Highlight Whitespace

Highlight unwanted whitespace across you project files. The fun part is that you can come up with your own palette of colors used for a specific pattern per a filetype!

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Go to the Current Colorscheme section to see what each color stands for.
_{^{(Unfortunately placing it here breaks syntax highlighting for all multi-line code blocks below it)}}

Installation

With lazy.nvim

{
  "lukoshkin/highlight-whitespace",
  config=true,
}

With packer.nvim

use "lukoshkin/highlight-whitespace"

Implementation Details

The plugin implements an efficient and flexible approach to "undesired" patterns highlighting:

• Smart Window Rendering - Scans only the visible part of the buffer to minimize performance impact
• Regex-Based Pattern Matching - Uses Neovim's regex engine as a compromise between Lua regex and pure regex
• Extmarks for Highlighting - Leverages Neovim's extmark API for efficient, non-intrusive highlighting
• Context-Aware Highlighting - Disables highlighting in insert mode at cursor position for better UX
• Namespace-Based Management - Uses separate highlight namespace to avoid conflicts with other plugins
• Filetype-Specific Customization - Allows different highlighting patterns and colors per filetype

Highlighting priorities are organized hierarchically:

• Trailing whitespace - 10
• Trailing whitespace override (till cursor position) - 11
• Other pattern highlighting - 12

The core implementation uses Neovim's API for all operations, making it performant even in large files.

Customization

tws keyword - "main" pattern for trailing whitespace highlighting
clear_on_bufleave - boolean opt to clear highlighting in the current buffer before switching to another

lazy.nvim

{
  "lukoshkin/highlight-whitespace",
  opts = {
    tws = "\\s\\+$",
    clear_on_bufleave = false,
    palette = {
      markdown = {
        tws = 'RosyBrown',
        ['\\S\\@<=\\s\\(\\.\\|,\\)\\@='] = 'CadetBlue3',
        ['\\S\\@<= \\{2,\\}\\S\\@='] = 'SkyBlue1',
        ['\\t\\+'] = 'plum4',
      },
      other = {
        tws = 'PaleVioletRed',
        ['\\S\\@<=\\s,\\@='] = 'coral1',
        ['\\S\\@<=\\(#\\|--\\)\\@<! \\{2,3\\}\\S\\@=\\(#\\|--\\)\\@!'] = 'LightGoldenrod3',
        ['\\(#\\|--\\)\\@<= \\{2,\\}\\S\\@='] = '#3B3B3B',
        ['\\S\\@<= \\{3,\\}\\(#\\|--\\)\\@='] = '#3B3B3B',
        ['\\t\\+'] = 'plum4',
      }
    }
  }
}

packer.nvim

use {
  'lukoshkin/highlight-whitespace',
  config = function ()
    require'highlight-whitespace'.setup {
      tws = '\\s\\+$',
      clear_on_bufleave = false,
      palette = {
        markdown = {
          tws = 'RosyBrown',
          ['\\S\\@<=\\s\\(\\.\\|,\\)\\@='] = 'CadetBlue3',
          ['\\S\\@<= \\{2,\\}\\S\\@='] = 'SkyBlue1',
          ['\\t\\+'] = 'plum4',
        },
        other = {
          tws = 'PaleVioletRed',
          ['\\S\\@<=\\s,\\@='] = 'coral1',
          ['\\S\\@<=\\(#\\|--\\)\\@<! \\{2,3\\}\\S\\@=\\(#\\|--\\)\\@!'] = 'LightGoldenrod3',
          ['\\(#\\|--\\)\\@<= \\{2,\\}\\S\\@='] = '#3B3B3B',
          ['\\S\\@<= \\{3,\\}\\(#\\|--\\)\\@='] = '#3B3B3B',
          ['\\t\\+'] = 'plum4',
        }
      }
    }
  end
}

Ignoring filetypes

Ignoring specific filetypes is possible by setting an empty table next to a filetype in the palette.

To highlight only python and markdown filetypes

      palette = {
        python = {
          -- some patterns
        },
        markdown = {
          -- some patterns
        },
        other = {},
      }

To ignore highlighting only in javascript

      palette = {
        javascript = {},
        other = {
          -- some patterns
        },
      }

Current Colorscheme

This section refers to the GIF at the README beginning

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$$ {\color{PaleVioletRed}red}\text{ color ─ trailing whitespace in Python (other than md)} $$

$$ {\color{#3B3B3B}dark\ gray}\text{ ─ leading and trailing whitespace in comment sections} $$

$${\color{RosyBrown}brown}\text{ ─ in markdown}$$

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$$ {\color{#CDBE70}yellow}\text{ color ─ redundant (multiple) spaces in Python} $$

$${\color{#87CEFF}blue}\text{ ─ in markdown}$$

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$${\color{#FF7256}orange}\text{ color ─ a space before a comma in Python}$$

$${\color{#7AC5CD}"green"}\text{ ─ in markdown}$$

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$${\color{#8B668B}purple}\text{ color ─ tab indents instead of spaces}$$