19 files changed, 611 insertions, 205 deletions

diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index b7a86af134..fa4b8e5f7d 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -19,6 +19,7 @@
 #include "nvim/mark.h"
 #include "nvim/fileio.h"
 #include "nvim/move.h"
+#include "nvim/syntax.h"
 #include "nvim/window.h"
 #include "nvim/undo.h"
 
@@ -514,6 +515,99 @@ ArrayOf(Integer, 2) buffer_get_mark(Buffer buffer, String name, Error *err)
   return rv;
 }
 
+/// Adds a highlight to buffer.
+///
+/// This can be used for plugins which dynamically generate highlights to a
+/// buffer (like a semantic highlighter or linter). The function adds a single
+/// highlight to a buffer. Unlike matchaddpos() highlights follow changes to
+/// line numbering (as lines are inserted/removed above the highlighted line),
+/// like signs and marks do.
+///
+/// "src_id" is useful for batch deletion/updating of a set of highlights. When
+/// called with src_id = 0, an unique source id is generated and returned.
+/// Succesive calls can pass in it as "src_id" to add new highlights to the same
+/// source group. All highlights in the same group can then be cleared with
+/// buffer_clear_highlight. If the highlight never will be manually deleted
+/// pass in -1 for "src_id".
+///
+/// If "hl_group" is the empty string no highlight is added, but a new src_id
+/// is still returned. This is useful for an external plugin to synchrounously
+/// request an unique src_id at initialization, and later asynchronously add and
+/// clear highlights in response to buffer changes.
+///
+/// @param buffer The buffer handle
+/// @param src_id Source group to use or 0 to use a new group,
+///               or -1 for ungrouped highlight
+/// @param hl_group Name of the highlight group to use
+/// @param line The line to highlight
+/// @param col_start Start of range of columns to highlight
+/// @param col_end End of range of columns to highlight,
+///                or -1 to highlight to end of line
+/// @param[out] err Details of an error that may have occurred
+/// @return The src_id that was used
+Integer buffer_add_highlight(Buffer buffer,
+                             Integer src_id,
+                             String hl_group,
+                             Integer line,
+                             Integer col_start,
+                             Integer col_end,
+                             Error *err)
+{
+  buf_T *buf = find_buffer_by_handle(buffer, err);
+  if (!buf) {
+    return 0;
+  }
+
+  if (line < 0 || line >= MAXLNUM) {
+    api_set_error(err, Validation, _("Line number outside range"));
+    return 0;
+  }
+  if (col_start < 0 || col_start > MAXCOL) {
+    api_set_error(err, Validation, _("Column value outside range"));
+    return 0;
+  }
+  if (col_end < 0 || col_end > MAXCOL) {
+    col_end = MAXCOL;
+  }
+
+  int hlg_id = syn_name2id((char_u*)hl_group.data);
+  src_id = bufhl_add_hl(buf, (int)src_id, hlg_id, (linenr_T)line+1,
+                        (colnr_T)col_start+1, (colnr_T)col_end);
+  return src_id;
+}
+
+/// Clears highlights from a given source group and a range of lines
+///
+/// To clear a source group in the entire buffer, pass in 1 and -1 to
+/// line_start and line_end respectively.
+///
+/// @param buffer The buffer handle
+/// @param src_id Highlight source group to clear, or -1 to clear all groups.
+/// @param line_start Start of range of lines to clear
+/// @param line_end End of range of lines to clear (exclusive)
+///                 or -1 to clear to end of file.
+/// @param[out] err Details of an error that may have occurred
+void buffer_clear_highlight(Buffer buffer,
+                            Integer src_id,
+                            Integer line_start,
+                            Integer line_end,
+                            Error *err)
+{
+  buf_T *buf = find_buffer_by_handle(buffer, err);
+  if (!buf) {
+    return;
+  }
+
+  if (line_start < 0 || line_start >= MAXLNUM) {
+    api_set_error(err, Validation, _("Line number outside range"));
+    return;
+  }
+  if (line_end < 0 || line_end > MAXLNUM) {
+    line_end = MAXLNUM;
+  }
+
+  bufhl_clear_line_range(buf, (int)src_id, (int)line_start+1, (int)line_end);
+}
 
 // Check if deleting lines made the cursor position invalid.
 // Changed the lines from "lo" to "hi" and added "extra" lines (negative if
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index c05090bbf6..62ab7495da 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -580,16 +580,17 @@ free_buffer_stuff (
 )
 {
   if (free_options) {
-    clear_wininfo(buf);                 /* including window-local options */
-    free_buf_options(buf, TRUE);
+    clear_wininfo(buf);                 // including window-local options
+    free_buf_options(buf, true);
     ga_clear(&buf->b_s.b_langp);
   }
-  vars_clear(&buf->b_vars->dv_hashtab);   /* free all internal variables */
+  vars_clear(&buf->b_vars->dv_hashtab);   // free all internal variables
   hash_init(&buf->b_vars->dv_hashtab);
-  uc_clear(&buf->b_ucmds);              /* clear local user commands */
-  buf_delete_signs(buf);                /* delete any signs */
-  map_clear_int(buf, MAP_ALL_MODES, TRUE, FALSE);    /* clear local mappings */
-  map_clear_int(buf, MAP_ALL_MODES, TRUE, TRUE);     /* clear local abbrevs */
+  uc_clear(&buf->b_ucmds);              // clear local user commands
+  buf_delete_signs(buf);                // delete any signs
+  bufhl_clear_all(buf);                // delete any highligts
+  map_clear_int(buf, MAP_ALL_MODES, true, false);    // clear local mappings
+  map_clear_int(buf, MAP_ALL_MODES, true, true);     // clear local abbrevs
   xfree(buf->b_start_fenc);
   buf->b_start_fenc = NULL;
 }
@@ -4870,6 +4871,224 @@ void sign_mark_adjust(linenr_T line1, linenr_T line2, long amount, long amount_a
     }
 }
 
