vim-patch:9.1.0394: Cannot get a list of positions describing a region

Problem:  Cannot get a list of positions describing a region
          (Justin M. Keyes, after v9.1.0120)
Solution: Add the getregionpos() function
          (Shougo Matsushita)

fixes: vim/vim#14609
closes: vim/vim#14617

https://github.com/vim/vim/commit/b4757e627e6c83d1c8e5535d4887a82d6a5efdd0

Co-authored-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Co-authored-by: Justin M. Keyes <justinkz@gmail.com>

2 files changed, 184 insertions, 69 deletions

diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index f0eeca2f10..0653a51f96 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -4414,6 +4414,31 @@ M.funcs = {
     returns = 'string[]',
     signature = 'getregion({pos1}, {pos2} [, {opts}])',
   },
+  getregionpos = {
+    args = { 2, 3 },
+    base = 1,
+    desc = [=[
+      Same as |getregion()|, but returns a list of positions
+      describing the buffer text segments bound by {pos1} and
+      {pos2}.
+      The segments are a pair of positions for every line: >
+      	[[{start_pos}, {end_pos}], ...]
+      <
+      The position is a |List| with four numbers:
+          [bufnum, lnum, col, off]
+      "bufnum" is the buffer number.
+      "lnum" and "col" are the position in the buffer.  The first
+      column is 1.
+      The "off" number is zero, unless 'virtualedit' is used.  Then
+      it is the offset in screen columns from the start of the
+      character.  E.g., a position within a <Tab> or after the last
+      character.
+    ]=],
+    name = 'getregionpos',
+    params = { { 'pos1', 'table' }, { 'pos2', 'table' }, { 'opts', 'table' } },
+    returns = 'integer[][][]',
+    signature = 'getregionpos({pos1}, {pos2} [, {opts}])',
+  },
   getregtype = {
     args = { 0, 1 },
     base = 1,
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 0b4b79c6ca..2667f4a694 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -2823,24 +2823,25 @@ static char *block_def2str(struct block_def *bd)
   return ret;
 }
 
-/// "getregion()" function
-static void f_getregion(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+static int getregionpos(typval_T *argvars, typval_T *rettv, pos_T *p1, pos_T *p2,
+                        bool *const inclusive, MotionType *region_type, oparg_T *oa,
+                        int *const fnum)
+  FUNC_ATTR_NONNULL_ALL
 {
   tv_list_alloc_ret(rettv, kListLenMayKnow);
 
   if (tv_check_for_list_arg(argvars, 0) == FAIL
       || tv_check_for_list_arg(argvars, 1) == FAIL
       || tv_check_for_opt_dict_arg(argvars, 2) == FAIL) {
-    return;
+    return FAIL;
   }
 
   int fnum1 = -1;
   int fnum2 = -1;
-  pos_T p1, p2;
-  if (list2fpos(&argvars[0], &p1, &fnum1, NULL, false) != OK
-      || list2fpos(&argvars[1], &p2, &fnum2, NULL, false) != OK
+  if (list2fpos(&argvars[0], p1, &fnum1, NULL, false) != OK
+      || list2fpos(&argvars[1], p2, &fnum2, NULL, false) != OK
       || fnum1 != fnum2) {
-    return;
+    return FAIL;
   }
 
   bool is_select_exclusive;
@@ -2858,108 +2859,123 @@ static void f_getregion(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     type = default_type;
   }
 
-  MotionType region_type = kMTUnknown;
   if (type[0] == 'v' && type[1] == NUL) {
-    region_type = kMTCharWise;
+    *region_type = kMTCharWise;
   } else if (type[0] == 'V' && type[1] == NUL) {
-    region_type = kMTLineWise;
+    *region_type = kMTLineWise;
   } else if (type[0] == Ctrl_V && type[1] == NUL) {
-    region_type = kMTBlockWise;
+    *region_type = kMTBlockWise;
   } else {
     semsg(_(e_invargNval), "type", type);
-    return;
+    return FAIL;
   }
 
   buf_T *findbuf = fnum1 != 0 ? buflist_findnr(fnum1) : curbuf;
+  *fnum = fnum1 != 0 ? fnum1 : curbuf->b_fnum;
   if (findbuf == NULL || findbuf->b_ml.ml_mfp == NULL) {
     emsg(_(e_buffer_is_not_loaded));
-    return;
+    return FAIL;
   }
 
