feat: Initial implementation for completion support

lua/null-ls/builtins/completion.lua

@@ -0,0 +1,36 @@
+local h = require("null-ls.helpers")
+local methods = require("null-ls.methods")
+local utils = require("null-ls.utils")
+
+local COMPLETION = methods.internal.COMPLETION
+
+local M = {}
+
+M.tags = h.make_builtin({
+    method = COMPLETION,
+    filetypes = {},
+    name = "tags",
+    generator = {
+        fn = function(params, done)
+            local tags = vim.fn.taglist(params.word_to_complete)
+            local words = {}
+            local items = {}
+            for _, tag in ipairs(tags) do
+                table.insert(words, tag.name)
+            end
+            words = utils.tbl_uniq(words)
+            for _, word in ipairs(words) do
+                table.insert(items, {
+                    label = word,
+                    insertText = word,
+                })
+            end
+
+            done(items)
+        end,
+        async = true,
+        use_cache = true,
+    },
+})
+
+return M

lua/null-ls/builtins/init.lua

@@ -3,6 +3,7 @@ local paths = {
     formatting = "null-ls.builtins.formatting",
     code_actions = "null-ls.builtins.code-actions",
     hover = "null-ls.builtins.hover",
+    completion = "null-ls.builtins.completion",
     _test = "null-ls.builtins.test",
 }
 

lua/null-ls/completion.lua

@@ -0,0 +1,33 @@
+local u = require("null-ls.utils")
+local methods = require("null-ls.methods")
+
+local M = {}
+
+M.handler = function(method, original_params, handler)
+    local params = u.make_params(original_params, methods.map[method])
+    if method == methods.lsp.COMPLETION then
+        require("null-ls.generators").run_registered({
+            filetype = params.ft,
+            method = methods.map[method],
+            params = params,
+            callback = function(results)
+                u.debug_log("received completion results from generators")
+                u.debug_log(results)
+                if #results == 0 then
+                    handler({})
+                else
+                    for index, item in ipairs(results) do
+                        if type(item) == "string" then
+                            results[index] = { label = item, insertText = item }
+                        end
+                    end
+
+                    handler({ isIncomplete = false, items = results })
+                end
+            end,
+        })
+        original_params._null_ls_handled = true
+    end
+end
+
+return M

lua/null-ls/methods.lua

@@ -11,6 +11,7 @@ local lsp_methods = {
     DID_OPEN = "textDocument/didOpen",
     DID_CLOSE = "textDocument/didClose",
     HOVER = "textDocument/hover",
+    COMPLETION = "textDocument/completion",
 }
 vim.tbl_add_reverse_lookup(lsp_methods)
 
@@ -20,6 +21,7 @@ local internal_methods = {
     FORMATTING = "NULL_LS_FORMATTING",
     RANGE_FORMATTING = "NULL_LS_RANGE_FORMATTING",
     HOVER = "NULL_LS_HOVER",
+    COMPLETION = "NULL_LS_COMPLETION",
 }
 vim.tbl_add_reverse_lookup(internal_methods)
 
@@ -30,6 +32,7 @@ local lsp_to_internal_map = {
     [lsp_methods.DID_OPEN] = internal_methods.DIAGNOSTICS,
     [lsp_methods.DID_CHANGE] = internal_methods.DIAGNOSTICS,
     [lsp_methods.HOVER] = internal_methods.HOVER,
+    [lsp_methods.COMPLETION] = internal_methods.COMPLETION,
 }
 
 local readable_map = {
@@ -38,6 +41,7 @@ local readable_map = {
     [internal_methods.FORMATTING] = "Formatting",
     [internal_methods.RANGE_FORMATTING] = "Range formatting",
     [internal_methods.HOVER] = "Hover",
+    [internal_methods.COMPLETION] = "Completion",
 }
 
 local M = {}

lua/null-ls/rpc.lua

@@ -8,6 +8,7 @@ local capabilities = {
     executeCommandProvider = true,
     documentFormattingProvider = true,
     documentRangeFormattingProvider = true,
+    completionProvider = true,
     textDocumentSync = {
         change = 1, -- prompt LSP client to send full document text on didOpen and didChange
         openClose = true,
@@ -82,6 +83,7 @@ function M.start(dispatchers)
             require("null-ls.code-actions").handler(method, params, send)
             require("null-ls.formatting").handler(method, params, send)
             require("null-ls.hover").handler(method, params, send)
+            require("null-ls.completion").handler(method, params, send)
             if not params._null_ls_handled then
                 send()
             end

lua/null-ls/utils.lua

@@ -119,6 +119,13 @@ M.make_params = function(original_params, method)
         params.range = M.range.from_lsp(original_params.range)
     end
 
+    if params.lsp_method == methods.lsp.COMPLETION then
+        local pos = vim.api.nvim_win_get_cursor(0)
+        local line = vim.api.nvim_get_current_line()
+        local line_to_cursor = line:sub(1, pos[2])
+        params.word_to_complete = line:sub(vim.fn.match(line_to_cursor, "\\k*$") + 1, params.col)
+    end
+
     return params
 end
 
@@ -199,4 +206,17 @@ function M.throttle(ms, fn)
     end
 end
 
+function M.tbl_uniq(t)
+    local new_table = {}
+    local hash = {}
+    for _, v in pairs(t) do
+        if not hash[v] then
+            table.insert(new_table, v)
+            hash[v] = true
+        end
+    end
+
+    return new_table
+end
+
 return M