gno/bin/less/line.c

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/*
* 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.
*/
#pragma noroot
#include "less.h"
#ifdef _ORCAC_
segment "LoadSegONE";
#endif
static char linebuf[1024]; /* Buffer which holds the current output line */
static char attr[1024]; /* 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;
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 sc_width, sc_height;
static int pwidth(int c, int a);
static void backc(void);
static int storec(int c, int a);
static int do_append(int c);
/*
* Rewind the line buffer.
*/
public void
prewind(void)
{
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 != 2)
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(). }}
*/
do
{
linebuf[curr] = ' ';
attr[curr++] = 0;
column++;
} while ((column % tabstop) != 0);
}
/*
* Return the printing width of the start (enter) sequence
* for a given character attribute.
*/
int
attr_swidth(a)
int a;
{
switch (a)
{
case BOLD: return (bo_s_width);
case UNDERLINE: return (ul_s_width);
case BLINK: return (bl_s_width);
}
return (0);
}
/*
* Return the printing width of the end (exit) sequence
* for a given character attribute.
*/
int
attr_ewidth(a)
int a;
{
switch (a)
{
case BOLD: return (bo_e_width);
case UNDERLINE: return (ul_e_width);
case BLINK: return (bl_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 (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(void)
{
curr--;
column -= pwidth(linebuf[curr], attr[curr]);
}
/*
* Append a character and attribute to the line buffer.
*/
static int
storec(c, a)
int c;
int a;
{
register int w;
w = pwidth(c, a);
if (ctldisp > 0 && 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 != NORMAL &&
linebuf[curr-1] == ' ' && attr[curr-1] == NORMAL &&
attr_swidth(a) > 0)
{
/*
* We are about to append an enter-attribute sequence
* just after a space. Delete the space.
*/
attr[curr-1] = INVIS;
column--;
} else if (curr > 0 && attr[curr-1] != NORMAL &&
attr[curr-1] != INVIS && c == ' ' && a == NORMAL &&
attr_ewidth(attr[curr-1]) > 0)
{
/*
* We are about to append a space just after an
* exit-attribute sequence. Delete the space.
*/
a = 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)
register int c;
{
if (pendc)
{
if (do_append(pendc))
/*
* 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 ((c == '\r' || c == '\n') && 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;
return (0);
}
return (do_append(c));
}
static int
do_append(c)
int c;
{
register char *s;
register int a;
#define STOREC(c,a) if (storec((c),(a))) return (1); else curr++
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 (c == linebuf[curr])
STOREC(linebuf[curr], BOLD);
else if (c == '_')
STOREC(linebuf[curr], UNDERLINE);
else if (linebuf[curr] == '_')
STOREC(c, UNDERLINE);
else if (control_char(c))
goto do_control_char;
else
STOREC(c, NORMAL);
} else if (c == '\b')
{
switch (bs_mode)
{
case BS_NORMAL:
STOREC(c, NORMAL);
break;
case BS_CONTROL:
goto do_control_char;
case BS_SPECIAL:
if (curr == 0)
break;
backc();
overstrike = 1;
break;
}
} else if (c == '\t')
{
/*
* Expand a tab into spaces.
*/
do
{
STOREC(' ', NORMAL);
} while ((column % tabstop) != 0);
} else if (control_char(c))
{
do_control_char:
if (ctldisp == 0)
{
/*
* Output as a normal character.
*/
STOREC(c, NORMAL);
} else
{
/*
* Output in the (blinking) ^X format.
*/
s = prchar(c);
a = binattr;
/*
* Make sure we can get the entire representation
* the character on this line.
*/
if (column + strlen(s) +
attr_swidth(a) + attr_ewidth(a) > sc_width)
return (1);
for ( ; *s != 0; s++)
STOREC(*s, a);
}
} else
{
STOREC(c, NORMAL);
}
return (0);
}
/*
* Terminate the line in the line buffer.
*/
public void
pdone(endline)
int endline;
{
/* if (pendc && (pendc != '\r' || !endline)) */
if (pendc && ((pendc != '\n' && pendc != '\n') || !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);
/*
* Add a newline if necessary,
* and append a '\0' to the end of the line.
*/
if (column < sc_width || !auto_wrap || ignaw || ctldisp == 0)
{
/* linebuf[curr] = '\n'; */
linebuf[curr] = '\r';
attr[curr] = NORMAL;
curr++;
}
linebuf[curr] = '\0';
attr[curr] = NORMAL;
}
/*
* 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;
{
if (is_null_line)
{
/*
* If there is no current line, we pretend the line is
* either "~" or "", depending on the "twiddle" flag.
*/
*ap = NORMAL;
if (twiddle)
/* return ("~\n"[i]);
return ("\n"[i]); */
return ("~\r"[i]);
return ("\r"[i]);
}
*ap = attr[i];
return (linebuf[i] & 0377);
}
/*
* Indicate that there is no current line.
*/
public void
null_line(void)
{
is_null_line = 1;
}
/*
* 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) */
if (c == '\r' || 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') */
if (c == '\r' || 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);
}