+// bufhl: plugin highlights associated with a buffer
+
+/// Adds a highlight to buffer.
+///
+/// Unlike matchaddpos() highlights follow changes to line numbering (as lines
+/// are inserted/removed above the highlighted line), like signs and marks do.
+///
+/// When called with "src_id" set to 0, a unique source id is generated and
+/// returned. Succesive calls can pass it in as "src_id" to add new highlights
+/// to the same source group. All highlights in the same group can be cleared
+/// at once. If the highlight never will be manually deleted pass in -1 for
+/// "src_id"
+///
+/// if "hl_id" or "lnum" is invalid no highlight is added, but a new src_id
+/// is still returned.
+///
+/// @param buf The buffer to add highlights to
+/// @param src_id src_id to use or 0 to use a new src_id group,
+///               or -1 for ungrouped highlight.
+/// @param hl_id Id of the highlight group to use
+/// @param lnum The line to highlight
+/// @param col_start First column to highlight
+/// @param col_end The last column to highlight,
+///                or -1 to highlight to end of line
+/// @return The src_id that was used
+int bufhl_add_hl(buf_T *buf,
+                 int src_id,
+                 int hl_id,
+                 linenr_T lnum,
+                 colnr_T col_start,
+                 colnr_T col_end) {
+  static int next_src_id = 1;
+  if (src_id == 0) {
+    src_id = next_src_id++;
+  }
+  if (hl_id <= 0) {
+      // no highlight group or invalid line, just return src_id
+      return src_id;
+  }
+  if (!buf->b_bufhl_info) {
+    buf->b_bufhl_info = map_new(linenr_T, bufhl_vec_T)();
+  }
+  bufhl_vec_T* lineinfo = map_ref(linenr_T, bufhl_vec_T)(buf->b_bufhl_info,
+                                                         lnum, true);
+
+  bufhl_hl_item_T *hlentry = kv_pushp(bufhl_hl_item_T, *lineinfo);
+  hlentry->src_id = src_id;
+  hlentry->hl_id = hl_id;
+  hlentry->start = col_start;
+  hlentry->stop = col_end;
+
+  if (0 < lnum && lnum <= buf->b_ml.ml_line_count) {
+    changed_lines_buf(buf, lnum, lnum+1, 0);
+    redraw_buf_later(buf, VALID);
+  }
+  return src_id;
+}
+
+/// Clear bufhl highlights from a given source group and range of lines.
+///
+/// @param buf The buffer to remove highlights from
+/// @param src_id highlight source group to clear, or -1 to clear all groups.
+/// @param line_start first line to clear
+/// @param line_end last line to clear or MAXLNUM to clear to end of file.
+void bufhl_clear_line_range(buf_T *buf,
+                            int src_id,
+                            linenr_T line_start,
+                            linenr_T line_end) {
+  if (!buf->b_bufhl_info) {
+    return;
+  }
+  linenr_T line;
+  linenr_T first_changed = MAXLNUM, last_changed = -1;
+  // In the case line_start - line_end << bufhl_info->size
+  // it might be better to reverse this, i e loop over the lines
+  // to clear on.
+  bufhl_vec_T unused;
+  map_foreach(buf->b_bufhl_info, line, unused, {
+    (void)unused;
+    if (line_start <= line && line <= line_end) {
+      if (bufhl_clear_line(buf->b_bufhl_info, src_id, line)) {
+        if (line > last_changed) {
+          last_changed = line;
+        }
+        if (line < first_changed) {
+          first_changed = line;
+        }
+      }
+    }
+  })
+
+  if (last_changed != -1) {
+    changed_lines_buf(buf, first_changed, last_changed+1, 0);
+    redraw_buf_later(buf, VALID);
+  }
+}
+
+/// Clear bufhl highlights from a given source group and given line
+///
+/// @param bufhl_info The highlight info for the buffer
+/// @param src_id Highlight source group to clear, or -1 to clear all groups.
+/// @param lnum Linenr where the highlight should be cleared
+static bool bufhl_clear_line(bufhl_info_T *bufhl_info, int src_id, int lnum) {
+  bufhl_vec_T* lineinfo = map_ref(linenr_T, bufhl_vec_T)(bufhl_info,
+                                                         lnum, false);
+  size_t oldsize = kv_size(*lineinfo);
+  if (src_id < 0) {
+    kv_size(*lineinfo) = 0;
+  } else {
+    size_t newind = 0;
+    for (size_t i = 0; i < kv_size(*lineinfo); i++) {
+      if (kv_A(*lineinfo, i).src_id != src_id) {
+        if (i != newind) {
+          kv_A(*lineinfo, newind) = kv_A(*lineinfo, i);
+        }
+        newind++;
+      }
+    }
+    kv_size(*lineinfo) = newind;
+  }
+
+  if (kv_size(*lineinfo) == 0) {
+    kv_destroy(*lineinfo);
+    map_del(linenr_T, bufhl_vec_T)(bufhl_info, lnum);
+  }
+  return kv_size(*lineinfo) != oldsize;
+}
+
+/// Remove all highlights and free the highlight data
+void bufhl_clear_all(buf_T* buf) {
+  if (!buf->b_bufhl_info) {
+    return;
+  }
+  bufhl_clear_line_range(buf, -1, 1, MAXLNUM);
+  map_free(linenr_T, bufhl_vec_T)(buf->b_bufhl_info);
+  buf->b_bufhl_info = NULL;
+}
+
+/// Adjust a placed highlight for inserted/deleted lines.
+void bufhl_mark_adjust(buf_T* buf,
+                       linenr_T line1,
+                       linenr_T line2,
+                       long amount,
+                       long amount_after) {
+  if (!buf->b_bufhl_info) {
+    return;
+  }
+
+  bufhl_info_T *newmap = map_new(linenr_T, bufhl_vec_T)();
+  linenr_T line;
+  bufhl_vec_T lineinfo;
+  map_foreach(buf->b_bufhl_info, line, lineinfo, {
+    if (line >= line1 && line <= line2) {
+      if (amount == MAXLNUM) {
+        bufhl_clear_line(buf->b_bufhl_info, -1, line);
+        continue;
+      } else {
+        line += amount;
+      }
+    } else if (line > line2) {
+      line += amount_after;
+    }
+    map_put(linenr_T, bufhl_vec_T)(newmap, line, lineinfo);
+  });
+  map_free(linenr_T, bufhl_vec_T)(buf->b_bufhl_info);
+  buf->b_bufhl_info = newmap;
+}
+
+
+/// Get highlights to display at a specific line
+///
+/// @param buf The buffer handle
+/// @param lnum The line number
+/// @param[out] info The highligts for the line
+/// @return true if there was highlights to display
+bool bufhl_start_line(buf_T *buf, linenr_T lnum, bufhl_lineinfo_T *info) {
+  if (!buf->b_bufhl_info) {
+    return false;
+  }
+
+  info->valid_to = -1;
+  info->entries = map_get(linenr_T, bufhl_vec_T)(buf->b_bufhl_info, lnum);
+  return kv_size(info->entries) > 0;
+}
+
+/// get highlighting at column col
+///
+/// It is is assumed this will be called with
+/// non-decreasing column nrs, so that it is
+/// possible to only recalculate highlights
+/// at endpoints.
+///
+/// @param info The info returned by bufhl_start_line
+/// @param col The column to get the attr for
+/// @return The highilight attr to display at the column
+int bufhl_get_attr(bufhl_lineinfo_T *info, colnr_T col) {
+  if (col <= info->valid_to) {
+    return info->current;
+  }
+  int attr = 0;
+  info->valid_to = MAXCOL;
+  for (size_t i = 0; i < kv_size(info->entries); i++) {
+    bufhl_hl_item_T entry = kv_A(info->entries, i);
+    if (entry.start <= col && col <= entry.stop) {
+      int entry_attr = syn_id2attr(entry.hl_id);
+      attr = hl_combine_attr(attr, entry_attr);
+      if (entry.stop < info->valid_to) {
+        info->valid_to = entry.stop;
+      }
+    } else if (col < entry.start && entry.start-1 < info->valid_to) {
+      info->valid_to = entry.start-1;
+    }
+  }
+  info->current = attr;
+  return attr;
+}
+
+
 /*
  * Set 'buflisted' for curbuf to "on" and trigger autocommands if it changed.
  */
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index bdea609820..936a14b903 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -28,6 +28,8 @@ typedef struct file_buffer buf_T; // Forward declaration
 #include "nvim/profile.h"
 // for String
 #include "nvim/api/private/defs.h"
+// for Map(K, V)
+#include "nvim/map.h"
 
