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+/*
+ Dynamic paragraph formatting.
+
+ Copyright (C) 2011-2023
+ Free Software Foundation, Inc.
+
+ Copyright (C) 1996 Paul Sheer
+
+ Written by:
+ Paul Sheer, 1996
+ Andrew Borodin <aborodin@vmail.ru>, 2013, 2014
+
+ This file is part of the Midnight Commander.
+
+ The Midnight Commander is free software: you can redistribute it
+ and/or modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation, either version 3 of the License,
+ or (at your option) any later version.
+
+ The Midnight Commander is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** \file
+ * \brief Source: Dynamic paragraph formatting
+ * \author Paul Sheer
+ * \date 1996
+ * \author Andrew Borodin
+ * \date 2013, 2014
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+#include <sys/stat.h>
+
+#include <stdlib.h>
+
+#include "lib/global.h"
+#include "lib/util.h" /* whitespace() */
+
+#include "edit-impl.h"
+#include "editwidget.h"
+
+/*** global variables ****************************************************************************/
+
+/*** file scope macro definitions ****************************************************************/
+
+#define FONT_MEAN_WIDTH 1
+
+/*** file scope type declarations ****************************************************************/
+
+/*** forward declarations (file scope functions) *************************************************/
+
+/*** file scope variables ************************************************************************/
+
+/* --------------------------------------------------------------------------------------------- */
+/*** file scope functions ************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+static off_t
+line_start (const edit_buffer_t * buf, long line)
+{
+ off_t p;
+ long l;
+
+ l = buf->curs_line;
+ p = buf->curs1;
+
+ if (line < l)
+ p = edit_buffer_get_backward_offset (buf, p, l - line);
+ else if (line > l)
+ p = edit_buffer_get_forward_offset (buf, p, line - l, 0);
+
+ p = edit_buffer_get_bol (buf, p);
+ while (strchr ("\t ", edit_buffer_get_byte (buf, p)) != NULL)
+ p++;
+ return p;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static gboolean
+bad_line_start (const edit_buffer_t * buf, off_t p)
+{
+ int c;
+
+ c = edit_buffer_get_byte (buf, p);
+ if (c == '.')
+ {
+ /* `...' is acceptable */
+ return !(edit_buffer_get_byte (buf, p + 1) == '.'
+ && edit_buffer_get_byte (buf, p + 2) == '.');
+ }
+ if (c == '-')
+ {
+ /* `---' is acceptable */
+ return !(edit_buffer_get_byte (buf, p + 1) == '-'
+ && edit_buffer_get_byte (buf, p + 2) == '-');
+ }
+
+ return (edit_options.stop_format_chars != NULL
+ && strchr (edit_options.stop_format_chars, c) != NULL);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Find the start of the current paragraph for the purpose of formatting.
+ * Return position in the file.
+ */
+
+static off_t
+begin_paragraph (WEdit * edit, gboolean force, long *lines)
+{
+ long i;
+
+ for (i = edit->buffer.curs_line - 1; i >= 0; i--)
+ if (edit_line_is_blank (edit, i) ||
+ (force && bad_line_start (&edit->buffer, line_start (&edit->buffer, i))))
+ {
+ i++;
+ break;
+ }
+
+ *lines = edit->buffer.curs_line - i;
+
+ return edit_buffer_get_backward_offset (&edit->buffer,
+ edit_buffer_get_current_bol (&edit->buffer), *lines);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Find the end of the current paragraph for the purpose of formatting.
+ * Return position in the file.
