feat: add blackd support (#1606)

* feat: add blackd

* fix: format only on 200 http status

* fix: headers should start with "X-"

* fix: use factory instead allowing args

* fix: let users choose the parameters based on official docs

* perf: use async generator

* fix: user config instead of args

* fix: use generator key instead of factory key

* feat: add descriptions and default values

* fix: missing default

* docs: add info about config in description

* fix: move curl require inside the callback

Author: tiagovla

lua/null-ls/builtins/formatting/blackd.lua

@@ -0,0 +1,84 @@
+local h = require("null-ls.helpers")
+local methods = require("null-ls.methods")
+
+local FORMATTING = methods.internal.FORMATTING
+
+return h.make_builtin({
+    name = "blackd",
+    meta = {
+        url = "https://github.com/psf/black",
+        description = "blackd is a small HTTP server that exposes Black’s functionality over a simple protocol. The main benefit of using it is to avoid the cost of starting up a new Black process every time you want to blacken a file. The only way to configure the formatter is by using the provided config options, it will not pick up on config files.",
+
+        config = {
+            {
+                key = "hostname",
+                type = "string",
+                description = "Address to bind the server to. Defaults to localhost.",
+            },
+            { key = "port", type = "string", description = "Port to listen on. Defaults to 45484." },
+            {
+                key = "line_length",
+                type = "number",
+                description = "Set how many characters per line to allow. Defaults to 88.",
+            },
+            {
+                key = "skip_source_first_line",
+                type = "boolean",
+                description = "If set to true, the first line of the source code will be ignored. Defaults to false.",
+            },
+            {
+                key = "skip_string_normalization",
+                type = "boolean",
+                description = "If set to true, no string normalization will be performed. Defaults to false.",
+            },
+            {
+                key = "skip_magic_trailing_comma",
+                type = "boolean",
+                description = "If set to true, trailing commas will not be used as a reason to split lines. Defaults to false.",
+            },
+            {
+                key = "preview",
+                type = "boolean",
+                description = "If set to true, experimental and potentially disruptive style changes will be used. Defaults to false.",
+            },
+            {
+                key = "fast",
+                type = "boolean",
+                description = "If set to true, Black will not perform an AST safety check after formatting. Defaults to false.",
+            },
+            {
+                key = "python_variant",
+                type = "string",
+                description = "If set to pyi, Black will format all input files like typing stubs regardless of the file extension. Otherwise, its value must correspond to a Python version or a set of comma-separated Python versions, optionally prefixed with py. (e.g. py3.5,py3.6). Defaults to empty string.",
+            },
+        },
+    },
+    method = FORMATTING,
+    filetypes = { "python" },
+    generator = {
+        async = true,
+        fn = function(params, done)
+            local config = params:get_config()
+            local hostname = config.hostname or "localhost"
+            local port = config.port or 45484
+            require("plenary.curl").post(hostname .. ":" .. port, {
+                body = table.concat(params.content, "\n"),
+                headers = {
+                    ["X-Line-Length"] = config.line_length or 88,
+                    ["X-Skip-Source-First-Line"] = config.skip_source_first_line or nil,
+                    ["X-Skip-String-Normalization"] = config.skip_string_normalization or nil,
+                    ["X-Skip-Magic-Trailing-Comma"] = config.skip_magic_trailing_comma or nil,
+                    ["X-Preview"] = config.preview or nil,
+                    ["X-Fast-Or-Safe"] = config.fast == "fast" and "fast" or nil,
+                    ["X-Python-Variant"] = config.python_variant or "",
+                },
+                callback = function(response)
+                    if response.status == 200 then
+                        return done({ { text = response.body } })
+                    end
+                    return done()
+                end,
+            })
+        end,
+    },
+})