implement interface for applying snippetTextEdits.

Author: L3MON4D3

lua/luasnip/extras/lsp.lua

@@ -0,0 +1,63 @@
+local luasnip_ns_id = require("luasnip.session").ns_id
+local ls = require("luasnip")
+
+local M = {}
+
+---Apply text/snippetTextEdits (at most one snippetText though).
+---@param snippet_or_text_edits `(snippetTextEdit|textEdit)[]`
+--- snippetTextEdit as defined in https://github.com/rust-lang/rust-analyzer/blob/master/docs/dev/lsp-extensions.md#snippet-textedit)
+---@param bufnr number, buffer where the snippet should be expanded.
+---@param offset_encoding string|nil, 'utf-8,16,32' or ni
+---@param apply_text_edits_fn function, has to apply regular textEdits, most
+--- likely `vim.lsp.util.apply_text_edits` (we expect its' interface).
+function M.apply_text_edits(snippet_or_text_edits, bufnr, offset_encoding, apply_text_edits_fn)
+	-- plain textEdits, applied using via `apply_text_edits_fn`.
+	local text_edits = {}
+	-- contains keys
+	--  - snippet (parsed snippet)
+	--  - mark (extmark, textrange replaced by the snippet)
+	local snippet_params
+
+	for _, v in ipairs(snippet_or_text_edits) do
+		if v.newText and v.insertTextFormat == 2 then
+			assert(snippet_params == nil, "Only one snippetTextEdit may be applied at once.")
+
+			-- from vim.lsp.apply_text_edits.
+			local start_row = v.range.start.line
+			local start_col = vim.lsp.util._get_line_byte_from_position(bufnr, v.range.start, offset_encoding)
+			local end_row = v.range['end'].line
+			local end_col = vim.lsp.util._get_line_byte_from_position(bufnr, v.range['end'], offset_encoding)
+
+			snippet_params = {
+				snippet_body = v.newText,
+				mark = vim.api.nvim_buf_set_extmark(bufnr, luasnip_ns_id, start_row, start_col, {
+					end_row = end_row,
+					end_col = end_col
+				}),
+			}
+		else
+			table.insert(text_edits, v)
+		end
+	end
+
+	-- first apply regular textEdits...
+	apply_text_edits_fn(text_edits, bufnr, offset_encoding)
+
+	-- ...then the snippet.
+	local mark_info = vim.api.nvim_buf_get_extmark_by_id(bufnr, luasnip_ns_id, snippet_params.mark, {details = true})
+	local mark_begin_pos = {mark_info[1], mark_info[2]}
+	local mark_end_pos = {mark_info[3].end_row, mark_info[3].end_col}
+
+	-- luasnip can only expand snippets in the active buffer, so switch (nop if
+	-- buf already active).
+	vim.api.nvim_set_current_buf(bufnr)
+	ls.lsp_expand(snippet_params.snippet_body, {
+		pos = mark_begin_pos,
+		clear_region = {
+			from = mark_begin_pos,
+			to = mark_end_pos,
+		},
+	})
+end
+
+return M