+ */
+
+static off_t
+end_paragraph (WEdit * edit, gboolean force)
+{
+ long i;
+
+ for (i = edit->buffer.curs_line + 1; i <= edit->buffer.lines; i++)
+ if (edit_line_is_blank (edit, i) ||
+ (force && bad_line_start (&edit->buffer, line_start (&edit->buffer, i))))
+ {
+ i--;
+ break;
+ }
+
+ return edit_buffer_get_eol (&edit->buffer,
+ edit_buffer_get_forward_offset (&edit->buffer,
+ edit_buffer_get_current_bol
+ (&edit->buffer),
+ i - edit->buffer.curs_line, 0));
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static GString *
+get_paragraph (const edit_buffer_t * buf, off_t p, off_t q, gboolean indent)
+{
+ GString *t;
+
+ t = g_string_sized_new (128);
+
+ for (; p < q; p++)
+ {
+ if (indent && edit_buffer_get_byte (buf, p - 1) == '\n')
+ while (strchr ("\t ", edit_buffer_get_byte (buf, p)) != NULL)
+ p++;
+
+ g_string_append_c (t, edit_buffer_get_byte (buf, p));
+ }
+
+ g_string_append_c (t, '\n');
+
+ return t;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static inline void
+strip_newlines (unsigned char *t, off_t size)
+{
+ unsigned char *p;
+
+ for (p = t; size-- != 0; p++)
+ if (*p == '\n')
+ *p = ' ';
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ This function calculates the number of chars in a line specified to length l in pixels
+ */
+
+static inline off_t
+next_tab_pos (off_t x)
+{
+ x += TAB_SIZE - x % TAB_SIZE;
+ return x;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static inline off_t
+line_pixel_length (unsigned char *t, off_t b, off_t l, gboolean utf8)
+{
+ off_t xn, x; /* position counters */
+ off_t char_length = 0; /* character length in bytes */
+
+#ifndef HAVE_CHARSET
+ (void) utf8;
+#endif
+
+ for (xn = 0, x = 0; xn <= l; x = xn)
+ {
+ char *tb;
+
+ b += char_length;
+ tb = (char *) t + b;
+ char_length = 1;
+
+ switch (tb[0])
+ {
+ case '\n':
+ return b;
+ case '\t':
+ xn = next_tab_pos (x);
+ break;
+ default:
+#ifdef HAVE_CHARSET
+ if (utf8)
+ {
+ gunichar ch;
+
+ ch = g_utf8_get_char_validated (tb, -1);
+ if (ch != (gunichar) (-2) && ch != (gunichar) (-1))
+ {
+ char *next_ch;
+
+ /* Calculate UTF-8 char length */
+ next_ch = g_utf8_next_char (tb);
+ char_length = next_ch - tb;
+
+ if (g_unichar_iswide (ch))
+ x++;
+ }
+ }
+#endif
+
+ xn = x + 1;
+ break;
+ }
+ }
+
+ return b;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static off_t
+next_word_start (unsigned char *t, off_t q, off_t size)
+{
+ off_t i;
+ gboolean saw_ws = FALSE;
+
+ for (i = q; i < size; i++)
+ {
+ switch (t[i])
+ {
+ case '\n':
+ return -1;
+ case '\t':
+ case ' ':
+ saw_ws = TRUE;
+ break;
+ default:
+ if (saw_ws)
+ return i;
+ break;
+ }
+ }
+ return (-1);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/** find the start of a word */
+
+static inline int
+word_start (unsigned char *t, off_t q, off_t size)
+{
+ off_t i;
+
+ if (whitespace (t[q]))
+ return next_word_start (t, q, size);
+
+ for (i = q;; i--)
+ {
+ unsigned char c;
+
+ if (i == 0)
+ return (-1);
+ c = t[i - 1];
+ if (c == '\n')
+ return (-1);
+ if (whitespace (c))
+ return i;
+ }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/** replaces ' ' with '\n' to properly format a paragraph */
+
+static inline void
+format_this (unsigned char *t, off_t size, long indent, gboolean utf8)
+{
+ off_t q = 0, ww;
+
+ strip_newlines (t, size);
+ ww = edit_options.word_wrap_line_length * FONT_MEAN_WIDTH - indent;
+ if (ww < FONT_MEAN_WIDTH * 2)
+ ww = FONT_MEAN_WIDTH * 2;
+
+ while (TRUE)
+ {
+ off_t p;
+
+ q = line_pixel_length (t, q, ww, utf8);
+ if (q > size)
+ break;
+ if (t[q] == '\n')
+ break;
+ p = word_start (t, q, size);
+ if (p == -1)
+ q = next_word_start (t, q, size); /* Return the end of the word if the beginning
+ of the word is at the beginning of a line
+ (i.e. a very long word) */
+ else
+ q = p;
+ if (q == -1) /* end of paragraph */
+ break;
+ if (q != 0)
+ t[q - 1] = '\n';
+ }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static inline void
+replace_at (WEdit * edit, off_t q, int c)
+{
+ edit_cursor_move (edit, q - edit->buffer.curs1);
+ edit_delete (edit, TRUE);
+ edit_insert_ahead (edit, c);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static long
