1 files changed, 298 insertions, 1 deletions

diff --git a/src/nvim/plines.c b/src/nvim/plines.c
index 60d194d781..6718b7f7a4 100644
--- a/src/nvim/plines.c
+++ b/src/nvim/plines.c
@@ -1,7 +1,7 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
-// plines.c: functions that calculate the vertical and horizontal size of text
+// plines.c: calculate the vertical and horizontal size of text in a window
 
 #include <assert.h>
 #include <inttypes.h>
@@ -17,6 +17,7 @@
 #include "nvim/diff.h"
 #include "nvim/func_attr.h"
 #include "nvim/fold.h"
+#include "nvim/indent.h"
 #include "nvim/main.h"
 #include "nvim/mbyte.h"
 #include "nvim/memline.h"
@@ -32,6 +33,8 @@
 # include "plines.c.generated.h"
 #endif
 
+/// Functions calculating vertical size of text when displayed inside a window.
+/// Calls horizontal size functions defined below.
 
 /// @param winheight when true limit to window height
 int plines_win(win_T *wp, linenr_T lnum, bool winheight)
@@ -182,3 +185,297 @@ int plines_m_win(win_T *wp, linenr_T first, linenr_T last)
   }
   return count;
 }
+
+/// Functions calculating horizontal size of text, when displayed in a window.
+
+/// Return the number of characters 'c' will take on the screen, taking
+/// into account the size of a tab.
+/// Also see getvcol()
+///
+/// @param p
+/// @param col
+///
+/// @return Number of characters.
+int win_chartabsize(win_T *wp, char_u *p, colnr_T col)
+{
+  buf_T *buf = wp->w_buffer;
+  if (*p == TAB && (!wp->w_p_list || wp->w_p_lcs_chars.tab1)) {
+    return tabstop_padding(col, buf->b_p_ts, buf->b_p_vts_array);
+  } else {
+    return ptr2cells(p);
+  }
+}
+
+/// Return the number of characters the string 's' will take on the screen,
+/// taking into account the size of a tab.
+///
+/// @param s
+///
+/// @return Number of characters the string will take on the screen.
+int linetabsize(char_u *s)
+{
+  return linetabsize_col(0, s);
+}
+
+/// Like linetabsize(), but starting at column "startcol".
+///
+/// @param startcol
+/// @param s
+///
+/// @return Number of characters the string will take on the screen.
+int linetabsize_col(int startcol, char_u *s)
+{
+  colnr_T col = startcol;
+  char_u *line = s;  // pointer to start of line, for breakindent
+
+  while (*s != NUL) {
+    col += lbr_chartabsize_adv(line, &s, col);
+  }
+  return (int)col;
+}
+
+/// Like linetabsize(), but for a given window instead of the current one.
+///
+/// @param wp
+/// @param line
+/// @param len
+///
+/// @return Number of characters the string will take on the screen.
+unsigned int win_linetabsize(win_T *wp, char_u *line, colnr_T len)
+{
+  colnr_T col = 0;
+
+  for (char_u *s = line;
+       *s != NUL && (len == MAXCOL || s < line + len);
+       MB_PTR_ADV(s)) {
+    col += win_lbr_chartabsize(wp, line, s, col, NULL);
+  }
+
+  return (unsigned int)col;
+}
+
+/// like win_chartabsize(), but also check for line breaks on the screen
+///
+/// @param line
+/// @param s
+/// @param col
+///
+/// @return The number of characters taken up on the screen.
+int lbr_chartabsize(char_u *line, unsigned char *s, colnr_T col)
+{
+  if (!curwin->w_p_lbr && (*p_sbr == NUL) && !curwin->w_p_bri) {
+    if (curwin->w_p_wrap) {
+      return win_nolbr_chartabsize(curwin, s, col, NULL);
+    }
+    return win_chartabsize(curwin, s, col);
+  }
+  return win_lbr_chartabsize(curwin, line == NULL ? s: line, s, col, NULL);
+}
+
+/// Call lbr_chartabsize() and advance the pointer.
+///
+/// @param line
+/// @param s
+/// @param col
+///
+/// @return The number of characters take up on the screen.
+int lbr_chartabsize_adv(char_u *line, char_u **s, colnr_T col)
+{
+  int retval;
+
+  retval = lbr_chartabsize(line, *s, col);
+  MB_PTR_ADV(*s);
+  return retval;
+}
+
+/// This function is used very often, keep it fast!!!!
+///
+/// If "headp" not NULL, set *headp to the size of what we for 'showbreak'
+/// string at start of line.  Warning: *headp is only set if it's a non-zero
+/// value, init to 0 before calling.
+///
+/// @param wp
+/// @param line
+/// @param s
+/// @param col
+/// @param headp
+///
+/// @return The number of characters taken up on the screen.
+int win_lbr_chartabsize(win_T *wp, char_u *line, char_u *s,
+                        colnr_T col, int *headp)
+{
+  colnr_T col2;
+  colnr_T col_adj = 0;  // col + screen size of tab
+  colnr_T colmax;
+  int added;
+  int mb_added = 0;
+  int numberextra;
+  char_u *ps;
+  int n;
+
+  // No 'linebreak', 'showbreak' and 'breakindent': return quickly.
+  if (!wp->w_p_lbr && !wp->w_p_bri && (*p_sbr == NUL)) {