 #define MODIFIABLE(buf) (!buf->terminal && buf->b_p_ma)
 
@@ -59,21 +61,21 @@ typedef struct file_buffer buf_T; // Forward declaration
 #define VALID_BOTLINE_AP 0x40   /* w_botine is approximated */
 #define VALID_TOPLINE   0x80    /* w_topline is valid (for cursor position) */
 
-/* flags for b_flags */
-#define BF_RECOVERED    0x01    /* buffer has been recovered */
-#define BF_CHECK_RO     0x02    /* need to check readonly when loading file
-                                   into buffer (set by ":e", may be reset by
-                                   ":buf" */
-#define BF_NEVERLOADED  0x04    /* file has never been loaded into buffer,
-                                   many variables still need to be set */
-#define BF_NOTEDITED    0x08    /* Set when file name is changed after
-                                   starting to edit, reset when file is
-                                   written out. */
-#define BF_NEW          0x10    /* file didn't exist when editing started */
-#define BF_NEW_W        0x20    /* Warned for BF_NEW and file created */
-#define BF_READERR      0x40    /* got errors while reading the file */
-#define BF_DUMMY        0x80    /* dummy buffer, only used internally */
-#define BF_PRESERVED    0x100   /* ":preserve" was used */
+// flags for b_flags
+#define BF_RECOVERED    0x01    // buffer has been recovered
+#define BF_CHECK_RO     0x02    // need to check readonly when loading file
+                                // into buffer (set by ":e", may be reset by
+                                // ":buf")
+#define BF_NEVERLOADED  0x04    // file has never been loaded into buffer,
+                                // many variables still need to be set
+#define BF_NOTEDITED    0x08    // Set when file name is changed after
+                                // starting to edit, reset when file is
+                                // written out.
+#define BF_NEW          0x10    // file didn't exist when editing started
+#define BF_NEW_W        0x20    // Warned for BF_NEW and file created
+#define BF_READERR      0x40    // got errors while reading the file
+#define BF_DUMMY        0x80    // dummy buffer, only used internally
+#define BF_PRESERVED    0x100   // ":preserve" was used
 
 /* Mask to check for flags that prevent normal writing */
 #define BF_WRITE_MASK   (BF_NOTEDITED + BF_NEW + BF_READERR)
@@ -101,6 +103,11 @@ typedef int scid_T;                     /* script ID */
 // for signlist_T
 #include "nvim/sign_defs.h"
 
+// for bufhl_*_T
+#include "nvim/bufhl_defs.h"
+
+typedef Map(linenr_T, bufhl_vec_T) bufhl_info_T;
+
 // for FileID
 #include "nvim/os/fs_defs.h"
 
@@ -754,6 +761,8 @@ struct file_buffer {
   dict_T *additional_data;      // Additional data from shada file if any.
 
   int b_mapped_ctrl_c;          // modes where CTRL-C is mapped
+
+  bufhl_info_T *b_bufhl_info;   // buffer stored highlights
 };
 
 /*
diff --git a/src/nvim/bufhl_defs.h b/src/nvim/bufhl_defs.h
new file mode 100644
index 0000000000..e47bb2a238
--- /dev/null
+++ b/src/nvim/bufhl_defs.h
@@ -0,0 +1,25 @@
+#ifndef NVIM_BUFHL_DEFS_H
+#define NVIM_BUFHL_DEFS_H
+
+#include "nvim/pos.h"
+#include "nvim/lib/kvec.h"
+// bufhl: buffer specific highlighting
+
+struct bufhl_hl_item
+{
+  int src_id;
+  int hl_id;  // highlight group
+  colnr_T start;  // first column to highlight
+  colnr_T stop;  // last column to highlight
+};
+typedef struct bufhl_hl_item bufhl_hl_item_T;
+
+typedef kvec_t(struct bufhl_hl_item) bufhl_vec_T;
+
+typedef struct {
+  bufhl_vec_T entries;
+  int current;
+  colnr_T valid_to;
+} bufhl_lineinfo_T;
+
+#endif  // NVIM_BUFHL_DEFS_H
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index b011ee9d54..31175773f0 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -7324,10 +7324,10 @@ static struct fst {
   { "setcharsearch",     1, 1, f_setcharsearch },
   { "setcmdpos",         1, 1, f_setcmdpos },
   { "setline",           2, 2, f_setline },
-  { "setloclist",        2, 3, f_setloclist },
+  { "setloclist",        2, 4, f_setloclist },
   { "setmatches",        1, 1, f_setmatches },
   { "setpos",            2, 2, f_setpos },
-  { "setqflist",         1, 2, f_setqflist },
+  { "setqflist",         1, 3, f_setqflist },
   { "setreg",            2, 3, f_setreg },
   { "settabvar",         3, 3, f_settabvar },
   { "settabwinvar",      4, 4, f_settabwinvar },
@@ -15215,14 +15215,26 @@ static void f_setline(typval_T *argvars, typval_T *rettv)
     appended_lines_mark(lcount, added);
 }
 
-
-/*
- * Used by "setqflist()" and "setloclist()" functions
- */
-static void set_qf_ll_list(win_T *wp, typval_T *list_arg, typval_T *action_arg, typval_T *rettv)
+/// Create quickfix/location list from VimL values
+///
+/// Used by `setqflist()` and `setloclist()` functions. Accepts invalid
+/// list_arg, action_arg and title_arg arguments in which case errors out,
+/// including VAR_UNKNOWN parameters.
+///
+/// @param[in,out]  wp  Window to create location list for. May be NULL in
+///                     which case quickfix list will be created.
+/// @param[in]  list_arg  Quickfix list contents.
+/// @param[in]  action_arg  Action to perform: append to an existing list,
+///                         replace its content or create a new one.
+/// @param[in]  title_arg  New list title. Defaults to caller function name.
+/// @param[out]  rettv  Return value: 0 in case of success, -1 otherwise.
+static void set_qf_ll_list(win_T *wp, typval_T *list_arg, typval_T *action_arg,
+                           typval_T *title_arg, typval_T *rettv)
+  FUNC_ATTR_NONNULL_ARG(2, 3, 4, 5)
 {
   char_u      *act;
   int action = ' ';
+  char_u *title = NULL;
 
   rettv->vval.v_number = -1;
 
