From f560613ef6cd3765092925430847a1a14b2708c5 Mon Sep 17 00:00:00 2001
From: JINNOUCHI Yasushi <d+github@delphinus.dev>
Date: Sun, 30 May 2021 17:58:00 +0900
Subject: [PATCH] feat: move telescope `string` functions into plenary module
 (#96)

---
 README.md                      |  15 +-
 lua/plenary/strings.lua        | 167 ++++++++++++++++++++++
 lua/plenary/window/border.lua  |  16 ++-
 tests/plenary/strings_spec.lua | 248 +++++++++++++++++++++++++++++++++
 4 files changed, 442 insertions(+), 4 deletions(-)
 create mode 100644 lua/plenary/strings.lua
 create mode 100644 tests/plenary/strings_spec.lua

diff --git a/README.md b/README.md
index 1b671a32..81ad0ee1 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,7 @@ Plug 'nvim-lua/plenary.nvim'
 - `plenary.context_manager`
 - `plenary.test_harness`
 - `plenary.filetype`
+- `plenary.strings`
 
 ### plenary.job
 
@@ -179,6 +180,19 @@ return {
 }
 ```
 
+### plenary.strings
+
+Re-implement VimL funcs to use them in Lua loop.
+
+* `strings.strdisplaywidth`
+* `strings.strcharpart`
+
+And some other funcs are here to deal with common problems.
+
+* `strings.truncate`
+* `strings.align_str`
+* `strings.dedent`
+
 ### plenary.popup
 
 `popup_*` clone of Vim's commands. If it gets good enough, will submit PR to Neovim and write C wrappers
@@ -205,4 +219,3 @@ This will enable debuggin for the plugin.
 ### plenary.neorocks
 
 DELETED: Please use packer.nvim or other lua-rocks wrapper instead. This no longer exists.
-
diff --git a/lua/plenary/strings.lua b/lua/plenary/strings.lua
new file mode 100644
index 00000000..2b14f62d
--- /dev/null
+++ b/lua/plenary/strings.lua
@@ -0,0 +1,167 @@
+local path = require('plenary.path').path
+
+local M = {}
+
+M.strdisplaywidth = (function()
+  if jit and path.sep ~= [[\]] then
+    local ffi = require('ffi')
+    ffi.cdef[[
+      typedef unsigned char char_u;
+      int linetabsize_col(int startcol, char_u *s);
+    ]]
+
+    return function(str, col)
+      str = tostring(str)
+      local startcol = col or 0
+      local s = ffi.new('char[?]', #str + 1)
+      ffi.copy(s, str)
+      return ffi.C.linetabsize_col(startcol, s) - startcol
+    end
+  else
+    return function(str, col)
+      str = tostring(str)
+      if vim.in_fast_loop() then
+        return #str - (col or 0)
+      end
+      return vim.fn.strdisplaywidth(str, col)
+    end
+  end
+end)()
+
+M.strcharpart = (function()
+  if jit and path.sep ~= [[\]] then
+    local ffi = require('ffi')
+    ffi.cdef[[
+      typedef unsigned char char_u;
+      int utf_ptr2len(const char_u *const p);
+    ]]
+
+    local function utf_ptr2len(str)
+      local c_str = ffi.new('char[?]', #str + 1)
+      ffi.copy(c_str, str)
+      return ffi.C.utf_ptr2len(c_str)
+    end
+
+    return function(str, nchar, charlen)
+      local nbyte = 0
+      if nchar > 0 then
+        while nchar > 0 and nbyte < #str do
+          nbyte = nbyte + utf_ptr2len(str:sub(nbyte + 1))
+          nchar = nchar - 1
+        end
+      else
+        nbyte = nchar
+      end
+
+      local len = 0
+      if charlen then
+        while charlen > 0 and nbyte + len < #str do
+          local off = nbyte + len
+          if off < 0 then
+            len = len + 1
+          else
+            len = len + utf_ptr2len(str:sub(off + 1))
+          end
+          charlen = charlen - 1
+        end
+      else
+        len = #str - nbyte
+      end
+
+      if nbyte < 0 then
+        len = len + nbyte
+        nbyte = 0
+      elseif nbyte > #str then
+        nbyte = #str
+      end
+      if len < 0 then
+        len = 0
+      elseif nbyte + len > #str then
+        len = #str - nbyte
+      end
+
+      return str:sub(nbyte + 1, nbyte + len)
+    end
+  else
+    return function(str, nchar, charlen)
+      if vim.in_fast_loop() then
+        return str:sub(nchar + 1, charlen)
+      end
+      return vim.fn.strcharpart(str, nchar, charlen)
+    end
+  end
+end)()
+
+M.truncate = function(str, len, dots)
+  str = tostring(str) -- We need to make sure its an actually a string and not a number
+  dots = dots or '…'
+  if M.strdisplaywidth(str) <= len then
+    return str
+  end
+  local start = 0
+  local current = 0
+  local result = ''
+  local len_of_dots = M.strdisplaywidth(dots)
+  while true do
+    local part = M.strcharpart(str, start, 1)
+    current = current + M.strdisplaywidth(part)
+    if (current + len_of_dots) > len then
+      result = result .. dots
+      break
+    end
+    result = result .. part
+    start = start + 1
+  end
+  return result
+end
+
+M.align_str = function(string, width, right_justify)
+  local str_len = M.strdisplaywidth(string)
+  return right_justify
+    and string.rep(" ", width - str_len)..string
+    or string..string.rep(" ", width - str_len)
+end
+
+M.dedent = function(str, leave_indent)
+  -- Check each line and detect the minimum indent.