-  if (p1.lnum < 1 || p1.lnum > findbuf->b_ml.ml_line_count) {
-    semsg(_(e_invalid_line_number_nr), p1.lnum);
-    return;
+  if (p1->lnum < 1 || p1->lnum > findbuf->b_ml.ml_line_count) {
+    semsg(_(e_invalid_line_number_nr), p1->lnum);
+    return FAIL;
   }
-  if (p1.col == MAXCOL) {
-    p1.col = ml_get_buf_len(findbuf, p1.lnum) + 1;
-  } else if (p1.col < 1 || p1.col > ml_get_buf_len(findbuf, p1.lnum) + 1) {
-    semsg(_(e_invalid_column_number_nr), p1.col);
-    return;
+  if (p1->col == MAXCOL) {
+    p1->col = ml_get_buf_len(findbuf, p1->lnum) + 1;
+  } else if (p1->col < 1 || p1->col > ml_get_buf_len(findbuf, p1->lnum) + 1) {
+    semsg(_(e_invalid_column_number_nr), p1->col);
+    return FAIL;
   }
 
-  if (p2.lnum < 1 || p2.lnum > findbuf->b_ml.ml_line_count) {
-    semsg(_(e_invalid_line_number_nr), p2.lnum);
-    return;
+  if (p2->lnum < 1 || p2->lnum > findbuf->b_ml.ml_line_count) {
+    semsg(_(e_invalid_line_number_nr), p2->lnum);
+    return FAIL;
   }
-  if (p2.col == MAXCOL) {
-    p2.col = ml_get_buf_len(findbuf, p2.lnum) + 1;
-  } else if (p2.col < 1 || p2.col > ml_get_buf_len(findbuf, p2.lnum) + 1) {
-    semsg(_(e_invalid_column_number_nr), p2.col);
-    return;
+  if (p2->col == MAXCOL) {
+    p2->col = ml_get_buf_len(findbuf, p2->lnum) + 1;
+  } else if (p2->col < 1 || p2->col > ml_get_buf_len(findbuf, p2->lnum) + 1) {
+    semsg(_(e_invalid_column_number_nr), p2->col);
+    return FAIL;
   }
 
-  buf_T *const save_curbuf = curbuf;
   curbuf = findbuf;
   curwin->w_buffer = curbuf;
-  const TriState save_virtual = virtual_op;
   virtual_op = virtual_active(curwin);
 
-  // NOTE: Adjust is needed.
-  p1.col--;
-  p2.col--;
+  // NOTE: Adjustment is needed.
+  p1->col--;
+  p2->col--;
 
-  if (!lt(p1, p2)) {
+  if (!lt(*p1, *p2)) {
     // swap position
-    pos_T p = p1;
-    p1 = p2;
-    p2 = p;
+    pos_T p = *p1;
+    *p1 = *p2;
+    *p2 = p;
   }
 
-  oparg_T oa;
-  bool inclusive = true;
-
-  if (region_type == kMTCharWise) {
+  if (*region_type == kMTCharWise) {
     // handle 'selection' == "exclusive"
-    if (is_select_exclusive && !equalpos(p1, p2)) {
-      if (p2.coladd > 0) {
-        p2.coladd--;
-      } else if (p2.col > 0) {
-        p2.col--;
-        mark_mb_adjustpos(curbuf, &p2);
-      } else if (p2.lnum > 1) {
-        p2.lnum--;
-        p2.col = ml_get_len(p2.lnum);
-        if (p2.col > 0) {
-          p2.col--;
-          mark_mb_adjustpos(curbuf, &p2);
+    if (is_select_exclusive && !equalpos(*p1, *p2)) {
+      if (p2->coladd > 0) {
+        p2->coladd--;
+      } else if (p2->col > 0) {
+        p2->col--;
+        mark_mb_adjustpos(curbuf, p2);
+      } else if (p2->lnum > 1) {
+        p2->lnum--;
+        p2->col = ml_get_len(p2->lnum);
+        if (p2->col > 0) {
+          p2->col--;
+          mark_mb_adjustpos(curbuf, p2);
         }
       }
     }
     // if fp2 is on NUL (empty line) inclusive becomes false
-    if (*ml_get_pos(&p2) == NUL && !virtual_op) {
-      inclusive = false;
+    if (*ml_get_pos(p2) == NUL && !virtual_op) {
+      *inclusive = false;
     }
-  } else if (region_type == kMTBlockWise) {
+  } else if (*region_type == kMTBlockWise) {
     colnr_T sc1, ec1, sc2, ec2;
-    getvvcol(curwin, &p1, &sc1, NULL, &ec1);
-    getvvcol(curwin, &p2, &sc2, NULL, &ec2);
-    oa.motion_type = kMTBlockWise;
-    oa.inclusive = true;
-    oa.op_type = OP_NOP;
-    oa.start = p1;
-    oa.end = p2;
-    oa.start_vcol = MIN(sc1, sc2);
+    getvvcol(curwin, p1, &sc1, NULL, &ec1);
+    getvvcol(curwin, p2, &sc2, NULL, &ec2);
+    oa->motion_type = kMTBlockWise;
+    oa->inclusive = true;
+    oa->op_type = OP_NOP;
+    oa->start = *p1;
+    oa->end = *p2;
+    oa->start_vcol = MIN(sc1, sc2);
     if (is_select_exclusive && ec1 < sc2 && 0 < sc2 && ec2 > ec1) {
-      oa.end_vcol = sc2 - 1;
+      oa->end_vcol = sc2 - 1;
     } else {
-      oa.end_vcol = MAX(ec1, ec2);
+      oa->end_vcol = MAX(ec1, ec2);
     }
   }
 