@@ -15231,7 +15243,7 @@ static void set_qf_ll_list(win_T *wp, typval_T *list_arg, typval_T *action_arg,
   else {
     list_T  *l = list_arg->vval.v_list;
 
-    if (action_arg->v_type == VAR_STRING) {
+    if (action_arg->v_type != VAR_UNKNOWN) {
       act = get_tv_string_chk(action_arg);
       if (act == NULL)
         return;                 /* type error; errmsg already given */
@@ -15239,9 +15251,20 @@ static void set_qf_ll_list(win_T *wp, typval_T *list_arg, typval_T *action_arg,
         action = *act;
     }
 
-    if (l != NULL && set_errorlist(wp, l, action,
-            (char_u *)(wp == NULL ? "setqflist()" : "setloclist()")) == OK)
+    if (title_arg->v_type != VAR_UNKNOWN) {
+      title = get_tv_string_chk(title_arg);
+      if (!title) {
+        return;  // type error; errmsg already given
+      }
+    }
+
+    if (!title) {
+      title = (char_u*)(wp ? "setloclist()" : "setqflist()");
+    }
+
+    if (l && set_errorlist(wp, l, action, title) == OK) {
       rettv->vval.v_number = 0;
+    }
   }
 }
 
@@ -15255,8 +15278,9 @@ static void f_setloclist(typval_T *argvars, typval_T *rettv)
   rettv->vval.v_number = -1;
 
   win = find_win_by_nr(&argvars[0], NULL);
-  if (win != NULL)
-    set_qf_ll_list(win, &argvars[1], &argvars[2], rettv);
+  if (win != NULL) {
+    set_qf_ll_list(win, &argvars[1], &argvars[2], &argvars[3], rettv);
+  }
 }
 
 /*
@@ -15392,7 +15416,7 @@ static void f_setpos(typval_T *argvars, typval_T *rettv)
  */
 static void f_setqflist(typval_T *argvars, typval_T *rettv)
 {
-  set_qf_ll_list(NULL, &argvars[0], &argvars[1], rettv);
+  set_qf_ll_list(NULL, &argvars[0], &argvars[1], &argvars[2], rettv);
 }
 
 /*
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 2d17b31f0f..3a24f194c1 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -4320,7 +4320,7 @@ static void ex_unmap(exarg_T *eap)
  */
 static void ex_mapclear(exarg_T *eap)
 {
-  map_clear(eap->cmd, eap->arg, eap->forceit, FALSE);
+  map_clear_mode(eap->cmd, eap->arg, eap->forceit, false);
 }
 
 /*
@@ -4328,7 +4328,7 @@ static void ex_mapclear(exarg_T *eap)
  */
 static void ex_abclear(exarg_T *eap)
 {
-  map_clear(eap->cmd, eap->arg, TRUE, TRUE);
+  map_clear_mode(eap->cmd, eap->arg, true, true);
 }
 
 static void ex_autocmd(exarg_T *eap)
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index 73b3de0b5d..437495faa4 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2915,9 +2915,9 @@ do_map (
                 did_it = TRUE;
               }
             }
-            if (mp->m_mode == 0) {              /* entry can be deleted */
-              map_free(mpp);
-              continue;                         /* continue with *mpp */
+            if (mp->m_mode == 0) {              // entry can be deleted
+              mapblock_free(mpp);
+              continue;                         // continue with *mpp
             }
 
             /*
@@ -3012,7 +3012,7 @@ theend:
  * Delete one entry from the abbrlist or maphash[].
  * "mpp" is a pointer to the m_next field of the PREVIOUS entry!
  */
-static void map_free(mapblock_T **mpp)
+static void mapblock_free(mapblock_T **mpp)
 {
   mapblock_T  *mp;
 
@@ -3080,7 +3080,7 @@ int get_map_mode(char_u **cmdp, int forceit)
  * Clear all mappings or abbreviations.
  * 'abbr' should be FALSE for mappings, TRUE for abbreviations.
  */
-void map_clear(char_u *cmdp, char_u *arg, int forceit, int abbr)
+void map_clear_mode(char_u *cmdp, char_u *arg, int forceit, int abbr)
 {
   int mode;
   int local;
@@ -3132,8 +3132,8 @@ map_clear_int (
       mp = *mpp;
       if (mp->m_mode & mode) {
         mp->m_mode &= ~mode;
-        if (mp->m_mode == 0) {       /* entry can be deleted */
-          map_free(mpp);
+        if (mp->m_mode == 0) {       // entry can be deleted
+          mapblock_free(mpp);
           continue;
         }
         /*
diff --git a/src/nvim/if_cscope.c b/src/nvim/if_cscope.c
index d236501b3f..7169a1d963 100644
--- a/src/nvim/if_cscope.c
+++ b/src/nvim/if_cscope.c
@@ -1632,77 +1632,79 @@ static char *cs_pathcomponents(char *path)
   return s;
 }
 
-/*
- * PRIVATE: cs_print_tags_priv
- *
- * called from cs_manage_matches()
- */
+/// Print cscope output that was converted into ctags style entries.
+///
+/// Only called from cs_manage_matches().
+///
+/// @param matches     Array of cscope lines in ctags style. Every entry was
+//                     produced with a format string of the form
+//                          "%s\t%s\t%s;\"\t%s" or
+//                          "%s\t%s\t%s;\""
+//                     by cs_make_vim_style_matches().
+/// @param cntxts      Context for matches.
+/// @param num_matches Number of entries in matches/cntxts, always greater 0.
 static void cs_print_tags_priv(char **matches, char **cntxts,
-                                size_t num_matches)
+                               size_t num_matches) FUNC_ATTR_NONNULL_ALL
 {
-  char        *ptag;
-  char        *fname, *lno, *extra, *tbuf;
-  size_t      num;
-  char        *globalcntx = "GLOBAL";
-  char        *context;
-  char        *cstag_msg = _("Cscope tag: %s");
+  char *globalcntx = "GLOBAL";
+  char *cstag_msg = _("Cscope tag: %s");
 
-  assert (num_matches > 0);
+  assert(num_matches > 0);
+  assert(strcnt(matches[0], '\t') >= 2);
 
