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line.c
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line.c
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/*
* Copyright (C) 1984-2005 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"
#include "charset.h"
static char *linebuf = NULL; /* Buffer which holds the current output line */
static char *attr = NULL; /* Extension of linebuf to hold attributes */
public int size_linebuf = 0; /* Size of line buffer (and attr buffer) */
static int cshift; /* Current left-shift of output line buffer */
public int hshift; /* Desired left-shift of output line buffer */
public int tabstops[TABSTOP_MAX] = { 0 }; /* Custom tabstops */
public int ntabstops = 1; /* Number of tabstops */
public int tabdefault = 8; /* Default repeated tabstops */
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 last_overstrike = AT_NORMAL;
static int is_null_line; /* There is no current line */
static int lmargin; /* Left margin */
static int line_matches; /* Number of search matches in this line */
static char pendc;
static POSITION pendpos;
static char *end_ansi_chars;
static char *mid_ansi_chars;
static int attr_swidth();
static int attr_ewidth();
static int do_append();
extern int sigs;
extern int bs_mode;
extern int linenums;
extern int ctldisp;
extern int twiddle;
extern int binattr;
extern int status_col;
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;
extern POSITION start_attnpos;
extern POSITION end_attnpos;
static char mbc_buf[MAX_UTF_CHAR_LEN];
static int mbc_buf_len = 0;
static int mbc_buf_index = 0;
static POSITION mbc_pos;
/*
* 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";
mid_ansi_chars = lgetenv("LESSANSIMIDCHARS");
if (mid_ansi_chars == NULL || *mid_ansi_chars == '\0')
mid_ansi_chars = "0123456789;[?!\"'#%()*+ ";
linebuf = (char *) ecalloc(LINEBUF_SIZE, sizeof(char));
attr = (char *) ecalloc(LINEBUF_SIZE, sizeof(char));
size_linebuf = LINEBUF_SIZE;
}
/*
* Expand the line buffer.
*/
static int
expand_linebuf()
{
/* Double the size of the line buffer. */
int new_size = size_linebuf * 2;
/* Just realloc to expand the buffer, if we can. */
#if HAVE_REALLOC
char *new_buf = (char *) realloc(linebuf, new_size);
char *new_attr = (char *) realloc(attr, new_size);
#else
char *new_buf = (char *) calloc(new_size, sizeof(char));
char *new_attr = (char *) calloc(new_size, sizeof(char));
#endif
if (new_buf == NULL || new_attr == NULL)
{
if (new_attr != NULL)
free(new_attr);
if (new_buf != NULL)
free(new_buf);
return 1;
}
#if HAVE_REALLOC
/*
* We realloc'd the buffers; they already have the old contents.
*/
#if 0
memset(new_buf + size_linebuf, 0, new_size - size_linebuf);
memset(new_attr + size_linebuf, 0, new_size - size_linebuf);
#endif
#else
/*
* We just calloc'd the buffers; copy the old contents.
*/
memcpy(new_buf, linebuf, size_linebuf * sizeof(char));
memcpy(new_attr, attr, size_linebuf * sizeof(char));
free(attr);
free(linebuf);
#endif
linebuf = new_buf;
attr = new_attr;
size_linebuf = new_size;
return 0;
}
/*
* Is a character ASCII?
*/
public int
is_ascii_char(ch)
LWCHAR ch;
{
return (ch <= 0x7F);
}
/*
* Rewind the line buffer.
*/
public void
prewind()
{
curr = 0;
column = 0;
cshift = 0;
overstrike = 0;
last_overstrike = AT_NORMAL;
mbc_buf_len = 0;
is_null_line = 0;
pendc = '\0';
lmargin = 0;
if (status_col)
lmargin += 1;
#if HILITE_SEARCH
line_matches = 0;
#endif
}
/*
* Insert the line number (of the given position) into the line buffer.
*/
public void
plinenum(pos)
POSITION pos;
{
register LINENUM linenum = 0;
register int i;
if (linenums == OPT_ONPLUS)
{
/*
* 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. }}
* {{ Since forw_raw_line modifies linebuf, we must
* do this first, before storing anything in linebuf. }}
*/
linenum = find_linenum(pos);
}
/*
* Display a status column if the -J option is set.
