add function to preview definitions (#883)

* add function to preview definitions

* add funciton to preview types and implementations

* add borders

Co-authored-by: Abouzar Parvan <abzcoding@users.noreply.github.com>

lua/lsp/init.lua

@@ -20,6 +20,7 @@ vim.cmd "nnoremap <silent> gd <cmd>lua vim.lsp.buf.definition()<CR>"
 vim.cmd "nnoremap <silent> gD <cmd>lua vim.lsp.buf.declaration()<CR>"
 vim.cmd "nnoremap <silent> gr <cmd>lua vim.lsp.buf.references()<CR>"
 vim.cmd "nnoremap <silent> gi <cmd>lua vim.lsp.buf.implementation()<CR>"
+vim.cmd "nnoremap <silent> gp <cmd>lua require'lsp'.PeekDefinition()<CR>"
 vim.cmd "nnoremap <silent> K :lua vim.lsp.buf.hover()<CR>"
 -- vim.cmd('nnoremap <silent> <C-k> <cmd>lua vim.lsp.buf.signature_help()<CR>')
 vim.cmd "nnoremap <silent> <C-p> :lua vim.lsp.diagnostic.goto_prev({popup_opts = {border = O.lsp.popup_border}})<CR>"
@@ -103,6 +104,71 @@ local function documentHighlight(client, bufnr)
 end
 local lsp_config = {}
 
+-- Taken from https://www.reddit.com/r/neovim/comments/gyb077/nvimlsp_peek_defination_javascript_ttserver/
+function lsp_config.preview_location(location, context, before_context)
+  -- location may be LocationLink or Location (more useful for the former)
+  context = context or 15
+  before_context = before_context or 0
+  local uri = location.targetUri or location.uri
+  if uri == nil then
+    return
+  end
+  local bufnr = vim.uri_to_bufnr(uri)
+  if not vim.api.nvim_buf_is_loaded(bufnr) then
+    vim.fn.bufload(bufnr)
+  end
+
+  local range = location.targetRange or location.range
+  local contents = vim.api.nvim_buf_get_lines(
+    bufnr,
+    range.start.line - before_context,
+    range["end"].line + 1 + context,
+    false
+  )
+  local filetype = vim.api.nvim_buf_get_option(bufnr, "filetype")
+  return vim.lsp.util.open_floating_preview(contents, filetype, { border = O.lsp.popup_border })
+end
+
+function lsp_config.preview_location_callback(_, method, result)
+  local context = 15
+  if result == nil or vim.tbl_isempty(result) then
+    print("No location found: " .. method)
+    return nil
+  end
+  if vim.tbl_islist(result) then
+    lsp_config.floating_buf, lsp_config.floating_win = lsp_config.preview_location(result[1], context)
+  else
+    lsp_config.floating_buf, lsp_config.floating_win = lsp_config.preview_location(result, context)
+  end
+end
+
+function lsp_config.PeekDefinition()
+  if vim.tbl_contains(vim.api.nvim_list_wins(), lsp_config.floating_win) then
+    vim.api.nvim_set_current_win(lsp_config.floating_win)
+  else
+    local params = vim.lsp.util.make_position_params()
+    return vim.lsp.buf_request(0, "textDocument/definition", params, lsp_config.preview_location_callback)
+  end
+end
+
+function lsp_config.PeekTypeDefinition()
+  if vim.tbl_contains(vim.api.nvim_list_wins(), lsp_config.floating_win) then
+    vim.api.nvim_set_current_win(lsp_config.floating_win)
+  else
+    local params = vim.lsp.util.make_position_params()
+    return vim.lsp.buf_request(0, "textDocument/typeDefinition", params, lsp_config.preview_location_callback)
+  end
+end
+
+function lsp_config.PeekImplementation()
+  if vim.tbl_contains(vim.api.nvim_list_wins(), lsp_config.floating_win) then
+    vim.api.nvim_set_current_win(lsp_config.floating_win)
+  else
+    local params = vim.lsp.util.make_position_params()
+    return vim.lsp.buf_request(0, "textDocument/implementation", params, lsp_config.preview_location_callback)
+  end
+end
+
 if O.lsp.document_highlight then
   function lsp_config.common_on_attach(client, bufnr)
     documentHighlight(client, bufnr)