-  tbuf = xmalloc(strlen(matches[0]) + 1);
+  char *ptag = matches[0];
+  char *ptag_end = strchr(ptag, '\t');
+  assert(ptag_end >= ptag);
+  // NUL terminate tag string in matches[0].
+  *ptag_end = NUL;
 
-  strcpy(tbuf, matches[0]);
-  ptag = strtok(tbuf, "\t");
-
-  size_t newsize = strlen(cstag_msg) + strlen(ptag);
+  // The "%s" in cstag_msg won't appear in the result string, so we don't need
+  // extra memory for terminating NUL.
+  size_t newsize = strlen(cstag_msg) + (size_t)(ptag_end - ptag);
   char *buf = xmalloc(newsize);
   size_t bufsize = newsize;  // Track available bufsize
-  (void)sprintf(buf, cstag_msg, ptag);
+  (void)snprintf(buf, bufsize, cstag_msg, ptag);
   MSG_PUTS_ATTR(buf, hl_attr(HLF_T));
+  msg_clr_eos();
 
-  xfree(tbuf);
+  // restore matches[0]
+  *ptag_end = '\t';
 
-  MSG_PUTS_ATTR(_("\n   #   line"), hl_attr(HLF_T));      /* strlen is 7 */
+  // Column headers for match number, line number and filename.
+  MSG_PUTS_ATTR(_("\n   #   line"), hl_attr(HLF_T));
   msg_advance(msg_col + 2);
   MSG_PUTS_ATTR(_("filename / context / line\n"), hl_attr(HLF_T));
 
-  num = 1;
   for (size_t i = 0; i < num_matches; i++) {
-    size_t idx = i;
-
-    /* if we really wanted to, we could avoid this malloc and strcpy
-     * by parsing matches[i] on the fly and placing stuff into buf
-     * directly, but that's too much of a hassle
-     */
-    tbuf = xmalloc(strlen(matches[idx]) + 1);
-    (void)strcpy(tbuf, matches[idx]);
-
-    if (strtok(tbuf, (const char *)"\t") == NULL)
-      continue;
-    if ((fname = strtok(NULL, (const char *)"\t")) == NULL)
-      continue;
-    if ((lno = strtok(NULL, (const char *)"\t")) == NULL)
-      continue;
-    extra = strtok(NULL, (const char *)"\t");
-
-    lno[strlen(lno)-2] = '\0';      /* ignore ;" at the end */
+    assert(strcnt(matches[i], '\t') >= 2);
+
+    // Parse filename, line number and optional part.
+    char *fname = strchr(matches[i], '\t') + 1;
+    char *fname_end = strchr(fname, '\t');
+    // Replace second '\t' in matches[i] with NUL to terminate fname.
+    *fname_end = NUL;
+
+    char *lno = fname_end + 1;
+    char *extra = xstrchrnul(lno, '\t');
+    // Ignore ;" at the end of lno.
+    char *lno_end = extra - 2;
+    *lno_end = NUL;
+    // Do we have an optional part?
+    extra = *extra ? extra + 1 : NULL;
 
     const char *csfmt_str = "%4zu %6s  ";
-    /* hopefully 'num' (num of matches) will be less than 10^16 */
-    newsize = strlen(csfmt_str) + 16 + strlen(lno);
+    // hopefully num_matches will be less than 10^16
+    newsize = strlen(csfmt_str) + 16 + (size_t)(lno_end - lno);
     if (bufsize < newsize) {
       buf = xrealloc(buf, newsize);
       bufsize = newsize;
     }
-    (void)sprintf(buf, csfmt_str, num, lno);
+    (void)snprintf(buf, bufsize, csfmt_str, i + 1, lno);
     MSG_PUTS_ATTR(buf, hl_attr(HLF_CM));
     MSG_PUTS_LONG_ATTR(cs_pathcomponents(fname), hl_attr(HLF_CM));
 
-    /* compute the required space for the context */
-    if (cntxts[idx] != NULL)
-      context = cntxts[idx];
-    else
-      context = globalcntx;
+    // compute the required space for the context
+    char *context = cntxts[i] ? cntxts[i] : globalcntx;
 
     const char *cntxformat = " <<%s>>";
     // '%s' won't appear in result string, so:
@@ -1713,11 +1715,13 @@ static void cs_print_tags_priv(char **matches, char **cntxts,
       buf = xrealloc(buf, newsize);
       bufsize = newsize;
     }
-    (void)sprintf(buf, cntxformat, context);
+    int buf_len = snprintf(buf, bufsize, cntxformat, context);
+    assert(buf_len >= 0);
 
-    /* print the context only if it fits on the same line */
-    if (msg_col + (int)strlen(buf) >= (int)Columns)
+    // Print the context only if it fits on the same line.
+    if (msg_col + buf_len >= (int)Columns) {
       msg_putchar('\n');
+    }
     msg_advance(12);
     MSG_PUTS_LONG(buf);
     msg_putchar('\n');
@@ -1726,23 +1730,23 @@ static void cs_print_tags_priv(char **matches, char **cntxts,
       MSG_PUTS_LONG(extra);
     }
 
-    xfree(tbuf);     /* only after printing extra due to strtok use */
+    // restore matches[i]
+    *fname_end = '\t';
+    *lno_end = ';';
 
-    if (msg_col)
+    if (msg_col) {
       msg_putchar('\n');
+    }
 
     os_breakcheck();
     if (got_int) {
-      got_int = FALSE;          /* don't print any more matches */
+      got_int = false;  // don't print any more matches
       break;
     }
-
-    num++;
-  }   /* for all matches */
+  }
 
   xfree(buf);
-} /* cs_print_tags_priv */
-
+}
 
 /*
  * PRIVATE: cs_read_prompt
diff --git a/src/nvim/lib/khash.h b/src/nvim/lib/khash.h
index 56be29d14c..8287cb14da 100644
--- a/src/nvim/lib/khash.h
+++ b/src/nvim/lib/khash.h
@@ -184,7 +184,7 @@ typedef khint_t khiter_t;
 #define kfree(P) xfree(P)
 #endif
 
-static const double __ac_HASH_UPPER = 0.77;
+#define __ac_HASH_UPPER 0.77
 
 #define __KHASH_TYPE(name, khkey_t, khval_t) \
 	typedef struct { \
diff --git a/src/nvim/lib/kvec.h b/src/nvim/lib/kvec.h
index 0466cb229c..53ecf232c6 100644
--- a/src/nvim/lib/kvec.h
+++ b/src/nvim/lib/kvec.h
@@ -77,10 +77,10 @@ int main() {
 		(v).items[(v).size++] = (x);										\
 	} while (0)
 
