vim-patch:8.2.3937: Insert mode completion function is too long

Problem:    Insert mode completion function is too long.
Solution:   Refactor into multiple functions. (Yegappan Lakshmanan,
            closes vim/vim#9423)
https://github.com/vim/vim/commit/edc6f103907a004b9e2265e232dc8be8bc594601

Cherry-pick a typo fix from patch 8.2.3637.

2 files changed, 480 insertions, 313 deletions

diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 938189f343..68acc3012b 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -2464,6 +2464,422 @@ static bool thesaurus_func_complete(int type)
          && (*curbuf->b_p_tsrfu != NUL || *p_tsrfu != NUL);
 }
 
+/// Return value of process_next_cpt_value()
+enum {
+  INS_COMPL_CPT_OK = 1,
+  INS_COMPL_CPT_CONT,
+  INS_COMPL_CPT_END,
+};
+
+/// Process the next 'complete' option value in "e_cpt_arg".
+///
+/// If successful, the arguments are set as below:
+///   e_cpt_arg - pointer to the next option value in 'e_cpt_arg'
+///   compl_type_arg - type of insert mode completion to use
+///   found_all_arg - all matches of this type are found
+///   buf_arg - search for completions in this buffer
+///   first_match_pos - position of the first completion match
+///   last_match_pos - position of the last completion match
+///   set_match_pos - true if the first match position should be saved to avoid
+///                   loops after the search wraps around.
+///   dict - name of the dictionary or thesaurus file to search
+///   dict_f - flag specifying whether "dict" is an exact file name or not
+///
+/// @return  INS_COMPL_CPT_OK if the next value is processed successfully.
+///          INS_COMPL_CPT_CONT to skip the current value and process the next
+///          option value.
+///          INS_COMPL_CPT_END if all the values in "e_cpt" are processed.
+static int process_next_cpt_value(char **e_cpt_arg, int *compl_type_arg, bool *found_all_arg,
+                                  buf_T **buf_arg, pos_T *start_match_pos, pos_T *first_match_pos,
+                                  pos_T *last_match_pos, bool *set_match_pos, char_u **dict_arg,
+                                  int *dict_flag)
+{
+  char *e_cpt = *e_cpt_arg;
+  int compl_type = -1;
+  int status = INS_COMPL_CPT_OK;
+  buf_T *buf = *buf_arg;
+  bool found_all = false;
+  char_u *dict = NULL;
+  int dict_f = 0;
+
+  while (*e_cpt == ',' || *e_cpt == ' ') {
+    e_cpt++;
+  }
+  if (*e_cpt == '.' && !curbuf->b_scanned) {
+    buf = curbuf;
+    *first_match_pos = *start_match_pos;
+    // Move the cursor back one character so that ^N can match the
+    // word immediately after the cursor.
+    if (ctrl_x_mode_normal() && dec(first_match_pos) < 0) {
+      // Move the cursor to after the last character in the
+      // buffer, so that word at start of buffer is found
+      // correctly.
+      first_match_pos->lnum = buf->b_ml.ml_line_count;
+      first_match_pos->col = (colnr_T)STRLEN(ml_get(first_match_pos->lnum));
+    }
+    *last_match_pos = *first_match_pos;
+    compl_type = 0;
+
+    // Remember the first match so that the loop stops when we
+    // wrap and come back there a second time.
+    *set_match_pos = true;
+  } else if (vim_strchr("buwU", *e_cpt) != NULL
+             && (buf = ins_compl_next_buf(buf, *e_cpt)) != curbuf) {
+    // Scan a buffer, but not the current one.
+    if (buf->b_ml.ml_mfp != NULL) {  // loaded buffer
+      compl_started = true;
+      first_match_pos->col = last_match_pos->col = 0;
+      first_match_pos->lnum = buf->b_ml.ml_line_count + 1;
+      last_match_pos->lnum = 0;
+      compl_type = 0;
+    } else {  // unloaded buffer, scan like dictionary
+      found_all = true;
+      if (buf->b_fname == NULL) {
+        status = INS_COMPL_CPT_CONT;
+        goto done;
+      }
+      compl_type = CTRL_X_DICTIONARY;
+      dict = (char_u *)buf->b_fname;
+      dict_f = DICT_EXACT;
+    }
+    msg_hist_off = true;  // reset in msg_trunc_attr()
+    vim_snprintf((char *)IObuff, IOSIZE, _("Scanning: %s"),
+                 buf->b_fname == NULL
+                 ? buf_spname(buf)
+                 : buf->b_sfname == NULL
+                 ? buf->b_fname
+                 : buf->b_sfname);
+    (void)msg_trunc_attr((char *)IObuff, true, HL_ATTR(HLF_R));
+  } else if (*e_cpt == NUL) {
+    status = INS_COMPL_CPT_END;
+  } else {
+    if (ctrl_x_mode_line_or_eval()) {
+      compl_type = -1;
+    } else if (*e_cpt == 'k' || *e_cpt == 's') {
+      if (*e_cpt == 'k') {
+        compl_type = CTRL_X_DICTIONARY;
+      } else {
+        compl_type = CTRL_X_THESAURUS;
+      }
+      if (*++e_cpt != ',' && *e_cpt != NUL) {
+        dict = (char_u *)e_cpt;
+        dict_f = DICT_FIRST;
+      }
+    } else if (*e_cpt == 'i') {
+      compl_type = CTRL_X_PATH_PATTERNS;
+    } else if (*e_cpt == 'd') {
+      compl_type = CTRL_X_PATH_DEFINES;
+    } else if (*e_cpt == ']' || *e_cpt == 't') {
+      msg_hist_off = true;  // reset in msg_trunc_attr()
+      compl_type = CTRL_X_TAGS;
+      vim_snprintf((char *)IObuff, IOSIZE, "%s", _("Scanning tags."));
+      (void)msg_trunc_attr((char *)IObuff, true, HL_ATTR(HLF_R));
+    } else {
+      compl_type = -1;
+    }
+
+    // in any case e_cpt is advanced to the next entry
+    (void)copy_option_part(&e_cpt, (char *)IObuff, IOSIZE, ",");
+
+    found_all = true;
+    if (compl_type == -1) {
+      status = INS_COMPL_CPT_CONT;
+    }
+  }
+
+done:
+  *e_cpt_arg = e_cpt;
+  *compl_type_arg = compl_type;
+  *found_all_arg = found_all;
+  *buf_arg = buf;
+  *dict_arg = dict;
