Vim使用什么算法将段落分成段落填充（gq）？
它是一个简单的贪婪算法，就像在Emacs中使用的算法，或者像TeX中使用的更复杂的算法？
最重要的是，我在哪里查看源代码以确认使用的算法？
答案 0 :(得分：6)
您可以获取vim的源代码here。下载该格式并且格式化功能位于vim/src/ops.c line: 4710。您可能还想查看par。
format_lines(line_count, avoid_fex)
linenr_T line_count;
int avoid_fex; /* don't use 'formatexpr' */
{
int max_len;
int is_not_par; /* current line not part of parag. */
int next_is_not_par; /* next line not part of paragraph */
int is_end_par; /* at end of paragraph */
int prev_is_end_par = FALSE;/* prev. line not part of parag. */
int next_is_start_par = FALSE;
#ifdef FEAT_COMMENTS
int leader_len = 0; /* leader len of current line */
int next_leader_len; /* leader len of next line */
char_u *leader_flags = NULL; /* flags for leader of current line */
char_u *next_leader_flags; /* flags for leader of next line */
int do_comments; /* format comments */
int do_comments_list = 0; /* format comments with 'n' or '2' */
#endif
int advance = TRUE;
int second_indent = -1; /* indent for second line (comment
* aware) */
int do_second_indent;
int do_number_indent;
int do_trail_white;
int first_par_line = TRUE;
int smd_save;
long count;
int need_set_indent = TRUE; /* set indent of next paragraph */
int force_format = FALSE;
int old_State = State;
/* length of a line to force formatting: 3 * 'tw' */
max_len = comp_textwidth(TRUE) * 3;
/* check for 'q', '2' and '1' in 'formatoptions' */
#ifdef FEAT_COMMENTS
do_comments = has_format_option(FO_Q_COMS);
#endif
do_second_indent = has_format_option(FO_Q_SECOND);
do_number_indent = has_format_option(FO_Q_NUMBER);
do_trail_white = has_format_option(FO_WHITE_PAR);
/*
* Get info about the previous and current line.
*/
if (curwin->w_cursor.lnum > 1)
is_not_par = fmt_check_par(curwin->w_cursor.lnum - 1
#ifdef FEAT_COMMENTS
, &leader_len, &leader_flags, do_comments
#endif
);
else
is_not_par = TRUE;
next_is_not_par = fmt_check_par(curwin->w_cursor.lnum
#ifdef FEAT_COMMENTS
, &next_leader_len, &next_leader_flags, do_comments
#endif
);
is_end_par = (is_not_par || next_is_not_par);
if (!is_end_par && do_trail_white)
is_end_par = !ends_in_white(curwin->w_cursor.lnum - 1);
curwin->w_cursor.lnum--;
for (count = line_count; count != 0 && !got_int; --count)
{
/*
* Advance to next paragraph.
*/
if (advance)
{
curwin->w_cursor.lnum++;
prev_is_end_par = is_end_par;
is_not_par = next_is_not_par;
#ifdef FEAT_COMMENTS
leader_len = next_leader_len;
leader_flags = next_leader_flags;
#endif
}
/*
* The last line to be formatted.
*/
if (count == 1 || curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count)
{
next_is_not_par = TRUE;
#ifdef FEAT_COMMENTS
next_leader_len = 0;
next_leader_flags = NULL;
#endif
}
else
{
next_is_not_par = fmt_check_par(curwin->w_cursor.lnum + 1
#ifdef FEAT_COMMENTS
, &next_leader_len, &next_leader_flags, do_comments
#endif
);
if (do_number_indent)
next_is_start_par =
(get_number_indent(curwin->w_cursor.lnum + 1) > 0);
}
advance = TRUE;
is_end_par = (is_not_par || next_is_not_par || next_is_start_par);
if (!is_end_par && do_trail_white)
is_end_par = !ends_in_white(curwin->w_cursor.lnum);
/*
* Skip lines that are not in a paragraph.
*/
if (is_not_par)
{
if (line_count < 0)
break;
}
else
{
/*
* For the first line of a paragraph, check indent of second line.
* Don't do this for comments and empty lines.
