Introduce YANG LSP support (#4390)

CHANGELOG.org

@@ -116,6 +116,7 @@
   * Add Cucumber support.
   * Add COBOL support.
   * Add Common Lisp support.
+  * Add YANG support using TypeFox/yang-lsp Server.
 
 ** Release 8.0.0
   * Add ~lsp-clients-angular-node-get-prefix-command~ to get the Angular server from another location which is still has ~/lib/node_modules~ in it.

clients/lsp-yang.el

@@ -0,0 +1,122 @@
+;;; lsp-yang.el --- YANG Client settings         -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2024 Siddharth Sharma
+
+;; Author: Siddharth Sharma <siddharth.sharma@ericsson.com>
+;; Keywords: languages, yang, lsp
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; LSP support for YANG using using an external language server. Currently
+;; the supported server is:
+;;
+;; yang-lsp (yls).
+;; See https://github.com/TypeFox/yang-lsp/blob/master/docs/Settings.md
+;; for setting up the user/project/workspace files.
+
+;;; Code:
+
+(require 'lsp-mode)
+
+(defgroup lsp-yang nil
+  "LSP support for the YANG data modeling language using yang-lsp server."
+  :group 'lsp-yang
+  :link '(url-link "https://github.com/TypeFox/yang-lsp"))
+
+(defcustom lsp-yang-yls-version "0.7.6"
+  "yang-lsp server version to download.
+
+It has to be set before `lsp-yang.el' is loaded and it has to
+be available here: https://github.com/TypeFox/yang-lsp/releases/"
+  :type 'string
+  :group 'lsp-yang
+  :package-version '(lsp-mode . "8.0.1"))
+
+(add-to-list 'auto-mode-alist '("^yang\\.settings$" . jsonc-mode))
+
+(defcustom lsp-yang-yls-settings-schema-url
+  (format "https://raw.githubusercontent.com/TypeFox/yang-lsp/v%s/schema/yang-lsp-settings-schema.json"
+          lsp-yang-yls-version)
+  "URL for yang-lsp server settings schema"
+  :type 'string
+  :group 'lsp-yang
+  :package-version '(lsp-mode . "8.0.1"))
+
+(defcustom lsp-yang-yls-executable "yang-language-server"
+  "The yang-lsp server executable to use.
+
+Leave as just the executable name to use the default behavior of finding the
+executable with variable `exec-path'."
+  :group 'lsp-yang
+  :type 'string)
+
+(defcustom lsp-yang-yls-download-url
+  (format "https://github.com/TypeFox/yang-lsp/releases/download/v%s/yang-language-server_%s.zip"
+          lsp-yang-yls-version
+          lsp-yang-yls-version)
+  "Automatic download url for yang-lsp server"
+  :type 'string
+  :group 'lsp-yang
+  :package-version '(lsp-mode . "8.0.1"))
+
+(defcustom lsp-yang-yls-store-path
+  (f-join lsp-server-install-dir "yang-lsp" "yang-lsp")
+  "The path to the file in which `yang-language-server' will be stored."
+  :type 'file
+  :group 'lsp-yang
+  :package-version '(lsp-mode . "8.0.1"))
+
+(defcustom lsp-yang-yls-binary-path
+  (f-join lsp-server-install-dir (format "yang-lsp/yang-language-server-%s/bin"
+                                         lsp-yang-yls-version)
+          (pcase system-type
+            ('windows-nt "yang-language-server.bat")
+            (_ "yang-language-server")))
+  "The path to `yang-language-server' binary."
+  :type 'file
+  :group 'lsp-yang
+  :package-version '(lsp-mode . "8.0.1"))
+
+(defun lsp-yang--stored-yls-executable ()
+  "Return the stored yang-lsp server executable."
+  (executable-find lsp-yang-yls-binary-path))
+
+(lsp-dependency
+  'yang-lsp
+  `(:download :url lsp-yang-yls-download-url
+              :decompress :zip
+              :store-path lsp-yang-yls-store-path
+              :binary-path lsp-yang-yls-binary-path
+              :set-exectutable? t))
+
+(lsp-register-client
+ (make-lsp-client
+  :new-connection (lsp-stdio-connection
+                   (lambda () (or (executable-find lsp-yang-yls-executable)
+                                  (lsp-yang--stored-yls-executable)))
+                   (lambda () (or (executable-find lsp-yang-yls-executable)
+                                  (file-executable-p (lsp-yang--stored-yls-executable)))))
+  :major-modes '(yang-mode)
+  :language-id "YANG"
+  :priority -1
+  :server-id 'yls
+  :download-server-fn (lambda (_client callback error-callback _update?)
+                        (lsp-package-ensure 'yang-lsp callback error-callback))))
+
+(lsp-consistency-check lsp-yang)
+
+(provide 'lsp-yang)
+;;; lsp-yang.el ends here

