fix：fix #107, for not handle '\t' properly when get specfied pos char

lua/hlchunk/mods/chunk/init.lua

@@ -98,7 +98,7 @@ function ChunkMod:get_chunk_data(range, virt_text_list, row_list, virt_text_win_
         chars = utf8Split(mid)
         -- when use click `<<` or `>>` to indent, we should make sure the line would not encounter the indent char
         for i = 1, mid_char_nums do
-            local char = Pos.get_char_at_pos(Pos(range.bufnr, range.start + i, start_col))
+            local char = Pos.get_char_at_pos(Pos(range.bufnr, range.start + i, start_col), self.meta.shiftwidth)
             if not char:match("%s") and #char ~= 0 then
                 chars[i] = ""
             end

lua/hlchunk/utils/cFunc.lua

@@ -23,7 +23,7 @@ local M = {}
 ---@return number
 function M.get_indent(bufnr, lnum)
     local line_cnt = vim.api.nvim_buf_line_count(bufnr)
-    if lnum >= line_cnt then
+    if lnum >= line_cnt or lnum <= 0 then
         return -1
     end
     local handler = C.find_buffer_by_handle(bufnr, ffi.new("Error"))
@@ -40,19 +40,19 @@ end
 ---@return string
 function M.get_line(bufnr, lnum)
     local line_cnt = vim.api.nvim_buf_line_count(bufnr)
-    if lnum >= line_cnt then
+    if lnum >= line_cnt or lnum <= 0 then
         return ""
     end
     local handler = C.find_buffer_by_handle(bufnr, ffi.new("Error"))
-    return C.ml_get_buf(handler, lnum + 1)
+    return ffi.string(C.ml_get_buf(handler, lnum + 1))
 end
 
 ---@param bufnr number
 ---@param lnum number 0-index
 ---@return number
 function M.get_line_len(bufnr, lnum)
     local line_cnt = vim.api.nvim_buf_line_count(bufnr)
-    if lnum >= line_cnt then
+    if lnum >= line_cnt or lnum <= 0 then
         return 0
     end
     local handler = C.find_buffer_by_handle(bufnr, ffi.new("Error"))

lua/hlchunk/utils/position.lua

@@ -1,4 +1,5 @@
 local class = require("hlchunk.utils.class")
+local cFunc = require("hlchunk.utils.cFunc")
 
 ---@class Pos
 ---@field bufnr number
@@ -14,12 +15,15 @@ local Pos = class(function(self, bufnr, row, col)
 end)
 
 ---@param pos Pos
+---@param expand_tab_width? number when the field is given, the tab will be expand to blank with the width, like "\t\t" -> "    " when the width is 2
 ---@return string
-function Pos.get_char_at_pos(pos)
-    local row = pos.row
-    local col = pos.col
-    local char = vim.api.nvim_buf_get_text(pos.bufnr, row, col, row, col + 1, {})[1]
-    return char
+function Pos.get_char_at_pos(pos, expand_tab_width)
+    local line = cFunc.get_line(pos.bufnr, pos.row)
+    if expand_tab_width then
+        local expanded_tab = string.rep(" ", expand_tab_width)
+        line = line:gsub("\t", expanded_tab)
+    end
+    return line:sub(pos.col + 1, pos.col + 1)
 end
 
 return Pos