-#define kv_pushp(type, v) (((v).size == (v).capacity)?							\
+#define kv_pushp(type, v) ((((v).size == (v).capacity)?							\
 						   ((v).capacity = ((v).capacity? (v).capacity<<1 : 8),				\
 							(v).items = (type*)xrealloc((v).items, sizeof(type) * (v).capacity), 0)	\
-						   : 0), ((v).items + ((v).size++))
+						   : 0), ((v).items + ((v).size++)))
 
 #define kv_a(type, v, i) (((v).capacity <= (size_t)(i)? \
 						  ((v).capacity = (v).size = (i) + 1, kv_roundup32((v).capacity), \
diff --git a/src/nvim/map.c b/src/nvim/map.c
index ed7bda4cce..d4262ae9a8 100644
--- a/src/nvim/map.c
+++ b/src/nvim/map.c
@@ -18,6 +18,9 @@
 #define uint32_t_eq kh_int_hash_equal
 #define int_hash kh_int_hash_func
 #define int_eq kh_int_hash_equal
+#define linenr_T_hash kh_int_hash_func
+#define linenr_T_eq kh_int_hash_equal
+
 
 #if defined(ARCH_64)
 #define ptr_t_hash(key) uint64_t_hash((uint64_t)key)
@@ -78,6 +81,25 @@
     return rv;                                                                \
   }                                                                           \
                                                                               \
+  U *map_##T##_##U##_ref(Map(T, U) *map, T key, bool put)                     \
+  {                                                                           \
+    int ret;                                                                  \
+    khiter_t k;                                                               \
+    if (put) {                                                                \
+      k = kh_put(T##_##U##_map, map->table, key, &ret);                       \
+      if (ret) {                                                              \
+        kh_val(map->table, k) = INITIALIZER(T, U);                            \
+      }                                                                       \
+    } else {                                                                  \
+      k = kh_get(T##_##U##_map, map->table, key);                             \
+      if (k == kh_end(map->table)) {                                          \
+        return NULL;                                                          \
+      }                                                                       \
+    }                                                                         \
+                                                                              \
+    return &kh_val(map->table, k);                                            \
+  }                                                                           \
+                                                                              \
   U map_##T##_##U##_del(Map(T, U) *map, T key)                                \
   {                                                                           \
     U rv = INITIALIZER(T, U);                                                 \
@@ -118,3 +140,5 @@ MAP_IMPL(ptr_t, ptr_t, DEFAULT_INITIALIZER)
 MAP_IMPL(uint64_t, ptr_t, DEFAULT_INITIALIZER)
 #define MSGPACK_HANDLER_INITIALIZER {.fn = NULL, .async = false}
 MAP_IMPL(String, MsgpackRpcRequestHandler, MSGPACK_HANDLER_INITIALIZER)
+#define KVEC_INITIALIZER { .size = 0, .capacity = 0, .items = NULL }
+MAP_IMPL(linenr_T, bufhl_vec_T, KVEC_INITIALIZER)
diff --git a/src/nvim/map.h b/src/nvim/map.h
index c0e2ca3aac..e90cc360ce 100644
--- a/src/nvim/map.h
+++ b/src/nvim/map.h
@@ -6,6 +6,7 @@
 #include "nvim/map_defs.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/msgpack_rpc/defs.h"
+#include "nvim/bufhl_defs.h"
 
 #define MAP_DECLS(T, U)                                                       \
   KHASH_DECLARE(T##_##U##_map, T, U)                                          \
@@ -19,6 +20,7 @@
   U map_##T##_##U##_get(Map(T, U) *map, T key);                               \
   bool map_##T##_##U##_has(Map(T, U) *map, T key);                            \
   U map_##T##_##U##_put(Map(T, U) *map, T key, U value);                      \
+  U *map_##T##_##U##_ref(Map(T, U) *map, T key, bool put);                    \
   U map_##T##_##U##_del(Map(T, U) *map, T key);                               \
   void map_##T##_##U##_clear(Map(T, U) *map);
 
@@ -28,12 +30,14 @@ MAP_DECLS(cstr_t, ptr_t)
 MAP_DECLS(ptr_t, ptr_t)
 MAP_DECLS(uint64_t, ptr_t)
 MAP_DECLS(String, MsgpackRpcRequestHandler)
+MAP_DECLS(linenr_T, bufhl_vec_T)
 
 #define map_new(T, U) map_##T##_##U##_new
 #define map_free(T, U) map_##T##_##U##_free
 #define map_get(T, U) map_##T##_##U##_get
 #define map_has(T, U) map_##T##_##U##_has
 #define map_put(T, U) map_##T##_##U##_put
+#define map_ref(T, U) map_##T##_##U##_ref
 #define map_del(T, U) map_##T##_##U##_del
 #define map_clear(T, U) map_##T##_##U##_clear
 
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index e2f212340c..fe802e48ba 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -922,6 +922,7 @@ void mark_adjust(linenr_T line1, linenr_T line2, long amount, long amount_after)
     }
 
     sign_mark_adjust(line1, line2, amount, amount_after);
+    bufhl_mark_adjust(curbuf, line1, line2, amount, amount_after);
   }
 
   /* previous context mark */
diff --git a/src/nvim/misc1.c b/src/nvim/misc1.c
index 6c969a43fc..db303fd54a 100644
--- a/src/nvim/misc1.c
+++ b/src/nvim/misc1.c
@@ -1985,13 +1985,13 @@ changed_lines (
   changed_common(lnum, col, lnume, xtra);
 }
 
-static void 
-changed_lines_buf (
-    buf_T *buf,
-    linenr_T lnum,              /* first line with change */
-    linenr_T lnume,             /* line below last changed line */
-    long xtra                  /* number of extra lines (negative when deleting) */
-)
+/// Mark line range in buffer as changed.
+///
+/// @param buf the buffer where lines were changed
+/// @param lnum first line with change
+/// @param lnume line below last changed line
+/// @param xtra number of extra lines (negative when deleting)
+void changed_lines_buf(buf_T *buf, linenr_T lnum, linenr_T lnume, long xtra)
 {
   if (buf->b_mod_set) {
     /* find the maximum area that must be redisplayed */
diff --git a/src/nvim/msgpack_rpc/defs.h b/src/nvim/msgpack_rpc/defs.h
index d97cf28ca1..5611636d4f 100644
--- a/src/nvim/msgpack_rpc/defs.h
+++ b/src/nvim/msgpack_rpc/defs.h
@@ -1,8 +1,6 @@
 #ifndef NVIM_MSGPACK_RPC_DEFS_H
 #define NVIM_MSGPACK_RPC_DEFS_H
 
-#include <msgpack.h>
-
 
 /// The rpc_method_handlers table, used in msgpack_rpc_dispatch(), stores
 /// functions of this type.
@@ -24,22 +22,6 @@ void msgpack_rpc_add_method_handler(String method,
 
 void msgpack_rpc_init_function_metadata(Dictionary *metadata);
 