*/
if (status_col)
{
linebuf[curr] = ' ';
if (start_attnpos != NULL_POSITION &&
pos >= start_attnpos && pos < end_attnpos)
attr[curr] = AT_NORMAL|AT_HILITE;
else
attr[curr] = AT_NORMAL;
curr++;
column++;
}
/*
* Display the line number at the start of each line
* if the -N option is set.
*/
if (linenums == OPT_ONPLUS)
{
char buf[INT_STRLEN_BOUND(pos) + 2];
int n;
linenumtoa(linenum, buf);
n = strlen(buf);
if (n < MIN_LINENUM_WIDTH)
n = MIN_LINENUM_WIDTH;
sprintf(linebuf+curr, "%*s ", n, buf);
n++; /* One space after the line number. */
for (i = 0; i < n; i++)
attr[curr+i] = AT_NORMAL;
curr += n;
column += n;
lmargin += n;
}
/*
* Append enough spaces to bring us to the lmargin.
*/
while (column < lmargin)
{
linebuf[curr] = ' ';
attr[curr++] = AT_NORMAL;
column++;
}
}
/*
* Shift the input line left.
* This means discarding N printable chars at the start of the buffer.
*/
static void
pshift(shift)
int shift;
{
LWCHAR prev_ch = 0;
unsigned char c;
int shifted = 0;
int to;
int from;
int len;
int width;
int prev_attr;
int next_attr;
if (shift > column - lmargin)
shift = column - lmargin;
if (shift > curr - lmargin)
shift = curr - lmargin;
to = from = lmargin;
/*
* We keep on going when shifted == shift
* to get all combining chars.
*/
while (shifted <= shift && from < curr)
{
c = linebuf[from];
if (c == ESC && ctldisp == OPT_ONPLUS)
{
/* Keep cumulative effect. */
linebuf[to] = c;
attr[to++] = attr[from++];
while (from < curr && linebuf[from])
{
linebuf[to] = linebuf[from];
attr[to++] = attr[from];
if (!is_ansi_middle(linebuf[from++]))
break;
}
continue;
}
width = 0;
if (!IS_ASCII_OCTET(c) && utf_mode)
{
/* Assumes well-formedness validation already done. */
LWCHAR ch;
len = utf_len(c);
if (from + len > curr)
break;
ch = get_wchar(linebuf + from);
if (!is_composing_char(ch) && !is_combining_char(prev_ch, ch))
width = is_wide_char(ch) ? 2 : 1;
prev_ch = ch;
} else
{
len = 1;
if (c == '\b')
/* XXX - Incorrect if several '\b' in a row. */
width = (utf_mode && is_wide_char(prev_ch)) ? -2 : -1;
else if (!control_char(c))
width = 1;
prev_ch = 0;
}
if (width == 2 && shift - shifted == 1) {
/* Should never happen when called by pshift_all(). */
attr[to] = attr[from];
/*
* Assume a wide_char will never be the first half of a
* combining_char pair, so reset prev_ch in case we're
* followed by a '\b'.
*/
prev_ch = linebuf[to++] = ' ';
from += len;
shifted++;
continue;
}
/* Adjust width for magic cookies. */
prev_attr = (to > 0) ? attr[to-1] : AT_NORMAL;
next_attr = (from + len < curr) ? attr[from + len] : prev_attr;
if (!is_at_equiv(attr[from], prev_attr) &&
!is_at_equiv(attr[from], next_attr))
{
width += attr_swidth(attr[from]);
if (from + len < curr)
width += attr_ewidth(attr[from]);
if (is_at_equiv(prev_attr, next_attr))
{
width += attr_ewidth(prev_attr);
if (from + len < curr)
width += attr_swidth(next_attr);
}
}
if (shift - shifted < width)
break;
from += len;
shifted += width;
if (shifted < 0)
shifted = 0;
}
while (from < curr)
{
linebuf[to] = linebuf[from];
attr[to++] = attr[from++];
}
curr = to;
column -= shifted;
cshift += shifted;
}
/*
*
*/
public void
pshift_all()
{
pshift(column);
}
/*
* Return the printing width of the start (enter) sequence
* for a given character attribute.
*/
static int
attr_swidth(a)
int a;
{
int w = 0;
a = apply_at_specials(a);
if (a & AT_UNDERLINE)
w += ul_s_width;
if (a & AT_BOLD)
w += bo_s_width;
if (a & AT_BLINK)
w += bl_s_width;
if (a & AT_STANDOUT)
w += so_s_width;
return w;
}
/*
* Return the printing width of the end (exit) sequence
* for a given character attribute.
