Import the [now] dual licensed version 3.5.4 of less. It is

distributed under your choice of the GPL or a BSD style license.

Reviewed by:	peter
Obtained from:	http://home.flash.net/~marknu/less/

1 files changed, 696 insertions, 0 deletions

diff --git a/contrib/less/line.c b/contrib/less/line.c
new file mode 100644
index 0000000..6632940
--- /dev/null
+++ b/contrib/less/line.c
@@ -0,0 +1,696 @@
+/*
+ * Copyright (C) 1984-2000  Mark Nudelman
+ *
+ * You may distribute under the terms of either the GNU General Public
+ * License or the Less License, as specified in the README file.
+ *
+ * For more information about less, or for information on how to 
+ * contact the author, see the README file.
+ */
+
+
+/*
+ * Routines to manipulate the "line buffer".
+ * The line buffer holds a line of output as it is being built
+ * in preparation for output to the screen.
+ */
+
+#include "less.h"
+
+#define IS_CONT(c)  (((c) & 0xC0) == 0x80)
+
+/* Buffer which holds the current output line */
+public char linebuf[LINEBUF_SIZE];
+public int size_linebuf = sizeof(linebuf);
+
+public int cshift;		/* Current left-shift of output line buffer */
+public int hshift;		/* Desired left-shift of output line buffer */
+
+static char attr[LINEBUF_SIZE];	/* Extension of linebuf to hold attributes */
+static int curr;		/* Index into linebuf */
+static int column;		/* Printable length, accounting for
+				   backspaces, etc. */
+static int overstrike;		/* Next char should overstrike previous char */
+static int is_null_line;	/* There is no current line */
+static char pendc;
+static POSITION pendpos;
+static char *end_ansi_chars;
+
+static int do_append();
+
+extern int bs_mode;
+extern int tabstop;
+extern int linenums;
+extern int ctldisp;
+extern int twiddle;
+extern int binattr;
+extern int auto_wrap, ignaw;
+extern int bo_s_width, bo_e_width;
+extern int ul_s_width, ul_e_width;
+extern int bl_s_width, bl_e_width;
+extern int so_s_width, so_e_width;
+extern int sc_width, sc_height;
+extern int utf_mode;
+
+/*
+ * Initialize from environment variables.
+ */
+	public void
+init_line()
+{
+	end_ansi_chars = lgetenv("LESSANSIENDCHARS");
+	if (end_ansi_chars == NULL || *end_ansi_chars == '\0')
+		end_ansi_chars = "m";
+}
+
+/*
+ * Rewind the line buffer.
+ */
+	public void
+prewind()
+{
+	curr = 0;
+	column = 0;
+	overstrike = 0;
+	is_null_line = 0;
+	pendc = '\0';
+}
+
+/*
+ * Insert the line number (of the given position) into the line buffer.
+ */
+	public void
+plinenum(pos)
+	POSITION pos;
+{
+	register int lno;
+	register int i;
+	register int n;
+
+	/*
+	 * We display the line number at the start of each line
+	 * only if the -N option is set.
+	 */
+	if (linenums != OPT_ONPLUS)
+		return;
+
+	/*
+	 * Get the line number and put it in the current line.
+	 * {{ Note: since find_linenum calls forw_raw_line,
+	 *    it may seek in the input file, requiring the caller 
+	 *    of plinenum to re-seek if necessary. }}
+	 */
+	lno = find_linenum(pos);
+
+	sprintf(&linebuf[curr], "%6d", lno);
+	n = strlen(&linebuf[curr]);
+	column += n;
+	for (i = 0;  i < n;  i++)
+		attr[curr++] = 0;
+
+	/*
+	 * Append enough spaces to bring us to the next tab stop.
+	 * {{ We could avoid this at the cost of adding some
+	 *    complication to the tab stop logic in pappend(). }}
+	 */
+	if (tabstop == 0)
+		tabstop = 1;
+	do
+	{
+		linebuf[curr] = ' ';
+		attr[curr++] = AT_NORMAL;
+		column++;
+	} while (((column + cshift) % tabstop) != 0);
+}
+
+/*
+ *
+ */
+	static int
+utf_len(char *s, int len)
+{
+	int ulen = 0;
+
+	while (*s != '\0' && len > 0)
+	{
+		if (!IS_CONT(*s))
+			len--;
+		s++;
+		ulen++;
+	}
+	while (IS_CONT(*s))
+	{
+		s++;
+		ulen++;
+	}
+	return (ulen);
+}
+
+/*
+ * Shift the input line left.
+ * This means discarding N printable chars at the start of the buffer.