+  local indent
+  local info = {}
+  for line in str:gmatch('[^\n]*\n?') do
+    -- It matches '' for the last line.
+    if line ~= '' then
+      local chars, width
+      local line_indent = line:match('^[ \t]+')
+      if line_indent then
+        chars = #line_indent
+        width = M.strdisplaywidth(line_indent)
+        if not indent or width < indent then
+          indent = width
+        end
+      -- Ignore empty lines
+      elseif line ~= '\n' then
+        indent = 0
+      end
+      table.insert(info, {line = line, chars = chars, width = width})
+    end
+  end
+
+  -- Build up the result
+  leave_indent = leave_indent or 0
+  local result = {}
+  for _, i in ipairs(info) do
+    local line
+    if i.chars then
+      local content = i.line:sub(i.chars + 1)
+      local indent_width = i.width - indent + leave_indent
+      line = (' '):rep(indent_width) .. content
+    elseif i.line == '\n' then
+      line = '\n'
+    else
+      line = (' '):rep(leave_indent) .. i.line
+    end
+    table.insert(result, line)
+  end
+  return table.concat(result)
+end
+
+return M
diff --git a/lua/plenary/window/border.lua b/lua/plenary/window/border.lua
index f8db15b2..c447a12a 100644
--- a/lua/plenary/window/border.lua
+++ b/lua/plenary/window/border.lua
@@ -1,4 +1,5 @@
 local tbl = require('plenary.tbl')
+local strings = require('plenary.strings')
 
 local Border = {}
 
@@ -29,14 +30,23 @@ function Border._create_lines(content_win_options, border_win_options)
 
   if content_win_options.row > 0 then
     if border_win_options.title then
+      local title_len
       local title = border_win_options.title
-      if title ~= '' then
+      if title == '' then
+        title_len = 0
+      else
+        local len = strings.strdisplaywidth(title)
+        local max_title_width = content_win_options.width - 2
+        if len > max_title_width then
+          title = strings.truncate(title, max_title_width)
+          len = strings.strdisplaywidth(title)
+        end
         title = string.format(" %s ", title)
+        title_len = len + 2
       end
-      local title_len = string.len(title)
 
       local midpoint = math.floor(content_win_options.width / 2)
-      local left_start = midpoint - math.floor(title_len / 2)
+      local left_start = midpoint - math.ceil(title_len / 2)
 
       topline = string.format("%s%s%s%s%s",
         topleft,
diff --git a/tests/plenary/strings_spec.lua b/tests/plenary/strings_spec.lua
new file mode 100644
index 00000000..a528414f
--- /dev/null
+++ b/tests/plenary/strings_spec.lua
@@ -0,0 +1,248 @@
+local strings = require('plenary.strings')
+local eq = assert.are.same
+
+describe('strings', function()
+  describe('strdisplaywidth', function()
+    for _, case in ipairs{
+      {str = 'abcde', expected = {single = 5, double = 5}},
+      -- This space below is a tab (U+0009)
+      {str = 'abc	de', expected = {single = 10, double = 10}},
+      {str = 'アイウエオ', expected = {single = 10, double = 10}},
+      {str = '├─┤', expected = {single = 3, double = 6}},
+      {str = 123, expected = {single = 3, double = 3}},
+    } do
+      for _, ambiwidth in ipairs{'single', 'double'} do
+        local item = type(case.str) == 'string' and '"%s"' or '%s'
+        local msg = ('ambiwidth = %s, '..item..' -> %d'):format(ambiwidth, case.str, case.expected[ambiwidth])
+        local original = vim.o.ambiwidth
+        vim.o.ambiwidth = ambiwidth
+        it('lua: '..msg, function()
+          eq(case.expected[ambiwidth], strings.strdisplaywidth(case.str))
+        end)
+        it('vim: '..msg, function()
