--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/miscellany/less-177/mark.c	Mon Apr 18 23:46:02 2005 +0900
@@ -0,0 +1,237 @@
+#include "less.h"
+#include "position.h"
+
+extern IFILE curr_ifile;
+extern int sc_height;
+extern int jump_sline;
+
+/*
+ * A mark is an ifile (input file) plus a position within the file.
+ */
+struct mark {
+	IFILE m_ifile;
+	struct scrpos m_scrpos;
+};
+
+/*
+ * The table of marks.
+ * Each mark is identified by a lowercase or uppercase letter.
+ */
+#define	NMARKS		(2*26)		/* a-z, A-Z */
+static struct mark marks[NMARKS];
+
+/*
+ * Special mark for the "last mark"; addressed by the apostrophe.
+ */
+static struct mark lmark;
+
+/*
+ * Initialize the mark table to show no marks are set.
+ */
+	public void
+init_mark()
+{
+	int i;
+
+	for (i = 0;  i < NMARKS;  i++)
+		marks[i].m_scrpos.pos = NULL_POSITION;
+	lmark.m_scrpos.pos = NULL_POSITION;
+}
+
+/*
+ * See if a mark letter is valid (between a and z).
+ */
+	static struct mark *
+getumark(c)
+	int c;
+{
+	if (c >= 'a' && c <= 'z')
+		return (&marks[c-'a']);
+
+	if (c >= 'A' && c <= 'Z')
+		return (&marks[c-'A'+26]);
+
+	error("Invalid mark letter", NULL_PARG);
+	return (NULL);
+}
+
+/*
+ * Get the mark structure identified by a character.
+ * The mark struct may come either from the mark table
+ * or may be constructed on the fly for certain characters like ^, $.
+ */
+	static struct mark *
+getmark(c)
+	int c;
+{
+	register struct mark *m;
+	static struct mark sm;
+
+	switch (c)
+	{
+	case '^':
+		/*
+		 * Beginning of the current file.
+		 */
+		m = &sm;
+		m->m_scrpos.pos = ch_zero();
+		m->m_scrpos.ln = 0;
+		m->m_ifile = curr_ifile;
+		break;
+	case '$':
+		/*
+		 * End of the current file.
+		 */
+		if (ch_end_seek())
+		{
+			error("Cannot seek to end of file", NULL_PARG);
+			return (NULL);
+		}
+		m = &sm;
+		m->m_scrpos.pos = ch_tell();
+		m->m_scrpos.ln = sc_height-1;
+		m->m_ifile = curr_ifile;
+		break;
+	case '.':
+		/*
+		 * Current position in the current file.
+		 */
+		m = &sm;
+		m->m_scrpos.pos = ch_tell();
+		m->m_scrpos.ln = 0;
+		m->m_ifile = curr_ifile;
+		break;
+	case '\'':
+		/*
+		 * The "last mark".
+		 */
+		m = &lmark;
+		break;
+	default:
+		/*
+		 * Must be a user-defined mark.
+		 */
+		m = getumark(c);
+		if (m == NULL)
+			break;
+		if (m->m_scrpos.pos == NULL_POSITION)
+		{
+			error("Mark not set", NULL_PARG);
+			return (NULL);
+		}
+		break;
+	}
+	return (m);
+}
+
+/*
+ * Is a mark letter is invalid?
+ */
+	public int
+badmark(c)
+	int c;
+{
+	return (getmark(c) == NULL);
+}
+
+/*
+ * Set a user-defined mark.
+ */
+	public void
+setmark(c)
+	int c;
+{
+	register struct mark *m;
+	struct scrpos scrpos;
+
+	m = getumark(c);
+	if (m == NULL)
+		return;
+	get_scrpos(&scrpos);
+	m->m_scrpos = scrpos;
+	m->m_ifile = curr_ifile;
+}
+
+/*
+ * Set lmark (the mark named by the apostrophe).
+ */
+	public void
+lastmark()
+{
+	struct scrpos scrpos;
+
+	get_scrpos(&scrpos);
+	if (scrpos.pos == NULL_POSITION)
+		return;
+	lmark.m_scrpos = scrpos;
+	lmark.m_ifile = curr_ifile;
+}
+
+/*
+ * Go to a mark.
+ */
+	public void
+gomark(c)
+	int c;
+{
+	register struct mark *m;
+	struct scrpos scrpos;
+
+	m = getmark(c);
+	if (m == NULL)
+		return;
+
+	/*
+	 * If we're trying to go to the lastmark and 
+	 * it has not been set to anything yet,
+	 * set it to the beginning of the current file.
+	 */
+	if (m == &lmark && m->m_scrpos.pos == NULL_POSITION)
+	{
+		m->m_ifile = curr_ifile;
+		m->m_scrpos.pos = ch_zero();
+		m->m_scrpos.ln = jump_sline;
+	}
+
+	/*
+	 * If we're using lmark, we must save the screen position now,
+	 * because if we call edit() below, lmark will change.
+	 * (We save the screen position even if we're not using lmark.)
+	 */
+	scrpos = m->m_scrpos;
+	if (m->m_ifile != curr_ifile)
+	{
+		/*
+		 * Not in the current file; edit the correct file.
+		 */
+		if (edit(get_filename(m->m_ifile), 0))
+			return;
+	}
+
+	jump_loc(scrpos.pos, scrpos.ln);
+}
+
+/*
+ * Return the position associated with a given mark letter.
+ *
+ * We don't return which screen line the position 
+ * is associated with, but this doesn't matter much,
+ * because it's always the first non-blank line on the screen.
+ */
+	public POSITION
+markpos(c)
+	int c;
+{
+	register struct mark *m;
+
+	m = getmark(c);
+	if (m == NULL)
+		return (NULL_POSITION);
+
+	if (m->m_ifile != curr_ifile)
+	{
+		error("Mark not in current file", NULL_PARG);
+		return (NULL_POSITION);
+	}
+	return (m->m_scrpos.pos);
+}