docs/lsp-clients.json

@@ -1203,6 +1203,14 @@
     "lsp-install-server": "yamlls",
     "debugger": "Not available"
   },
+  {
+    "name": "yang",
+    "full-name": "YANG",
+    "server-name": "yang-lsp",
+    "server-url": "https://github.com/TypeFox/yang-lsp",
+    "installation-url": "https://github.com/TypeFox/yang-lsp/releases",
+    "debugger": "Not available"
+  },
   {
     "name": "zig",
     "full-name": "Zig",

docs/manual-language-docs/lsp-yang.md

@@ -0,0 +1,49 @@
+---
+author: esmasth
+root_file: docs/manual-language-docs/lsp-yang.md
+---
+# YANG (yang-lsp)
+
+`lsp-mode` provides YANG language support via the [TypeFox/yang-lsp][1] Server.
+The server identifier is `yls` as an abbreviation of the released binary called
+`yang-language-server`.
+
+## Configuration
+
+Add following configuration in `.emacs` or `init.el` to hook lsp on YANG files,
+since [`yang-mode`][2] is the supported major mode.
+
+```lisp
+(add-hook 'yang-mode-hook 'lsp)
+```
+
+It recommended to add following configuration for the `yang.settings` file,
+which resides at the user/project/workspace root, to be validated via
+[`lsp-json`][5]. This may be automated by `lsp-yang` in later stages.
+
+```lisp
+(setq lsp-json-schemas
+      `[(:fileMatch ["yang.settings"] :url lsp-yang-yls-settings-schema-url)])
+```
+
+To automatically trigger the [`lsp-json`][5] based validation, following
+configuration is recommended.
+
+```lisp
+(add-hook 'jsonc-mode-hook 'lsp)
+```
+
+## Known Issues
+
+* Files in the project need to be opened in buffer to be known by LSP server
+* `yang.settings` is not associated with its [JSON schema][3]
+  [`yang-lsp-settings-schema.json`][4] yet
+* yang-lsp settings file `yang.settings` is not respected
+* `lsp-format-buffer` does not follow `yang-mode` or `yang.settings`
+* Snippets have a bad format with extraneous characters
+
+[1]: https://github.com/TypeFox/yang-lsp
+[2]: https://github.com/mbj4668/yang-mode
+[3]: https://json-schema.org/
+[4]: https://raw.githubusercontent.com/TypeFox/yang-lsp/v0.7.6/schema/yang-lsp-settings-schema.json
+[5]: https://emacs-lsp.github.io/lsp-mode/page/lsp-json/

lsp-mode.el

@@ -174,23 +174,25 @@ As defined by the Language Server Protocol 3.16."
   :package-version '(lsp-mode . "6.1"))
 