*/
if (first_par_line
&& (do_second_indent || do_number_indent)
&& prev_is_end_par
&& curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
{
if (do_second_indent && !lineempty(curwin->w_cursor.lnum + 1))
{
#ifdef FEAT_COMMENTS
if (leader_len == 0 && next_leader_len == 0)
{
/* no comment found */
#endif
second_indent =
get_indent_lnum(curwin->w_cursor.lnum + 1);
#ifdef FEAT_COMMENTS
}
else
{
second_indent = next_leader_len;
do_comments_list = 1;
}
#endif
}
else if (do_number_indent)
{
#ifdef FEAT_COMMENTS
if (leader_len == 0 && next_leader_len == 0)
{
/* no comment found */
#endif
second_indent =
get_number_indent(curwin->w_cursor.lnum);
#ifdef FEAT_COMMENTS
}
else
{
/* get_number_indent() is now "comment aware"... */
second_indent =
get_number_indent(curwin->w_cursor.lnum);
do_comments_list = 1;
}
#endif
}
}
/*
* When the comment leader changes, it's the end of the paragraph.
*/
if (curwin->w_cursor.lnum >= curbuf->b_ml.ml_line_count
#ifdef FEAT_COMMENTS
|| !same_leader(curwin->w_cursor.lnum,
leader_len, leader_flags,
next_leader_len, next_leader_flags)
#endif
)
is_end_par = TRUE;
/*
* If we have got to the end of a paragraph, or the line is
* getting long, format it.
*/
if (is_end_par || force_format)
{
if (need_set_indent)
/* replace indent in first line with minimal number of
* tabs and spaces, according to current options */
(void)set_indent(get_indent(), SIN_CHANGED);
/* put cursor on last non-space */
State = NORMAL; /* don't go past end-of-line */
coladvance((colnr_T)MAXCOL);
while (curwin->w_cursor.col && vim_isspace(gchar_cursor()))
dec_cursor();
/* do the formatting, without 'showmode' */
State = INSERT; /* for open_line() */
smd_save = p_smd;
p_smd = FALSE;
insertchar(NUL, INSCHAR_FORMAT
#ifdef FEAT_COMMENTS
+ (do_comments ? INSCHAR_DO_COM : 0)
+ (do_comments && do_comments_list
? INSCHAR_COM_LIST : 0)
#endif
+ (avoid_fex ? INSCHAR_NO_FEX : 0), second_indent);
State = old_State;
p_smd = smd_save;
second_indent = -1;
/* at end of par.: need to set indent of next par. */
need_set_indent = is_end_par;
if (is_end_par)
{
/* When called with a negative line count, break at the
* end of the paragraph. */
if (line_count < 0)
break;
first_par_line = TRUE;
}
force_format = FALSE;
}
/*
* When still in same paragraph, join the lines together. But
* first delete the comment leader from the second line.
*/
if (!is_end_par)
{
advance = FALSE;
curwin->w_cursor.lnum++;
curwin->w_cursor.col = 0;
if (line_count < 0 && u_save_cursor() == FAIL)
break;
#ifdef FEAT_COMMENTS
(void)del_bytes((long)next_leader_len, FALSE, FALSE);
if (next_leader_len > 0)
mark_col_adjust(curwin->w_cursor.lnum, (colnr_T)0, 0L,
(long)-next_leader_len);
#endif
curwin->w_cursor.lnum--;
if (do_join(2, TRUE, FALSE, FALSE) == FAIL)
{
beep_flush();
break;
}
first_par_line = FALSE;
/* If the line is getting long, format it next time */
if (STRLEN(ml_get_curline()) > (size_t)max_len)
force_format = TRUE;
else
force_format = FALSE;
}
}
line_breakcheck();
}
}
答案 1 :(得分：4)
与许多vim一样，它是可定制的。默认是一个贪婪的算法（“更长[比textwidth]行将在空格后被破坏以获得此宽度”），但通过设置formatexpr，您可以使用vimscript格式化段落，并通过设置formatprg（例如，设置为fmt或par）您可以将控制权交给外部程序。
答案 2 :(得分：3)
第一步是:help gq和:help formatoptions。在那之后，我会简单地下载整个源代码并从中解决问题。如果所有这些都失败了，我会搜索vim-dev的档案，并可能在那里询问更多细节。