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-rw-r--r--contrib/less/input.c493
1 files changed, 493 insertions, 0 deletions
diff --git a/contrib/less/input.c b/contrib/less/input.c
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+/*
+ * Copyright (C) 1984-2021 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;
+extern int show_attn;
+#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_seg(curr_pos, get_segpos)
+ POSITION curr_pos;
+ int get_segpos;
+{
+ POSITION base_pos;
+ POSITION new_pos;
+ int c;
+ int blankline;
+ int endline;
+ int chopped;
+ 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);
+ curr_pos = next_unfiltered(curr_pos);
+ }
+#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();
+ plinestart(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.
+ */
+ chopped = FALSE;
+ 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) && !get_segpos)
+ {
+ /* Read to end of line. */
+ 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;
+ chopped = TRUE;
+ } else
+ {
+ new_pos = ch_tell() - backchars;
+ endline = FALSE;
+ }
+ break;
+ }
+ c = ch_forw_get();
+ }
+
+#if HILITE_SEARCH
+ if (blankline && show_attn)
+ {
+ /* Add spurious space to carry possible attn hilite. */
+ pappend(' ', ch_tell()-1);
+ }
+#endif
+ pdone(endline, chopped, 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)
+ {
+ int attr = is_hilited_attr(base_pos, ch_tell()-1, 1, NULL);
+ if (attr)
+ set_status_col('*', attr);
+ }
+#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);
+}
+
+ public POSITION
+forw_line(curr_pos)
+ POSITION curr_pos;
+{
+ return forw_line_seg(curr_pos, FALSE);
+}
+
+/*
+ * 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 chopped;
+ 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();
+ plinestart(new_pos);
+ loop:
+ begin_new_pos = new_pos;
+ (void) ch_seek(new_pos);
+ chopped = FALSE;
+
+ 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;
+ chopped = 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, chopped, 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)
+ {
+ int attr = is_hilited_attr(base_pos, curr_pos-1, 1, NULL);
+ if (attr)
+ set_status_col('*', attr);
+ }
+#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)
+ break;
+ if (c == '\n' || c == '\r')
+ {
+ (void) ch_back_get();
+ break;
+ }
+ pos++;
+ }
+ end_attnpos = pos;
+ for (;;)
+ {
+ c = ch_back_get();
+ if (c == EOI || c == '\n' || c == '\r')
+ break;
+ pos--;
+ }
+ }
+ start_attnpos = pos;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 11:25:26 +0000