+  *dict_flag = dict_f;
+  return status;
+}
+
+/// Get the next set of identifiers or defines matching "compl_pattern" in
+/// included files.
+static void get_next_include_file_completion(int compl_type)
+{
+  find_pattern_in_path((char_u *)compl_pattern, compl_direction,
+                       STRLEN(compl_pattern), false, false,
+                       ((compl_type == CTRL_X_PATH_DEFINES
+                         && !(compl_cont_status & CONT_SOL))
+                        ? FIND_DEFINE : FIND_ANY),
+                       1L, ACTION_EXPAND, 1, MAXLNUM);
+}
+
+/// Get the next set of words matching "compl_pattern" in dictionary or
+/// thesaurus files.
+static void get_next_dict_tsr_completion(int compl_type, char_u **dict, int dict_f)
+{
+  if (thesaurus_func_complete(compl_type)) {
+    expand_by_function(compl_type, (char_u *)compl_pattern);
+  } else {
+    ins_compl_dictionaries(*dict != NULL ? *dict
+                           : (compl_type == CTRL_X_THESAURUS
+                              ? (*curbuf->b_p_tsr == NUL ? p_tsr : curbuf->b_p_tsr)
+                              : (*curbuf->b_p_dict == NUL ? p_dict : curbuf->b_p_dict)),
+                           (char_u *)compl_pattern,
+                           *dict != NULL ? dict_f : 0,
+                           compl_type == CTRL_X_THESAURUS);
+  }
+  *dict = NULL;
+}
+
+/// Get the next set of tag names matching "compl_pattern".
+static void get_next_tag_completion(void)
+{
+  // set p_ic according to p_ic, p_scs and pat for find_tags().
+  const int save_p_ic = p_ic;
+  p_ic = ignorecase((char_u *)compl_pattern);
+
+  // Find up to TAG_MANY matches.  Avoids that an enormous number
+  // of matches is found when compl_pattern is empty
+  g_tag_at_cursor = true;
+  char **matches;
+  int num_matches;
+  if (find_tags((char_u *)compl_pattern, &num_matches, &matches,
+                TAG_REGEXP | TAG_NAMES | TAG_NOIC | TAG_INS_COMP
+                | (ctrl_x_mode_not_default() ? TAG_VERBOSE : 0),
+                TAG_MANY, (char_u *)curbuf->b_ffname) == OK && num_matches > 0) {
+    ins_compl_add_matches(num_matches, matches, p_ic);
+  }
+  g_tag_at_cursor = false;
+  p_ic = save_p_ic;
+}
+
+/// Get the next set of filename matching "compl_pattern".
+static void get_next_filename_completion(void)
+{
+  char **matches;
+  int num_matches;
+  if (expand_wildcards(1, &compl_pattern, &num_matches, &matches,
+                       EW_FILE|EW_DIR|EW_ADDSLASH|EW_SILENT) != OK) {
+    return;
+  }
+
+  // May change home directory back to "~".
+  tilde_replace((char_u *)compl_pattern, num_matches, matches);
+#ifdef BACKSLASH_IN_FILENAME
+  if (curbuf->b_p_csl[0] != NUL) {
+    for (int i = 0; i < num_matches; i++) {
+      char_u *ptr = matches[i];
+      while (*ptr != NUL) {
+        if (curbuf->b_p_csl[0] == 's' && *ptr == '\\') {
+          *ptr = '/';
+        } else if (curbuf->b_p_csl[0] == 'b' && *ptr == '/') {
+          *ptr = '\\';
+        }
+        ptr += utfc_ptr2len(ptr);
+      }
+    }
+  }
+#endif
+  ins_compl_add_matches(num_matches, matches, p_fic || p_wic);
+}
+
+/// Get the next set of command-line completions matching "compl_pattern".
+static void get_next_cmdline_completion(void)
+{
+  char **matches;
+  int num_matches;
+  if (expand_cmdline(&compl_xp, (char_u *)compl_pattern,
+                     (int)STRLEN(compl_pattern),
+                     &num_matches, &matches) == EXPAND_OK) {
+    ins_compl_add_matches(num_matches, matches, false);
+  }
+}
+
+/// Get the next set of spell suggestions matching "compl_pattern".
+static void get_next_spell_completion(linenr_T lnum)
+{
+  char **matches;
+  int num_matches = expand_spelling(lnum, (char_u *)compl_pattern, &matches);
+  if (num_matches > 0) {
+    ins_compl_add_matches(num_matches, matches, p_ic);
+  }
+}
+
+/// Get the next set of words matching "compl_pattern" for default completion(s)
+/// (normal ^P/^N and ^X^L).
+/// Search for "compl_pattern" in the buffer "ins_buf" starting from the
+/// position "start_pos" in the "compl_direction" direction. If "save_match_pos"
+/// is true, then set the "first_match_pos" and "last_match_pos".
+///
+/// @param ins_buf          buffer being scanned
+/// @param start_pos        search start position
+/// @param cur_match_pos    current match position
+/// @param prev_match_pos   previous match position
+/// @param save_match_pos   set first_match_pos/last_match_pos
+/// @param first_match_pos  first match position
+/// @param last_match_pos   last match position
+/// @param scan_curbuf      scan current buffer for completion
+///
+/// @return  OK if a new next match is found, otherwise FAIL.
+static int get_next_default_completion(buf_T *ins_buf, pos_T *start_pos, pos_T *cur_match_pos,
+                                       pos_T *prev_match_pos, bool *save_match_pos,
+                                       pos_T *first_match_pos, pos_T *last_match_pos,
+                                       bool scan_curbuf)
+{
+  // If 'infercase' is set, don't use 'smartcase' here
+  const int save_p_scs = p_scs;
+  assert(ins_buf);
+  if (ins_buf->b_p_inf) {
+    p_scs = false;
+  }
+
+  // Buffers other than curbuf are scanned from the beginning or the
+  // end but never from the middle, thus setting nowrapscan in this
+  // buffers is a good idea, on the other hand, we always set
+  // wrapscan for curbuf to avoid missing matches -- Acevedo,Webb
+  const int save_p_ws = p_ws;
+  if (ins_buf != curbuf) {
+    p_ws = false;
+  } else if (scan_curbuf) {
+    p_ws = true;
