refactor(plines): use a struct for chartabsize state

This is a refactor extracted from vim-patch 9.0.0067: cannot show virtual text

The logic for inline virtual text is going to be different in nvim than
text property based text in vim, but this refactor is still useful,
as calculation of displayed linesize is going to be stateful in a
similar way.

1 files changed, 47 insertions, 33 deletions

diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index ed625e1d6e..e785a46dae 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1665,28 +1665,28 @@ void change_indent(int type, int amount, int round, int replaced, int call_chang
   } else if (!(State & MODE_INSERT)) {
     new_cursor_col = curwin->w_cursor.col;
   } else {
-    /*
-     * Compute the screen column where the cursor should be.
-     */
+    // Compute the screen column where the cursor should be.
     vcol = get_indent() - vcol;
     curwin->w_virtcol = (colnr_T)((vcol < 0) ? 0 : vcol);
 
-    /*
-     * Advance the cursor until we reach the right screen column.
-     */
-    vcol = last_vcol = 0;
-    new_cursor_col = -1;
+    // Advance the cursor until we reach the right screen column.
+    last_vcol = 0;
     ptr = get_cursor_line_ptr();
-    while (vcol <= (int)curwin->w_virtcol) {
-      last_vcol = vcol;
-      if (new_cursor_col >= 0) {
-        new_cursor_col += utfc_ptr2len((char *)ptr + new_cursor_col);
-      } else {
-        new_cursor_col++;
+    chartabsize_T cts;
+    init_chartabsize_arg(&cts, curwin, 0, 0, ptr, ptr);
+    while (cts.cts_vcol <= (int)curwin->w_virtcol) {
+      last_vcol = cts.cts_vcol;
+      if (cts.cts_vcol > 0) {
+        MB_PTR_ADV(cts.cts_ptr);
+      }
+      if (*cts.cts_ptr == NUL) {
+        break;
       }
-      vcol += lbr_chartabsize(ptr, ptr + new_cursor_col, (colnr_T)vcol);
+      cts.cts_vcol += lbr_chartabsize(&cts);
     }
     vcol = last_vcol;
+    new_cursor_col = (int)(cts.cts_ptr - cts.cts_line);
+    clear_chartabsize_arg(&cts);
 
     /*
      * May need to insert spaces to be able to position the cursor on
@@ -2991,7 +2991,7 @@ static void replace_do_bs(int limit_col)
       // Get the number of screen cells used by the character we are
       // going to delete.
       getvcol(curwin, &curwin->w_cursor, NULL, &start_vcol, NULL);
-      orig_vcols = win_chartabsize(curwin, get_cursor_pos_ptr(), start_vcol);
+      orig_vcols = win_chartabsize(curwin, (char *)get_cursor_pos_ptr(), start_vcol);
     }
     (void)del_char_after_col(limit_col);
     if (l_State & VREPLACE_FLAG) {
@@ -3006,7 +3006,7 @@ static void replace_do_bs(int limit_col)
       ins_len = (int)STRLEN(p) - orig_len;
       vcol = start_vcol;
       for (i = 0; i < ins_len; i++) {
-        vcol += win_chartabsize(curwin, p + i, vcol);
+        vcol += win_chartabsize(curwin, (char *)p + i, vcol);
         i += utfc_ptr2len((char *)p) - 1;
       }
       vcol -= start_vcol;
@@ -4644,11 +4644,15 @@ static bool ins_tab(void)
     getvcol(curwin, &fpos, &vcol, NULL, NULL);
     getvcol(curwin, cursor, &want_vcol, NULL, NULL);
 
+    char_u *tab = (char_u *)"\t";
+    chartabsize_T cts;
+    init_chartabsize_arg(&cts, curwin, 0, vcol, tab, tab);
+
     // Use as many TABs as possible.  Beware of 'breakindent', 'showbreak'
     // and 'linebreak' adding extra virtual columns.
     while (ascii_iswhite(*ptr)) {
-      i = lbr_chartabsize(NULL, (char_u *)"\t", vcol);
-      if (vcol + i > want_vcol) {
+      i = lbr_chartabsize(&cts);
+      if (cts.cts_vcol + i > want_vcol) {
         break;
       }
       if (*ptr != TAB) {
@@ -4663,19 +4667,24 @@ static bool ins_tab(void)
       }
       fpos.col++;
       ptr++;
-      vcol += i;
+      cts.cts_vcol += i;
     }
+    vcol = cts.cts_vcol;
+    clear_chartabsize_arg(&cts);
 
     if (change_col >= 0) {
       int repl_off = 0;
-      char_u *line = ptr;
-
       // Skip over the spaces we need.
-      while (vcol < want_vcol && *ptr == ' ') {
-        vcol += lbr_chartabsize(line, ptr, vcol);
-        ptr++;
+      init_chartabsize_arg(&cts, curwin, 0, vcol, ptr, ptr);
+      while (cts.cts_vcol < want_vcol && *cts.cts_ptr == ' ') {
+        cts.cts_vcol += lbr_chartabsize(&cts);
+        cts.cts_ptr++;
         repl_off++;
       }
+      ptr = (char_u *)cts.cts_ptr;
+      vcol = cts.cts_vcol;
+      clear_chartabsize_arg(&cts);
+
       if (vcol > want_vcol) {
         // Must have a char with 'showbreak' just before it.
         ptr--;
@@ -4855,7 +4864,6 @@ static int ins_digraph(void)
 int ins_copychar(linenr_T lnum)
 {
   int c;
-  int temp;
   char_u *ptr, *prev_ptr;
   char_u *line;
 
@@ -4865,17 +4873,23 @@ int ins_copychar(linenr_T lnum)
   }
 
   // try to advance to the cursor column
-  temp = 0;
-  line = ptr = ml_get(lnum);
-  prev_ptr = ptr;
+  line = ml_get(lnum);
+  prev_ptr = line;
   validate_virtcol();
-  while ((colnr_T)temp < curwin->w_virtcol && *ptr != NUL) {
-    prev_ptr = ptr;
-    temp += lbr_chartabsize_adv(line, &ptr, (colnr_T)temp);
+
+  chartabsize_T cts;
+  init_chartabsize_arg(&cts, curwin, lnum, 0, line, line);
+  while (cts.cts_vcol < curwin->w_virtcol && *cts.cts_ptr != NUL) {
+    prev_ptr = (char_u *)cts.cts_ptr;
+    cts.cts_vcol += lbr_chartabsize_adv(&cts);
   }
-  if ((colnr_T)temp > curwin->w_virtcol) {
+
+  if (cts.cts_vcol > curwin->w_virtcol) {
     ptr = prev_ptr;
+  } else {
+    ptr = (char_u *)cts.cts_ptr;
   }
+  clear_chartabsize_arg(&cts);
 
   c = utf_ptr2char((char *)ptr);
   if (c == NUL) {