*/
static int
attr_ewidth(a)
int a;
{
int w = 0;
a = apply_at_specials(a);
if (a & AT_UNDERLINE)
w += ul_e_width;
if (a & AT_BOLD)
w += bo_e_width;
if (a & AT_BLINK)
w += bl_e_width;
if (a & AT_STANDOUT)
w += so_e_width;
return w;
}
/*
* 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(ch, a, prev_ch)
LWCHAR ch;
int a;
LWCHAR prev_ch;
{
int w;
if (ch == '\b')
/*
* Backspace moves backwards one or two positions.
* XXX - Incorrect if several '\b' in a row.
*/
return (utf_mode && is_wide_char(prev_ch)) ? -2 : -1;
if (!utf_mode || is_ascii_char(ch))
{
if (control_char((char)ch))
{
/*
* Control characters do unpredictable 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);
}
} else
{
if (is_composing_char(ch) || is_combining_char(prev_ch, ch))
{
/*
* Composing and combining chars take up no space.
*
* Some terminals, upon failure to compose a
* composing character with the character(s) that
* precede(s) it will actually take up one column
* for the composing character; there isn't much
* we could do short of testing the (complex)
* composition process ourselves and printing
* a binary representation when it fails.
*/
return (0);
}
}
/*
* Other characters take one or two columns,
* plus the width of any attribute enter/exit sequence.
*/
w = 1;
if (is_wide_char(ch))
w++;
if (curr > 0 && !is_at_equiv(attr[curr-1], a))
w += attr_ewidth(attr[curr-1]);
if ((apply_at_specials(a) != AT_NORMAL) &&
(curr == 0 || !is_at_equiv(attr[curr-1], a)))
w += attr_swidth(a);
return (w);
}
/*
* Delete to the previous base character in the line buffer.
* Return 1 if one is found.
*/
static int
backc()
{
LWCHAR prev_ch;
char *p = linebuf + curr;
LWCHAR ch = step_char(&p, -1, linebuf + lmargin);
int width;
/* This assumes that there is no '\b' in linebuf. */
while ( curr > lmargin
&& column > lmargin
&& (!(attr[curr - 1] & (AT_ANSI|AT_BINARY))))
{
curr = p - linebuf;
prev_ch = step_char(&p, -1, linebuf + lmargin);
width = pwidth(ch, attr[curr], prev_ch);
column -= width;
if (width > 0)
return 1;
ch = prev_ch;
}
return 0;
}
/*
* Are we currently within a recognized ANSI escape sequence?
*/
static int
in_ansi_esc_seq()
{
char *p;
/*
* 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 (p = &linebuf[curr]; p > linebuf; )
{
LWCHAR ch = step_char(&p, -1, linebuf);
if (ch == ESC)
return (1);
if (!is_ansi_middle(ch))
return (0);
}
return (0);
}
/*
* Is a character the end of an ANSI escape sequence?
*/
public int
is_ansi_end(ch)
LWCHAR ch;
{
if (!is_ascii_char(ch))
return (0);
return (strchr(end_ansi_chars, (char) ch) != NULL);
}
/*
*
*/
public int
is_ansi_middle(ch)
LWCHAR ch;
{
if (!is_ascii_char(ch))
return (0);
if (is_ansi_end(ch))
return (0);
return (strchr(mid_ansi_chars, (char) ch) != NULL);
}
/*
* Append a character and attribute to the line buffer.
*/
#define STORE_CHAR(ch,a,rep,pos) \
do { \
if (store_char((ch),(a),(rep),(pos))) return (1); \
} while (0)
static int
store_char(ch, a, rep, pos)
LWCHAR ch;
int a;
char *rep;
POSITION pos;
{
int w;
int replen;
char cs;
w = (a & (AT_UNDERLINE|AT_BOLD)); /* Pre-use w. */
if (w != AT_NORMAL)
last_overstrike = w;
#if HILITE_SEARCH
{
int matches;
if (is_hilited(pos, pos+1, 0, &matches))
{
/*
* This character should be highlighted.
* Override the attribute passed in.