+          eq(case.expected[ambiwidth], vim.fn.strdisplaywidth(case.str))
+        end)
+        vim.o.ambiwidth = original
+      end
+    end
+  end)
+
+  describe('strcharpart', function()
+    for _, case in ipairs{
+      {args = {'abcde', 2}, expected = 'cde'},
+      {args = {'abcde', 2, 2}, expected = 'cd'},
+      {args = {'アイウエオ', 2, 2}, expected = 'ウエ'},
+      {args = {'├───┤', 2, 2}, expected = '──'},
+    } do
+      local msg = ('("%s", %d, %s) -> "%s"'):format(case.args[1], case.args[2], tostring(case.args[3]), case.expected)
+      it('lua: '..msg, function()
+        eq(case.expected, strings.strcharpart(unpack(case.args)))
+      end)
+      it('vim: '..msg, function()
+        eq(case.expected, vim.fn.strcharpart(unpack(case.args)))
+      end)
+    end
+  end)
+
+  describe('truncate', function()
+    for _, case in ipairs{
+      {args = {'abcde', 6}, expected = {single = 'abcde', double = 'abcde'}},
+      {args = {'abcde', 5}, expected = {single = 'abcde', double = 'abcde'}},
+      {args = {'abcde', 4}, expected = {single = 'abc…', double = 'ab…'}},
+      {args = {'アイウエオ', 11}, expected = {single = 'アイウエオ', double = 'アイウエオ'}},
+      {args = {'アイウエオ', 10}, expected = {single = 'アイウエオ', double = 'アイウエオ'}},
+      {args = {'アイウエオ', 9}, expected = {single = 'アイウエ…', double = 'アイウ…'}},
+      {args = {'アイウエオ', 8}, expected = {single = 'アイウ…', double = 'アイウ…'}},
+      {args = {'├─┤', 7}, expected = {single = '├─┤', double = '├─┤'}},
+      {args = {'├─┤', 6}, expected = {single = '├─┤', double = '├─┤'}},
+      {args = {'├─┤', 5}, expected = {single = '├─┤', double = '├…'}},
+      {args = {'├─┤', 4}, expected = {single = '├─┤', double = '├…'}},
+      {args = {'├─┤', 3}, expected = {single = '├─┤', double = '…'}},
+      {args = {'├─┤', 2}, expected = {single = '├…', double = '…'}},
+    } do
+      for _, ambiwidth in ipairs{'single', 'double'} do
+        local msg = ('ambiwidth = %s, [%s, %d] -> %s'):format(
+          ambiwidth,
+          case.args[1],
+          case.args[2],
+          case.expected[ambiwidth]
+        )
+        it(msg, function()
+          local original = vim.o.ambiwidth
+          vim.o.ambiwidth = ambiwidth
+          eq(case.expected[ambiwidth], strings.truncate(unpack(case.args)))
+          vim.o.ambiwidth = original
+        end)
+      end
+    end
+  end)
+
+  describe('align_str', function()
+    for _, case in ipairs{
+      {args = {'abcde', 8}, expected = {single = 'abcde   ', double = 'abcde   '}},
+      {args = {'アイウ', 8}, expected = {single = 'アイウ  ', double = 'アイウ  '}},
+      {args = {'├─┤', 8}, expected = {single = '├─┤     ', double = '├─┤  '}},
+      {args = {'abcde', 8, true}, expected = {single = '   abcde', double = '   abcde'}},
+      {args = {'アイウ', 8, true}, expected = {single = '  アイウ', double = '  アイウ'}},
+      {args = {'├─┤', 8, true}, expected = {single = '     ├─┤', double = '  ├─┤'}},
+    } do
+      for _, ambiwidth in ipairs{'single', 'double'} do
+        local msg = ('ambiwidth = %s, [%s, %d, %s] -> "%s"'):format(
+          ambiwidth,
+          case.args[1],
+          case.args[2],
+          tostring(case.args[3]),
+          case.expected[ambiwidth]
+        )
+        it(msg, function()
+          local original = vim.o.ambiwidth
+          vim.o.ambiwidth = ambiwidth
+          eq(case.expected[ambiwidth], strings.align_str(unpack(case.args)))
+          vim.o.ambiwidth = original
+        end)
+      end
+    end
+  end)
+
+  describe('dedent', function()
+    local function lines(t)
+      return table.concat(t, '\n')