   // Include the trailing byte of a multi-byte char.
-  int l = utfc_ptr2len(ml_get_pos(&p2));
+  int l = utfc_ptr2len(ml_get_pos(p2));
   if (l > 1) {
-    p2.col += l - 1;
+    p2->col += l - 1;
+  }
+
+  return OK;
+}
+
+/// "getregion()" function
+static void f_getregion(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+{
+  buf_T *const save_curbuf = curbuf;
+  const TriState save_virtual = virtual_op;
+
+  pos_T p1, p2;
+  bool inclusive = true;
+  MotionType region_type = kMTUnknown;
+  oparg_T oa;
+  int fnum;
+
+  if (getregionpos(argvars, rettv,
+                   &p1, &p2, &inclusive, &region_type, &oa, &fnum) == FAIL) {
+    return;
   }
 
   for (linenr_T lnum = p1.lnum; lnum <= p2.lnum; lnum++) {
@@ -2983,6 +2999,80 @@ static void f_getregion(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     tv_list_append_allocated_string(rettv->vval.v_list, akt);
   }
 
+  // getregionpos() breaks curbuf and virtual_op
+  curbuf = save_curbuf;
+  curwin->w_buffer = curbuf;
+  virtual_op = save_virtual;
+}
+
+static void add_regionpos_range(typval_T *rettv, int bufnr, int lnum1, int col1, int coladd1,
+                                int lnum2, int col2, int coladd2)
+{
+  list_T *l1 = tv_list_alloc(2);
+  tv_list_append_list(rettv->vval.v_list, l1);
+
+  list_T *l2 = tv_list_alloc(4);
+  tv_list_append_list(l1, l2);
+
+  list_T *l3 = tv_list_alloc(4);
+  tv_list_append_list(l1, l3);
+
+  buf_T *findbuf = bufnr != 0 ? buflist_findnr(bufnr) : curbuf;
+
+  int max_col1 = ml_get_buf_len(findbuf, lnum1);
+  tv_list_append_number(l2, bufnr);
+  tv_list_append_number(l2, lnum1);
+  tv_list_append_number(l2, col1 > max_col1 ? max_col1 : col1);
+  tv_list_append_number(l2, coladd1);
+
+  int max_col2 = ml_get_buf_len(findbuf, lnum2);
+  tv_list_append_number(l3, bufnr);
+  tv_list_append_number(l3, lnum2);
+  tv_list_append_number(l3, col2 > max_col2 ? max_col2 : col2);
+  tv_list_append_number(l3, coladd2);
+}
+
+/// "getregionpos()" function
+static void f_getregionpos(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+{
+  buf_T *const save_curbuf = curbuf;
+  const TriState save_virtual = virtual_op;
+
+  pos_T p1, p2;
+  bool inclusive = true;
+  MotionType region_type = kMTUnknown;
+  oparg_T oa;
+  int fnum;
+
+  if (getregionpos(argvars, rettv,
+                   &p1, &p2, &inclusive, &region_type, &oa, &fnum) == FAIL) {
+    return;
+  }
+
+  for (linenr_T lnum = p1.lnum; lnum <= p2.lnum; lnum++) {
+    int start_col, end_col;
+
+    if (region_type == kMTLineWise) {
+      start_col = 1;
+      end_col = MAXCOL;
+    } else if (region_type == kMTBlockWise) {
+      struct block_def bd;
+      block_prep(&oa, &bd, lnum, false);
+      start_col = bd.start_vcol + 1;
+      end_col = bd.end_vcol;
+    } else if (p1.lnum < lnum && lnum < p2.lnum) {
+      start_col = 1;
+      end_col = MAXCOL;
+    } else {
+      start_col = p1.lnum == lnum ? p1.col + 1 : 1;
+      end_col = p2.lnum == lnum ? p2.col + 1 : MAXCOL;
+    }
+
+    add_regionpos_range(rettv, fnum, lnum, start_col,
+                        p1.coladd, lnum, end_col, p2.coladd);
+  }
+
+  // getregionpos() may change curbuf and virtual_op
   curbuf = save_curbuf;
   curwin->w_buffer = curbuf;
   virtual_op = save_virtual;