+    if (wp->w_p_wrap) {
+      return win_nolbr_chartabsize(wp, s, col, headp);
+    }
+    return win_chartabsize(wp, s, col);
+  }
+
+  // First get normal size, without 'linebreak'
+  int size = win_chartabsize(wp, s, col);
+  int c = *s;
+  if (*s == TAB) {
+      col_adj = size - 1;
+  }
+
+  // If 'linebreak' set check at a blank before a non-blank if the line
+  // needs a break here
+  if (wp->w_p_lbr
+      && vim_isbreak(c)
+      && !vim_isbreak((int)s[1])
+      && wp->w_p_wrap
+      && (wp->w_width_inner != 0)) {
+    // Count all characters from first non-blank after a blank up to next
+    // non-blank after a blank.
+    numberextra = win_col_off(wp);
+    col2 = col;
+    colmax = (colnr_T)(wp->w_width_inner - numberextra - col_adj);
+
+    if (col >= colmax) {
+        colmax += col_adj;
+        n = colmax + win_col_off2(wp);
+
+      if (n > 0) {
+        colmax += (((col - colmax) / n) + 1) * n - col_adj;
+      }
+    }
+
+    for (;;) {
+      ps = s;
+      MB_PTR_ADV(s);
+      c = *s;
+
+      if (!(c != NUL
+            && (vim_isbreak(c) || col2 == col || !vim_isbreak((int)(*ps))))) {
+        break;
+      }
+
+      col2 += win_chartabsize(wp, s, col2);
+
+      if (col2 >= colmax) {  // doesn't fit
+        size = colmax - col + col_adj;
+        break;
+      }
+    }
+  } else if ((size == 2)
+             && (MB_BYTE2LEN(*s) > 1)
+             && wp->w_p_wrap
+             && in_win_border(wp, col)) {
+    // Count the ">" in the last column.
+    size++;
+    mb_added = 1;
+  }
+
+  // May have to add something for 'breakindent' and/or 'showbreak'
+  // string at start of line.
+  // Set *headp to the size of what we add.
+  added = 0;
+
+  if ((*p_sbr != NUL || wp->w_p_bri) && wp->w_p_wrap && (col != 0)) {
+    colnr_T sbrlen = 0;
+    int numberwidth = win_col_off(wp);
+
+    numberextra = numberwidth;
+    col += numberextra + mb_added;
+
+    if (col >= (colnr_T)wp->w_width_inner) {
+      col -= wp->w_width_inner;
+      numberextra = wp->w_width_inner - (numberextra - win_col_off2(wp));
+      if (col >= numberextra && numberextra > 0) {
+        col %= numberextra;
+      }
+      if (*p_sbr != NUL) {
+        sbrlen = (colnr_T)MB_CHARLEN(p_sbr);
+        if (col >= sbrlen) {
+          col -= sbrlen;
+        }
+      }
+      if (col >= numberextra && numberextra > 0) {
+        col %= numberextra;
+      } else if (col > 0 && numberextra > 0) {
+        col += numberwidth - win_col_off2(wp);
+      }
+
+      numberwidth -= win_col_off2(wp);
+    }
+
+    if (col == 0 || (col + size + sbrlen > (colnr_T)wp->w_width_inner)) {
+      if (*p_sbr != NUL) {
+        if (size + sbrlen + numberwidth > (colnr_T)wp->w_width_inner) {
+          // Calculate effective window width.
+          int width = (colnr_T)wp->w_width_inner - sbrlen - numberwidth;
+          int prev_width = col ? ((colnr_T)wp->w_width_inner - (sbrlen + col))
+                               : 0;
+
+          if (width <= 0) {
+            width = 1;
+          }
+          added += ((size - prev_width) / width) * vim_strsize(p_sbr);
+          if ((size - prev_width) % width) {
+            // Wrapped, add another length of 'sbr'.
+            added += vim_strsize(p_sbr);
+          }
+        } else {
+          added += vim_strsize(p_sbr);
+        }
+      }
+
+      if (wp->w_p_bri) {
+        added += get_breakindent_win(wp, line);
+      }
+
+      size += added;
+      if (col != 0) {
+        added = 0;
+      }
+    }
+  }
+
+  if (headp != NULL) {
+    *headp = added + mb_added;
+  }
+  return size;
+}
+
+/// Like win_lbr_chartabsize(), except that we know 'linebreak' is off and
+/// 'wrap' is on.  This means we need to check for a double-byte character that
+/// doesn't fit at the end of the screen line.
+///
+/// @param wp
+/// @param s
+/// @param col
+/// @param headp
+///
+/// @return The number of characters take up on the screen.
+static int win_nolbr_chartabsize(win_T *wp, char_u *s, colnr_T col, int *headp)
+{
+  int n;
+
+  if ((*s == TAB) && (!wp->w_p_list || wp->w_p_lcs_chars.tab1)) {
+    return tabstop_padding(col,
+                           wp->w_buffer->b_p_ts,
+                           wp->w_buffer->b_p_vts_array);
+  }
+  n = ptr2cells(s);
+
+  // Add one cell for a double-width character in the last column of the
+  // window, displayed with a ">".
+  if ((n == 2) && (MB_BYTE2LEN(*s) > 1) && in_win_border(wp, col)) {
+    if (headp != NULL) {
+      *headp = 1;
+    }
+    return 3;
+  }
+  return n;
+}
+