+ */
+	static void
+pshift(shift)
+	int shift;
+{
+	int i;
+	int real_shift;
+
+	if (shift > column)
+		shift = column;
+	if (shift > curr)
+		shift = curr;
+
+	if (!utf_mode)
+		real_shift = shift;
+	else
+	{
+		real_shift = utf_len(linebuf, shift);
+		if (real_shift > curr)
+			real_shift = curr;
+	}
+	for (i = 0;  i < curr - real_shift;  i++)
+	{
+		linebuf[i] = linebuf[i + real_shift];
+		attr[i] = attr[i + real_shift];
+	}
+	column -= shift;
+	curr -= real_shift;
+	cshift += shift;
+}
+
+/*
+ * Return the printing width of the start (enter) sequence
+ * for a given character attribute.
+ */
+	static int
+attr_swidth(a)
+	int a;
+{
+	switch (a)
+	{
+	case AT_BOLD:		return (bo_s_width);
+	case AT_UNDERLINE:	return (ul_s_width);
+	case AT_BLINK:		return (bl_s_width);
+	case AT_STANDOUT:	return (so_s_width);
+	}
+	return (0);
+}
+
+/*
+ * Return the printing width of the end (exit) sequence
+ * for a given character attribute.
+ */
+	static int
+attr_ewidth(a)
+	int a;
+{
+	switch (a)
+	{
+	case AT_BOLD:		return (bo_e_width);
+	case AT_UNDERLINE:	return (ul_e_width);
+	case AT_BLINK:		return (bl_e_width);
+	case AT_STANDOUT:	return (so_e_width);
+	}
+	return (0);
+}
+
+/*
+ * Return the printing width of a given character and attribute,
+ * if the character were added to the current position in the line buffer.
+ * Adding a character with a given attribute may cause an enter or exit
+ * attribute sequence to be inserted, so this must be taken into account.
+ */
+	static int
+pwidth(c, a)
+	int c;
+	int a;
+{
+	register int w;
+
+	if (utf_mode && IS_CONT(c))
+		return (0);
+
+	if (c == '\b')
+		/*
+		 * Backspace moves backwards one position.
+		 */
+		return (-1);
+
+	if (control_char(c))
+		/*
+		 * Control characters do unpredicatable things,
+		 * so we don't even try to guess; say it doesn't move.
+		 * This can only happen if the -r flag is in effect.
+		 */
+		return (0);
+
+	/*
+	 * Other characters take one space,
+	 * plus the width of any attribute enter/exit sequence.
+	 */
+	w = 1;
+	if (curr > 0 && attr[curr-1] != a)
+		w += attr_ewidth(attr[curr-1]);
+	if (a && (curr == 0 || attr[curr-1] != a))
+		w += attr_swidth(a);
+	return (w);
+}
+
+/*
+ * Delete the previous character in the line buffer.
+ */
+	static void
+backc()
+{
+	curr--;
+	column -= pwidth(linebuf[curr], attr[curr]);
+}
+
+/*
+ * Are we currently within a recognized ANSI escape sequence?
+ */
+	static int
+in_ansi_esc_seq()
+{
+	int i;
+
+	/*
+	 * Search backwards for either an ESC (which means we ARE in a seq);
+	 * or an end char (which means we're NOT in a seq).
+	 */
+	for (i = curr-1;  i >= 0;  i--)
+	{
+		if (linebuf[i] == ESC)
+			return (1);
+		if (strchr(end_ansi_chars, linebuf[i]) != NULL)
+			return (0);
+	}
+	return (0);
+}
+
+/*
+ * Append a character and attribute to the line buffer.
+ */
+	static int
+storec(c, a, pos)
+	int c;
+	int a;
+	POSITION pos;
+{
+	register int w;
+
+#if HILITE_SEARCH
+	if (is_hilited(pos, pos+1, 0))
+		/*
+		 * This character should be highlighted.
+		 * Override the attribute passed in.
+		 */
+		a = AT_STANDOUT;
+#endif
+	if (ctldisp == OPT_ONPLUS && in_ansi_esc_seq())
+		w = 0;
+	else
+		w = pwidth(c, a);
+	if (ctldisp != OPT_ON && column + w + attr_ewidth(a) > sc_width)
+		/*
+		 * Won't fit on screen.
+		 */
+		return (1);
+
+	if (curr >= sizeof(linebuf)-2)
+		/*
+		 * Won't fit in line buffer.
+		 */
+		return (1);
+
+	/*
+	 * Special handling for "magic cookie" terminals.
+	 * If an attribute enter/exit sequence has a printing width > 0,
+	 * and the sequence is adjacent to a space, delete the space.
+	 * We just mark the space as invisible, to avoid having too
+	 * many spaces deleted.
+	 * {{ Note that even if the attribute width is > 1, we
+	 *    delete only one space.  It's not worth trying to do more.