+  }
+  bool looped_around = false;
+  int found_new_match = FAIL;
+  for (;;) {
+    bool cont_s_ipos = false;
+
+    msg_silent++;  // Don't want messages for wrapscan.
+    // ctrl_x_mode_line_or_eval() || word-wise search that
+    // has added a word that was at the beginning of the line.
+    if (ctrl_x_mode_line_or_eval()
+        || (compl_cont_status & CONT_SOL)) {
+      found_new_match = search_for_exact_line(ins_buf, cur_match_pos,
+                                              compl_direction, (char_u *)compl_pattern);
+    } else {
+      found_new_match = searchit(NULL, ins_buf, cur_match_pos, NULL,
+                                 compl_direction,
+                                 (char_u *)compl_pattern, 1L, SEARCH_KEEP + SEARCH_NFMSG,
+                                 RE_LAST, NULL);
+    }
+    msg_silent--;
+    if (!compl_started || *save_match_pos) {
+      // set "compl_started" even on fail
+      compl_started = true;
+      *first_match_pos = *cur_match_pos;
+      *last_match_pos = *cur_match_pos;
+      *save_match_pos = false;
+    } else if (first_match_pos->lnum == last_match_pos->lnum
+               && first_match_pos->col == last_match_pos->col) {
+      found_new_match = FAIL;
+    } else if ((compl_direction == FORWARD)
+               && (prev_match_pos->lnum > cur_match_pos->lnum
+                   || (prev_match_pos->lnum == cur_match_pos->lnum
+                       && prev_match_pos->col >= cur_match_pos->col))) {
+      if (looped_around) {
+        found_new_match = FAIL;
+      } else {
+        looped_around = true;
+      }
+    } else if ((compl_direction != FORWARD)
+               && (prev_match_pos->lnum < cur_match_pos->lnum
+                   || (prev_match_pos->lnum == cur_match_pos->lnum
+                       && prev_match_pos->col <= cur_match_pos->col))) {
+      if (looped_around) {
+        found_new_match = FAIL;
+      } else {
+        looped_around = true;
+      }
+    }
+    *prev_match_pos = *cur_match_pos;
+    if (found_new_match == FAIL) {
+      break;
+    }
+
+    // when ADDING, the text before the cursor matches, skip it
+    if ((compl_cont_status & CONT_ADDING) && ins_buf == curbuf
+        && start_pos->lnum == cur_match_pos->lnum
+        && start_pos->col == cur_match_pos->col) {
+      continue;
+    }
+    char_u *ptr = ml_get_buf(ins_buf, cur_match_pos->lnum, false) + cur_match_pos->col;
+    int len;
+    if (ctrl_x_mode_line_or_eval()) {
+      if (compl_cont_status & CONT_ADDING) {
+        if (cur_match_pos->lnum >= ins_buf->b_ml.ml_line_count) {
+          continue;
+        }
+        ptr = ml_get_buf(ins_buf, cur_match_pos->lnum + 1, false);
+        if (!p_paste) {
+          ptr = (char_u *)skipwhite((char *)ptr);
+        }
+      }
+      len = (int)STRLEN(ptr);
+    } else {
+      char_u *tmp_ptr = ptr;
+
+      if (compl_cont_status & CONT_ADDING) {
+        tmp_ptr += compl_length;
+        // Skip if already inside a word.
+        if (vim_iswordp(tmp_ptr)) {
+          continue;
+        }
+        // Find start of next word.
+        tmp_ptr = find_word_start(tmp_ptr);
+      }
+      // Find end of this word.
+      tmp_ptr = find_word_end(tmp_ptr);
+      len = (int)(tmp_ptr - ptr);
+
+      if ((compl_cont_status & CONT_ADDING) && len == compl_length) {
+        if (cur_match_pos->lnum < ins_buf->b_ml.ml_line_count) {
+          // Try next line, if any. the new word will be "join" as if the
+          // normal command "J" was used. IOSIZE is always greater than
+          // compl_length, so the next STRNCPY always works -- Acevedo
+          STRNCPY(IObuff, ptr, len);  // NOLINT(runtime/printf)
+          ptr = ml_get_buf(ins_buf, cur_match_pos->lnum + 1, false);
+          tmp_ptr = ptr = (char_u *)skipwhite((char *)ptr);
+          // Find start of next word.
+          tmp_ptr = find_word_start(tmp_ptr);
+          // Find end of next word.
+          tmp_ptr = find_word_end(tmp_ptr);
+          if (tmp_ptr > ptr) {
+            if (*ptr != ')' && IObuff[len - 1] != TAB) {
+              if (IObuff[len - 1] != ' ') {
+                IObuff[len++] = ' ';
+              }
+              // IObuf =~ "\k.* ", thus len >= 2
+              if (p_js
+                  && (IObuff[len - 2] == '.'
+                      || IObuff[len - 2] == '?'
+                      || IObuff[len - 2] == '!')) {
+                IObuff[len++] = ' ';
+              }
+            }
+            // copy as much as possible of the new word
+            if (tmp_ptr - ptr >= IOSIZE - len) {
+              tmp_ptr = ptr + IOSIZE - len - 1;
+            }
+            STRLCPY(IObuff + len, ptr, IOSIZE - len);
+            len += (int)(tmp_ptr - ptr);
+            cont_s_ipos = true;
+          }
+          IObuff[len] = NUL;
+          ptr = IObuff;
+        }
+        if (len == compl_length) {
+          continue;
+        }
+      }
+    }
+    if (ins_compl_add_infercase(ptr, len, p_ic,
+                                ins_buf == curbuf ? NULL : (char_u *)ins_buf->b_sfname,
+                                0, cont_s_ipos) != NOTDONE) {
+      found_new_match = OK;
+      break;
+    }
+  }
+  p_scs = save_p_scs;
+  p_ws = save_p_ws;
+
+  return found_new_match;
+}
+
 /// Get the next expansion(s), using "compl_pattern".
 /// The search starts at position "ini" in curbuf and in the direction
 /// compl_direction.
@@ -2481,16 +2897,9 @@ static int ins_compl_get_exp(pos_T *ini)
   static buf_T *ins_buf = NULL;          // buffer being scanned
 