*/
if (a != AT_ANSI)
a |= AT_HILITE;
}
line_matches += matches;
}
#endif
if (ctldisp == OPT_ONPLUS && in_ansi_esc_seq())
{
if (!is_ansi_end(ch) && !is_ansi_middle(ch)) {
/* Remove whole unrecognized sequence. */
do {
--curr;
} while (linebuf[curr] != ESC);
return 0;
}
a = AT_ANSI; /* Will force re-AT_'ing around it. */
w = 0;
}
else if (ctldisp == OPT_ONPLUS && ch == ESC)
{
a = AT_ANSI; /* Will force re-AT_'ing around it. */
w = 0;
}
else
{
char *p = &linebuf[curr];
LWCHAR prev_ch = step_char(&p, -1, linebuf);
w = pwidth(ch, a, prev_ch);
}
if (ctldisp != OPT_ON && column + w + attr_ewidth(a) > sc_width)
/*
* Won't fit on screen.
*/
return (1);
if (rep == NULL)
{
cs = (char) ch;
rep = &cs;
replen = 1;
} else
{
replen = utf_len(rep[0]);
}
if (curr + replen >= size_linebuf-6)
{
/*
* Won't fit in line buffer.
* Try to expand it.
*/
if (expand_linebuf())
return (1);
}
while (replen-- > 0)
{
linebuf[curr] = *rep++;
attr[curr] = a;
curr++;
}
column += w;
return (0);
}
/*
* Append a tab to the line buffer.
* Store spaces to represent the tab.
*/
#define STORE_TAB(a,pos) \
do { if (store_tab((a),(pos))) return (1); } while (0)
static int
store_tab(attr, pos)
int attr;
POSITION pos;
{
int to_tab = column + cshift - lmargin;
int i;
if (ntabstops < 2 || to_tab >= tabstops[ntabstops-1])
to_tab = tabdefault -
((to_tab - tabstops[ntabstops-1]) % tabdefault);
else
{
for (i = ntabstops - 2; i >= 0; i--)
if (to_tab >= tabstops[i])
break;
to_tab = tabstops[i+1] - to_tab;
}
if (column + to_tab - 1 + pwidth(' ', attr, 0) + attr_ewidth(attr) > sc_width)
return 1;
do {
STORE_CHAR(' ', attr, " ", pos);
} while (--to_tab > 0);
return 0;
}
#define STORE_PRCHAR(c, pos) \
do { if (store_prchar((c), (pos))) return 1; } while (0)
static int
store_prchar(c, pos)
char c;
POSITION pos;
{
char *s;
/*
* Convert to printable representation.
*/
s = prchar(c);
/*
* Make sure we can get the entire representation
* of the character on this line.
*/
if (column + (int) strlen(s) - 1 +
pwidth(' ', binattr, 0) + attr_ewidth(binattr) > sc_width)
return 1;
for ( ; *s != 0; s++)
STORE_CHAR(*s, AT_BINARY, NULL, pos);
return 0;
}
static int
flush_mbc_buf(pos)
POSITION pos;
{
int i;
for (i = 0; i < mbc_buf_index; i++)
if (store_prchar(mbc_buf[i], pos))
return mbc_buf_index - i;
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)
char c;
POSITION pos;
{
int r;
if (pendc)
{
if (do_append(pendc, NULL, 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)
{
if (mbc_buf_len > 0) /* utf_mode must be on. */
{
/* Flush incomplete (truncated) sequence. */
r = flush_mbc_buf(mbc_pos);
mbc_buf_index = r + 1;
mbc_buf_len = 0;
if (r)
return (mbc_buf_index);
}
/*
* 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);
}
if (!utf_mode)
{
r = do_append((LWCHAR) c, NULL, pos);
} else
{
/* Perform strict validation in all possible cases. */
if (mbc_buf_len == 0)
{
retry:
mbc_buf_index = 1;
*mbc_buf = c;
if (IS_ASCII_OCTET(c))
r = do_append((LWCHAR) c, NULL, pos);
else if (IS_UTF8_LEAD(c))
{
mbc_buf_len = utf_len(c);
mbc_pos = pos;
return (0);
} else
/* UTF8_INVALID or stray UTF8_TRAIL */
r = flush_mbc_buf(pos);
} else if (IS_UTF8_TRAIL(c))
{
mbc_buf[mbc_buf_index++] = c;
if (mbc_buf_index < mbc_buf_len)
return (0);
if (is_utf8_well_formed(mbc_buf))
r = do_append(get_wchar(mbc_buf), mbc_buf, mbc_pos);
else
/* Complete, but not shortest form, sequence. */
mbc_buf_index = r = flush_mbc_buf(mbc_pos);
mbc_buf_len = 0;
} else
{
/* Flush incomplete (truncated) sequence. */
r = flush_mbc_buf(mbc_pos);
mbc_buf_index = r + 1;
mbc_buf_len = 0;
/* Handle new char. */
if (!r)
goto retry;
}
}
/*
* 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)
{
linebuf[curr] = '\0';
pshift(hshift - cshift);
}
if (r)
{
/* How many chars should caller back up? */
r = (!utf_mode) ? 1 : mbc_buf_index;
}
return (r);
}
static int
do_append(ch, rep, pos)
LWCHAR ch;
char *rep;
POSITION pos;
{
register int a;
LWCHAR prev_ch;
a = AT_NORMAL;
if (ch == '\b')
{
if (bs_mode == BS_CONTROL)
goto do_control_char;
/*
* A better test is needed here so we don't
* backspace over part of the printed
* representation of a binary character.