-/// Dispatches to the actual API function after basic payload validation by
-/// `msgpack_rpc_call`. It is responsible for validating/converting arguments
-/// to C types, and converting the return value back to msgpack types.
-/// The implementation is generated at compile time with metadata extracted
-/// from the api/*.h headers,
-///
-/// @param channel_id The channel id
-/// @param method_id The method id
-/// @param req The parsed request object
-/// @param error Pointer to error structure
-/// @return Some object
-Object msgpack_rpc_dispatch(uint64_t channel_id,
-                            msgpack_object *req,
-                            Error *error)
-  FUNC_ATTR_NONNULL_ARG(2) FUNC_ATTR_NONNULL_ARG(3);
-
 MsgpackRpcRequestHandler msgpack_rpc_get_handler_for(const char *name,
                                                      size_t name_len)
   FUNC_ATTR_NONNULL_ARG(1);
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 0f6874e941..af7b272467 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -5947,13 +5947,17 @@ option_value2string (
   if (opp->flags & P_NUM) {
     long wc = 0;
 
-    if (wc_use_keyname(varp, &wc))
-      STRCPY(NameBuff, get_special_key_name((int)wc, 0));
-    else if (wc != 0)
-      STRCPY(NameBuff, transchar((int)wc));
-    else
-      sprintf((char *)NameBuff, "%" PRId64, (int64_t)*(long *)varp);
-  } else { /* P_STRING */
+    if (wc_use_keyname(varp, &wc)) {
+      STRLCPY(NameBuff, get_special_key_name((int)wc, 0), sizeof(NameBuff));
+    } else if (wc != 0) {
+      STRLCPY(NameBuff, transchar((int)wc), sizeof(NameBuff));
+    } else {
+      snprintf((char *)NameBuff,
+               sizeof(NameBuff),
+               "%" PRId64,
+               (int64_t)*(long *)varp);
+    }
+  } else {  // P_STRING
     varp = *(char_u **)(varp);
     if (varp == NULL)                       /* just in case */
       NameBuff[0] = NUL;
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 3b5836f0b5..cd440fe8dc 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -2184,6 +2184,10 @@ win_line (
   int prev_c1 = 0;                      /* first composing char for prev_c */
   int did_line_attr = 0;
 
+  bool has_bufhl = false;                // this buffer has highlight matches
+  int bufhl_attr = 0;                   // attributes desired by bufhl
+  bufhl_lineinfo_T bufhl_info;          // bufhl data for this line
+
   /* draw_state: items that are drawn in sequence: */
 #define WL_START        0               /* nothing done yet */
 # define WL_CMDLINE     WL_START + 1    /* cmdline window column */
@@ -2244,6 +2248,11 @@ win_line (
     }
   }
 
+  if (bufhl_start_line(wp->w_buffer, lnum, &bufhl_info)) {
+    has_bufhl = true;
+    extra_check = true;
+  }
+
   /* Check for columns to display for 'colorcolumn'. */
   color_cols = wp->w_buffer->terminal ? NULL : wp->w_p_cc_cols;
   if (color_cols != NULL)
@@ -3335,6 +3344,17 @@ win_line (
             char_attr = hl_combine_attr(spell_attr, char_attr);
         }
 
+        if (has_bufhl && v > 0) {
+          bufhl_attr = bufhl_get_attr(&bufhl_info, (colnr_T)v);
+          if (bufhl_attr != 0) {
+            if (!attr_pri) {
+              char_attr = hl_combine_attr(char_attr, bufhl_attr);
+            } else {
+              char_attr = hl_combine_attr(bufhl_attr, char_attr);
+            }
+          }
+        }
+
         if (wp->w_buffer->terminal) {
           char_attr = hl_combine_attr(char_attr, term_attrs[vcol]);
         }
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index fb74569e3b..42fd81f643 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -141,10 +141,6 @@ struct terminal {
   int pressed_button;
   // pending width/height
   bool pending_resize;
-  // color palette. this isn't set directly in the vterm instance because
-  // the default values are used to obtain the color numbers passed to cterm
-  // colors
-  RgbValue colors[256];
   // With a reference count of 0 the terminal can be freed.
   size_t refcount;
 };
@@ -205,6 +201,7 @@ void terminal_teardown(void)
 
 Terminal *terminal_open(TerminalOptions opts)
 {
+  bool true_color = ui_rgb_attached();
   // Create a new terminal instance and configure it
   Terminal *rv = xcalloc(1, sizeof(Terminal));
   rv->opts = opts;
@@ -220,7 +217,7 @@ Terminal *terminal_open(TerminalOptions opts)
   // Set up screen
   rv->vts = vterm_obtain_screen(rv->vt);
   vterm_screen_enable_altscreen(rv->vts, true);
-    // delete empty lines at the end of the buffer
+  // delete empty lines at the end of the buffer
   vterm_screen_set_callbacks(rv->vts, &vterm_screen_callbacks, rv);
   vterm_screen_set_damage_merge(rv->vts, VTERM_DAMAGE_SCROLL);
   vterm_screen_reset(rv->vts, 1);
@@ -250,12 +247,18 @@ Terminal *terminal_open(TerminalOptions opts)
   rv->sb_size = MIN(rv->sb_size, 100000);
   rv->sb_buffer = xmalloc(sizeof(ScrollbackLine *) * rv->sb_size);
 
+  if (!true_color) {
+    return rv;
+  }
+
+  vterm_state_set_bold_highbright(state, true);
+
   // Configure the color palette. Try to get the color from:
   //
   // - b:terminal_color_{NUM}
   // - g:terminal_color_{NUM}
   // - the VTerm instance
-  for (int i = 0; i < (int)ARRAY_SIZE(rv->colors); i++) {
+  for (int i = 0; i < 16; i++) {
     RgbValue color_val = -1;
     char var[64];
     snprintf(var, sizeof(var), "terminal_color_%d", i);
@@ -265,16 +268,13 @@ Terminal *terminal_open(TerminalOptions opts)
       xfree(name);
 
       if (color_val != -1) {
-        rv->colors[i] = color_val;
+        VTermColor color;
+        color.red = (uint8_t)((color_val >> 16) & 0xFF);
+        color.green = (uint8_t)((color_val >> 8) & 0xFF);
+        color.blue = (uint8_t)((color_val >> 0) & 0xFF);
+        vterm_state_set_palette_color(state, i, &color);
       }
     }
-
-    if (color_val == -1) {
-      // the default is taken from vterm
-      VTermColor color;
-      vterm_state_get_palette_color(state, i, &color);
-      rv->colors[i] = RGB(color.red, color.green, color.blue);
-    }
   }
 