   pos_T *pos;
-  char **matches;
-  int save_p_scs;
-  bool save_p_ws;
-  int save_p_ic;
   int i;
-  int num_matches;
-  int len;
   int found_new_match;
   int type = ctrl_x_mode;
-  char_u *ptr;
   char_u *dict = NULL;
   int dict_f = 0;
   bool set_match_pos;
@@ -2524,89 +2933,14 @@ static int ins_compl_get_exp(pos_T *ini)
     // entries from 'complete' that look in loaded buffers.
     if ((ctrl_x_mode_normal() || ctrl_x_mode_line_or_eval())
         && (!compl_started || found_all)) {
-      found_all = false;
-      while (*e_cpt == ',' || *e_cpt == ' ') {
-        e_cpt++;
-      }
-      if (*e_cpt == '.' && !curbuf->b_scanned) {
-        ins_buf = curbuf;
-        first_match_pos = *ini;
-        // Move the cursor back one character so that ^N can match the
-        // word immediately after the cursor.
-        if (ctrl_x_mode_normal() && dec(&first_match_pos) < 0) {
-          // Move the cursor to after the last character in the
-          // buffer, so that word at start of buffer is found
-          // correctly.
-          first_match_pos.lnum = ins_buf->b_ml.ml_line_count;
-          first_match_pos.col = (colnr_T)STRLEN(ml_get(first_match_pos.lnum));
-        }
-        last_match_pos = first_match_pos;
-        type = 0;
-
-        // Remember the first match so that the loop stops when we
-        // wrap and come back there a second time.
-        set_match_pos = true;
-      } else if (vim_strchr("buwU", *e_cpt) != NULL
-                 && (ins_buf = ins_compl_next_buf(ins_buf, *e_cpt)) != curbuf) {
-        // Scan a buffer, but not the current one.
-        if (ins_buf->b_ml.ml_mfp != NULL) {         // loaded buffer
-          compl_started = true;
-          first_match_pos.col = last_match_pos.col = 0;
-          first_match_pos.lnum = ins_buf->b_ml.ml_line_count + 1;
-          last_match_pos.lnum = 0;
-          type = 0;
-        } else {      // unloaded buffer, scan like dictionary
-          found_all = true;
-          if (ins_buf->b_fname == NULL) {
-            continue;
-          }
-          type = CTRL_X_DICTIONARY;
-          dict = (char_u *)ins_buf->b_fname;
-          dict_f = DICT_EXACT;
-        }
-        msg_hist_off = true;  // reset in msg_trunc_attr()
-        vim_snprintf((char *)IObuff, IOSIZE, _("Scanning: %s"),
-                     ins_buf->b_fname == NULL
-                     ? buf_spname(ins_buf)
-                     : ins_buf->b_sfname == NULL
-                     ? ins_buf->b_fname
-                     : ins_buf->b_sfname);
-        (void)msg_trunc_attr((char *)IObuff, true, HL_ATTR(HLF_R));
-      } else if (*e_cpt == NUL) {
+      int status = process_next_cpt_value(&e_cpt, &type, &found_all,
+                                          &ins_buf, ini, &first_match_pos, &last_match_pos,
+                                          &set_match_pos, &dict, &dict_f);
+      if (status == INS_COMPL_CPT_END) {
         break;
-      } else {
-        if (ctrl_x_mode_line_or_eval()) {
-          type = -1;
-        } else if (*e_cpt == 'k' || *e_cpt == 's') {
-          if (*e_cpt == 'k') {
-            type = CTRL_X_DICTIONARY;
-          } else {
-            type = CTRL_X_THESAURUS;
-          }
-          if (*++e_cpt != ',' && *e_cpt != NUL) {
-            dict = (char_u *)e_cpt;
-            dict_f = DICT_FIRST;
-          }
-        } else if (*e_cpt == 'i') {
-          type = CTRL_X_PATH_PATTERNS;
-        } else if (*e_cpt == 'd') {
-          type = CTRL_X_PATH_DEFINES;
-        } else if (*e_cpt == ']' || *e_cpt == 't') {
-          msg_hist_off = true;  // reset in msg_trunc_attr()
-          type = CTRL_X_TAGS;
-          vim_snprintf((char *)IObuff, IOSIZE, "%s", _("Scanning tags."));
-          (void)msg_trunc_attr((char *)IObuff, true, HL_ATTR(HLF_R));
-        } else {
-          type = -1;
-        }
-
-        // in any case e_cpt is advanced to the next entry
-        (void)copy_option_part(&e_cpt, (char *)IObuff, IOSIZE, ",");
-
-        found_all = true;
-        if (type == -1) {
-          continue;
-        }
+      }
+      if (status == INS_COMPL_CPT_CONT) {
+        continue;
       }
     }
 
