diff options
Diffstat (limited to 'input.c')
| -rwxr-xr-x | input.c | 457 |
1 files changed, 457 insertions, 0 deletions
@@ -0,0 +1,457 @@ +/* + * Copyright (C) 1984-2012 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, see the README file. + */ + + +/* + * High level routines dealing with getting lines of input + * from the file being viewed. + * + * When we speak of "lines" here, we mean PRINTABLE lines; + * lines processed with respect to the screen width. + * We use the term "raw line" to refer to lines simply + * delimited by newlines; not processed with respect to screen width. + */ + +#include "less.h" + +extern int squeeze; +extern int chopline; +extern int hshift; +extern int quit_if_one_screen; +extern int sigs; +extern int ignore_eoi; +extern int status_col; +extern POSITION start_attnpos; +extern POSITION end_attnpos; +#if HILITE_SEARCH +extern int hilite_search; +extern int size_linebuf; +#endif + +/* + * Get the next line. + * A "current" position is passed and a "new" position is returned. + * The current position is the position of the first character of + * a line. The new position is the position of the first character + * of the NEXT line. The line obtained is the line starting at curr_pos. + */ + public POSITION +forw_line(curr_pos) + POSITION curr_pos; +{ + POSITION base_pos; + POSITION new_pos; + register int c; + int blankline; + int endline; + int backchars; + +get_forw_line: + if (curr_pos == NULL_POSITION) + { + null_line(); + return (NULL_POSITION); + } +#if HILITE_SEARCH + if (hilite_search == OPT_ONPLUS || is_filtering() || status_col) + /* + * If we are ignoring EOI (command F), only prepare + * one line ahead, to avoid getting stuck waiting for + * slow data without displaying the data we already have. + * If we're not ignoring EOI, we *could* do the same, but + * for efficiency we prepare several lines ahead at once. + */ + prep_hilite(curr_pos, curr_pos + 3*size_linebuf, + ignore_eoi ? 1 : -1); +#endif + if (ch_seek(curr_pos)) + { + null_line(); + return (NULL_POSITION); + } + + /* + * Step back to the beginning of the line. + */ + base_pos = curr_pos; + for (;;) + { + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + c = ch_back_get(); + if (c == EOI) + break; + if (c == '\n') + { + (void) ch_forw_get(); + break; + } + --base_pos; + } + + /* + * Read forward again to the position we should start at. + */ + prewind(); + plinenum(base_pos); + (void) ch_seek(base_pos); + new_pos = base_pos; + while (new_pos < curr_pos) + { + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + c = ch_forw_get(); + backchars = pappend(c, new_pos); + new_pos++; + if (backchars > 0) + { + pshift_all(); + new_pos -= backchars; + while (--backchars >= 0) + (void) ch_back_get(); + } + } + (void) pflushmbc(); + pshift_all(); + + /* + * Read the first character to display. + */ + c = ch_forw_get(); + if (c == EOI) + { + null_line(); + return (NULL_POSITION); + } + blankline = (c == '\n' || c == '\r'); + + /* + * Read each character in the line and append to the line buffer. + */ + for (;;) + { + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + if (c == '\n' || c == EOI) + { + /* + * End of the line. + */ + backchars = pflushmbc(); + new_pos = ch_tell(); + if (backchars > 0 && !chopline && hshift == 0) + { + new_pos -= backchars + 1; + endline = FALSE; + } else + endline = TRUE; + break; + } + if (c != '\r') + blankline = 0; + + /* + * Append the char to the line and get the next char. + */ + backchars = pappend(c, ch_tell()-1); + if (backchars > 0) + { + /* + * The char won't fit in the line; the line + * is too long to print in the screen width. + * End the line here. + */ + if (chopline || hshift > 0) + { + do + { + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + c = ch_forw_get(); + } while (c != '\n' && c != EOI); + new_pos = ch_tell(); + endline = TRUE; + quit_if_one_screen = FALSE; + } else + { + new_pos = ch_tell() - backchars; + endline = FALSE; + } + break; + } + c = ch_forw_get(); + } + + pdone(endline, 1); + +#if HILITE_SEARCH + if (is_filtered(base_pos)) + { + /* + * We don't want to display this line. + * Get the next line. + */ + curr_pos = new_pos; + goto get_forw_line; + } + + if (status_col && is_hilited(base_pos, ch_tell()-1, 1, NULL)) + set_status_col('*'); +#endif + + if (squeeze && blankline) + { + /* + * This line is blank. + * Skip down to the last contiguous blank line + * and pretend it is the one which we are returning. + */ + while ((c = ch_forw_get()) == '\n' || c == '\r') + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + if (c != EOI) + (void) ch_back_get(); + new_pos = ch_tell(); + } + + return (new_pos); +} + +/* + * Get the previous line. + * A "current" position is passed and a "new" position is returned. + * The current position is the position of the first character of + * a line. The new position is the position of the first character + * of the PREVIOUS line. The line obtained is the one starting at new_pos. + */ + public POSITION +back_line(curr_pos) + POSITION curr_pos; +{ + POSITION new_pos, begin_new_pos, base_pos; + int c; + int endline; + int backchars; + +get_back_line: + if (curr_pos == NULL_POSITION || curr_pos <= ch_zero()) + { + null_line(); + return (NULL_POSITION); + } +#if HILITE_SEARCH + if (hilite_search == OPT_ONPLUS || is_filtering() || status_col) + prep_hilite((curr_pos < 3*size_linebuf) ? + 0 : curr_pos - 3*size_linebuf, curr_pos, -1); +#endif + if (ch_seek(curr_pos-1)) + { + null_line(); + return (NULL_POSITION); + } + + if (squeeze) + { + /* + * Find out if the "current" line was blank. + */ + (void) ch_forw_get(); /* Skip the newline */ + c = ch_forw_get(); /* First char of "current" line */ + (void) ch_back_get(); /* Restore our position */ + (void) ch_back_get(); + + if (c == '\n' || c == '\r') + { + /* + * The "current" line was blank. + * Skip over any preceding blank lines, + * since we skipped them in forw_line(). + */ + while ((c = ch_back_get()) == '\n' || c == '\r') + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + if (c == EOI) + { + null_line(); + return (NULL_POSITION); + } + (void) ch_forw_get(); + } + } + + /* + * Scan backwards until we hit the beginning of the line. + */ + for (;;) + { + if (ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + c = ch_back_get(); + if (c == '\n') + { + /* + * This is the newline ending the previous line. + * We have hit the beginning of the line. + */ + base_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. + */ + base_pos = ch_tell(); + break; + } + } + + /* + * Now scan forwards from the beginning of this line. + * We keep discarding "printable lines" (based on screen width) + * until we reach the curr_pos. + * + * {{ This algorithm is pretty inefficient if the lines + * are much longer than the screen width, + * but I don't know of any better way. }} + */ + new_pos = base_pos; + if (ch_seek(new_pos)) + { + null_line(); + return (NULL_POSITION); + } + endline = FALSE; + prewind(); + plinenum(new_pos); + loop: + begin_new_pos = new_pos; + (void) ch_seek(new_pos); + + do + { + c = ch_forw_get(); + if (c == EOI || ABORT_SIGS()) + { + null_line(); + return (NULL_POSITION); + } + new_pos++; + if (c == '\n') + { + backchars = pflushmbc(); + if (backchars > 0 && !chopline && hshift == 0) + { + backchars++; + goto shift; + } + endline = TRUE; + break; + } + backchars = pappend(c, ch_tell()-1); + if (backchars > 0) + { + /* + * Got a full printable line, but we haven't + * reached our curr_pos yet. Discard the line + * and start a new one. + */ + if (chopline || hshift > 0) + { + endline = TRUE; + quit_if_one_screen = FALSE; + break; + } + shift: + pshift_all(); + while (backchars-- > 0) + { + (void) ch_back_get(); + new_pos--; + } + goto loop; + } + } while (new_pos < curr_pos); + + pdone(endline, 0); + +#if HILITE_SEARCH + if (is_filtered(base_pos)) + { + /* + * We don't want to display this line. + * Get the previous line. + */ + curr_pos = begin_new_pos; + goto get_back_line; + } + + if (status_col && curr_pos > 0 && is_hilited(base_pos, curr_pos-1, 1, NULL)) + set_status_col('*'); +#endif + + return (begin_new_pos); +} + +/* + * Set attnpos. + */ + public void +set_attnpos(pos) + POSITION pos; +{ + int c; + + if (pos != NULL_POSITION) + { + if (ch_seek(pos)) + return; + for (;;) + { + c = ch_forw_get(); + if (c == EOI) + return; + if (c != '\n' && c != '\r') + break; + pos++; + } + } + start_attnpos = pos; + for (;;) + { + c = ch_forw_get(); + pos++; + if (c == EOI || c == '\n' || c == '\r') + break; + } + end_attnpos = pos; +} |