   return rv;
@@ -548,10 +548,6 @@ void terminal_get_line_attributes(Terminal *term, win_T *wp, int linenr,
                     map_get(int, int)(color_indexes, vt_fg) : 0;
     int vt_bg_idx = vt_bg != default_vt_bg ?
                     map_get(int, int)(color_indexes, vt_bg) : 0;
-    // The index is now used to get the final rgb value from the
-    // user-customizable palette.
-    int vt_fg_rgb = vt_fg_idx != 0 ? term->colors[vt_fg_idx - 1] : -1;
-    int vt_bg_rgb = vt_bg_idx != 0 ? term->colors[vt_bg_idx - 1] : -1;
 
     int hl_attrs = (cell.attrs.bold ? HL_BOLD : 0)
                  | (cell.attrs.italic ? HL_ITALIC : 0)
@@ -566,8 +562,8 @@ void terminal_get_line_attributes(Terminal *term, win_T *wp, int linenr,
         .cterm_fg_color = vt_fg_idx,
         .cterm_bg_color = vt_bg_idx,
         .rgb_ae_attr = (int16_t)hl_attrs,
-        .rgb_fg_color = vt_fg_rgb,
-        .rgb_bg_color = vt_bg_rgb,
+        .rgb_fg_color = vt_fg,
+        .rgb_bg_color = vt_bg,
       });
     }
 
diff --git a/src/nvim/undo.c b/src/nvim/undo.c
index b8cdffcda0..4a8a24d79d 100644
--- a/src/nvim/undo.c
+++ b/src/nvim/undo.c
@@ -4,29 +4,29 @@
  * The saved lines are stored in a list of lists (one for each buffer):
  *
  * b_u_oldhead------------------------------------------------+
- *							      |
- *							      V
- *		  +--------------+    +--------------+	  +--------------+
- * b_u_newhead--->| u_header	 |    | u_header     |	  | u_header	 |
- *		  |	uh_next------>|     uh_next------>|	uh_next---->NULL
- *	   NULL<--------uh_prev  |<---------uh_prev  |<---------uh_prev  |
- *		  |	uh_entry |    |     uh_entry |	  |	uh_entry |
- *		  +--------|-----+    +--------|-----+	  +--------|-----+
- *			   |		       |		   |
- *			   V		       V		   V
- *		  +--------------+    +--------------+	  +--------------+
- *		  | u_entry	 |    | u_entry      |	  | u_entry	 |
- *		  |	ue_next  |    |     ue_next  |	  |	ue_next  |
- *		  +--------|-----+    +--------|-----+	  +--------|-----+
- *			   |		       |		   |
- *			   V		       V		   V
- *		  +--------------+	      NULL		  NULL
- *		  | u_entry	 |
- *		  |	ue_next  |
- *		  +--------|-----+
- *			   |
- *			   V
- *			  etc.
+ *                                                            |
+ *                                                            V
+ *                +--------------+    +--------------+    +--------------+
+ * b_u_newhead--->| u_header     |    | u_header     |    | u_header     |
+ *                |     uh_next------>|     uh_next------>|     uh_next---->NULL
+ *         NULL<--------uh_prev  |<---------uh_prev  |<---------uh_prev  |
+ *                |     uh_entry |    |     uh_entry |    |     uh_entry |
+ *                +--------|-----+    +--------|-----+    +--------|-----+
+ *                         |                   |                   |
+ *                         V                   V                   V
+ *                +--------------+    +--------------+    +--------------+
+ *                | u_entry      |    | u_entry      |    | u_entry      |
+ *                |     ue_next  |    |     ue_next  |    |     ue_next  |
+ *                +--------|-----+    +--------|-----+    +--------|-----+
+ *                         |                   |                   |
+ *                         V                   V                   V
+ *                +--------------+            NULL                NULL
+ *                | u_entry      |
+ *                |     ue_next  |
+ *                +--------|-----+
+ *                         |
+ *                         V
+ *                        etc.
  *
  * Each u_entry list contains the information for one undo or redo.
  * curbuf->b_u_curhead points to the header of the last undo (the next redo),
@@ -37,30 +37,30 @@
  * uh_seq field is numbered sequentially to be able to find a newer or older
  * branch.
  *
- *		   +---------------+	+---------------+
- * b_u_oldhead --->| u_header	   |	| u_header	|
- *		   |   uh_alt_next ---->|   uh_alt_next ----> NULL
- *	   NULL <----- uh_alt_prev |<------ uh_alt_prev |
- *		   |   uh_prev	   |	|   uh_prev	|
- *		   +-----|---------+	+-----|---------+
- *			 |		      |
- *			 V		      V
- *		   +---------------+	+---------------+
- *		   | u_header	   |	| u_header	|
- *		   |   uh_alt_next |	|   uh_alt_next |
- * b_u_newhead --->|   uh_alt_prev |	|   uh_alt_prev |
- *		   |   uh_prev	   |	|   uh_prev	|
- *		   +-----|---------+	+-----|---------+
- *			 |		      |
- *			 V		      V
- *		       NULL		+---------------+    +---------------+
- *					| u_header	|    | u_header      |
- *					|   uh_alt_next ---->|	 uh_alt_next |
- *					|   uh_alt_prev |<------ uh_alt_prev |
- *					|   uh_prev	|    |	 uh_prev     |
- *					+-----|---------+    +-----|---------+
- *					      |			   |
- *					     etc.		  etc.
+ *                 +---------------+    +---------------+
+ * b_u_oldhead --->| u_header      |    | u_header      |
+ *                 |   uh_alt_next ---->|   uh_alt_next ----> NULL
+ *         NULL <----- uh_alt_prev |<------ uh_alt_prev |
+ *                 |   uh_prev     |    |   uh_prev     |
+ *                 +-----|---------+    +-----|---------+
+ *                       |                    |
+ *                       V                    V
+ *                 +---------------+    +---------------+
+ *                 | u_header      |    | u_header      |
+ *                 |   uh_alt_next |    |   uh_alt_next |
+ * b_u_newhead --->|   uh_alt_prev |    |   uh_alt_prev |
+ *                 |   uh_prev     |    |   uh_prev     |
+ *                 +-----|---------+    +-----|---------+
+ *                       |                    |
+ *                       V                    V
+ *                     NULL             +---------------+    +---------------+
+ *                                      | u_header      |    | u_header      |
+ *                                      |   uh_alt_next ---->|   uh_alt_next |
+ *                                      |   uh_alt_prev |<------ uh_alt_prev |
+ *                                      |   uh_prev     |    |   uh_prev     |
+ *                                      +-----|---------+    +-----|---------+
+ *                                            |                    |
+ *                                           etc.                 etc.
  *
  *
  * All data is allocated and will all be freed when the buffer is unloaded.