@@ -2621,80 +2955,25 @@ static int ins_compl_get_exp(pos_T *ini)
       break;
     case CTRL_X_PATH_PATTERNS:
     case CTRL_X_PATH_DEFINES:
-      find_pattern_in_path((char_u *)compl_pattern, compl_direction,
-                           STRLEN(compl_pattern), false, false,
-                           ((type == CTRL_X_PATH_DEFINES
-                             && !(compl_cont_status & CONT_SOL))
-                            ? FIND_DEFINE
-                            : FIND_ANY),
-                           1L, ACTION_EXPAND, 1, MAXLNUM);
+      get_next_include_file_completion(type);
       break;
 
     case CTRL_X_DICTIONARY:
     case CTRL_X_THESAURUS:
-      if (thesaurus_func_complete(type)) {
-        expand_by_function(type, (char_u *)compl_pattern);
-      } else {
-        ins_compl_dictionaries(dict != NULL ? dict
-                               : (type == CTRL_X_THESAURUS
-                                  ? (*curbuf->b_p_tsr == NUL ? p_tsr : curbuf->b_p_tsr)
-                                  : (*curbuf->b_p_dict ==
-                                     NUL ? p_dict : curbuf->b_p_dict)),
-                               (char_u *)compl_pattern,
-                               dict != NULL ? dict_f : 0, type == CTRL_X_THESAURUS);
-      }
-      dict = NULL;
+      get_next_dict_tsr_completion(type, &dict, dict_f);
       break;
 