+edit_indent_width (const WEdit * edit, off_t p)
+{
+ off_t q = p;
+
+ /* move to the end of the leading whitespace of the line */
+ while (strchr ("\t ", edit_buffer_get_byte (&edit->buffer, q)) != NULL
+ && q < edit->buffer.size - 1)
+ q++;
+ /* count the number of columns of indentation */
+ return (long) edit_move_forward3 (edit, p, 0, q);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+edit_insert_indent (WEdit * edit, long indent)
+{
+ if (!edit_options.fill_tabs_with_spaces)
+ while (indent >= TAB_SIZE)
+ {
+ edit_insert (edit, '\t');
+ indent -= TAB_SIZE;
+ }
+
+ while (indent-- > 0)
+ edit_insert (edit, ' ');
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/** replaces a block of text */
+
+static inline void
+put_paragraph (WEdit * edit, unsigned char *t, off_t p, long indent, off_t size)
+{
+ off_t cursor;
+ off_t i;
+ int c = '\0';
+
+ cursor = edit->buffer.curs1;
+ if (indent != 0)
+ while (strchr ("\t ", edit_buffer_get_byte (&edit->buffer, p)) != NULL)
+ p++;
+ for (i = 0; i < size; i++, p++)
+ {
+ if (i != 0 && indent != 0)
+ {
+ if (t[i - 1] == '\n' && c == '\n')
+ {
+ while (strchr ("\t ", edit_buffer_get_byte (&edit->buffer, p)) != NULL)
+ p++;
+ }
+ else if (t[i - 1] == '\n')
+ {
+ off_t curs;
+
+ edit_cursor_move (edit, p - edit->buffer.curs1);
+ curs = edit->buffer.curs1;
+ edit_insert_indent (edit, indent);
+ if (cursor >= curs)
+ cursor += edit->buffer.curs1 - p;
+ p = edit->buffer.curs1;
+ }
+ else if (c == '\n')
+ {
+ edit_cursor_move (edit, p - edit->buffer.curs1);
+ while (strchr ("\t ", edit_buffer_get_byte (&edit->buffer, p)) != NULL)
+ {
+ edit_delete (edit, TRUE);
+ if (cursor > edit->buffer.curs1)
+ cursor--;
+ }
+ p = edit->buffer.curs1;
+ }
+ }
+
+ c = edit_buffer_get_byte (&edit->buffer, p);
+ if (c != t[i])
+ replace_at (edit, p, t[i]);
+ }
+ edit_cursor_move (edit, cursor - edit->buffer.curs1); /* restore cursor position */
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static inline long
+test_indent (const WEdit * edit, off_t p, off_t q)
+{
+ long indent;
+
+ indent = edit_indent_width (edit, p++);
+ if (indent == 0)
+ return 0;
+
+ for (; p < q; p++)
+ if (edit_buffer_get_byte (&edit->buffer, p - 1) == '\n'
+ && indent != edit_indent_width (edit, p))
+ return 0;
+ return indent;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/*** public functions ****************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+void
+format_paragraph (WEdit * edit, gboolean force)
+{
+ off_t p, q;
+ long lines;
+ off_t size;
+ GString *t;
+ long indent;
+ unsigned char *t2;
+ gboolean utf8 = FALSE;
+
+ if (edit_options.word_wrap_line_length < 2)
+ return;
+ if (edit_line_is_blank (edit, edit->buffer.curs_line))
+ return;
+
+ p = begin_paragraph (edit, force, &lines);
+ q = end_paragraph (edit, force);
+ indent = test_indent (edit, p, q);
+
+ t = get_paragraph (&edit->buffer, p, q, indent != 0);
+ size = t->len - 1;
+
+ if (!force)
+ {
+ off_t i;
+ char *stop_format_chars;
+
+ if (edit_options.stop_format_chars != NULL
+ && strchr (edit_options.stop_format_chars, t->str[0]) != NULL)
+ {
+ g_string_free (t, TRUE);
+ return;
+ }
+
+ if (edit_options.stop_format_chars == NULL || *edit_options.stop_format_chars == '\0')
+ stop_format_chars = g_strdup ("\t");
+ else
+ stop_format_chars = g_strconcat (edit_options.stop_format_chars, "\t", (char *) NULL);
+
+ for (i = 0; i < size - 1; i++)
+ if (t->str[i] == '\n' && strchr (stop_format_chars, t->str[i + 1]) != NULL)
+ {
+ g_free (stop_format_chars);
+ g_string_free (t, TRUE);
+ return;
+ }
+
+ g_free (stop_format_chars);
+ }
+
+ t2 = (unsigned char *) g_string_free (t, FALSE);
+#ifdef HAVE_CHARSET
+ utf8 = edit->utf8;
+#endif
+ format_this (t2, q - p, indent, utf8);
+ put_paragraph (edit, t2, p, indent, size);
+ g_free ((char *) t2);
+
+ /* Scroll left as much as possible to show the formatted paragraph */
+ edit_scroll_left (edit, -edit->start_col);
+}
+
+/* --------------------------------------------------------------------------------------------- */
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