 (defcustom lsp-client-packages
-  '( ccls lsp-actionscript lsp-ada lsp-angular lsp-ansible lsp-autotools lsp-awk
-     lsp-asm lsp-astro lsp-bash lsp-beancount lsp-bufls lsp-clangd lsp-clojure
-     lsp-cmake lsp-cobol lsp-credo lsp-crystal lsp-csharp lsp-css lsp-cucumber
-     lsp-cypher lsp-d lsp-dart lsp-dhall lsp-docker lsp-dockerfile lsp-elm lsp-elixir
-     lsp-emmet lsp-erlang lsp-eslint lsp-fortran lsp-fsharp lsp-gdscript lsp-go
-     lsp-golangci-lint lsp-gleam lsp-glsl lsp-graphql lsp-hack lsp-grammarly
-     lsp-groovy lsp-haskell lsp-haxe lsp-idris lsp-java lsp-javascript lsp-json
-     lsp-kotlin lsp-latex lsp-lisp lsp-ltex lsp-lua lsp-markdown lsp-marksman lsp-mdx
-     lsp-mint lsp-move lsp-nginx lsp-nim lsp-nix lsp-magik lsp-mojo lsp-metals
-     lsp-mssql lsp-nushell lsp-ocaml lsp-openscad lsp-pascal lsp-perl lsp-perlnavigator
-     lsp-pls lsp-php lsp-pwsh lsp-pyls lsp-pylsp lsp-pyright lsp-python-ms
-     lsp-purescript lsp-qml lsp-r lsp-racket lsp-remark lsp-ruff-lsp lsp-rf lsp-rubocop
-     lsp-rust lsp-semgrep lsp-shader lsp-solargraph lsp-sorbet lsp-sourcekit
-     lsp-sonarlint lsp-tailwindcss lsp-tex lsp-terraform lsp-toml lsp-ttcn3
-     lsp-typeprof lsp-v lsp-vala lsp-verilog lsp-vetur lsp-volar lsp-vhdl
-     lsp-vimscript lsp-wgsl lsp-xml lsp-yaml lsp-ruby-lsp lsp-ruby-syntax-tree
-     lsp-solidity lsp-sqls lsp-svelte lsp-steep lsp-tilt lsp-trunk lsp-zig lsp-jq)
+  '( ccls lsp-actionscript lsp-ada lsp-angular lsp-ansible lsp-asm lsp-astro
+     lsp-autotools lsp-awk lsp-bash lsp-beancount lsp-bufls lsp-clangd
+     lsp-clojure lsp-cmake lsp-cobol lsp-credo lsp-crystal lsp-csharp lsp-css
+     lsp-cucumber lsp-cypher lsp-d lsp-dart lsp-dhall lsp-docker lsp-dockerfile
+     lsp-elixir lsp-elm lsp-emmet lsp-erlang lsp-eslint lsp-fortran lsp-fsharp
+     lsp-gdscript lsp-gleam lsp-glsl lsp-go lsp-golangci-lint lsp-grammarly
+     lsp-graphql lsp-groovy lsp-hack lsp-haskell lsp-haxe lsp-idris lsp-java
+     lsp-javascript lsp-jq lsp-json lsp-kotlin lsp-latex lsp-lisp lsp-ltex
+     lsp-lua lsp-magik lsp-markdown lsp-marksman lsp-mdx lsp-metals lsp-mint
+     lsp-mojo lsp-move lsp-mssql lsp-nginx lsp-nim lsp-nix lsp-nushell lsp-ocaml
+     lsp-openscad lsp-pascal lsp-perl lsp-perlnavigator lsp-php lsp-pls
+     lsp-purescript lsp-pwsh lsp-pyls lsp-pylsp lsp-pyright lsp-python-ms
+     lsp-qml lsp-r lsp-racket lsp-remark lsp-rf lsp-rubocop lsp-ruby-lsp
+     lsp-ruby-syntax-tree lsp-ruff-lsp lsp-rust lsp-semgrep lsp-shader
+     lsp-solargraph lsp-solidity lsp-sonarlint lsp-sorbet lsp-sourcekit lsp-sqls
+     lsp-steep lsp-svelte lsp-tailwindcss lsp-terraform lsp-tex lsp-tilt
+     lsp-toml lsp-trunk lsp-ttcn3 lsp-typeprof lsp-v lsp-vala lsp-verilog
+     lsp-vetur lsp-vhdl lsp-vimscript lsp-volar lsp-wgsl lsp-xml lsp-yaml
+     lsp-yang lsp-zig)
   "List of the clients to be automatically required."
   :group 'lsp-mode
   :type '(repeat symbol))
@@ -795,7 +797,8 @@ Changes take effect only when a new session is started."
     ("\\ya?ml$" . "yaml")
     ("^PKGBUILD$" . "shellscript")
     ("^go\\.mod\\'" . "go.mod")
-    ("^settings.json$" . "jsonc")
+    ("^settings\\.json$" . "jsonc")
+    ("^yang\\.settings$" . "jsonc")
     (ada-mode . "ada")
     (ada-ts-mode . "ada")
     (awk-mode . "awk")
@@ -958,7 +961,8 @@ Changes take effect only when a new session is started."
     (jq-ts-mode . "jq")
     (protobuf-mode . "protobuf")
     (nushell-mode . "nushell")
-    (nushell-ts-mode . "nushell"))
+    (nushell-ts-mode . "nushell")
+    (yang-mode . "yang"))
   "Language id configuration.")
 
 (defvar lsp--last-active-workspaces nil
@@ -6036,6 +6040,7 @@ Request codeAction/resolve for more info if server supports."
     (typescript-mode            . typescript-indent-level)          ; Typescript
     (typescript-ts-mode         . typescript-ts-mode-indent-offset) ; Typescript (tree-sitter, Emacs29)
     (yaml-mode                  . yaml-indent-offset)               ; YAML
+    (yang-mode                  . c-basic-offset)                   ; YANG (yang-mode)
 
     (default                    . standard-indent))                 ; default fallback
   "A mapping from `major-mode' to its indent variable.")

mkdocs.yml

@@ -176,6 +176,7 @@ nav:
     - wgsl: page/lsp-wgsl.md
     - XML: page/lsp-xml.md
     - YAML: page/lsp-yaml.md
+    - YANG: page/lsp-yang.md
     - Zig: page/lsp-zig.md
   - Debugging:
       - https://emacs-lsp.github.io/dap-mode