     case CTRL_X_TAGS:
-      // set p_ic according to p_ic, p_scs and pat for find_tags().
-      save_p_ic = p_ic;
-      p_ic = ignorecase((char_u *)compl_pattern);
-
-      // Find up to TAG_MANY matches.  Avoids that an enormous number
-      // of matches is found when compl_pattern is empty
-      g_tag_at_cursor = true;
-      if (find_tags((char_u *)compl_pattern, &num_matches, &matches,
-                    TAG_REGEXP | TAG_NAMES | TAG_NOIC | TAG_INS_COMP
-                    | (ctrl_x_mode_not_default() ? TAG_VERBOSE : 0),
-                    TAG_MANY, (char_u *)curbuf->b_ffname) == OK && num_matches > 0) {
-        ins_compl_add_matches(num_matches, matches, p_ic);
-      }
-      g_tag_at_cursor = false;
-      p_ic = save_p_ic;
+      get_next_tag_completion();
       break;
 
     case CTRL_X_FILES:
-      if (expand_wildcards(1, &compl_pattern, &num_matches, &matches,
-                           EW_FILE|EW_DIR|EW_ADDSLASH|EW_SILENT) == OK) {
-        // May change home directory back to "~".
-        tilde_replace((char_u *)compl_pattern, num_matches, matches);
-#ifdef BACKSLASH_IN_FILENAME
-        if (curbuf->b_p_csl[0] != NUL) {
-          for (int i = 0; i < num_matches; i++) {
-            char_u *ptr = matches[i];
-            while (*ptr != NUL) {
-              if (curbuf->b_p_csl[0] == 's' && *ptr == '\\') {
-                *ptr = '/';
-              } else if (curbuf->b_p_csl[0] == 'b' && *ptr == '/') {
-                *ptr = '\\';
-              }
-              ptr += utfc_ptr2len(ptr);
-            }
-          }
-        }
-#endif
-        ins_compl_add_matches(num_matches, matches, p_fic || p_wic);
-      }
+      get_next_filename_completion();
       break;
 
     case CTRL_X_CMDLINE:
     case CTRL_X_CMDLINE_CTRL_X:
-      if (expand_cmdline(&compl_xp, (char_u *)compl_pattern,
-                         (int)STRLEN(compl_pattern),
-                         &num_matches, &matches) == EXPAND_OK) {
-        ins_compl_add_matches(num_matches, matches, false);
-      }
+      get_next_cmdline_completion();
       break;
 
     case CTRL_X_FUNCTION:
@@ -2703,172 +2982,16 @@ static int ins_compl_get_exp(pos_T *ini)
       break;
 
     case CTRL_X_SPELL:
-      num_matches = expand_spelling(first_match_pos.lnum,
-                                    (char_u *)compl_pattern, &matches);
-      if (num_matches > 0) {
-        ins_compl_add_matches(num_matches, matches, p_ic);
-      }
+      get_next_spell_completion(first_match_pos.lnum);
       break;
 