+	 *    It's hardly worth doing this much. }}
+	 */
+	if (curr > 0 && a != AT_NORMAL && 
+		linebuf[curr-1] == ' ' && attr[curr-1] == AT_NORMAL &&
+		attr_swidth(a) > 0)
+	{
+		/*
+		 * We are about to append an enter-attribute sequence
+		 * just after a space.  Delete the space.
+		 */
+		attr[curr-1] = AT_INVIS;
+		column--;
+	} else if (curr > 0 && attr[curr-1] != AT_NORMAL && 
+		attr[curr-1] != AT_INVIS && c == ' ' && a == AT_NORMAL &&
+		attr_ewidth(attr[curr-1]) > 0)
+	{
+		/*
+		 * We are about to append a space just after an 
+		 * exit-attribute sequence.  Delete the space.
+		 */
+		a = AT_INVIS;
+		column--;
+	}
+	/* End of magic cookie handling. */
+
+	linebuf[curr] = c;
+	attr[curr] = a;
+	column += w;
+	return (0);
+}
+
+/*
+ * Append a character to the line buffer.
+ * Expand tabs into spaces, handle underlining, boldfacing, etc.
+ * Returns 0 if ok, 1 if couldn't fit in buffer.
+ */
+	public int
+pappend(c, pos)
+	register int c;
+	POSITION pos;
+{
+	int r;
+
+	if (pendc)
+	{
+		if (do_append(pendc, pendpos))
+			/*
+			 * Oops.  We've probably lost the char which
+			 * was in pendc, since caller won't back up.
+			 */
+			return (1);
+		pendc = '\0';
+	}
+
+	if (c == '\r' && bs_mode == BS_SPECIAL)
+	{
+		/*
+		 * Don't put the CR into the buffer until we see 
+		 * the next char.  If the next char is a newline,
+		 * discard the CR.
+		 */
+		pendc = c;
+		pendpos = pos;
+		return (0);
+	}
+
+	r = do_append(c, pos);
+	/*
+	 * If we need to shift the line, do it.
+	 * But wait until we get to at least the middle of the screen,
+	 * so shifting it doesn't affect the chars we're currently
+	 * pappending.  (Bold & underline can get messed up otherwise.)
+	 */
+	if (cshift < hshift && column > sc_width / 2)
+		pshift(hshift - cshift);
+	return (r);
+}
+
+	static int
+do_append(c, pos)
+	int c;
+	POSITION pos;
+{
+	register char *s;
+	register int a;
+
+#define	STOREC(c,a) \
+	if (storec((c),(a),pos)) return (1); else curr++
+
+	if (c == '\b')
+	{
+		switch (bs_mode)
+		{
+		case BS_NORMAL:
+			STOREC(c, AT_NORMAL);
+			break;
+		case BS_CONTROL:
+			goto do_control_char;
+		case BS_SPECIAL:
+			if (curr == 0)
+				break;
+			backc();
+			overstrike = 1;
+			break;
+		}
+	} else if (overstrike)
+	{
+		/*
+		 * Overstrike the character at the current position
+		 * in the line buffer.  This will cause either 
+		 * underline (if a "_" is overstruck), 
+		 * bold (if an identical character is overstruck),
+		 * or just deletion of the character in the buffer.
+		 */
+		overstrike = 0;
+		if ((char)c == linebuf[curr])
+			STOREC(linebuf[curr], AT_BOLD);
+		else if (c == '_')
+			STOREC(linebuf[curr], AT_UNDERLINE);
+		else if (linebuf[curr] == '_')
+			STOREC(c, AT_UNDERLINE);
+		else if (control_char(c))
+			goto do_control_char;
+		else
+			STOREC(c, AT_NORMAL);
+	} else if (c == '\t') 
+	{
+		/*
+		 * Expand a tab into spaces.
+		 */
+		if (tabstop == 0)
+			tabstop = 1;
+		switch (bs_mode)
+		{
+		case BS_CONTROL:
+			goto do_control_char;
+		case BS_NORMAL:
+		case BS_SPECIAL:
+			do
+			{
+				STOREC(' ', AT_NORMAL);
+			} while (((column + cshift) % tabstop) != 0);
+			break;
+		}
+	} else if (control_char(c))
+	{
+	do_control_char:
+		if (ctldisp == OPT_ON || (ctldisp == OPT_ONPLUS && c == ESC))
+		{
+			/*
+			 * Output as a normal character.
+			 */
+			STOREC(c, AT_NORMAL);
+		} else 
+		{
+			/*
+			 * Convert to printable representation.
+			 */
+			s = prchar(c);  
+			a = binattr;
+
+			/*
+			 * Make sure we can get the entire representation
+			 * of the character on this line.
+			 */
+			if (column + (int) strlen(s) + 
+			    attr_swidth(a) + attr_ewidth(a) > sc_width)
+				return (1);
+
+			for ( ;  *s != 0;  s++)
+				STOREC(*s, a);
+		}
+	} else
+	{
+		STOREC(c, AT_NORMAL);
+	}
+
+	return (0);
+}
+
+/*
+ * Terminate the line in the line buffer.