+    end
+    for _, case in ipairs{
+      {
+        msg = 'empty string',
+        tabstop = 8,
+        args = {''},
+        expected = '',
+      },
+      {
+        msg = 'in case tabs are longer than spaces',
+        tabstop = 8,
+        args = {
+          lines{
+            '		<Tab><Tab> -> 13 spaces',
+            '     5 spaces -> 0 space',
+          },
+        },
+        expected = lines{
+          '           <Tab><Tab> -> 13 spaces',
+          '5 spaces -> 0 space',
+        },
+      },
+      {
+        msg = 'in case tabs are shorter than spaces',
+        tabstop = 2,
+        args = {
+          lines{
+            '		<Tab><Tab> -> 0 space',
+            '     5spaces -> 1 space',
+          },
+        },
+        expected = lines{
+          '<Tab><Tab> -> 0 space',
+          ' 5spaces -> 1 space',
+        },
+      },
+      {
+        msg = 'ignores empty lines',
+        tabstop = 2,
+        args = {
+          lines{
+            '',
+            '',
+            '',
+            '        8 spaces -> 3 spaces',
+            '',
+            '',
+            '     5 spaces -> 0 space',
+            '',
+            '',
+            '',
+          },
+        },
+        expected = lines{
+          '',
+          '',
+          '',
+          '   8 spaces -> 3 spaces',
+          '',
+          '',
+          '5 spaces -> 0 space',
+          '',
+          '',
+          '',
+        },
+      },
+      {
+        msg = 'no indent',
+        tabstop = 2,
+        args = {
+          lines{
+            '	<Tab> -> 2 spaces',
+            'Here is no indent.',
+            '    4 spaces will remain',
+          },
+        },
+        expected = lines{
+          '  <Tab> -> 2 spaces',
+          'Here is no indent.',
+          '    4 spaces will remain',
+        },
+      },
+      {
+        msg = 'leave_indent = 4',
+        tabstop = 2,
+        args = {
+          lines{
+            '	<Tab> -> 6 spaces',
+            '0 indent -> 4 spaces',
+            '    4 spaces -> 8 spaces',
+          },
+          4,
+        },
+        expected = lines{
+          '      <Tab> -> 6 spaces',
+          '    0 indent -> 4 spaces',
+          '        4 spaces -> 8 spaces',
+        },
+      },
+      {
+        msg = 'typical usecase: <Tab> to 5 spaces',
+        tabstop = 4,
+        args = {
+          lines{
+            '',
+            '		Chapter 1',
+            '',
+            '	  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed',
+            '	do eiusmod tempor incididunt ut labore et dolore magna aliqua.',
+            '',
+            '	  Ut enim ad minim veniam, quis nostrud exercitation ullamco',
+            '	laboris nisi ut aliquip ex ea commodo consequat.',
+            '',
+          },
+          5,
+        },
+        expected = lines{
+          '',
+          '         Chapter 1',
+          '',
+          '       Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed',
+          '     do eiusmod tempor incididunt ut labore et dolore magna aliqua.',
+          '',
+          '       Ut enim ad minim veniam, quis nostrud exercitation ullamco',
+          '     laboris nisi ut aliquip ex ea commodo consequat.',
+          '',
+        },
+      },
+    } do
+      local msg = ('tabstop = %d, %s'):format(case.tabstop, case.msg)
+      it(msg, function()
+        local original = vim.bo.tabstop
+        vim.bo.tabstop = case.tabstop
+        eq(case.expected, strings.dedent(unpack(case.args)))
+        vim.bo.tabstop = original
+      end)
+    end
+  end)
+end)