     default:            // normal ^P/^N and ^X^L
-      // If 'infercase' is set, don't use 'smartcase' here
-      save_p_scs = p_scs;
-      assert(ins_buf);
-      if (ins_buf->b_p_inf) {
-        p_scs = false;
-      }
-
-      // Buffers other than curbuf are scanned from the beginning or the
-      // end but never from the middle, thus setting nowrapscan in this
-      // buffers is a good idea, on the other hand, we always set
-      // wrapscan for curbuf to avoid missing matches -- Acevedo,Webb
-      save_p_ws = p_ws;
-      if (ins_buf != curbuf) {
-        p_ws = false;
-      } else if (*e_cpt == '.') {
-        p_ws = true;
-      }
-      bool looped_around = false;
-      for (;;) {
-        bool cont_s_ipos = false;
-
-        msg_silent++;          // Don't want messages for wrapscan.
-        // ctrl_x_mode_line_or_eval() || word-wise search that
-        // has added a word that was at the beginning of the line.
-        if (ctrl_x_mode_line_or_eval()
-            || (compl_cont_status & CONT_SOL)) {
-          found_new_match = search_for_exact_line(ins_buf, pos,
-                                                  compl_direction,
-                                                  (char_u *)compl_pattern);
-        } else {
-          found_new_match = searchit(NULL, ins_buf, pos, NULL,
-                                     compl_direction,
-                                     (char_u *)compl_pattern, 1L,
-                                     SEARCH_KEEP + SEARCH_NFMSG,
-                                     RE_LAST, NULL);
-        }
-        msg_silent--;
-        if (!compl_started || set_match_pos) {
-          // set "compl_started" even on fail
-          compl_started = true;
-          first_match_pos = *pos;
-          last_match_pos = *pos;
-          set_match_pos = false;
-        } else if (first_match_pos.lnum == last_match_pos.lnum
-                   && first_match_pos.col == last_match_pos.col) {
-          found_new_match = FAIL;
-        } else if ((compl_direction == FORWARD)
-                   && (prev_pos.lnum > pos->lnum
-                       || (prev_pos.lnum == pos->lnum
-                           && prev_pos.col >= pos->col))) {
-          if (looped_around) {
-            found_new_match = FAIL;
-          } else {
-            looped_around = true;
-          }
-        } else if ((compl_direction != FORWARD)
-                   && (prev_pos.lnum < pos->lnum
-                       || (prev_pos.lnum == pos->lnum
-                           && prev_pos.col <= pos->col))) {
-          if (looped_around) {
-            found_new_match = FAIL;
-          } else {
-            looped_around = true;
-          }
-        }
-        prev_pos = *pos;
-        if (found_new_match == FAIL) {
-          if (ins_buf == curbuf) {
-            found_all = true;
-          }
-          break;
-        }
-
-        // when ADDING, the text before the cursor matches, skip it
-        if ((compl_cont_status & CONT_ADDING) && ins_buf == curbuf
-            && ini->lnum == pos->lnum
-            && ini->col == pos->col) {
-          continue;
-        }
-        ptr = ml_get_buf(ins_buf, pos->lnum, false) + pos->col;
-        if (ctrl_x_mode_line_or_eval()) {
-          if (compl_cont_status & CONT_ADDING) {
-            if (pos->lnum >= ins_buf->b_ml.ml_line_count) {
-              continue;
-            }
-            ptr = ml_get_buf(ins_buf, pos->lnum + 1, false);
-            if (!p_paste) {
-              ptr = (char_u *)skipwhite((char *)ptr);
-            }
-          }
-          len = (int)STRLEN(ptr);
-        } else {
-          char_u *tmp_ptr = ptr;
-
-          if (compl_cont_status & CONT_ADDING) {
-            tmp_ptr += compl_length;
-            // Skip if already inside a word.
-            if (vim_iswordp(tmp_ptr)) {
-              continue;
-            }
-            // Find start of next word.
-            tmp_ptr = find_word_start(tmp_ptr);
-          }
-          // Find end of this word.
-          tmp_ptr = find_word_end(tmp_ptr);
-          len = (int)(tmp_ptr - ptr);
-
-          if ((compl_cont_status & CONT_ADDING)
-              && len == compl_length) {
-            if (pos->lnum < ins_buf->b_ml.ml_line_count) {
-              // Try next line, if any. the new word will be "join" as if the
-              // normal command "J" was used. IOSIZE is always greater than
-              // compl_length, so the next STRNCPY always works -- Acevedo
-              STRNCPY(IObuff, ptr, len);  // NOLINT(runtime/printf)
-              ptr = ml_get_buf(ins_buf, pos->lnum + 1, false);
-              tmp_ptr = ptr = (char_u *)skipwhite((char *)ptr);
-              // Find start of next word.
-              tmp_ptr = find_word_start(tmp_ptr);
-              // Find end of next word.
-              tmp_ptr = find_word_end(tmp_ptr);
-              if (tmp_ptr > ptr) {
-                if (*ptr != ')' && IObuff[len - 1] != TAB) {
-                  if (IObuff[len - 1] != ' ') {
-                    IObuff[len++] = ' ';
-                  }
-                  // IObuf =~ "\k.* ", thus len >= 2
-                  if (p_js
-                      && (IObuff[len - 2] == '.'
-                          || IObuff[len - 2] == '?'
-                          || IObuff[len - 2] == '!')) {
-                    IObuff[len++] = ' ';
-                  }
-                }
-                // copy as much as possible of the new word
-                if (tmp_ptr - ptr >= IOSIZE - len) {
-                  tmp_ptr = ptr + IOSIZE - len - 1;
-                }
-                STRLCPY(IObuff + len, ptr, IOSIZE - len);
-                len += (int)(tmp_ptr - ptr);
-                cont_s_ipos = true;
-              }
-              IObuff[len] = NUL;
-              ptr = IObuff;
-            }
-            if (len == compl_length) {
-              continue;
-            }
-          }
-        }
-        if (ins_compl_add_infercase(ptr, len, p_ic,
-                                    ins_buf == curbuf ? NULL : (char_u *)ins_buf->b_sfname,
-                                    0, cont_s_ipos) != NOTDONE) {
-          found_new_match = OK;
-          break;
-        }
+      found_new_match = get_next_default_completion(ins_buf, ini, pos, &prev_pos,
+                                                    &set_match_pos, &first_match_pos,
+                                                    &last_match_pos, (*e_cpt == '.'));
+      if (found_new_match == FAIL && ins_buf == curbuf) {
+        found_all = true;
       }
-      p_scs = save_p_scs;
-      p_ws = save_p_ws;
     }
 
