_tab.c
new file mode 100644
index 00000000..3e6fa5c1
--- /dev/null
+++ b/term_tab.c
@@ -0,0 +1,117 @@
+/*	$OpenBSD: term.c,v 1.119 2017/01/08 18:08:44 schwarze Exp $ */
+/*
+ * Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include <sys/types.h>
+
+#include <stddef.h>
+
+#include "mandoc_aux.h"
+#include "out.h"
+#include "term.h"
+
+struct tablist {
+	size_t	*t;	/* Allocated array of tab positions. */
+	size_t	 s;	/* Allocated number of positions. */
+	size_t	 n;	/* Currently used number of positions. */
+};
+
+static struct {
+	struct tablist	 a;	/* All tab positions for lookup. */
+	struct tablist	 p;	/* Periodic tab positions to add. */
+	size_t		 d;	/* Default tab width in units of n. */
+} tabs;
+
+
+void
+term_tab_set(const struct termp *p, const char *arg)
+{
+	static int	 recording_period;
+
+	struct roffsu	 su;
+	struct tablist	*tl;
+	size_t		 pos;
+	int		 add;
+
+	/* Special arguments: clear all tabs or switch lists. */
+
+	if (arg == NULL) {
+		tabs.a.n = tabs.p.n = 0;
+		recording_period = 0;
+		if (tabs.d == 0) {
+			a2roffsu(".8i", &su, SCALE_IN);
+			tabs.d = term_hspan(p, &su) / 24;
+		}
+		return;
+	}
+	if (arg[0] == 'T' && arg[1] == '\0') {
+		recording_period = 1;
+		return;
+	}
+
+	/* Parse the sign, the number, and the unit. */
+
+	if (*arg == '+') {
+		add = 1;
+		arg++;
+	} else
+		add = 0;
+	if (a2roffsu(arg, &su, SCALE_EM) == 0)
+		return;
+
+	/* Select the list, and extend it if it is full. */
+
+	tl = recording_period ? &tabs.p : &tabs.a;
+	if (tl->n >= tl->s) {
+		tl->s += 8;
+		tl->t = mandoc_reallocarray(tl->t, tl->s, sizeof(*tl->t));
+	}
+
+	/* Append the new position. */
+
+	pos = term_hspan(p, &su);
+	tl->t[tl->n] = pos;
+	if (add && tl->n)
+		tl->t[tl->n] += tl->t[tl->n - 1];
+	tl->n++;
+}
+
+size_t
+term_tab_next(size_t prev)
+{
+	size_t	 i, j;
+
+	for (i = 0;; i++) {
+		if (i == tabs.a.n) {
+			if (tabs.p.n == 0)
+				return prev;
+/*
+				return i ? prev :
+				    (prev / tabs.d + 1) * tabs.d;
+ */
+			tabs.a.n += tabs.p.n;
+			if (tabs.a.s < tabs.a.n) {
+				tabs.a.s = tabs.a.n;
+				tabs.a.t = mandoc_reallocarray(tabs.a.t,
+				    tabs.a.s, sizeof(*tabs.a.t));
+			}
+			for (j = 0; j < tabs.p.n; j++)
+				tabs.a.t[i + j] = tabs.p.t[j] +
+				    (i ? tabs.a.t[i - 1] : 0);
+		}
+		if (prev < tabs.a.t[i] / 24)
+			return tabs.a.t[i] / 24;
+	}
+}