Using regexes and extmarks to highlight uses of word under the cursor. Keeps updates local to currently visible lines, thus enabling blazingly fast performance.

This plugin replaces nvim-treesitter/nvim-treesitter-refactor highlight-definitions which performs poorly on large files.

Using Lazy:

  {
      'tzachar/local-highlight.nvim',
      config = function()
        require('local-highlight').setup()
      end
  },

Make sure to specify file types to attach to, or use the attach interface documented below.

Multiple plugins to highlight the word under the cursor exist. However, none of them solved all of the following issues for me:

1. Performance (especially on large files)
2. Highlight mechanics: by using extmarks, the current format of each highlighted word remains the same (e.g., italics, treesitter highlights)

You can setup local-highlight as follows:

require('local-highlight').setup({
    file_types = {'python', 'cpp'},
    hlgroup = 'TSDefinitionUsage',
    cw_hlgroup = nil,
})

Specify the highlighting group to use.

By default, local-highlight will use the LocalHighlight highlight group, which it defines upon startup. If the group is already defined elsewhere in your config then it will not be overwritten. You can use any other group you desire.

Specify the highlighting group to use for the word under the cursor. Defaults to nil, which means "Do not apply any highlighting".

The plugin works out of the box if you want to use FileTypes to attach to buffers.

If you do not supply the file_types configuration option, local-highlight will attach by default to all buffers using the BufRead autocommand event.

If you want to directly attach the plugin to your buffers, you can use any autocommand to attach an event to your liking. For example, to attach to any buffer:

vim.api.nvim_create_autocmd('BufRead', {
  pattern = {'*.*'},
  callback = function(data)
    require('local-highlight').attach(data.buf)
  end
})

The plugin will take care not to reattach and to delete the autocommands when the buffer is closed.

Toggle local highlighting for the current buffer.

Turn local highlighting off for the current buffer.

Turn local highlighting on for the current buffer.

Echo timing information: total number of invocations and the average running time in milliseconds.

local-highlight will attach to a buffer and register an autocommand for the CursorHold event. Once the event fires, local-highlight will grab the word under the cursor and will highlight all of the usages of the same word in the visible lines of the buffer.

One implication of using CursorHold is that interactivity depends on updatetime, which is 4000 by default. A good advice is to set it to something more reasonable, like 500, to get good interactivity.