Add lsp.buf and hover implementation.

runtime/lua/vim/lsp/buf.lua

@@ -0,0 +1,85 @@
+local validate = vim.validate
+local api = vim.api
+local util = require 'vim.lsp.util'
+local protocol = require 'vim.lsp.protocol'
+
+local M = {}
+
+local function resolve_bufnr(bufnr)
+  validate { bufnr = { bufnr, 'n', true } }
+  if bufnr == nil or bufnr == 0 then
+    return api.nvim_get_current_buf()
+  end
+  return bufnr
+end
+
+local function ok_or_nil(status, ...)
+	if not status then return end
+	return ...
+end
+local function npcall(fn, ...)
+	return ok_or_nil(pcall(fn, ...))
+end
+
+local function find_window_by_var(name, value)
+	for _, win in ipairs(api.nvim_list_wins()) do
+		if npcall(api.nvim_win_get_var, win, name) == value then
+			return win
+		end
+	end
+end
+
+local hover_window_tag = 'lsp_hover'
+function M.hover(bufnr)
+	if npcall(api.nvim_win_get_var, 0, hover_window_tag) then
+		api.nvim_command("wincmd p")
+		return
+	end
+
+	bufnr = resolve_bufnr(bufnr)
+	do
+		local win = find_window_by_var(hover_window_tag, bufnr)
+		if win then
+			api.nvim_set_current_win(win)
+			return
+		end
+	end
+	local params = protocol.make_text_document_position_params()
+	vim.lsp.buf_request(bufnr, 'textDocument/hover', params, function(_, _, result, _)
+		if result == nil or vim.tbl_isempty(result) then
+			return
+		end
+
+		if result.contents ~= nil then
+			local markdown_lines = util.convert_input_to_markdown_lines(result.contents)
+			markdown_lines = util.trim_empty_lines(markdown_lines)
+			if vim.tbl_isempty(markdown_lines) then
+				markdown_lines = { 'No information available' }
+			end
+			local filetype = util.try_trim_markdown_code_blocks(markdown_lines)
+			local _, winnr = util.open_floating_preview(markdown_lines, filetype)
+			api.nvim_win_set_var(winnr, hover_window_tag, bufnr)
+		end
+	end)
+end
+
+function M.signature_help()
+end
+
+function M.declaration()
+end
+
+function M.type_definition()
+end
+
+function M.implementation()
+end
+
+-- TODO(ashkan) ?
+function M.completion()
+end
+
+function M.range_formatting()
+end
+
+return M