*/
if ( curr <= lmargin
|| column <= lmargin
|| (attr[curr - 1] & (AT_ANSI|AT_BINARY)))
STORE_PRCHAR('\b', pos);
else if (bs_mode == BS_NORMAL)
STORE_CHAR(ch, AT_NORMAL, NULL, pos);
else if (bs_mode == BS_SPECIAL)
overstrike = backc();
return 0;
}
if (overstrike > 0)
{
/*
* 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 = utf_mode ? -1 : 0;
/* To be correct, this must be a base character. */
prev_ch = get_wchar(linebuf + curr);
a = attr[curr];
if (ch == prev_ch)
{
/*
* Overstriking a char with itself means make it bold.
* But overstriking an underscore with itself is
* ambiguous. It could mean make it bold, or
* it could mean make it underlined.
* Use the previous overstrike to resolve it.
*/
if (ch == '_')
{
if ((a & (AT_BOLD|AT_UNDERLINE)) != AT_NORMAL)
a |= (AT_BOLD|AT_UNDERLINE);
else if (last_overstrike != AT_NORMAL)
a |= last_overstrike;
else
a |= AT_BOLD;
} else
a |= AT_BOLD;
} else if (ch == '_')
{
a |= AT_UNDERLINE;
ch = prev_ch;
rep = linebuf + curr;
} else if (prev_ch == '_')
{
a |= AT_UNDERLINE;
}
/* Else we replace prev_ch, but we keep its attributes. */
} else if (overstrike < 0)
{
if ( is_composing_char(ch)
|| is_combining_char(get_wchar(linebuf + curr), ch))
/* Continuation of the same overstrike. */
a = last_overstrike;
else
overstrike = 0;
}
if (ch == '\t')
{
/*
* Expand a tab into spaces.
*/
switch (bs_mode)
{
case BS_CONTROL:
goto do_control_char;
case BS_NORMAL:
case BS_SPECIAL:
STORE_TAB(a, pos);
break;
}
} else if ((!utf_mode || is_ascii_char(ch)) && control_char((char)ch))
{
do_control_char:
if (ctldisp == OPT_ON || (ctldisp == OPT_ONPLUS && ch == ESC))
{
/*
* Output as a normal character.
*/
STORE_CHAR(ch, AT_NORMAL, rep, pos);
} else
{
STORE_PRCHAR((char) ch, pos);
}
} else if (utf_mode && ctldisp != OPT_ON && is_ubin_char(ch))
{
char *s;
s = prutfchar(ch);
if (column + (int) strlen(s) - 1 +
pwidth(' ', binattr, 0) + attr_ewidth(binattr) > sc_width)
return (1);
for ( ; *s != 0; s++)
STORE_CHAR(*s, AT_BINARY, NULL, pos);
} else
{
STORE_CHAR(ch, a, rep, pos);
}
return (0);
}
/*
*
*/
public int
pflushmbc()
{
int r = 0;
if (mbc_buf_len > 0)
{
/* Flush incomplete (truncated) sequence. */
r = flush_mbc_buf(mbc_pos);
mbc_buf_len = 0;
}
return r;
}
/*
* Terminate the line in the line buffer.
*/
public void
pdone(endline)
int endline;
{
(void) pflushmbc();
if (pendc && (pendc != '\r' || !endline))
/*