     // check if compl_curr_match has changed, (e.g. other type of
diff --git a/src/nvim/testdir/test_ins_complete.vim b/src/nvim/testdir/test_ins_complete.vim
index 179218e48a..4cdede9cd0 100644
--- a/src/nvim/testdir/test_ins_complete.vim
+++ b/src/nvim/testdir/test_ins_complete.vim
@@ -44,11 +44,11 @@ func Test_ins_complete()
   exe "normal o\<C-X>\<C-P>\<C-P>\<C-X>\<C-X>\<C-N>\<C-X>\<C-N>\<C-N>"
   call assert_equal('run1 run2', getline('.'))
 
-  set cpt=.,w,i
+  set cpt=.,\ ,w,i
   " i-add-expands and switches to local
   exe "normal OM\<C-N>\<C-X>\<C-N>\<C-X>\<C-N>\<C-X>\<C-X>\<C-X>\<C-P>"
   call assert_equal("Makefile\tto\trun3", getline('.'))
-  " add-expands lines (it would end in an empty line if it didn't ignored
+  " add-expands lines (it would end in an empty line if it didn't ignore
   " itself)
   exe "normal o\<C-X>\<C-L>\<C-X>\<C-L>\<C-P>\<C-P>"
   call assert_equal("Makefile\tto\trun3", getline('.'))
@@ -721,6 +721,17 @@ func Test_complete_across_line()
   close!
 endfunc
 
+" Test for completing words with a '.' at the end of a word.
+func Test_complete_joinspaces()
+  new
+  call setline(1, ['one two.', 'three. four'])
+  set joinspaces
+  exe "normal Goon\<C-P>\<C-X>\<C-P>\<C-X>\<C-P>\<C-X>\<C-P>\<C-X>\<C-P>"
+  call assert_equal("one two.  three. four", getline(3))
+  set joinspaces&
+  bw!
+endfunc
+
 " Test for using CTRL-L to add one character when completing matching
 func Test_complete_add_onechar()
   new
@@ -741,6 +752,39 @@ func Test_complete_add_onechar()
   close!
 endfunc
 
+" Test for using CTRL-X CTRL-L to complete whole lines lines
+func Test_complete_wholeline()
+  new
+  " complete one-line
+  call setline(1, ['a1', 'a2'])
+  exe "normal ggoa\<C-X>\<C-L>"
+  call assert_equal(['a1', 'a1', 'a2'], getline(1, '$'))
+  " go to the next match (wrapping around the buffer)
+  exe "normal 2GCa\<C-X>\<C-L>\<C-N>"
+  call assert_equal(['a1', 'a', 'a2'], getline(1, '$'))
+  " go to the next match
+  exe "normal 2GCa\<C-X>\<C-L>\<C-N>\<C-N>"
+  call assert_equal(['a1', 'a2', 'a2'], getline(1, '$'))
+  exe "normal 2GCa\<C-X>\<C-L>\<C-N>\<C-N>\<C-N>"
+  call assert_equal(['a1', 'a1', 'a2'], getline(1, '$'))
+  " repeat the test using CTRL-L
+  " go to the next match (wrapping around the buffer)
+  exe "normal 2GCa\<C-X>\<C-L>\<C-L>"
+  call assert_equal(['a1', 'a2', 'a2'], getline(1, '$'))
+  " go to the next match
+  exe "normal 2GCa\<C-X>\<C-L>\<C-L>\<C-L>"
+  call assert_equal(['a1', 'a', 'a2'], getline(1, '$'))
+  exe "normal 2GCa\<C-X>\<C-L>\<C-L>\<C-L>\<C-L>"
+  call assert_equal(['a1', 'a1', 'a2'], getline(1, '$'))
+  %d
+  " use CTRL-X CTRL-L to add one more line
+  call setline(1, ['a1', 'b1'])
+  setlocal complete=.
+  exe "normal ggOa\<C-X>\<C-L>\<C-X>\<C-L>\<C-X>\<C-L>"
+  call assert_equal(['a1', 'b1', '', 'a1', 'b1'], getline(1, '$'))
+  bw!
+endfunc
+
 " Test insert completion with 'cindent' (adjust the indent)
 func Test_complete_with_cindent()
   new