+ */
+	public void
+pdone(endline)
+	int endline;
+{
+	if (pendc && (pendc != '\r' || !endline))
+		/*
+		 * If we had a pending character, put it in the buffer.
+		 * But discard a pending CR if we are at end of line
+		 * (that is, discard the CR in a CR/LF sequence).
+		 */
+		(void) do_append(pendc, pendpos);
+
+	/*
+	 * Make sure we've shifted the line, if we need to.
+	 */
+	if (cshift < hshift)
+		pshift(hshift - cshift);
+
+	/*
+	 * Add a newline if necessary,
+	 * and append a '\0' to the end of the line.
+	 */
+	if (column < sc_width || !auto_wrap || ignaw || ctldisp == OPT_ON)
+	{
+		linebuf[curr] = '\n';
+		attr[curr] = AT_NORMAL;
+		curr++;
+	}
+	linebuf[curr] = '\0';
+	attr[curr] = AT_NORMAL;
+	/*
+	 * If we are done with this line, reset the current shift.
+	 */
+	if (endline)
+		cshift = 0;
+}
+
+/*
+ * Get a character from the current line.
+ * Return the character as the function return value,
+ * and the character attribute in *ap.
+ */
+	public int
+gline(i, ap)
+	register int i;
+	register int *ap;
+{
+	char *s;
+	
+	if (is_null_line)
+	{
+		/*
+		 * If there is no current line, we pretend the line is
+		 * either "~" or "", depending on the "twiddle" flag.
+		 */
+		*ap = AT_BOLD;
+		s = (twiddle) ? "~\n" : "\n";
+		return (s[i]);
+	}
+
+	*ap = attr[i];
+	return (linebuf[i] & 0377);
+}
+
+/*
+ * Indicate that there is no current line.
+ */
+	public void
+null_line()
+{
+	is_null_line = 1;
+	cshift = 0;
+}
+
+/*
+ * Analogous to forw_line(), but deals with "raw lines":
+ * lines which are not split for screen width.
+ * {{ This is supposed to be more efficient than forw_line(). }}
+ */
+	public POSITION
+forw_raw_line(curr_pos, linep)
+	POSITION curr_pos;
+	char **linep;
+{
+	register char *p;
+	register int c;
+	POSITION new_pos;
+
+	if (curr_pos == NULL_POSITION || ch_seek(curr_pos) ||
+		(c = ch_forw_get()) == EOI)
+		return (NULL_POSITION);
+
+	p = linebuf;
+
+	for (;;)
+	{
+		if (c == '\n' || c == EOI)
+		{
+			new_pos = ch_tell();
+			break;
+		}
+		if (p >= &linebuf[sizeof(linebuf)-1])
+		{
+			/*
+			 * Overflowed the input buffer.
+			 * Pretend the line ended here.
+			 * {{ The line buffer is supposed to be big
+			 *    enough that this never happens. }}
+			 */
+			new_pos = ch_tell() - 1;
+			break;
+		}
+		*p++ = c;
+		c = ch_forw_get();
+	}
+	*p = '\0';
+	if (linep != NULL)
+		*linep = linebuf;
+	return (new_pos);
+}
+
+/*
+ * Analogous to back_line(), but deals with "raw lines".
+ * {{ This is supposed to be more efficient than back_line(). }}
+ */
+	public POSITION
+back_raw_line(curr_pos, linep)
+	POSITION curr_pos;
+	char **linep;
+{
+	register char *p;
+	register int c;
+	POSITION new_pos;
+
+	if (curr_pos == NULL_POSITION || curr_pos <= ch_zero() ||
+		ch_seek(curr_pos-1))
+		return (NULL_POSITION);
+
+	p = &linebuf[sizeof(linebuf)];
+	*--p = '\0';
+
+	for (;;)
+	{
+		c = ch_back_get();
+		if (c == '\n')
+		{
+			/*
+			 * This is the newline ending the previous line.
+			 * We have hit the beginning of the line.
+			 */
+			new_pos = ch_tell() + 1;
+			break;
+		}
+		if (c == EOI)
+		{
+			/*
+			 * We have hit the beginning of the file.
+			 * This must be the first line in the file.
+			 * This must, of course, be the beginning of the line.
+			 */
+			new_pos = ch_zero();
+			break;
+		}
+		if (p <= linebuf)
+		{
+			/*
+			 * Overflowed the input buffer.
+			 * Pretend the line ended here.
+			 */
+			new_pos = ch_tell() + 1;
+			break;
+		}
+		*--p = c;
+	}
+	if (linep != NULL)
+		*linep = p;
+	return (new_pos);
+}